JP3917564B2 - Heat- and oxidation-resistant thermal spray coating member and method for producing the same - Google Patents

Description

【００６１】
クロメート処理は、上記の合金粉末を、30mass％のクロム酸水溶液に15分間浸漬した後引き上げ、余分な水溶液をよく除いた後、380Ｋで30分間乾燥し、さらに、この合金粉末を750Ｋで30分間焼成する処理を一工程とし、この処理工程を３回繰返して行った。加熱実験は、電気炉を用い、大気中で、1423Ｋで９時間加熱した後、この合金粉末を合成樹脂に埋め込み、これをエメリー紙を用いて研磨して粉末の断面を露出させ、この断面を走査型電子顕微鏡(ＳＥＭ)によって観察して合金粉末の耐熱性を調べた。なお、比較例としてクロメート処理をしない無処理のＭCrAlＸ合金粉末も同じ条件で加熱実験に供した。
【００６２】
表２は、上記実験の結果を要約したもので、比較例のＭCrAlＸ合金粉末(No.８〜14)では、粒径の小さい粉末はすべて完全に酸化され、合金の状態を維持していたのは、大粒径のものだけであった。これに対して、クロメート処理を施した本発明の合金粉末(No.１〜７)は、小さな粒径の粉末でも酸化されることなく、現形を維持しており、優れた耐高温酸化性を示すことが確認された。
【００６３】
【表２】

【００６４】
図３は、上記加熱試験前後におけるＭCrAlＸ合金粉末の断面写真の代表例を示したものである。図３(a)は、加熱試験前の合金粉末の断面を走査型電子顕微鏡(ＳＥＭ)で観察したもので、大小すべての粒子の断面に白色部(合金粉末粒子Ｐ１)が確認できる。図３(b)は、クロメート処理をしていないＭCrAlＸ合金粉末を高温酸化試験した後の写真であり、白色部は未酸化の合金粉末粒子Ｐ１、暗色部は完全に酸化された合金粉末粒子Ｐ２を示しており、かなりの粉末が完全に酸化されていることがわかる。一方、図３(c)は、クロメート処理したＭCrAlＸ合金粉末の断面であり、小粒径の粉末でも酸化されずに健全な状態を維持している。以上の結果から、市販のＭCrAlＸ合金粉末は、早期に酸化消耗するが、これにクロメート処理を施こすことで、酸化消耗速度を著しく遅らせることができることがわかる。
【００６５】
（実施例２） 実験室内に、クロメート処理したものと処理しないＭCrAlＸ合金粉末を、１０日間放置して溶射材料とし、これらを大気プラズマ溶射法によって、ＳＵＳ３０４ステンレス鋼板(寸法300mm×300mm×3.2mmｔ)の表面に、目標膜厚50μmの皮膜を形成した後、鋼板を切断して溶射皮膜の厚さ分布を光学顕微鏡を用いて測定した。この試験には、表１に記載したＡ合金、Ｇ合金の合金粉末を用い、またクロメート処理条件は、実施例１と同条件とした。なお、比較例としてクロメート無処理の同じ合金を用いた調査を行った。
【００６６】
表３は、上記観察結果を示したものであり、本発明に従いクロメート処理を施こしたＭCrAlＸ合金粉末は、室内に放置されても水分の吸着がないため、溶射ガンへの流動が平滑で、均等な膜厚が形成されていた。これに対し、比較例の無処理の合金粉末は、水分の吸着が大きく、溶射ガンへの供給が不安定であるため、最高膜厚はクロメート処理品とほぼ同等であったが、最小膜厚が小さく不均一な皮膜であることが確認された。
【００６７】
【表３】

【００６８】
（実施例３） Ni基合金の基材(外径15mmφ×長さ50mmの丸棒)の表面に、クロメート処理を５回繰返したＭCrAlＸ合金粉末(耐熱・耐酸化性複合溶射材料)と無処理のＭCrAlＸ合金粉末(耐熱性溶射材料)を溶射材料とし、減圧プラズマ溶射法によって100μm厚の溶射皮膜を形成した。その後、溶射した試験片を、電気炉中でアルゴンガスを流しつつ、1373Ｋ×８hrの加熱処理を行った。この加熱後の試験片を切断し、光学顕微鏡およびＸ線マイクロアナライザーを用いて、その断面における合金皮膜成分のNi基合金基材中への拡散状況を観察した。なお、この実験に供した合金粉末は、表１記載のＡ，Ｃ，Ｅ，ＦおよびＧの５種類であり、またNi基合金基材の化学成分は、15.3mass％Cr‐７mass％Fe‐2.5mass％Ti‐２mass％Mo‐10mass％Co‐残Niであった。
【００６９】
表４は、上記加熱実験による溶射皮膜成分がNi基合金基材中へ拡散した深さを測定した結果をまとめたものである。この結果から明らかなように、比較例である無処理のＭCrAlＸ合金の溶射皮膜を形成した試験片(No.32，34，36，38，40)の拡散層厚さは88〜95μmに達しており、非常に拡散しやすいことがわかる。これに対して、クロメート処理を施こしたＭCrAlＸ合金粉末を溶射してなる酸化クロム含有耐熱・耐酸化性溶射皮膜を形成した基材(No.31，33，35，37，39)では30〜45μmに止まっており、クロメート処理により被成したCr₂Ｏ₃膜の存在によって、皮膜成分の拡散を防ぎ、基材の機械的性質の低下を抑制できることがうかがえる。
【００７０】
【表４】

【００７１】
（実施例４） 実施例３で基材として使用したNi基合金の試験片（寸法50mm×50mm×5mmｔ）の全面に、大気プラズマ溶射法と高速フレーム溶射法を用いて、表１に記載のＣ、Ｄ合金粉末を原料として300μm厚の溶射皮膜を形成した。なお上記合金粉末には、溶射に先立って、クロメート処理を３回繰り返したものを用いた。また、比較例として、無処理のＭCrAlＸ合金の他、耐高温酸化用の溶射用粉末材料として広く使用されている50mass％Ni‐50mass％Cr，80mass％Ni‐20mass％Crを用い、上記と同条件で溶射皮膜を形成した。成膜後の試験片は、電気炉中において、大気中で1473Ｋ×500時間の加熱酸化試験を行い、試験前後の試験片の重量変化(減少)から、皮膜の耐熱性・耐高温酸化性を評価した。なお、上記重量の減少は、加熱による酸化によって皮膜の表面に生成した酸化膜が試験中に脱落することによって発生するもので、酸化膜が緻密で良好な耐酸化性を示すものほど脱落量が少なく、重量減少が少ない。
【００７２】
表５は、上記の実験結果をまとめたものである。この結果から、無処理のＭCrAlＸ合金粉末を溶射してなる皮膜(No.43，44，47，48)の重量変化は180〜280mgの重量減少であるのに対し、クロメート処理したＭCrAlＸ合金粉末を溶射してなる皮膜(No.41，42，45，46)の重量変化は75〜95mgの重量減少にとどまっており、クロメート処理した合金粉末を溶射材料として溶射した酸化クロム含有耐熱・耐酸化性溶射皮膜は、耐高温酸化性に優れていることが確認された。また、他の比較例の皮膜(No.49〜52)の重量変化は、2010〜2250mgの大きな重量減少を示し、試験を行った皮膜中で最も耐高温酸化性能に劣っていた。
【００７３】
【表５】

【００７４】
（実施例５） クロメート処理したＭCrAlＸ合金を溶射してなる酸化クロム含有耐熱・耐酸化性溶射皮膜をアンダーコートとし、そのアンダーコートの上にZrＯ₂系酸化物セラミックスのトップコートを積層させた熱遮蔽皮膜の耐高温酸化特性と熱衝撃特性について調査した。アンダーコートは、溶射材料として、表１記載のＡ合金にクロメート処理を３回施したＭCrAlＸ合金を用い、8.11mass％Co‐15.8mass％Cr‐3.45mass％Al‐3.60mass％Ti‐1.78mass％Mo‐2.46mass％Ｗ‐1.92mass％Ta‐残りNiの成分組成を有するNi基合金の試験片(寸法：50mm×500mm×3.2mmｔ)の片面に減圧プラズマ溶射法により、150μm厚の皮膜を形成した。さらに、上記アンダーコートの上に、大気プラズマ溶射法によって、８mass％Ｙ₂Ｏ₃−ZrＯ₂セラミックスのトップコートを300μm厚に積層させた。また、比較例として、アンダーコートの溶射材料に、無処理のＭCrAlＸ合金を用い、他は上記と同じ条件としたものを作製した。
【００７５】
耐高温酸化特性と熱衝撃特性の試験は、大気雰囲気の電気炉中で1423Ｋ×200時間の加熱を行った後、試験片を切断して、その断面(主としてアンダーコートとトップコートの界面近傍)を走査型電子顕微鏡により観察し、アンダーコート表面におけるＭCrAlＸ合金元素の酸化挙動を調べた。また、熱衝撃試験は、1423Ｋ×200時間加熱後の試験片を一旦室温(290Ｋ)まで放冷した後、1270Ｋ×15分間の加熱とその後室温まで放冷する加熱冷却処理を１０回繰返し、トップコートの剥離状況を目視察することによって行った。
【００７６】
表６は、上記の試験結果を示したものである。この結果から、比較例である無処理のＭCrAlＸ合金を溶射してなる溶射皮膜をアンダーコートとしたもの(No.62)では、長時間の加熱によって、合金成分のCo，Cr，Ni，Alなどの金属元素の酸化物が皮膜表面に生成して厚い複合酸化物層を形成しており、しかもこの層は緻密性にも欠ける傾向が認められた。これに対し、発明例であるクロメート処理したＭCrAlＸ合金を溶射してなるアンダーコート層の表面(No.61)では、Al₂Ｏ₃を主成分とする緻密で薄くかつ保護性にも優れている酸化物層が生成しており、耐高温酸化特性が優れていることがわかった。一方、熱衝撃試験の結果は、比較例の皮膜では、トップコートに多数の亀裂が発生し、全面積の約10％に当る皮膜が脱落した。これに対して、発明例であるクロメート処理したＭCrAlＸ合金粉末を用いた試験片では、トップコートに亀裂の発生は無く、また皮膜の脱落も認められず、健全な状態を維持していた。
【００７７】
【表６】

【００７８】
（実施例６） 実施例４で用いたものと同じ基材試験片の全面に、３回のクロメート処理を施こしたＭCrAlＸ合金粉末を溶射してなる酸化クロム含有耐熱・耐酸化性溶射皮膜をアンダーコートとして形成し、そのアンダーコートの上に、３回のクロメート処理を施こしたＭCrAlＸ合金とZrＯ₂系酸化物セラミックスとの混合粉末を溶射材料とし、その両成分の配合を表７に示したように、基材側ほどＭCrAlＸ合金粉末の量を多く、表面側ほどZrＯ₂系酸化物セラミックス粉末の量を多くなるよう傾斜配分した溶射材料を溶射して中間層を設け、さらにその中間層の上に、ZrＯ₂系酸化物セラミックス(８mass％Ｙ₂Ｏ₃‐残部ZrＯ₂)溶射皮膜をトップコートとして積層した構造の熱遮蔽溶射皮膜を形成した後、この試験片に対して、1473Ｋ×500hの高温酸化試験を行い、耐酸化性を評価した。試験に用いたＭCrAlＸ合金粉末には、表１記載のＡ合金を用い、溶射法は、アンダーコートには高速フレーム溶射法、中間層およびトップコートには大気プラズマ溶射法を用いた。また、比較のため、無処理のＡ合金も用いて同様の溶射皮膜を形成し、耐高温酸化性を調査した。なお、アンダーコート、中間層、トップコートの各溶射膜の膜厚は表７の通りであった。
【００７９】
【表７】

【００８０】
高温酸化試験後、各試験片を切断し、皮膜の断面を観察した。結果を表８に示したが、無処理のＡ合金を用いた比較例の皮膜では、グラインダ砥石で切断する際、既に局部的にトップコートの剥離が認められるとともに、光学顕微鏡による観察の結果では、中間層のＡ合金粒子の大部分が完全に粒子の中心部まで酸化されていた。このため中間層を構成するZrＯ₂系粒子の一部も脱落していた。これに対して、クロメート処理したＡ合金を用いた本発明の中間層では、その殆どのＭCrAlＸ合金粉末が酸化されることなく健全な状態で残存しており、またZrＯ₂粒子の脱落も認められなかった。なお、クロメート処理したＡ合金粒子を走査電子顕微鏡で詳細に調査すると、合金粒子の外周部にはAl₂Ｏ₃層が形成されており、このAl₂Ｏ₃層が、耐高温酸化特性の維持に効果を発揮していることが判明した。
【００８１】
【表８】

【００８２】
【発明の効果】
以上説明したように、本発明によれば、耐高温・耐酸化性の溶射皮膜の形成材料として、ＭCrAlＸ合金粉末の表面に化学的処理によってCr₂Ｏ₃膜を形成してなる耐熱・耐酸化性複合溶射材料を用いることにより、吸湿に伴う変質や流動性の低下を防止することができ、また溶射ガンへの供給が円滑となり、安定した品質の皮膜を確保することができる。また、化学的処理により合金粉末の表面に被覆されたCr₂Ｏ₃膜は、溶射熱源によって合金粉末とともに溶融・軟化して溶射皮膜の一部を構成し、酸化物セラミックス成分としての機能を発揮し、高温度下において、基材へのＭCrAlＸ合金成分の過度な熱拡散を抑制する一方、皮膜表面では、優れた保護性を有するAl₂Ｏ₃の生成を促して、耐高温酸化特性を向上すると共に、トップコートとして形成する酸化物セラミックスの結合性の向上にも効果を発揮する。以上の作用効果によって、ガスタービン等の高温被曝用部材に対する溶射加工作業、皮膜品質、皮膜性質などを、溶射粉末材料の段階において改善することが可能となる。
【図面の簡単な説明】
【図１】 本発明の耐熱・耐酸化性に優れた溶射皮膜の断面構造を模式的に示した図である。
【図２】 本発明の耐熱・耐酸化性に優れた溶射皮膜の断面構造を模式的に示した図である。
【図３】 高温酸化試験前後のＭCrAlＸ合金粉末の断面を走査型電子顕微鏡で観察した写真であり、(a)は、高温酸化試験前の無処理のＭCrAlＸ合金粒子、(b)は、高温酸化試験後の無処理のＭCrAlＸ合金粒子、(c)は、高温酸化試験後のクロメート処理したＭCrAlＸ合金粒子のものである。
【符号の説明】
１ 金属製基材
２ クロメート処理したＭCrAlＸ合金粉末(耐熱・耐酸化性複合溶射材料)を溶射した酸化クロム含有耐熱・耐酸化性溶射皮膜
３ 酸化アルミニウムを主成分とする保護性酸化膜
４ ZrＯ₂系酸化物セラミックス溶射皮膜
５ 無処理のＭCrAlＸ合金からなる耐熱性溶射皮膜
６ 耐熱・耐酸化性複合溶射材料とZrＯ₂系酸化物セラミックスとの混合粉末を溶射した混合溶射皮膜
７ 耐熱・耐酸化性複合溶射材料とZrＯ₂系酸化物セラミックスとの混合量が傾斜配分された混合溶射皮膜
Ｐ１ 合金粒子または未酸化合金粒子
Ｐ２ 高温酸化された合金粒子[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat-resistant / oxidation-resistant thermal spray coating member coated with a chromium oxide-containing heat-resistant / oxidative thermal spray coating and a method for producing the same.
[0002]
[Prior art]
In recent years, research aimed at increasing the working gas temperature has been actively conducted to improve the thermal efficiency of gas turbines. As a result, the temperature is currently increasing until the turbine inlet temperature exceeds 1500 ° C.
[0003]
Such a high working gas temperature is largely due to the development of materials for turbine blade members that are directly exposed to high-temperature combustion gas and the progress of blade cooling technology, and is still an important research subject. In particular, turbine blades are subject to creep deformation due to centrifugal force during operation, thermal fatigue associated with starting and stopping, high cycle fatigue due to mechanical vibration, and sea salt particles, sulfur and vanadium contained in combustion gas and combustion air. Development of materials for turbine blade members is important because of the corrosive action caused by impurities such as
[0004]
On the other hand, the turbine vane is disposed in front of the turbine rotor blade and functions as a guide valve for combustion gas. For this reason, turbine stationary blades are in an environment where they are exposed to higher temperatures than rotor blades, and in the same way as rotor blades, they are susceptible to high temperature oxidation and high temperature corrosion, as well as high thermal stress and thermal shock. is there. For this reason, Ni-base alloys and Co-base alloys with excellent high-temperature strength characteristics are used for these turbine blades and vanes. Occupies an important position.
[0005]
However, since these Ni-base alloys and Co-base alloys are developed with emphasis on strength at high temperatures, they are effective in improving high-temperature oxidation resistance properties such as Al, Cr, and Si that have a small contribution to strength improvement. Therefore, there is a problem that oxidation resistance, particularly high temperature oxidation resistance is not sufficient as a constituent material of a gas turbine whose current use temperature is increased. Therefore, methods for improving high-temperature oxidation resistance by forming a film with excellent high-temperature oxidation resistance on the surface of turbine blades and vanes have been studied in the past. Techniques related to coating materials (film materials) have been proposed.
[0006]
For example, Patent Literature 1 and Patent Literature 2 disclose a technique for improving the high-temperature oxidation resistance by forming a high Cr concentration layer on the surface of a turbine rotor and vane using a Cr diffusion penetration method. However, these technologies are effective when the operating temperature of the gas turbine is low, but when used in an operating environment of 1500 ° C or higher as in the present, the Cr layer formed on the blade surface is vaporized. High pressure CrO_ThreeIt is volatilized and excellent high temperature oxidation resistance cannot be expected.
[0007]
As a solution to this problem, a coating with excellent high-temperature oxidation resistance called MCrAlX alloy is applied to high-temperature parts such as gas turbine moving and stationary blades and combustor inner cylinders (including tail cylinders) by electron beam evaporation or thermal spraying. Coating techniques have been developed. Here, M in the MCrAlX alloy is Ni, Co or Fe, or an alloy composed of a plurality of these elements, and X is an element such as Y, Hf, Se, Ce, La, Th, Pt, B and Si. Indicates. This technology is widely used for jet engine members and the like as well as current high-temperature gas turbines.
[0008]
Many MCrAlX alloys with various chemical compositions have been proposed according to the purpose of use (see, for example, Patent Documents 3 to 7). The chemical composition of these MCrAlX alloys is generally in the following range.
(M component) Ni: 0 to 75 mass%, Co: 0 to 75 mass%, Fe: 0 to 30 mass%, Cr: 5 to 70 mass%, Al: 1 to 29 mass%
(X component) Y: 0-5 mass%, Hf: 0-10 mass%, Ta: 1-20 mass%, Si: 0.1-14 mass%, B: 0-0.1 mass%, C: 0-0.25 mass% , Mn: 0-10 mass%, Zr: 0-3 mass%, W: 0-0.5 mass%, Pt: 0-20 mass%
[0009]
On the other hand, in addition to the technology for forming a heat-resistant sprayed coating by thermal spraying, using a chemical mainly composed of an aqueous chromic acid solution, the surface of the steel substrate is directly coated with fine Cr.₂O_ThreePatent Documents 8 to 11 disclose techniques for forming an aggregate film. Furthermore, a technique for applying this technique to a film obtained by various methods and improving it has been developed. For example, in Patent Documents 12 to 16, chromate treatment using a chemical agent (chromic anhydride aqueous solution) containing chromic acid as a main component on a thermally sprayed ceramic layer, a metal coating layer, and a hard plating film formed by electroplating. Has been proposed to fill and seal defects such as pores and cracks present in the film, and to prevent harmful effects caused by these defects.
[0010]
[Patent Document 1]
Japanese Patent No. 600213
[Patent Document 2]
Japanese Patent No. 828784
[Patent Document 3]
JP 59-001654 A
[Patent Document 4]
JP 59-006352 A
[Patent Document 5]
JP 59-089745 A
[Patent Document 6]
JP 59-118847 A
[Patent Document 7]
JP-A-60-141842
[Patent Document 8]
JP 59-009171 A
[Patent Document 9]
JP 61-052374 A
[Patent Document 10]
JP 63-126682 A
[Patent Document 11]
Japanese Unexamined Patent Publication No. Sho 63-317680
[Patent Document 12]
JP 59-205480
[Patent Document 13]
JP-A-61-194187
[Patent Document 14]
JP-A 63-000487
[Patent Document 15]
Japanese Utility Model Publication No. 03-063565.
[Patent Document 16]
Japanese Patent Laid-Open No. 10-018052
[0011]
[Problems to be solved by the invention]
By the way, the above-mentioned MCrAlX alloy is made into a powder state, and is coated on the surface of the substrate by an atmospheric plasma spraying method, a low pressure plasma spraying method, a high-speed flame spraying method, an explosion spraying method, or the like. However, the use of commercially available MCrAlX alloy powder for thermal spraying has the following problems.
[0012]
(1) The commercially available MCrAlX alloy powder is easy to absorb moisture. The moisture-absorbed alloy powder has poor fluidity, and the supply to the spray gun becomes inaccurate and unstable, so that the sprayed coating cannot be formed with a uniform thickness.
(2) In MCrAlX alloy powder, when the moisture absorption state lasts for a long time, Co, Cr, Al, Ni, etc. contained as alloy components change into hydroxides and oxides, and the characteristics as an alloy disappear.
(3) In order to prevent the harmful effects caused by the hygroscopicity of the MCrAlX alloy, it is necessary to enhance the dry storage equipment and introduce a storage management method, which leads to an increase in production cost.
(4) Further, the commercially available MCrAlX alloy powder has a particle size distribution in a wide range of 1 to 150 μm. When the alloy powder in this state is sprayed, the powder having a large particle size is sprayed without being completely melted by the spraying heat source, and is dispersed as unmelted particles in the coating. For this reason, the mutual bonding force between the alloy particles constituting the film is reduced, and the adhesion force with the metal substrate is reduced.
(5) On the other hand, fine MCrAlX alloy powder is melted in a short time by a thermal spraying heat source and oxidized, and as a result, all oxides are formed in the heat source. This oxide becomes a black fine powder and is dispersed in the thermal spray coating, weakening the mutual bonding force between the alloy particles constituting the coating and reducing the adhesion to the metal substrate.
(6) In addition, the black fine oxide with oxidized alloy particles adheres thinly to the sprayed coating surface in the absence of adhesion, such as wrinkles. Undercoat and then top coat (eg ZrO)₂When laminating a ceramic-based ceramic film), the adhesion between the two layers is reduced to promote the peeling of the top coat.
(7) Further, the black fine oxide generated during the thermal spraying of the alloy powder becomes so-called fume and contaminates the thermal spraying work environment, which is not preferable for safety and health.
[0013]
The object of the present invention is to solve the above-mentioned problems of commercially available MCrAlX alloy powders for thermal spraying, that is, increase in hygroscopicity due to the powder, decrease in powder flowability and thermal spraying efficiency associated therewith, and powder By using a heat- and oxidation-resistant composite sprayed material that has no problems such as alteration due to moisture absorption by moisture, it is possible to obtain a thermal spray coating coated member having excellent heat resistance and high-temperature oxidation resistance, and the advantage of such a member It is to propose a manufacturing method.
[0014]
[Means for Solving the Problems]
The inventors of the above-mentioned conventional thermal spraying technique using the MCrAlX alloy mainly arises from the emphasis placed on the adjustment of the component composition of the MCrAlX alloy component itself and the devices such as the thermal spraying method. Rather, in order to solve the above-mentioned problems, intensive research was conducted from the viewpoint that development should focus on the properties of the alloy powder that is the thermal spray material. As a result, a chromium oxide film is formed in advance on the surface of the heat-resistant alloy powder that will be the thermal spray material by chemical treatment, and the powder subjected to such treatment is used as the thermal spray material to solve the above problems. The present invention has been completed by finding out what can be done.
[0015]
  Examples of the present invention developed based on the above findings include the following gist configuration.
(1) In a member formed by coating a metal substrate with a thermal spray coating, the substrate is placed on the surface of the heat-resistant alloy powder.Produced by chromate treatment in which an aqueous solution containing chromic acid and / or chromate is deposited and then heat treatedOxidized blackCovering the filmA heat- and oxidation-resistant thermal spray coating member, which is coated with a chromium oxide-containing heat and oxidation-resistant thermal spray coating obtained by spraying a heat- and oxidation-resistant composite thermal spray material.
[0016]
(2) The above chromium oxide-containing heat- and oxidation-resistant thermal spray coating is MCrAlX (where M is one or more selected from Co, Ni and Fe, X is Y, Hf, Ta, Cs, Ce) , La, Th, W, Si, Pt, Mn, and B selected from one or more types, and the surface of the heat-resistant alloy powder having an average particle size of 5 to 100 μm is oxidized to a thickness of 0.1 to 10 μm Cr is formed by spraying and depositing a heat- and oxidation-resistant composite sprayed material made of a chromium film on the substrate surface in a molten or semi-molten state.₂O_ThreeThe heat- and oxidation-resistant sprayed coating member according to (1), which is composed of a layer in which ceramics and a MCrAlX alloy are mixed.
[0017]
(3) The protective oxide film mainly composed of aluminum oxide is formed on the surface of the chromium oxide-containing heat-resistant / oxidation-resistant sprayed coating as described in (1) or (2) Heat- and oxidation-resistant thermal spray coating coating material.
[0018]
(4) The chromium oxide-containing heat- and oxidation-resistant sprayed coating is an undercoat, and an oxide ceramic sprayed coating is formed as a top coat on the undercoat (1) or (2 The heat- and oxidation-resistant spray-coated member described in (1).
[0019]
(5) The chromium oxide-containing heat- and oxidation-resistant sprayed coating according to claim 1 or 2 is formed as an undercoat on the surface of the heat-resistant alloy substrate, and MCrAlX (however, an intermediate layer is formed on the undercoat. , M is one or more selected from Co, Ni and Fe, X is selected from Y, Hf, Ta, Cs, Ce, La, Th, W, Si, Pt, Mn and B Heat-resistant and oxidation-resistant composite sprayed material with a chromium oxide film on the surface of a heat-resistant alloy powder represented by 1 type or 2 types) and ZrO₂An intermediate layer sprayed coating is formed by spraying a mixed powder with an oxide ceramic, and ZrO is applied as a top coat on the intermediate sprayed coating.₂A heat-resistant and oxidation-resistant sprayed coating member characterized in that a system oxide ceramic sprayed coating is formed.
[0020]
(6) The intermediate layer sprayed coating is closer to the topcoat side.₂The heat- and oxidation-resistant thermal spray coating member according to (5), comprising a gradient blended layer with an increased content of a system oxide ceramic.
[0021]
(7) A heat-resistant alloy such as MCrAlX (where M is one or more selected from Co, Ni and Fe, X is Y, Hf, Ta, A heat-resistant thermal spray coating of a heat-resistant alloy represented by Cs, Ce, La, Th, W, Si, Pt, Mn and B) is formed on the undercoat A heat- and oxidation-resistant thermal spray coating member characterized in that the chromium oxide-containing heat and oxidation-resistant thermal spray coating according to (1) or (2) is formed as a top coat.
[0022]
(8) A heat-resistant alloy such as MCrAlX (where M is one or more selected from Co, Ni and Fe, and X is Y, Hf, Ta, etc.) , Cs, Ce, La, Th, W, Si, Pt, Mn, and B) are formed on the undercoat. As an intermediate layer, the chromium oxide-containing heat-resistant / oxidation-resistant thermal spray coating described in (1) or (2) is formed, and further, a ZrO as a top coat is formed on the intermediate layer.₂A heat-resistant and oxidation-resistant sprayed coating member characterized in that a system oxide ceramic sprayed coating is formed.
[0023]
(9) On the surface of metal base material, on the surface of heat-resistant alloy powderProduced by chromate treatment in which an aqueous solution containing chromic acid and / or chromate is deposited and then heat treatedOxidized blackCovering the filmA method for producing a heat-resistant / oxidation-resistant thermal spray coating member, comprising forming a chromium oxide-containing heat-resistant / oxidation-resistant thermal spray coating by spraying a heat-resistant / oxidation-resistant composite thermal spray material.
[0024]
(10) The heat and oxidation resistant thermal spray material is MCrAlX (where M is one or more selected from Co, Ni and Fe, X is Y, Hf, Ta, Cs, Ce, La, The surface of the heat-resistant alloy powder having an average particle size of 5 to 100 μm represented by Th, W, Si, Pt, Mn and B) is a chromium oxide film having a thickness of 0.1 to 10 μm. The method for producing a heat- and oxidation-resistant spray-coated member according to (9), wherein the heat- and oxidation-resistant spray-coated member is coated.
[0025]
(11) After forming a chromium oxide-containing heat-resistant / oxidation-resistant sprayed coating on the surface of the metal substrate, the surface of the sprayed coating is mainly composed of aluminum oxide by heating at 970-1500 K for 1-30 hours. The method for producing a heat-resistant / oxidation-resistant sprayed coating member according to (9) or (10), wherein a protective oxide film is produced.
[0026]
(12) After forming the chromium oxide-containing heat-resistant / oxidation-resistant sprayed coating, the oxide ceramic sprayed coating is formed on the oxide ceramic sprayed coating thereon (9) or (10) The manufacturing method of the heat-resistant / oxidation-resistant thermal spray coating coating member as described in 2.
[0027]
(13) On the surface of the heat-resistant alloy base material, as an undercoat, the chromium oxide-containing heat-resistant and oxidation-resistant sprayed coating described in (9) or (10) is formed, and an intermediate layer is formed on the undercoat. MCrAlX (where M is one or more selected from Co, Ni and Fe, X is Y, Hf, Ta, Cs, Ce, La, Th, W, Si, Pt, Mn and B) A heat-resistant and oxidation-resistant composite sprayed material having a chromium oxide film on the surface of a heat-resistant alloy powder represented by one or more selected from ZrO₂An intermediate layer sprayed coating is formed by spraying a mixed powder with an oxide ceramic, and ZrO is applied as a top coat on the intermediate sprayed coating.₂ZrO by thermal spraying of oxide ceramics₂A method for producing a heat- and oxidation-resistant thermal spray coating member characterized by forming an oxide-based ceramic thermal spray coating.
[0028]
(14) The intermediate layer sprayed coating is ZrO closer to the top coat side.₂A heat-resistant / oxidation-resistant sprayed coating member according to (13), characterized in that it is a gradient blended layer with an increased content of a system oxide ceramicManufacturing method.
[0029]
(15) On the surface of the heat-resistant alloy base material, as an undercoat, a heat-resistant alloy such as MCrAlX (where M is one or more selected from Co, Ni and Fe, X is Y, Hf, Ta, Cs, Ce, La, Th, W, Si, Pt, Mn and B selected from one or more heat-resistant alloy powders are sprayed to form a heat-resistant sprayed coating, On the undercoat, a heat- and oxidation-resistant composite sprayed material described in (9) or (10) is sprayed to form a chromium oxide-containing heat- and oxidation-resistant sprayed coating. Method for producing a thermally sprayable coating member.
[0030]
(16) On top of the above chromium oxide-containing heat- and oxidation-resistant thermal spray coating, ZrO₂ZrO by thermal spraying of oxide ceramics₂A method for producing a heat- and oxidation-resistant spray-coated member according to (15), characterized in that a system oxide ceramic spray-coated film is formed.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, as the heat-resistant alloy used as the raw material of the thermal spray material, preferably the MCrAlX alloy, known ones as described above (paragraph 0008) can be used. In general, in order to prepare metals and alloys to be prepared as raw materials for thermal spray materials, after melting them in an inert gas atmosphere, the molten metal is ejected from the tip of the nozzle and at the same time inert to the molten metal. A method of pulverizing and atomizing by jetting a strong jet of gas and collecting it (referred to as gas atomizing method, spraying method, etc.) is adopted, and MCrAlX alloy powder is also used in the same way It is manufactured. Thereafter, the powder may be subjected to a heat treatment of 900 to 1500 K × 1 to 30 hours in a vacuum or in an inert gas atmosphere.
[0032]
The MCrAlX alloy powder thus obtained has a spherical shape. And since this powder is manufactured and heat-processed in inert gas atmosphere, the amount of oxides is comparatively small, According to inventors' investigation, oxygen content is about 0.03-0.05 mass%. However, the particle size of the obtained powder is mixed from a large one of about 150 μm to a small one of about 1 μm. For this reason, the spraying material is usually used after being classified using a sieve and subjected to a treatment such that the average particle size is about 5 to 100 μm. However, in actual commercial products, fine particles of about 1 μm or less are also mixed, and these can also be used in the present invention.
[0033]
One of the characteristic structures in the present invention is that a chemical treatment is applied to the MCrAlX alloy powder having the particle size distribution as described above to form a thin chromium oxide film on the surface of the powder particles in advance. The product is formed and coated, that is, a heat- and oxidation-resistant composite sprayed material is used. In the chemical treatment, first, MCrAlX alloy powder is treated with chromic anhydride (CrO_Three), Ammonium chromate (NH_Four)₂CrO_FourAnd ammonium dichromate (NH_Four)₂Cr₂O₇After immersing in an aqueous solution containing chromic acid and / or chromate selected from the following (hereinafter abbreviated as “aqueous solution of chromic acid”) for several minutes, this is pulled up, dried at room temperature to 400 K, and further electric Heat treatment is performed in a furnace at 500 to 800 K × 0.5 to 5 hours. By this heat treatment, the MCrAlX alloy powder causes the aqueous solution of chromic acid or the like adhering to the surface thereof to undergo a chemical reaction as shown in the following formula, thereby causing₂O_ThreeIt will be covered with a thin film.
[0034]
・ CrO_Three→ 1 / 2Cr₂O_Three+ 3 / 4O₂
・ (NH_Four)₂CrO_Four→ 1 / 2Cr₂O_Three+ 2NH_Three+ H₂O + 3 / 4O₂
・ (NH_Four)₂Cr₂O₇→ Cr₂O_Three+ 2NH_Three+ H₂O + 3 / 2O₂
[0035]
In the present invention, Cr to MCrAlX alloy powder₂O_ThreeThe above-described chemical generation treatment of the film will be referred to as “chromate treatment” for convenience. In addition, Cr produced from the above aqueous solution such as chromic acid₂O_ThreeSince the film is an aggregate of ultrafine particles of about 0.01 μm or less, the surface of the MCrAlX alloy particles can be densely coated. In addition, Cr produced by one chromate treatment₂O_ThreeThe film thickness varies depending on the concentration of the aqueous solution such as chromic acid, but it is 30 mass% CrO._ThreeTaking an aqueous solution as an example, it is about 0.05 to 0.10 μm in one step. Cr produced by this chromate treatment₂O_ThreeSince the membrane is insoluble in water, it does not elute even when immersed again in an aqueous solution such as chromic acid. Therefore, by repeating this chromate treatment, Cr₂O_ThreeA film can be formed thick.
[0036]
After immersion in an aqueous solution of chromic acid, etc., the MCrAlX alloy powder pulled up may have an aqueous solution containing excess chromic acid or chromate. In such a case, a centrifuge is used. As a result, excess aqueous solution can be removed. Furthermore, in the present invention, instead of dipping in an aqueous solution of chromic acid or the like, a method of spraying an aqueous solution of chromic acid or the like on the MCrAlX alloy powder can also be applied to the surface of the powder.₂O_ThreeIt is possible to form this film.
[0037]
In the present invention, Cr covering the surface of the MCrAlX alloy powder₂O_ThreeThe preferred thickness of the membrane is in the range of 0.1-10 μm. If the thickness is less than 0.1 μm, the sufficient high-temperature oxidation resistance intended by the present invention cannot be obtained. On the other hand, if the thickness is greater than 10 μm, the individual effects cannot be obtained and the production cost increases. It is not preferable because it is only necessary.
[0038]
By the way, by using MCrAlX alloy powder with a particle size of 50μm, chromate treatment, 0.1μm thick Cr is formed on the surface₂O_ThreeWhen the film is coated, Cr contained in the alloy powder₂O_ThreeThe amount is about 1.2 vol%. This Cr₂O_ThreeThe oxygen content converted from the amount is about 0.26 mass%, which is less than about 2% of the oxygen content in the coating obtained by plasma spraying the untreated MCrAlX alloy powder in the atmosphere. In addition, MCrAlX alloy particles of the same particle size are added to 10 μm thick Cr.₂O_ThreeIf the film is coated, Cr₂O_ThreeTherefore, the alloy powder after the chromate treatment can be said to be an oxide-based cermet powder. Furthermore, the particle size of the MCrAlX alloy powder is 5 μm, and 10 μm thick Cr is formed on this surface.₂O_ThreeWhen the film is coated, most of the powder is Cr₂O_ThreeTherefore, the content of MCrAlX alloy is only 0.8 vol%. In this case, it may be appropriate to call the oxide ceramic powder.
[0039]
As described above, the composition of the MCrAlX alloy powder subjected to the chromate treatment used as the thermal spray material in the present invention is composed of the particle diameter of the MCrAlX alloy powder as a raw material and the Cr to be formed.₂O_ThreeDepending on the thickness of the film, alloy components and oxides (Cr₂O_ThreeHowever, any alloy powder can be suitably used for the purpose of the present invention. Therefore, depending on the application of the thermal spray coating, Cr in the thermal spray coating₂O_ThreeIf you want to adjust the amount, Cr covering the surface₂O_ThreeWhat is necessary is just to select a film thickness suitably.
[0040]
The chemical components of the MCrAlX alloy powder that can be suitably applied with the chromate treatment of the present invention are as follows.
(M component) Ni: 0 to 75 mass%, Co: 0 to 75 mass%, Fe: 0 to 30 mass%, Cr: 5 to 70 mass%, Al: 1 to 29 mass%
(X component) Y: 0-5 mass%, Hf: 0-10 mass%, Ta: 1-20 mass%, Si: 0.1-14 mass%, B: 0-0.1 mass%, C: 0-0.25 mass% , Mn: 0-10 mass%, Zr: 0-3 mass%, W: 0-0.5 mass%, Pt: 0-20 mass%
[0041]
On the surface of chromated MCrAlX alloy powder, Cr is in a dense state.₂O_ThreeSince the film is coated, the alloy powder does not come into direct contact with the outside air. Moreover, Cr₂O_ThreeThe film starts from the state of an aqueous solution, but since it has undergone a heating and baking process, it does not adsorb moisture (humidity) in the atmosphere and is in a very physicochemically stable state. That is, commercially available untreated MCrAlX alloy powders are composed of metals such as Co, Ni, Cr, Al, and Y that are easily oxidized. Since the components are oxidized and deteriorated and the fluidity of the alloy powder is deteriorated, it is necessary to always store it in a dry state. However, the chromate-treated alloy powder is not necessary. In addition, since the chromate-treated alloy powder has good fluidity, even when supplied to the spray gun, it is possible to always maintain a constant condition over a long period of time, so that it is possible to form a spray coating with an even thickness. .
[0042]
Methods for forming a thermal spray coating by spraying a heat- and oxidation-resistant composite thermal spray material made of chromated MCrAlX alloy powder include low-pressure plasma spraying, atmospheric plasma spraying, high-speed flame spraying, and explosion spraying. Since any coating method can be used to obtain a good coating, the spraying method is not particularly limited. In addition, the heat- and oxidation-resistant composite sprayed material made of chromated MCrAlX alloy powder is sprayed on the surface of a metal base material, in particular, a heat-resistant alloy base material, and contains a chromium oxide-containing heat-resistant and oxidation-resistant sprayed coating. In addition, it is formed by laminating a heat-resistant sprayed coating formed by spraying an untreated MCrAlX alloy powder or an oxide-based ceramic sprayed coating formed by spraying an oxide-based ceramic powder. A multilayer sprayed coating may be used.
In addition, chromium oxide-containing heat- and oxidation-resistant thermal spray coatings formed by spraying chromated MCrAlX alloys, untreated MCrAlX alloy powders and other ZrO₂Alternatively, a composite film may be formed by laminating a film obtained by thermal spraying a mixed powder of a system oxide ceramic.
[0043]
Next, the thermal spray coating according to the present invention obtained by thermal spraying the MCrAlX alloy powder subjected to the chromate treatment will be specifically described based on the cross-sectional structure of FIG. FIG. 1 (a) shows a thermal spray coating formed by spraying a chromated MCrAlX alloy powder on the surface of a metal substrate, for example, a heat-resistant alloy substrate 1, to form a chromium oxide-containing heat- and oxidation-resistant spray coating 2. It is sectional drawing which shows an example of a coating | coated member. In the thermal spray coating having such a structure, the following effects can be expected.
[0044]
The heat-resistant / oxidation-resistant composite thermal spray material made of chromated MCrAlX alloy powder is in a molten state and collides with and adheres to the surface of the base material while flying in the thermal spray heat source. At this time, the spherical particles are flattened and Cr is coated on the surface of the composite sprayed material powder.₂O_ThreeThe film is destroyed and the internal MCrAlX alloy is exposed. As a result, Cr₂O_ThreeA chromium oxide-containing heat- and oxidation-resistant sprayed coating in which ceramics and MCrAlX alloy are mixed is formed. At this time, Cr coating the surface of the MCrAlX alloy powder₂O_ThreeThe thicker the film, the greater the Cr in the chromium oxide-containing heat-resistant / oxidative-resistant sprayed coating and on its surface.₂O_ThreeThe ratio of increases. Cr present in this sprayed coating and on its surface₂O_ThreeIs chemically stable, and therefore exhibits particularly excellent heat resistance / high temperature oxidation resistance and corrosion resistance when a member coated with such a thermal spray coating is used in the combustion gas of fossil fuel.
[0045]
Furthermore, Cr contained in the chromium oxide-containing heat-resistant / oxidation-resistant thermal spray coating₂O_ThreeWhen exposed to high temperatures, this Cr₂O_ThreeIt reacts with Al in the MCrAlX alloy powder that is in contact with the metal, and as shown in the following formula, Cr acts as a driving force on the difference in free energy of metal oxide formation.₂O_ThreeAl with excellent protection (oxidation resistance) at the interface (MCrAlX alloy powder particle surface) between MCrAlX alloy powder particles and MCrAlX alloy powder particles₂O_ThreeProactively produce a film. Furthermore, the Cr produced here is oxidized again by the combustion gas, and Cr₂O_ThreeIt becomes. By such a reaction, the high temperature environment resistance of the MCrAlX alloy powder itself is also improved.
[0046]
・ Cr₂O_Three + 2Al → Al₂O_Three + 2Cr
[0047]
In the present invention, paying attention to the above phenomenon, a member obtained by spraying a heat-resistant / oxidizing-resistant composite material made of chromated MCrAlX alloy powder on the surface of the heat-resistant alloy base material is heated at 970-1500 K for 1-30 hours. Accordingly, as shown in FIG. 1B, a protective oxide film 3 mainly composed of aluminum oxide may be positively formed on the surface of the sprayed coating.
[0048]
On the other hand, the chromium oxide-containing heat-resistant / oxidation-resistant thermal spray coating according to the present invention is also effective at the interface with the heat-resistant alloy substrate.₂O_ThreeSince ceramics and MCrAlX alloy are mixed, the area where the MCrAlX alloy and the substrate are in direct contact with each other is reduced as compared with a heat-resistant sprayed coating formed by spraying only the MCrAlX alloy powder. Therefore, in a high temperature environment in which the base material and the MCrAlX alloy component thermally diffuse to each other, an effect of suppressing the deterioration of the mechanical properties of the base material is brought about. In particular, when the operating temperature of the turbine blade material is increasing due to the recent increase in operating temperature of the gas turbine, Al in the coating made of MCrAlX alloy or the like formed on the surface of the turbine blade, etc. This component causes a problem of thermal diffusion in the base material to generate a brittle Al intermetallic compound, which deteriorates the mechanical properties of the base material.
In this respect, the chromium oxide-containing heat- and oxidation-resistant thermal spray coating obtained by spraying the chromate-treated heat and oxidation-resistant composite thermal spray material used in the present invention has a contact area between the MCrAlX alloy / substrate as described above. Since there are few, it is very advantageous in suppressing deterioration of a base material.
[0049]
In the case of a sprayed coating structure comprising a single layer coating of a chromated MCrAlX alloy as shown in FIG. 1 (a), the thickness of the sprayed coating is preferably in the range of 30 to 800 μm. If the film thickness is less than 30 μm, the above effect cannot be expected because the film is too thin. This is because the film is locally broken.
[0050]
FIG. 1 (c) shows a heat-resistant / oxidation-resistant sprayed coating 2 containing chromium oxide formed on a surface of a heat-resistant alloy substrate 1 by spraying a heat-resistant / oxidation-resistant composite sprayed material made of chromated MCrAlX alloy powder. ZrO is formed as an undercoat and as a topcoat on top₂It is sectional drawing which shows the example which formed the oxide ceramic sprayed coating 4 which has heat resistance, such as a type | system | group. On the chromium oxide-containing heat-resistant / oxidation-resistant thermal spray coating 2 formed by spraying a heat-resistant / oxidation-resistant composite thermal spray material made of chromated MCrAlX alloy, ZrO₂Even if the oxide ceramics sprayed coating 4 is formed, the adhesion between the two is not impaired. Such oxide ceramic sprayed coatings are generally excellent in heat resistance, but are porous and therefore corrosive components (for example, H₂O, SO₂, SO_Three, NO_x, HCl, etc.) enter the inside through the pores, corrode the underlying MCrAlX alloy, and eventually cause the oxide ceramics to peel off. However, the chromium oxide-containing heat-resistant / oxidative-resistant sprayed coating formed in the present invention has a Cr₂O_ThreeTherefore, it is possible to minimize corrosion damage due to combustion gas, and Cr₂O_ThreeThe surface of MCrAlX alloy powder in contact with Al has excellent protection₂O_ThreeSince a film is formed, this sprayed coating also contributes to prevention of corrosion damage by the combustion gas.
[0051]
In addition, ZrO as the top coat shown in FIG. 1 (c)₂Instead of the system oxide ceramic 4, an untreated MCrAlX alloy film 5 may be formed as shown in FIG. Both heat-resistant and oxidation-resistant composite sprayed material made of chromate-treated MCrAlX alloy powder and untreated MCrAlX alloy powder-sprayed material are in a molten state (Cr₂O_ThreeTherefore, good adhesion can be obtained. In addition, although both of these films may be arranged one above the other, this point will be described later.
[0052]
The thickness of each sprayed coating in the case of the multilayer sprayed coating as shown in FIG. 1 (c) or FIG. 1 (d) is an undercoat made of a chromium oxide-containing heat-resistant / oxidative-resistant sprayed coating sprayed with a chromated MCrAlX alloy. 30 ~ 800μm, ZrO formed on it₂It is preferable to form a top coat such as an oxide ceramic sprayed coating of a system in the range of 100 to 800 μm. The reason why the thickness of the undercoat is regulated is the same as in FIG. On the other hand, when the film thickness of the top coat is less than 100 μm, the heat resistance and the heat shielding effect are small, and conversely, when it exceeds 800 μm, the mechanical strength of the film itself is lowered.
[0053]
FIG. 1 (e) shows a thermal spray coating 2 comprising a chromium oxide-containing heat- and oxidation-resistant thermal spray coating formed by spraying a chromated MCrAlX alloy powder on the surface of a heat-resistant alloy substrate 1, and an undercoat thereof. As an intermediate layer, chromated MCrAlX alloy and ZrO₂The intermediate layer sprayed coating 6 is formed by thermal spraying a thermal spray material composed of a mixed powder with an oxide ceramic, and ZrO as a top coat is further formed thereon.₂It is sectional drawing which shows the example which formed the heat resistant oxide ceramic sprayed coating 4 which consists of a system oxide ceramic. Further, as shown in FIG. 1 (f), the intermediate layer sprayed coating of FIG. 1 (e) is subjected to chromate-treated MCrAlX alloy and ZrO.₂The amount of MCrAlX alloy that is chromate-treated with the base oxide ceramics is increased on the undercoat side, and on the contrary, the ZrO on the topcoat side.₂You may form as the inclination distribution layer 7 which increased the quantity of the system oxide ceramics.
[0054]
1 (e) and 1 (f), for example, between the heat-resistant alloy sprayed coating and the oxide ceramic sprayed coating having different physical properties. The problem of the generation of thermal stress due to the difference in thermal expansion and delamination due to its concentration is to be solved by reducing the stress by changing the blending ratio of the two in an inclined manner.
[0055]
However, such intermediate layer sprayed coatings 6 and 7 cannot exhibit their functions when exposed to high temperatures unless the heat resistance and oxidation resistance of the alloy contained in the sprayed coating are sufficient. . In this respect, the heat- and oxidation-resistant composite thermal spray material made of chromated MCrAlX alloy powder used in the present invention has much better heat and oxidation resistance than the untreated MCrAlX alloy powder of the same composition. Therefore, the function as the intermediate layer can be exhibited over a long period of time.
[0056]
In the case of the thermal spray coating having the structure as shown in FIG. 1 (e) or FIG. 1 (f), the thickness of each thermal spray coating is 30-200 μm on the undercoat made of chromated MCrAlX alloy. The intermediate layer is 30 to 200 μm, and ZrO formed thereon₂The top coat made of the oxide ceramic is preferably in the range of 30 to 800 μm. The reason for regulating the thickness of the base coat is that the lower limit is the same as in FIGS. 1A and 1C, but the upper limit is preferably 200 μm from the viewpoint of the mechanical strength of the film. This is because if the film thickness of the intermediate layer is less than 30 μm, the function as the intermediate layer cannot be exhibited, and conversely if it exceeds 200 μm, the mechanical strength of the film is lowered. Further, if the film thickness of the top coat is less than 30 μm, the heat resistance and heat shielding properties are small, and conversely, if it exceeds 800 μm, the mechanical strength of the film decreases.
[0057]
Next, the structure of the thermal spray coating formed in the present invention is not limited to the example shown in FIG. 1, and the heat resistance / oxidation resistance made of the above-described chromated MCrAlX alloy powder somewhere on the substrate surface. Any structure may be used as long as the composite sprayed material is sprayed to form the chromium oxide-containing heat-resistant / oxidation-resistant sprayed coating 2. For example, as shown in FIG. 2 (a), an undercoat is first applied to the surface of the heat-resistant metal equipment, and an untreated MCrAlX alloy powder is sprayed to form a heat-resistant sprayed coating 5, on which a chromate treatment is applied. The heat-resistant / oxidation-resistant composite sprayed material made of the MCrAlX alloy powder may be sprayed to form the chromium oxide-containing heat-resistant / oxidation-resistant sprayed coating 2. Further, as shown in FIG. 2 (b), a chromium oxide-containing heat- and oxidation-resistant thermal spray coating 2 is formed as an intermediate layer on the undercoat, and ZrO is further formed as a top coat on the intermediate layer.₂The thermal spray coating 4 of the system oxide ceramics may be laminated, and the combination is free.
[0058]
In addition, the various sprayed coatings having the structure as shown in FIG. 1 of the present invention can be sufficiently used as they are, but if necessary, liquefaction treatment of 1273 to 1473 K × 1 to 10 hours is possible. Alternatively, by performing a heat treatment of either 973 to 1273 K × 1 to 30 hours or a combination of both, the mutual bonding force of the alloy particles constituting the thermal spray coating is strengthened, It is possible to improve the adhesion. In addition, a protective oxide film mainly composed of aluminum oxide can be generated, and further, the thermal spray coating can be densified and the residual stress generated during the thermal spraying can be removed.
[0059]
【Example】
(Example 1) Chromate treatment was performed on various commercially available MCrAlX alloy powders, and instead of a thermal spraying heat source, a heating experiment was conducted in an air atmosphere using an electric furnace to evaluate heat resistance and high temperature oxidation resistance. went. The reason for using the electric furnace is that the alloy powder is scattered by heating with a thermal spraying heat source, and it is difficult to collect the alloy powder after heating. Table 1 shows the chemical components of the tested alloy powders, all of which are commercially available as thermal spray materials. When these are classified by chemical composition, they are broadly divided into alloys that do not contain Ni (A), alloys that do not contain Co (B, C, D, E), and alloys that contain Ni and Co (F, G). The alloy contains 5 mass% of Ta which is not contained in other alloys. Common components contained in all alloys are Al, Cr, and Y, and Y is a content of 1 mass% or less. Moreover, when the particle size of these alloy powders was investigated, the average particle size was 10-30 μm, but the maximum diameter was 50 μm, many of which were small particles of 10 μm or less, and particle sizes of 1 μm or less were also included. It was.
[0060]
[Table 1]

[0061]
In the chromate treatment, the above alloy powder was dipped in a 30 mass% chromic acid aqueous solution for 15 minutes and then pulled up. After removing the excess aqueous solution, the alloy powder was dried at 380K for 30 minutes. The process of baking was made into one process, and this process process was repeated 3 times. In the heating experiment, after heating for 9 hours at 1423K in the air using an electric furnace, this alloy powder was embedded in a synthetic resin and polished with emery paper to expose the cross section of the powder. The heat resistance of the alloy powder was examined by observation with a scanning electron microscope (SEM). As a comparative example, an untreated MCrAlX alloy powder not subjected to chromate treatment was also subjected to a heating experiment under the same conditions.
[0062]
Table 2 summarizes the results of the above experiment. In the comparative MCrAlX alloy powders (Nos. 8 to 14), all the powders with small particle sizes were completely oxidized and maintained the state of the alloy. Were only of large particle size. On the other hand, the alloy powders (No. 1 to 7) of the present invention subjected to the chromate treatment maintain the current shape without being oxidized even with a powder having a small particle diameter, and have excellent high temperature oxidation resistance. It was confirmed to show.
[0063]
[Table 2]

[0064]
FIG. 3 shows a representative example of cross-sectional photographs of MCrAlX alloy powder before and after the heating test. FIG. 3A shows a cross section of the alloy powder before the heating test observed with a scanning electron microscope (SEM), and white portions (alloy powder particles P1) can be confirmed in the cross sections of all large and small particles. FIG. 3 (b) is a photograph after the high-temperature oxidation test of the MCrAlX alloy powder not subjected to chromate treatment, the white part is the unoxidized alloy powder particle P1, and the dark part is the completely oxidized alloy powder particle P2. It can be seen that considerable powder is completely oxidized. On the other hand, FIG. 3 (c) is a cross section of the chromated MCrAlX alloy powder, which maintains a healthy state without being oxidized even with a small particle size powder. From the above results, it can be seen that the commercially available MCrAlX alloy powder is oxidized and consumed at an early stage, but the oxidation consumption rate can be significantly delayed by subjecting it to chromate treatment.
[0065]
(Example 2) MCrAlX alloy powders treated with chromate and untreated in a laboratory were allowed to stand for 10 days to form thermal spray materials, and these were formed by SUS304 stainless steel plate (dimensions 300 mm x 300 mm x 3.2 mmt) by atmospheric plasma spraying. After forming a film with a target film thickness of 50 μm on the surface, the steel sheet was cut and the thickness distribution of the sprayed film was measured using an optical microscope. In this test, alloy powders of A alloy and G alloy shown in Table 1 were used, and the chromate treatment conditions were the same as those in Example 1. As a comparative example, an investigation using the same alloy not treated with chromate was conducted.
[0066]
Table 3 shows the above observation results. The MCrAlX alloy powder subjected to the chromate treatment according to the present invention does not adsorb moisture even when left in a room, and the flow to the spray gun is smooth. A uniform film thickness was formed. In contrast, the untreated alloy powder of the comparative example has a large moisture adsorption and unstable supply to the spray gun, so the maximum film thickness was almost the same as the chromate-treated product. Was confirmed to be a small and non-uniform film.
[0067]
[Table 3]

[0068]
(Example 3) MCrAlX alloy powder (heat-resistant / oxidation-resistant composite sprayed material) and non-treated with repeated chromate treatment on the surface of a Ni-based alloy base (round bar 15mmφ x 50mm in length) Using a MCrAlX alloy powder (heat-resistant thermal spray material) as a thermal spray material, a 100 μm thick thermal spray coating was formed by low pressure plasma spraying. Thereafter, the sprayed test piece was subjected to heat treatment at 1373 K × 8 hr while flowing argon gas in an electric furnace. The test piece after heating was cut, and the state of diffusion of the alloy film component into the Ni-based alloy base material in the cross section was observed using an optical microscope and an X-ray microanalyzer. The alloy powders used in this experiment are five types of A, C, E, F and G shown in Table 1, and the chemical composition of the Ni-based alloy base material is 15.3 mass% Cr-7 mass% Fe- 2.5 mass% Ti-2 mass% Mo-10 mass% Co-residual Ni.
[0069]
Table 4 summarizes the results of measuring the depth at which the thermal spray coating component diffused into the Ni-based alloy base material by the heating experiment. As is clear from this result, the diffusion layer thickness of the test piece (No. 32, 34, 36, 38, 40) on which the thermal spray coating of the untreated MCrAlX alloy as a comparative example was formed reached 88 to 95 μm. It can be seen that it is very easy to diffuse. On the other hand, in the base material (No.31, 33, 35, 37, 39) on which a chromium oxide-containing heat-resistant / oxidation-resistant thermal spray coating formed by thermal spraying of chromated MCrAlX alloy powder is 30 ~ Cr is 45μm and formed by chromate treatment₂O_ThreeIt can be seen that the presence of the film can prevent the diffusion of the film components and suppress the deterioration of the mechanical properties of the substrate.
[0070]
[Table 4]

[0071]
(Example 4) Using the atmospheric plasma spraying method and the high-speed flame spraying method on the entire surface of the Ni-based alloy test piece (dimensions 50 mm x 50 mm x 5 mmt) used as the base material in Example 3, it is described in Table 1. A 300 μm thick sprayed coating was formed using C and D alloy powders as raw materials. In addition, the said alloy powder used what repeated chromate process 3 times prior to thermal spraying. Moreover, as a comparative example, in addition to an untreated MCrAlX alloy, 50 mass% Ni-50 mass% Cr and 80 mass% Ni-20 mass% Cr widely used as thermal spraying powder materials for high-temperature oxidation resistance are used. A sprayed coating was formed under the conditions. The test piece after film formation is subjected to a thermal oxidation test of 1473K x 500 hours in the air in an electric furnace, and the heat resistance and high-temperature oxidation resistance of the film are determined from the weight change (reduction) of the test piece before and after the test. evaluated. The above weight reduction occurs when the oxide film formed on the surface of the film by oxidation due to heating falls off during the test. The more the oxide film is denser and shows better oxidation resistance, the more the amount of dropout is. Less weight loss.
[0072]
Table 5 summarizes the above experimental results. From this result, the change in the weight of the coating (No. 43, 44, 47, 48) sprayed from the untreated MCrAlX alloy powder is 180 to 280 mg, whereas the chromated MCrAlX alloy powder The change in the weight of the sprayed coating (No. 41, 42, 45, 46) is only 75 to 95 mg, and the chromium oxide-containing heat resistance and oxidation resistance are sprayed with the chromate-treated alloy powder as the thermal spray material. It was confirmed that the thermal spray coating is excellent in high temperature oxidation resistance. Moreover, the weight change of the film | membrane (No. 49-52) of another comparative example showed the big weight reduction of 2010-2250 mg, and was inferior to the high-temperature oxidation resistance performance in the film | membrane tested.
[0073]
[Table 5]

[0074]
(Example 5) A chromium oxide-containing heat- and oxidation-resistant sprayed coating formed by spraying a chromated MCrAlX alloy was used as an undercoat, and ZrO was formed on the undercoat.₂The high temperature oxidation resistance and thermal shock characteristics of the thermal barrier coating with the top coat of the base oxide ceramics were investigated. For the undercoat, MCrAlX alloy, which is the A alloy listed in Table 1 and subjected to chromate treatment three times, is used as the thermal spraying material. 8.11 mass% Co-15.8 mass% Cr-3.45 mass% Al-3.60 mass% Ti-1.78 mass% A 150μm thick coating is formed on one side of a Ni-base alloy specimen (dimensions: 50mm x 500mm x 3.2mmt) with a composition of Mo-2.46mass% W-1.92mass% Ta-remaining Ni by low pressure plasma spraying. did. Furthermore, 8 mass% Y is formed on the undercoat by atmospheric plasma spraying.₂O_Three-ZrO₂A ceramic top coat was laminated to a thickness of 300 μm. As a comparative example, an untreated MCrAlX alloy was used as the undercoat thermal spray material, and the other conditions were the same as above.
[0075]
Tests for high temperature oxidation resistance and thermal shock characteristics were conducted after heating for 1423K x 200 hours in an electric furnace in an air atmosphere, and then cutting the test piece to obtain a cross section (mainly near the interface between the undercoat and topcoat). Was observed with a scanning electron microscope, and the oxidation behavior of the MCrAlX alloy element on the undercoat surface was examined. In the thermal shock test, the test piece after heating for 1423K x 200 hours is allowed to cool to room temperature (290K), then heated for 1270K x 15 minutes and then cooled to room temperature 10 times. The coating was peeled off by visual inspection.
[0076]
Table 6 shows the test results. From this result, in the case where the thermal spray coating formed by spraying an untreated MCrAlX alloy as a comparative example is an undercoat (No. 62), the alloy components such as Co, Cr, Ni, Al, etc. are obtained by heating for a long time. The metal element oxide was formed on the surface of the film to form a thick composite oxide layer, and this layer was also found to lack a denseness. On the other hand, on the surface of the undercoat layer (No. 61) formed by thermal spraying the chromated MCrAlX alloy which is the invention example, Al₂O_ThreeIt was found that a dense, thin and excellent protective layer with a main component of was formed and excellent in high temperature oxidation resistance. On the other hand, as a result of the thermal shock test, in the film of the comparative example, a large number of cracks occurred in the top coat, and the film corresponding to about 10% of the total area dropped out. On the other hand, in the test piece using the chromate-treated MCrAlX alloy powder, which is an example of the invention, no crack was generated in the top coat, and no film was dropped, and the sound condition was maintained.
[0077]
[Table 6]

[0078]
(Example 6) A chromium oxide-containing heat-resistant / oxidation-resistant sprayed coating formed by spraying MCrAlX alloy powder subjected to chromate treatment three times on the entire surface of the same base material test piece used in Example 4 MCrAlX alloy and ZrO formed as an undercoat and chromate-treated three times on the undercoat₂As shown in Table 7, the amount of MCrAlX alloy powder is increased on the substrate side, and ZrO is increased on the surface side.₂An intermediate layer is formed by spraying a thermal spray material that is inclined and distributed so as to increase the amount of the system oxide ceramic powder, and on the intermediate layer, ZrO₂-Based oxide ceramics (8 mass% Y₂O_Three-Balance ZrO₂) After forming a heat shield sprayed coating having a structure in which the thermal sprayed coating was laminated as a top coat, the test piece was subjected to a high temperature oxidation test of 1473 K × 500 h to evaluate the oxidation resistance. As the MCrAlX alloy powder used in the test, the alloy A shown in Table 1 was used. As the thermal spraying method, the high-speed flame spraying method was used for the undercoat, and the atmospheric plasma spraying method was used for the intermediate layer and the topcoat. For comparison, a similar sprayed coating was formed using untreated A alloy, and the high temperature oxidation resistance was investigated. Table 7 shows the thicknesses of the sprayed films of the undercoat, intermediate layer, and topcoat.
[0079]
[Table 7]

[0080]
After the high temperature oxidation test, each test piece was cut and the cross section of the film was observed. The results are shown in Table 8. In the comparative example film using the untreated A alloy, when the grinder grindstone was used for cutting, the top coat was already partially peeled off. Most of the A alloy particles in the intermediate layer were completely oxidized to the center of the particles. For this reason, ZrO constituting the intermediate layer₂Some of the system particles were also missing. On the other hand, in the intermediate layer of the present invention using the chromated A alloy, most of the MCrAlX alloy powder remains in a healthy state without being oxidized, and ZrO₂No dropout of particles was observed. When the chromate-treated A alloy particles were examined in detail with a scanning electron microscope, Al₂O_ThreeLayer is formed, this Al₂O_ThreeIt has been found that the layer is effective in maintaining high temperature oxidation resistance.
[0081]
[Table 8]

[0082]
【The invention's effect】
As described above, according to the present invention, the surface of the MCrAlX alloy powder is formed by Cr on the surface of the MCrAlX alloy powder as a material for forming a high temperature and oxidation resistant thermal spray coating.₂O_ThreeBy using a heat- and oxidation-resistant composite thermal spray material that forms a film, it is possible to prevent deterioration due to moisture absorption and deterioration of fluidity, and smooth supply to the thermal spray gun, resulting in a stable quality coating Can be secured. Also, Cr coated on the surface of the alloy powder by chemical treatment₂O_ThreeThe film is melted and softened together with the alloy powder by a thermal spraying heat source to form a part of the thermal spray coating, and functions as an oxide ceramic component. Excessive heat of the MCrAlX alloy component on the substrate at high temperatures While suppressing diffusion, Al has excellent protective properties on the coating surface.₂O_ThreeIt is effective in improving the high-temperature oxidation resistance and improving the bondability of the oxide ceramic formed as a top coat. With the above-described effects, it is possible to improve the thermal spraying work, the coating quality, the coating properties, and the like for the high-temperature exposed member such as a gas turbine at the stage of the sprayed powder material.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing a cross-sectional structure of a thermal spray coating excellent in heat resistance and oxidation resistance according to the present invention.
FIG. 2 is a view schematically showing a cross-sectional structure of a thermal spray coating excellent in heat resistance and oxidation resistance of the present invention.
FIG. 3 is a photograph of a cross section of the MCrAlX alloy powder before and after the high temperature oxidation test observed with a scanning electron microscope. (A) is an untreated MCrAlX alloy particle before the high temperature oxidation test, and (b) is a high temperature oxidation. Untreated MCrAlX alloy particles after the test, (c), are those of the chromated MCrAlX alloy particles after the high temperature oxidation test.
[Explanation of symbols]
1 Metal substrate
2 Heat-resistant / oxidation-resistant sprayed coating containing chromium oxide sprayed with chromated MCrAlX alloy powder (heat-resistant / oxidation-resistant composite sprayed material)
3 Protective oxide film mainly composed of aluminum oxide
4 ZrO₂-Based oxide ceramic spray coating
5 Heat-resistant sprayed coating made of untreated MCrAlX alloy
6 Heat-resistant and oxidation-resistant composite sprayed material and ZrO₂Spray coating with thermal spraying of mixed powder with ceramic oxide ceramics
7 Heat-resistant and oxidation-resistant composite sprayed material and ZrO₂Spray coating with a gradient distribution of the amount mixed with a ceramic oxide ceramic
P1 alloy particles or unoxidized alloy particles
P2 High temperature oxidized alloy particles

Claims (16)

In a member formed by coating a metal substrate with a thermal spray coating, the substrate is generated by a chromate treatment in which an aqueous solution containing chromic acid and / or chromate is attached to the surface of the heat-resistant alloy powder, followed by heat treatment. heat and oxidation, characterized in that it is coated with oxide chromium film chromium oxide heat and oxidation resistance thermal spray coating obtained by spraying a heat and oxidation resistant composite thermal spray material formed by coating the you Thermal spray coating coated member. The chromium oxide-containing heat- and oxidation-resistant thermal spray coating is MCrAlX (where M is one or more selected from Co, Ni and Fe, X is Y, Hf, Ta, Cs, Ce, La, The surface of the heat-resistant alloy powder having an average particle size of 5 to 100 μm represented by Th, W, Si, Pt, Mn, and B is selected from Th, W, Si, Pt, Mn, and B) is 0.1 to 10 μm thick. A layer in which Cr ₂ O ₃ ceramics and MCrAlX alloy are mixed, in which a heat- and oxidation-resistant composite thermal spray material made of a film is sprayed and deposited on the substrate surface in a molten or semi-molten state The heat-resistant / oxidation-resistant sprayed coating member according to claim 1, wherein 3. The heat and oxidation resistance according to claim 1, wherein a protective oxide film mainly composed of aluminum oxide is formed on the surface of the chromium oxide-containing heat and oxidation resistance sprayed coating. Thermal spray coating coated member. The heat-resistant heat-resistant coating according to claim 1 or 2, wherein the chromium oxide-containing heat-resistant and oxidation-resistant sprayed coating is an undercoat, and an oxide ceramic sprayed coating is formed as a top coat on the undercoat.・ Oxidation-resistant sprayed coating material. The chromium oxide-containing heat-resistant / oxidation-resistant sprayed coating according to claim 1 or 2 is formed as an undercoat on the surface of the heat-resistant alloy base material, and MCrAlX (where M is One or more selected from Co, Ni and Fe, X is one selected from Y, Hf, Ta, Cs, Ce, La, Th, W, Si, Pt, Mn and B or intermediate layer sprayed coating formed by thermal spraying a mixed powder of heat-resistant alloys heat and oxidation resistance composite spray material formed by providing an oxide chromium film on the surface of the powder and ZrO ₂ based oxide ceramic represented by two or more) And a ZrO ₂ -based oxide ceramic sprayed coating is formed as a top coat on the intermediate sprayed coating. The heat-resistant / oxidation-resistant thermal spray coating member according to claim 5, wherein the intermediate thermal spray coating is composed of a gradient blended layer in which the content of ZrO ₂ -based oxide ceramics is increased toward the top coat side. A heat resistant thermal spray coating of the heat resistant alloy is formed on the surface of the heat resistant alloy substrate, and the chromium oxide-containing heat resistant / oxidation resistant thermal spray coating according to claim 1 is formed as a top coat on the undercoat. A heat- and oxidation-resistant thermal spray coating member characterized by A heat resistant thermal spray coating of the heat resistant alloy is formed on the surface of the heat resistant alloy substrate, and the chromium oxide-containing heat resistant / oxidation resistant thermal spray coating according to claim 1 or 2 is formed as an intermediate layer on the undercoat. A ZrO ₂ oxide ceramic sprayed coating is further formed as a top coat on the intermediate layer. On the surface of the metal substrate, heat and acid formed by covering the oxide chromium film formed by chromate treatment to heat treatment allowed to attach an aqueous solution containing chromic acid and / or chromate on the surface of the heat resistant alloy powder A method for producing a heat-resistant / oxidative-resistant sprayed coating member characterized by forming a chromium oxide-containing heat-resistant / oxidant-resistant thermal sprayed coating by spraying a heat-resistant composite sprayed material. The heat-resistant / oxidation-resistant thermal spray material is MCrAlX (where M is one or more selected from Co, Ni and Fe, X is Y, Hf, Ta, Cs, Ce, La, Th, W, W) , Si, Pt, Mn, and B selected from the group consisting of heat-resistant alloy powders having an average particle diameter of 5 to 100 μm represented by a chromium oxide film having a thickness of 0.1 to 10 μm. The method for producing a heat- and oxidation-resistant spray-coated member according to claim 9, wherein the member is coated. After forming a chromium oxide-containing heat-resistant / oxidation-resistant sprayed coating on the surface of a metal substrate, it is heated at 970-1500 K for 1-30 hours to protect the surface of the sprayed coating with aluminum oxide as a main component. The method for producing a heat- and oxidation-resistant spray-coated member according to claim 9 or 10, wherein a film is formed. The heat-resistant / oxidizing sprayed coating containing chromium oxide is formed, and then an oxide ceramic sprayed coating is formed thereon by spraying an oxide ceramic. A method for producing an oxidation-resistant spray-coated member. The chromium oxide-containing heat-resistant / oxidation-resistant sprayed coating according to claim 9 or 10 is formed on the surface of the heat-resistant alloy substrate as an undercoat, and MCrAlX (where M is One or more selected from Co, Ni and Fe, X is one selected from Y, Hf, Ta, Cs, Ce, La, Th, W, Si, Pt, Mn and B or by spraying a mixed powder of heat and oxidation resistance composite spray material and ZrO ₂ based oxide ceramics to form an intermediate layer sprayed coating having an oxide chromium film on the surface of the heat resistant alloy powder represented by two or more) further as a top coat on top of the intermediate layer sprayed coating, heat and oxidation resistance, which comprises forming a ZrO ₂ based oxide ceramic sprayed coating by spraying a ZrO ₂ based oxide ceramics Method for producing a morphism film covering member. Production of the intermediate layer sprayed coating a heat and oxidation resistant sprayed coating coated member according to claim 13, characterized in that an inclined containing layer that increase the content of ZrO ₂ based oxide ceramics as the topcoat side Way . The heat-resistant and oxidation-resistant composite according to claim 9 or 10 is formed on the surface of the heat-resistant alloy base material by spraying a heat-resistant alloy powder as an undercoat to form a heat-resistant sprayed coating. A method for producing a heat-resistant / oxidation-resistant thermal spray coating member characterized by spraying a thermal spray material to form a chromium oxide-containing heat-resistant / oxidation-resistant thermal spray coating. As a further top coat on said chromium oxide containing heat and oxidation resistance sprayed coating according to claim 15, characterized in that by spraying a ZrO ₂ based oxide ceramic to form a ZrO ₂ based oxide ceramic sprayed coating Manufacturing method of heat-resistant and oxidation-resistant thermal spray coating coated member.

Images