JP3552332B2 - Remelting reforming method of aluminum material - Google Patents

Description

【００２０】
実施例１は直流プラズマ法によるもので、センターガス流量を、Ａｒ（アルゴンガス）０．５５ｌ／ｍｉｎ＋Ｎ_２０．０５ｌ／ｍｉｎとし、シールドガス流量をＡｒ９ｌ／ｍｉｎ、電流を１００Ａ（又は８０Ａ）、導電条件を１分通電、１分停止の繰返しとして、電極の摩耗を調べた。
比較例１は従来の交流プラズマ法によるものであり、センターガス流量のみＡｒ０．６ｌ／ｍｉｎ（即ちＮ_２を混合せず）とし、他の条件は実施例１に合せた。
【００２１】
図７はタングステン電極の寿命比較グラフであり、横軸は使用回数、縦軸は電極の先端Ｒを示し、●は１００Ａ、○は８０Ａでの結果である。
１００Ａにおいて比較例１では４回程で寿命となったのに対して、実施例１では４２回は使用可能であり、寿命は約１０倍となっている。グラフ中、▲１▼〜▲４▼における電極１１の先端の形状は次の図に示す通りであった。
【００２２】
図８▲１▼〜▲４▼はタングステン電極の先端の形状説明図であり、▲１▼は未使用状態を示し、Ｒ＝０．１ｍｍ、Ｎ（使用回数）＝０、▲２▼，▲３▼は本発明方法での使用状態（途中）を示し、▲４▼は従来方法での使用状態（寿命）を示した。
従って、本発明によれば、アルミニウム材の再溶融改質が直流プラズマ法で実施可能になり、しかも電極の消耗を抑えることができ、交流プラズマ法よりも優れていることが明らかになった。
【００２３】
▲２▼本発明におけるＮ_２の適量；
前記実施例１ではセンターガスをＡｒ０．５５ｌ／ｍｉｎ＋Ｎ_２０．０５ｌ／ｍｉｎとしたが、このＮ_２の適量を調べることは重要である。そこで、本発明者等は、次の表２の条件での実験を実施した。
【００２４】
【表２】

【００２５】
比較例２はセンターガスをＡｒのみとしたので、本発明の還元性ガスが形成できず、酸化膜を除去することができないため処理は不良であった。
実施例２はＮ_２／Ａｒ比を１．７％、実施例３はＮ_２／Ａｒ比を１０％、実施例４はＮ_２／Ａｒ比を２０％、実施例５はＮ_２／Ａｒ比を３３％としたので、処理結果は良好であった。
【００２６】
比較例３はＮ_２／Ａｒ比を４３％としたもので、処理結果は不良であった。周知の通り、同一トーチ高さにおいて、センターガスをＡｒにした場合に比べて、Ｎ_２の場合は所要電圧が約２倍となる。即ち、電圧を倍増しなければＮ_２で所定のプラズマアークを発生させることはできない。従って、比較例３のようにＮ_２の比率が過剰になると良好なプラズマアークが得られず、所望の処理結果が得られない。
従って、本発明方法においては、センターガスのＮ_２／Ａｒ比を１．７％〜３３％範囲とすることが望ましい。この範囲であれば電圧や電流値を適度に抑えることができる。
【００２７】
▲３▼本発明におけるＭｇ含有材の適量；
表３はＭｇ含有材の量を変化させて前記図３に記載した実験を実施した。その条件及び結果を記載したものである。
【００２８】
【表３】

【００２９】
アルミニウム材及びＭｇ含有材の項を除いて、前記実施例１と同等条件であるから、この分の説明は省略する。
アルミニウム材はＡＣ４Ｃを使用した。この材料は含有Ｍｇ成分が０．２５〜０．４５重量％であり、含有Ｍｇの量が微量である。
一方、Ｍｇ含有材はＡＣ７Ｂの粉末を使用した。この材料は含有Ｍｇ成分が約１０重量％であり、含有Ｍｇの量が多量である。粉末の大きさは１０〜１００μｍとした。少量であれば、ＡＣ７Ｂ材をヤスリで削り、発生した粉を使用してもよい。
【００３０】
比較例４はＭｇ含有材を添加しなかった。アルミニウム材（ＡＣ４Ｃ）中のＭｇでは不足であったため、還元性ガスが生成せず、所定の処理ができなかった。実施例６はＭｇ含有材を２ｍｇ／ｃｍ^２、実施例７はＭｇ含有材を５ｍｇ／ｃｍ^２、実施例８はＭｇ含有材を１０ｍｇ／ｃｍ^２、実施例９はＭｇ含有材を２０ｍｇ／ｃｍ^２添加したところ満足すべき処理ができた。
比較例５はＭｇ含有材を３０ｍｇ／ｃｍ^２としたものであり、一部がアルミニウム材表面に残留してしまった。Ｍｇ含有材の供給量が多過ぎたためと考える。従って、本発明においてはＭｇ含有材の定量な供給量は２〜２０ｍｇ／ｃｍ^２である。
【００３１】
アルミニウム材をＭｇ成分の高いＡＣ７Ａ、ＡＣ７Ｂ、ＡＣ５Ａとすれば母材内のＭｇ成分が活用できるので、Ｍｇ含有材を節約若しくは無にすることができる。
【００３２】
上記Ｍｇ含有材をを添加するのと同様の作用を発揮するものとして、アルミニウム材自身に含まれるＭｇ成分を変える方法もある。
次の表４は、Ｍｇの含有量が０，２．０，５．０，７．０，２０，３０ｗｔ％のアルミニウム材を準備し、これらのアルミニウム材に表に示す条件の下で本発明の直流プラズマ処理を施した。
【００３３】
【表４】

【００３４】
Ｍｇが含まれていない比較例６では還元性ガスの生成が不足し、所望の改質効果は得られなかった。
従って、表４からＭｇを２．０〜２０ｗｔ％の範囲で含むアルミニウム材であれば良好な結果が得られることが分かった。
【００３５】
▲４▼本発明方法をシリンダヘッドの表面改質に適用した例；
図９はガソリンエンジンのシリンダヘッドの底面図であり、シリンダヘッド２０には２個の吸気ポート２１，２１、２個の排気ポート２２，２２及び点火栓孔２３が開けられており、図中のハッチング（／／／）を施した部分に本発明の再溶融改質処理を施すことにした。
【００３６】
【表５】

【００３７】
表５はその時の条件及び結果をまとめたものであり、シリンダヘッドはＭｇの含有成分が０．５％以下のＡＣ２Ｂである。ＡＣ２ＢのＭｇ成分は表３で述べたＡＣ４Ｃに近いので、Ｍｇ含有材を２ｍｇ／ｃｍ^２だけ図９のハッチング部分に載せた後、表４の条件で再溶融改質を実施した。
【００３８】
処理後のシリンダヘッド２０をシリンダブロックに組込み、ガソリンエンジンを完成し、６０００ｒｐｍで１００時間の連続運転を評価試験として実施した。運転後のエンジンを分解し、シリンダヘッド１２０の裏面を検査したところ、クラックの発生は認められなかった。
この種の改質処理を施さないシリンダブロックで同様の評価試験を実施すると、図９の排気ボート２２，２２間に微細なクラック２５の発生することがあり、非改質品に比べて本発明による改質品は耐久性の向上が認められた。
【００３９】
▲５▼本発明方法を突き合せ溶接に適用した例；
実施例１５及び比較例８：
本発明のプラズマアーク溶接法と従来のＴＩＧ（イナートガスタングステンアーク）溶接法との比較例である。

実施例１５の溶接部強度は比較例８の溶接部強度と遜色なかった。従って、よって、本発明の直流プラズマ溶接法によれば、従来のＴＩＧ法並みの突き合せ溶接が可能であることが確認できた。
【００４１】
▲６▼本発明方法を重ねすみ肉溶接に適用した例；
実施例１６及び比較例９：
本発明のプラズマアーク溶接法と従来のＴＩＧ（イナートガスタングステンアーク）溶接法との比較例である。

実施例１６の溶接部強度は比較例９の溶接部強度と遜色なかった。従って、よって、本発明の直流プラズマ溶接法によれば、従来のＴＩＧ法並みのすみ肉溶接が可能であることが確認できた。
【００４３】
尚、本発明のアルミニウム材２，２Ａはアルミニウム合金鋳物を含む広い意味のアルミニウム合金を意味する。
【００４４】
【発明の効果】
本発明は上記構成により次の効果を発揮する。
請求項１は、Ｍｇ _３ Ｎ _２ ガスと直流プラズマアークとの組合わせにより、アルミニウム材の処理を実現したものであり、しかも従来の交流プラズマ法に比べて電極の寿命が格段に延びるという格別の効果が得られる。
【００４６】
請求項１で用いるＭｇ _３ Ｎ _２ ガスを作動ガス中のＮ_２とアルミニウム材中のＭｇ成分又は外部から供給したＭｇ成分と反応させて生成するので、Ｍｇ _３ Ｎ _２ ガスは簡単に生成でき、生産コストの高騰を抑えることができる。
【００４７】
請求項２は、Ｍｇ _３ Ｎ _２ ガスと直流プラズマアークとの組合わせにより、アルミニウム材同士の突合せ部又はすみ肉部に照射することで、改質と同時に接合を行うことができる。
【図面の簡単な説明】
【図１】本発明に係る再溶融改質方法の原理図
【図２】本発明に係る還元性ガスの生成方法の第１原理図
【図３】本発明に係る還元性ガスの生成方法の第２原理図
【図４】本発明に係る還元性ガスの生成方法の第３原理図
【図５】プラズマトーチの原理図
【図６】タングステン電極の先端の拡大図
【図７】タングステン電極の寿命比較グラフ
【図８】タングステン電極の先端の形状説明図
【図９】ガソリンエンジンのシリンダヘッドの底面図
【図１０】従来のアルミニウム材に用いられる交流プラズマ法の原理図
【符号の説明】
１…酸化膜、２，２Ａ…アルミニウム材、３…電極、４…直流電源、５…Ｍｇ材、７…Ｍｇ含有材、１０…プラズマトーチ。[0001]
[Industrial applications]
The present invention relates to surface modification how the aluminum material.
[0002]
[Prior art]
Various methods, such as surface quenching, carburizing, and nitriding, have been used for the surface modification of metal materials. In recent years, a modification method by a remelting treatment method (hereinafter, abbreviated as “remelting modification method”) has been used. ) Is in practical use.
For example, Japanese Unexamined Patent Publication No. Sho 61-193773 discloses a method of improving a cylinder head for an aluminum alloy cast internal combustion engine by irradiating a required portion of an aluminum cylinder head with high-density energy and re-melting the same. In this embodiment, a TIG arc is used as the high-density energy, and a laser, an electron beam, or a plasma arc may be used.
[0003]
In the remelting reforming method, if the aluminum material having casting defects such as micropores is remelted and recooled, directional solidification can be performed from the base material side to the surface, and the casting defects are extruded to the surface. Therefore, reforming can be achieved. At the same time, since the non-melted portion acts as a chill with a large capacity, the re-melted portion is rapidly cooled, the structure becomes finer, and the surface can be modified.
[0004]
[Problems to be solved by the invention]
The present inventors have paid attention to the remelting reforming method, and in particular, have studied the surface modification of an aluminum material by a plasma arc and have found the following problems.
FIGS. 10A and 10B are principle diagrams of an AC plasma method conventionally used for an aluminum material. As is well known, the aluminum material 101 is covered with a strong Al ₂ O ₃ oxide film 102. By (a) setting the aluminum material 101 to "-" and the plasma torch electrode 103 to "+", electrons e are skipped from the aluminum material 101, and the electrons e break through the oxide film 102. Immediately after that, the electron e is skipped from the electrode 103 in (b) whose polarity is changed, and the surface of the aluminum material 101 is heated and re-melted by the energy of the electron e. That is, it is said that the "AC plasma method" in which the polarity is alternately changed and the above (a) and (b) are repeated is suitable for the aluminum material.
[0005]
However, in the case of the above (a), there is a problem that the electrons e collide not only with the oxide film 102 but also with the electrode 103, and the electrode 103 is greatly consumed. Details will be described later.
Therefore, the present inventors have intensively studied a new plasma method instead of the AC plasma method, and have succeeded in developing a technique that can satisfy surface modification and welding.
[0006]
[Means for Solving the Problems]
Specifically, in claim 1, when the surface of the aluminum material is irradiated with a high-density energy beam and the surface is reformed by re-melting the surface, the atmosphere is made of Mg ₃ N ₂ gas, Is a DC plasma arc having a positive pole on the aluminum material side .
[0008]
The Mg ₃ N ₂ gas, a nitrogen gas, which is part of the working gas, the Mg component supplied from Mg component or external in aluminum material is reacted by gasification, Ru to produce.
[0009]
In claim 2 , when the surface of the aluminum material is irradiated with a high-density energy beam, and the surface is reformed by re-melting the surface, the butt portion or the fillet portion between the aluminum materials is irradiated, thereby improving the quality. It is characterized by joining at the same time as quality .
[0010]
Note Oite above surface modification, the voltage of the electrode and the aluminum material surface is determined by the torch distance and gas body (atmosphere), in the torch distance, compared to the Ar atmosphere, a voltage is N ₂ atmosphere If it does not double, a predetermined plasma arc cannot be generated. Therefore, N ₂ is not generally used because discharge becomes difficult.
However, the present invention enables plasma processing in an N ₂ atmosphere by suppressing N ₂ to an appropriate amount.
[0011]
[Action]
The oxide film on the surface of the aluminum material is removed with Mg ₃ N ₂ gas to expose the aluminum material, and a plasma arc is applied to the exposed aluminum material.
[0012]
FIGS. 1A and 1B are principle diagrams of a remelting reforming method according to the present invention. In FIG. 1A, an electrode 3 is exposed on an aluminum material 2 covered with an oxide film 1 and the aluminum material 2 side. Is connected to the DC power supply 4 so that the electrode 3 becomes “+” and the electrode 3 side becomes “−”, and the processing atmosphere is Mg ₃ N ₂ which is a reducing gas.
Then, the oxide film 1 is removed by the reaction formula of Mg ₃ N ₂ + 2Al ₂ O ₃ + 3Mg → 2AlN + 6MgO + 2Al.
(B) shows that the electron e collides from the electrode 3 to the aluminum material 2 from which the oxide film 1 has been removed, and the direct current plasma arc allows the aluminum material 2 to be reformed again.
[0013]
Three examples of the method of generating the Mg ₃ N ₂ gas will be described.
FIGS. 2A and 2B are first principle diagrams of a method for generating a reducing gas according to the present invention. An aluminum material 2A containing an appropriate amount of (Mg) is used. When the electron e is emitted from the electrode 3 in (a), the oxide film 1 is locally heated and broken by the plasma arc to reach the aluminum material 2A, which is melted, and Mg in the components is gasified. This Mg reacts with a part of N _{2 of the} working gas as follows.
3Mg (gas) + N ₂ → Mg ₃ N ₂
(B) shows a state in which the atmosphere is changed to Mg ₃ N ₂ , and since this figure is the same as FIG. 1 (a), remelting reforming can be performed thereafter.
[0014]
FIG. 3 is a second principle view of the method for generating a reducing gas according to the present invention, in which an Mg material 5 is placed on the oxide film 1 in advance. The Mg material 5 is preferably in the form of a paste, sheet, or wire containing an Mg alloy because it is easy to handle.
When electrons e are irradiated from the electrode 3 to the Mg material 5 under the working gas N ₂ , the Mg component in the Mg material 5 is gasified by plasma heat, and the reaction of 3Mg (gas) + N ₂ → Mg ₃ N ₂ proceeds.
[0015]
FIG. 4 is a third principle view of the method for generating a reducing gas according to the present invention, in which Mg-containing material 7 is supplied onto oxide film 1 by supply means 6 and 6.
When the electron e is irradiated from the electrode 3 to the Mg-containing material 7 under the working gas N ₂ , the Mg component is gasified by plasma heat, and the reaction of 3Mg (gas) + N ₂ → Mg ₃ N ₂ proceeds.
[0016]
【Example】
Examples of the present invention will be described below. The examples are as follows: (1) comparison between DC plasma method and conventional AC plasma method, ( ₂ ) proper amount of N2 in the present invention, (3) proper amount of Mg-containing material in the present invention, and (4) present invention. Examples of applying the method to reforming a cylinder head, (5) and (6) consist of examples of the welding method of the present invention, and these will be described sequentially.
FIG. 5 is a diagram showing the principle of the plasma torch, which is provided for convenience of the following description. That is, the plasma torch 10 concentrically surrounds the tungsten electrode 11 (corresponding to the electrode 3) with the nozzle 12 and the shield cap 13, and allows a center gas (corresponding to the working gas) to flow between the electrode 11 and the nozzle 12. It has a structure in which a shield gas flows between the nozzle 12 and the shield cap 13.
[0017]
(1) Comparison between DC plasma method and conventional AC plasma method;
FIG. 6 is an enlarged view of the tip of the tungsten electrode. When the diameter D of the tungsten electrode 11 is 3 mm and the tip angle θ is 60 °, the initial tip R is 0.1 mm. This is because if R is large, it becomes difficult to generate an arc, the generated arc swings right and left, and the straightness deteriorates, and the arc diameter increases, making it difficult to narrow. Therefore, the use limit is set to R = 0.8 mm, and when this value is reached, the life is determined.
[0018]
Table 1 below summarizes the experimental conditions.
[0019]
[Table 1]

[0020]
The first embodiment is based on a DC plasma method, in which the center gas flow rate is 0.55 l / min of Ar (argon gas) +0.05 l / min of N ₂ , the shielding gas flow rate is 9 l / min, the current is 100 A (or 80 A), Electrode wear was examined under the conductive conditions of 1 minute energization and 1 minute stop.
Comparative Example 1 was based on the conventional AC plasma method, and the center gas flow rate was changed to Ar 0.6 l / min (that is, N ₂ was not mixed), and the other conditions were the same as in Example 1.
[0021]
FIG. 7 is a graph comparing the lifespan of the tungsten electrode, in which the horizontal axis represents the number of times of use and the vertical axis represents the tip R of the electrode.
At 100A, the life was about four times in Comparative Example 1, whereas in Example 1, it could be used 42 times, and the life was about ten times longer. In the graph, the shape of the tip of the electrode 11 in (1) to (4) was as shown in the following figure.
[0022]
FIGS. 8 (1) to 8 (4) are explanatory views of the shape of the tip of the tungsten electrode. FIG. 8 (1) shows an unused state, R = 0.1 mm, N (number of times of use) = 0, (2), ▲ 3) shows the state of use (on the way) in the method of the present invention, and (4) shows the state of use (life) in the conventional method.
Therefore, according to the present invention, it has been clarified that the remelting and reforming of the aluminum material can be performed by the direct current plasma method, and furthermore, the consumption of the electrodes can be suppressed, which is superior to the alternating current plasma method.
[0023]
( ₂₎ an appropriate amount of N _{2 in} the present invention;
In the first embodiment, the center gas is Ar 0.55 l / min + N ₂ 0.05 l / min. However, it is important to check the appropriate amount of N ₂ . Therefore, the present inventors conducted an experiment under the conditions shown in Table 2 below.
[0024]
[Table 2]

[0025]
In Comparative Example 2, since the center gas was only Ar, the reducing gas of the present invention could not be formed, and the oxide film could not be removed.
Example 2 has an N ₂ / Ar ratio of 1.7%, Example 3 has an N ₂ / Ar ratio of 10%, Example 4 has an N ₂ / Ar ratio of 20%, and Example 5 has an N ₂ / Ar ratio. Was 33%, so that the treatment result was good.
[0026]
In Comparative Example 3, the N ₂ / Ar ratio was set to 43%, and the processing result was poor. As is well known, at the same height of the torch, as compared with the case where the center gas to Ar, in the case of N ₂ required voltage is approximately doubled. That is, it is impossible to generate a predetermined plasma arc with N ₂ to be double the voltage. Therefore, good plasma arc when the ratio of N ₂ becomes excessive is not obtained as in Comparative Example 3 can not be obtained the desired processing result.
Therefore, in the method of the present invention, it is desirable that the N ₂ / Ar ratio of the center gas is in the range of 1.7% to 33%. Within this range, the voltage and current values can be appropriately suppressed.
[0027]
(3) an appropriate amount of the Mg-containing material in the present invention;
In Table 3, the experiment described in FIG. 3 was performed by changing the amount of the Mg-containing material. The conditions and results are described.
[0028]
[Table 3]

[0029]
Except for the aluminum material and the Mg-containing material, the conditions are the same as those of the first embodiment, and the description thereof will be omitted.
AC4C was used as the aluminum material. This material has a Mg content of 0.25 to 0.45% by weight, and the amount of Mg contained is very small.
On the other hand, as the Mg-containing material, AC7B powder was used. This material has a Mg content of about 10% by weight and a large amount of Mg. The size of the powder was 10 to 100 μm. If the amount is small, the AC7B material may be shaved with a file and the generated powder may be used.
[0030]
In Comparative Example 4, no Mg-containing material was added. Since Mg in the aluminum material (AC4C) was insufficient, no reducing gas was generated and the predetermined treatment could not be performed. Example 6 is 2 mg / cm ² of Mg-containing material, Example 7 is 5 mg / cm ² of Mg-containing material, Example 8 is 10 mg / cm ² of Mg-containing material, and Example 9 is 20 mg / cm ² of Mg-containing material. ^{When 2 was} added, satisfactory treatment was performed.
In Comparative Example 5, the content of the Mg-containing material was 30 mg / cm ² , and a part thereof remained on the surface of the aluminum material. It is considered that the supply amount of the Mg-containing material was too large. Therefore, in the present invention, the quantitative supply amount of the Mg-containing material is 2 to 20 mg / cm ² .
[0031]
If the aluminum material is made of AC7A, AC7B, or AC5A having a high Mg content, the Mg content in the base material can be utilized, so that the Mg-containing material can be saved or eliminated.
[0032]
There is a method of changing the Mg component contained in the aluminum material itself so as to exhibit the same effect as adding the Mg-containing material.
Table 4 below shows that aluminum materials having Mg contents of 0, 2.0, 5.0, 7.0, 20, and 30 wt% were prepared, and the present invention was applied to these aluminum materials under the conditions shown in the table. DC plasma treatment.
[0033]
[Table 4]

[0034]
In Comparative Example 6 containing no Mg, the generation of reducing gas was insufficient, and the desired reforming effect was not obtained.
Accordingly, it was found from Table 4 that good results were obtained with aluminum materials containing Mg in the range of 2.0 to 20 wt%.
[0035]
(4) Example in which the method of the present invention is applied to surface modification of a cylinder head;
FIG. 9 is a bottom view of the cylinder head of the gasoline engine. The cylinder head 20 has two intake ports 21, 21 and two exhaust ports 22, 22, and an ignition plug hole 23. The hatched portion (///) is subjected to the remelt reforming treatment of the present invention.
[0036]
[Table 5]

[0037]
Table 5 summarizes the conditions and results at that time. The cylinder head is made of AC2B containing 0.5% or less of Mg. Since the Mg component of AC2B is close to that of AC4C described in Table 3, the Mg-containing material was placed on the hatched portion of FIG. 9 by 2 mg / cm ² , and then remelt reforming was performed under the conditions of Table 4.
[0038]
The cylinder head 20 after the treatment was assembled in a cylinder block to complete a gasoline engine, and continuous operation at 6000 rpm for 100 hours was performed as an evaluation test. When the engine after operation was disassembled and the back surface of the cylinder head 120 was inspected, no crack was found.
When a similar evaluation test is performed on a cylinder block that is not subjected to this type of reforming treatment, fine cracks 25 may occur between the exhaust boats 22 in FIG. The improved product was found to have improved durability.
[0039]
{Circle over (5)} Examples in which the method of the present invention is applied to butt welding;
Example 15 and Comparative Example 8:
It is a comparative example of the plasma arc welding method of the present invention and a conventional TIG (inert gas tungsten arc) welding method.

The weld strength of Example 15 was comparable to the weld strength of Comparative Example 8. Therefore, according to the DC plasma welding method of the present invention, it was confirmed that butt welding comparable to the conventional TIG method was possible.
[0041]
{Circle around (6)} Example in which the method of the present invention is applied to fillet welding;
Example 16 and Comparative Example 9:
It is a comparative example of the plasma arc welding method of the present invention and a conventional TIG (inert gas tungsten arc) welding method.

The weld strength of Example 16 was comparable to the weld strength of Comparative Example 9. Therefore, according to the DC plasma welding method of the present invention, it was confirmed that fillet welding comparable to the conventional TIG method was possible.
[0043]
The aluminum materials 2 and 2A of the present invention mean aluminum alloys in a broad sense including aluminum alloy castings.
[0044]
【The invention's effect】
The present invention has the following effects by the above configuration.
The first aspect of the present invention realizes the treatment of an aluminum material by a combination of a Mg ₃ N ₂ gas and a DC plasma arc, and has a special advantage that the life of the electrode is significantly extended as compared with the conventional AC plasma method. The effect is obtained.
[0046]
Since the Mg ₃ N ₂ gas used in claim 1 is generated by reacting the N ₂ in the working gas with the Mg component in the aluminum material or the Mg component supplied from the outside, the Mg ₃ N ₂ gas can be easily generated, High production costs can be suppressed.
[0047]
According to the second aspect , the joint can be performed simultaneously with the reforming by irradiating the butted portion or the fillet portion between the aluminum materials by the combination of the Mg ₃ N ₂ gas and the DC plasma arc .
[Brief description of the drawings]
FIG. 1 is a principle diagram of a remelting reforming method according to the present invention. FIG. 2 is a first principle diagram of a reducing gas generating method according to the present invention. FIG. 3 is a diagram showing a reducing gas generating method according to the present invention. Second principle diagram [FIG. 4] Third principle diagram of the reducing gas generation method according to the present invention [FIG. 5] Principle diagram of plasma torch [FIG. 6] Enlarged view of tip of tungsten electrode [FIG. 7] Life comparison graph [Fig. 8] Illustration of tip shape of tungsten electrode [Fig. 9] Bottom view of cylinder head of gasoline engine [Fig. 10] Principle diagram of AC plasma method used for conventional aluminum material [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Oxide film, 2, 2A ... Aluminum material, 3 ... Electrode, 4 ... DC power supply, 5 ... Mg material, 7 ... Mg containing material, 10 ... Plasma torch.

Claims (2)

When irradiating the surface of the aluminum material with a high-density energy beam and re-melting the surface to modify the surface, the atmosphere is made of Mg ₃ N ₂ gas so that the aluminum material side of the high-density energy beam has a positive pole. A method for remelting and reforming an aluminum material to be a direct current plasma arc ,
The Mg ₃ N ₂ is produced by reacting N ₂ gas, which is a part of the working gas, with a Mg component in the aluminum material or a Mg component supplied from the outside , and re-melting reforming the aluminum material. Method. By irradiating the surface of the aluminum material with a high-density energy beam and re-melting the surface to modify the surface, the joint is formed simultaneously with the modification by irradiating the butt portion or the fillet portion between the aluminum materials. The method for remelting and reforming an aluminum material according to claim 1, wherein the method is performed .

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