JP4101981B2 - Heat-resistant platinum and method for producing the same - Google Patents

Description

【００３３】
又、応力１．４７ＭＰａ，１３００℃で高温クリープ特性を調査し、次の表２に示す結果を得た。
【００３４】
該結果から、高温耐久性は添加量と共に上昇し、無添加時の約２倍の効果をもたらした。
【００３５】
尚、添加量の増加とともに、破断に至るまでの時間は増加するが、伸びが減少傾向を示しており、延性が失われてゆき、比較例に示す材料では、伸びの低下とともに破断に至るまでの時間も低下し、脆化が認められた。
【表２】

【００３６】
【発明の効果】
以上、明らかなように、この出願の発明によれば、カルシウムの多量添加が可能となり、カルシウム、及び、ジルコニウムとの複合添加による相乗作用から、高温特性、特に、高温クリープ強度の向上が図られ、したがって、高温耐久性を要するつぼや装置、器具部材に適した耐熱白金が得られるという優れた効果を奏するものである。
【００３７】
又、添加物で脱酸効果と特性向上効果が得られるため、特殊な設備を必要とせず、コスト的にも、容易に大量に製造できる効果を有するものである。[0001]
[Industrial application fields]
The disclosed technology belongs to a technical field of manufacturing heat-resistant platinum suitable for platinum materials having excellent high-temperature characteristics, in particular, crucibles and apparatuses used in high temperatures, and instrument members.
[0002]
[Prior art]
Conventionally, platinum products are remarkably large, but platinum, platinum alloys, and the like are used for crucibles and physics and chemistry instruments used for glass melting and the like because of the conditions used at high temperatures.
[0003]
[Problems to be solved by the invention]
These platinum products cause a gradual decrease in strength and coarsening of crystal grains due to heat at high temperature, deformation due to deterioration of properties, specifically breakage during use, etc. There was a defect in heat resistance.
[0004]
In order to cope with this, there is also a so-called oxide dispersion type reinforced platinum material in which an oxide such as zirconium or yttrium is dispersed in order to improve the heat resistance characteristics, but when used as a melting crucible, cracking occurs without warning. There was a difficulty that required improvement in order to cause problems in the apparatus.
[0005]
Further, these oxide dispersion type reinforced platinum materials have a disadvantage that they are expensive in cost because a special manufacturing method must be used to uniformly disperse the oxide.
[0006]
On the other hand, various heat resistance characteristics are improved by alloying. For example, as disclosed in JP-A-3-4611, an alloy to which a small amount of calcium is added has been devised. Although it is not colored and increases the recrystallization temperature and is effective for crystal refinement, when the calcium content exceeds 100 ppm, for example, as disclosed in JP-A-6-212321, There were defects such as blistering and cracking due to interposition and segregation, making machining difficult and making it impossible to produce sound plates and lines.
[0007]
OBJECT OF THE INVENTION
The object of the invention of this application is a technical problem that should solve the above-mentioned various problems, and is a platinum material that is excellent in workability without causing blisters and cracks due to segregation and the like, and excellent in heat resistance characteristics In addition, it is intended to provide technology for use in the material industry for efficiently and inexpensively producing the platinum material.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the structure of the present invention, which is summarized in the scope of the above claims along with the above-mentioned object, includes calcium in an amount of 101 to 450 ppm , zirconium in an amount of 200 ppm or less , and other residues containing inevitable impurities. One of the basics is to be composed of platinum, preferably platinum having a purity of 99.95% or more, and while adding calcium to platinum containing inevitable impurities in an oxygen-free atmosphere and melting it, The other technical basis is that the dissolved oxygen is converted into calcium oxide, and the dissolved oxygen is floated and removed, and then the platinum is further melted uniformly by adding calcium and zirconium if necessary. It is a measure taken.
[0009]
[Action]
As a method of adding calcium disclosed as the prior art, there is a method in which an oxide of calcium is put into platinum as calcium by calcium reduction by hydrogen reduction. However, in such a method, addition of a desired amount of calcium is extremely difficult. If you try to force it in, unreduced calcium is mixed in, or gas components are involved, causing blisters and cracks after processing, making it very difficult to secure a good quality material. there were.
[0010]
In other words, the amount of calcium that can be added by reducing the oxide is very small, and it cannot be added in large quantities. It is difficult to obtain a sound material due to the residual air or gas when dissolved or cast in the atmosphere. Therefore, there is a technique using a calcium-boron compound as a deoxidizing material.
[0011]
However, it is still difficult to remove air and gas and to secure the amount of calcium to be added. To solve these problems, the invention of this application adds platinum to platinum in a non-oxidizing atmosphere while melting. In addition, the dissolved oxygen in the platinum is removed as much as possible, and further, calcium is added to the platinum and uniformly melted, so that a large amount of calcium of several hundred ppm or more is achieved, and there is no mixing of air and gas components. It has been found that a high-quality material that can be easily processed into a plate or a wire can be manufactured.
[0012]
[Reason for limitation]
In the heat-resistant platinum of the invention of this application, the reason for the numerical limit of calcium addition is that if it is 100 ppm or less, the characteristics of heat-resistant platinum cannot be obtained, while if it exceeds 450 ppm, it becomes too hard and cracks may occur during processing. The addition amount was 101 to 450 ppm because it was confirmed by experiments that the ductility decreased during use.
[0013]
Zirconium has high-temperature creep strength and crystal refining effect, and it is too little to add by itself, but the effect is small, but in combination with calcium, a synergistic effect is obtained. On the other hand, it has been confirmed by the same experiment that when the amount exceeds 200 ppm, the grain boundary becomes brittle, and the amount of addition is limited to 200 ppm or less .
[0014]
In addition, in the manufacturing method of the invention of this application, it is necessary to remove the components of the gas dissolved in the material, particularly oxygen, in order to produce the high-quality alloy ingot of the invention of this application. In this, calcium is added to platinum and melted to produce calcium oxide, which removes oxygen. When oxide is produced, it floats on the surface of the molten metal, is separated, and is oxidized. A part of the material adheres to the inner wall of the crucible or the like, but unless it is placed in a strong reducing atmosphere, it is reduced again and does not return into the material.
[0015]
Thereafter, it was further found that the target heat-resistant platinum can be obtained by further adding calcium and, if necessary, zirconium to the platinum and uniformly melting the platinum.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Next, a mode to be implemented by the present invention will be described as an embodiment of the present invention with reference to a table as follows.
[0017]
[Example 1]
Insert 2kg of 99.97% pure platinum material and 0.2g of 99.5% or more calcium into a zirconia crucible, dissolve in a non-oxidizing atmosphere in a high-frequency melting furnace, and 3 minutes after the material is completely melted Hold and once solidified.
[0018]
Next, after removing the surface oxide, it was dissolved again, 0.4 g of calcium placed in another container was added, and after complete melting, it was cast into a flat mold having a width of 50 mm and a length of 70 mm, and the cast body After being formed into a plate shape by hot forging, surface cutting is performed, heat treatment is performed in the air at 1000 ° C. for 30 minutes, and then rolling and heat treatment are repeated to obtain a plate with a final working rate of 50% and 90%. A plate-like sample having a thickness of 0.5 mm was produced.
[0019]
When the produced sample was examined by an emission spectroscopic analysis method, it was found that calcium was contained at 180 ppm.
[0020]
[Example 2]
As described above, the same platinum raw material 2 as in Example 1 and 0.2 g of calcium were inserted into a zircoal crucible, dissolved in a non-oxidizing atmosphere in a high-frequency melting furnace, and held for 3 minutes after the material was completely dissolved, Once solidified and then removed of surface oxides, dissolved again, and 0.6 g of calcium placed in a separate container and 0.1 g of zirconium with a purity of 99.6% or more were added, and after complete melting And cast into a flat mold having a width of 50 mm and a length of 70 mm.
[0021]
Subsequent processing was performed in the same manner as in Example 1, and a plate-like sample having a plate thickness of 0.5 mm was prepared with a final processing rate of 50% and 90%.
[0022]
When the prepared sample was examined by an emission spectroscopic analysis method, it was found that 310 ppm of calcium and 45 ppm of zirconium were contained.
[0023]
[Conventional example 1]
Next, for comparison with the above-described embodiments, two examples of the conventional example are as follows.
[0024]
2. Use the same platinum raw material used in Example 1 and insert it into a zirconia crucible, melt in a non-oxidizing atmosphere in a high-frequency melting furnace, and after complete melting, form a flat mold with a width of 50 mm and a length of 70 mm. After casting, processing was performed in the same manner as in Example 1 above, and a plate-like sample having a final thickness of 50% and 90% and a thickness of 0.5 mm not containing calcium and zirconium was produced.
[0025]
[Conventional example 2]
As described above, the same platinum raw material as used in Example 1 was used, and inserted into a zirconia crucible in which calcia powder was pressed on the inner surface, a reducing flame was sprayed from the hot water surface, while reducing calcia, After completely covering the molten metal surface, it is poured into a mold to obtain a cast body, which is processed in the same manner as in Example 1 described above. Produced.
[0026]
When the prepared sample was examined by an emission spectroscopic analysis method, it was found that calcium was contained in an amount of 20 ppm or less.
[0027]
A comparative example of the above-described embodiment and the conventional example is shown below.
[Comparative example]
As described above, the same platinum raw material as used in Example 1 was used with 2 · and calcium.
[0029]
In this case, the calcium amount is 1.2 g, inserted into a zircoa crucible, melted in a non-oxidizing atmosphere in a high frequency melting furnace, completely melted and cast into a flat mold having a width of 50 mm and a length of 70 mm. Processing was performed in the same manner as in Example 1 to prepare a plate-like sample having a plate thickness of 0.5 mm with a final processing rate of 50% and 90%.
[0030]
When the prepared sample was examined by an emission spectroscopic analysis method, it contained 490 ppm of calcium.
[0031]
As described above, each of the prepared samples was subjected to state observation during processing and heat treatment at 1000 ° C. for 2 hours in the air to visually check for defects such as blisters, and the results shown in Table 1 below were obtained. .
[0032]
From these results, it was revealed that defects without deoxidation treatment caused defects during heat treatment, and that addition more than necessary hinders workability.
[Table 1]

[0033]
Further, the high temperature creep characteristics were investigated at a stress of 1.47 MPa and 1300 ° C., and the results shown in the following Table 2 were obtained.
[0034]
From the results, the high-temperature durability increased with the added amount, and brought about twice the effect when no additive was added.
[0035]
As the amount of addition increases, the time to break increases, but the elongation shows a decreasing trend, and the ductility is lost.In the materials shown in the comparative examples, the elongation decreases and breaks. The time was also reduced and embrittlement was observed.
[Table 2]

[0036]
【The invention's effect】
As is apparent from the above, according to the invention of this application, a large amount of calcium can be added, and the high temperature characteristics, particularly the high temperature creep strength, can be improved due to the synergistic effect of the combined addition with calcium and zirconium. Therefore, an excellent effect is obtained in that heat-resistant platinum suitable for crucibles, devices and instrument members that require high-temperature durability can be obtained.
[0037]
Further, since the deoxidation effect and the property improvement effect can be obtained with the additive, no special equipment is required, and the cost can be easily produced in large quantities.

Claims (2)

In heat-resistant platinum to which calcium and other additives are added,
A heat-resistant platinum, wherein the calcium is 101 to 450 ppm , the zirconium is 200 ppm or less , and the other balance is platinum containing inevitable impurities. A method for producing heat-resistant platinum according to claim 1,
While adding calcium to platinum containing inevitable impurities in a non-oxidizing atmosphere and melting it, the dissolved oxygen in the platinum is converted into calcium oxide, and the dissolved oxygen is floated and removed. Further, calcium and zirconium are further added to the platinum. In addition, a method for producing heat- resistant platinum, which is obtained by uniformly melting to obtain heat-resistant platinum .