KR101279553B1 - Method of manufacturing an oxide dispersion strengthened platinum materials using a plasma process - Google Patents

Abstract

The present invention relates to a method for producing an oxide dispersion-enhanced platinum material obtained by finely dispersing a platinum alloy powder and an oxide using plasma, and a manufacturing process in the production of platinum alloy powder and oxide dispersion-enhanced platinum material by conventional wet and dry methods. It is designed to overcome the disadvantages of complicated and high manufacturing cost as well as long time.
To this end, after the addition of the alloying element of the target composition to the platinum to produce a platinum alloy ingot, to produce a platinum alloy powder using an environmentally friendly plasma method, the prepared platinum powder is added to produce a shaped body, high temperature oxidation After improving the density through heat treatment and high temperature pressurized sintering, an object of the present invention is to produce an oxide dispersion-enhanced platinum material in which fine oxides are dispersed through hot working and cold working.

Description

Method of manufacturing an oxide dispersion strengthened platinum materials using a plasma process}

The present invention is to produce a platinum alloy powder by using an environmentally friendly plasma, and to manufacture an oxide dispersion-enhanced platinum material using the same, platinum devices used in the glass-related industries (melting device, Crucible, The present invention relates to a method for producing a platinum material which is widely used where high strength is required.

Platinum is a face-centered cubic structure, which is easy to process at room temperature and high temperature, has a high melting point, chemical stability at high temperature, resistance to oxidation and volatility, and excellent corrosion resistance to acids and chemicals. It is used for various purposes.

In particular, with the recent growth of the LCD industry, platinum has been widely used in materials and devices for manufacturing high-quality glass for LCDs. In order to manufacture such a high-quality glass, platinum material having a stronger strength than that of conventional platinum is used. In order to improve the strength of platinum, conventionally, platinum (Au), rhodium (Rh), etc. are alloyed with platinum and solid-solution strengthened. Although a lot of materials have been used, alloy elements used as reinforcing elements have a high cost and have a disadvantage of coloring according to alloying components, and recently, they have been replaced by oxide dispersion-reinforced platinum materials having higher high temperature strength than these alloys.

In order to solve the problems of the solid solution strengthened platinum material, using elements such as zirconium (Zr), samarium (Sm), yttrium (Y), europium (Eu), hafnium (Hf), which is superior to the platinum Platinum materials that form and disperse oxides have been developed. Platinum materials containing these oxides have no grain growth and little deformation even when used for a long time at high temperatures of more than 1200 ° C. It is known to have crystal grains and exhibit high high temperature creep strength.

As a conventional manufacturing method for the oxide dispersion-enhanced platinum material, a wet method and a dry method are known by a method of producing platinum powder. In the wet method, the powder to be used is prepared by the wet method by chemicals such as acid, and is manufactured by cold isotropic pressure forming (CIP), pressure sintering, oxidation heat treatment, hot working, and cold rolling to produce the final platinum material. The process is difficult to control the content of the oxide element due to the difficulty in controlling the chemical reaction due to the wet method characteristics, there is a disadvantage in that it takes a long time to manufacture the powder and the manufacturing cost increases.

In the dry method, in order to facilitate the control of the content of the oxide element of the wet method, vacuum melting and alloying, the alloy material is wired and sprayed on a water-cooled curtain using an arc spray device to powder And the final platinum material through powder pulverization, degassing, molding, hot working and cold rolling, which has the advantages of easier control of oxide content and uniform product characteristics compared to the wet method. Due to the complexity of the process, there is a concern that the purity of platinum material may decrease, and the cost may increase, and the overall manufacturing time may increase.

In the present invention, in the production of platinum-dispersed platinum material, by introducing the world's first environmentally friendly plasma method, instead of the conventional wet method to produce a powder, significantly shorten the powder manufacturing time and at the same time minimize the contamination of the powder of high purity An object of the present invention is to prepare a platinum powder, and to produce an oxide dispersion-enhanced platinum material using the same.

To solve this problem, a platinum alloy ingot is prepared by adding an alloying element of platinum to a target composition, and a platinum alloy powder is prepared using plasma, followed by fabrication of a molded body through atmospheric heat treatment, oxidation heat treatment, high temperature pressurization heat treatment, and hot working. It is aimed to produce oxide dispersed platinum material by cold working and final recrystallization heat treatment.

The present invention is to prepare a platinum alloy ingot of the target composition by adding the alloying composition of the target composition to the platinum in a vacuum atmosphere or inert atmosphere, to prepare a platinum alloy powder using plasma, the platinum through a pressureless vacuum or atmosphere heat treatment It is characterized in that the production of alloy compacts, oxidation of alloy elements through high temperature atmospheric heat treatment, high density sintered compacts through high temperature press molding, and hot dispersion, cold working and recrystallization heat treatment to produce oxide dispersion-enhanced platinum material. .

In the production of powder of oxide dispersion-enhanced platinum material, when the wet method known in the art is applied, it is difficult to control the content of alloying elements and handles dangerous acid solutions such as nitric acid and hydrochloric acid, and therefore there are considerable restrictions on handling. There is a disadvantage that it takes a long time to prepare the powder by the repeated process of condensation and purification.

In addition, in the case of the recently known dry method, the content control and the high temperature creep strength of the oxide element have been improved, compared with the wet method, but it has a disadvantage in that it takes a long time to manufacture the platinum alloy powder and the platinum material.

However, the core structure of the present invention is to use a dry method rather than a wet method in the production of the oxide dispersion-enhanced platinum powder, and by using a plasma rather than a spray method to significantly reduce the production time of the platinum alloy powder, and strengthened platinum by eliminating the grinding process The contamination of the powder can be minimized, and the overall manufacturing time is also reduced.

1 is a FESEM image taken after classification to a predetermined size or less for the Pt-Zr powder prepared by the plasma according to an embodiment of the present invention.
2 is a view showing the TEM and component analysis results of the oxide dispersion-enhanced platinum material prepared according to an embodiment of the present invention.

In preparing the oxide dispersion-enhanced platinum material, the vacuum melting method is applied to the production of the platinum alloy ingot, and the powder is manufactured by using plasma, which is an environmentally friendly method, in the production of the platinum alloy powder. Through this, it is possible to produce a platinum alloy powder with a reduced production time and minimized contamination compared to conventional wet and dry powder manufacturing methods.

The production method for producing an oxide dispersion-enhanced platinum material comprises the steps of: adding an alloying element to platinum to produce a platinum alloy ingot; Preparing a platinum alloy powder using a plasma on the prepared platinum alloy ingot; Preparing a molded article through a pressureless heat treatment to the platinum alloy powder and a oxidized platinum alloy molded article of an oxide element through queuing; Improving the density of the molded body subjected to the oxidative heat treatment through hot pressing; And manufacturing the final material through hot working, cold working and recrystallization heat treatment.

Hereinafter, each process step will be described in detail.

First, a platinum alloy ingot is prepared by adding an alloying element of the target composition to pure platinum.

At this time, as a metal element to be added as an alloying element, zirconium (Zr), samarium (Sm), yttrium (Y), europium (Eu), hafnium (Hf) and the like are added to prepare a platinum alloy ingot. Although various kinds of alloying elements can be added, it is preferable to select an element having a higher oxidation degree than platinum (Pt) without sacrificing corrosion resistance in view of the use in the glass industry. The amount of alloying element added is characterized in that 0.02 wt% to 1 wt%, the dispersion strengthening effect is not obtained at less than 0.02 wt%, the dispersion strengthening effect by the residual dispersed particles is increased when it exceeds 1 wt% There is a disadvantage in that workability is lowered. Therefore, the amount of the alloying element and the alloying element is characterized in that the workability is improved while maximizing dispersion strengthening effect. These elements are more oxidative than platinum (Pt), but when dissolved in the air, it is difficult to control the content of the target composition by oxidation and vaporization, so it is preferable to carry out in a vacuum or inert atmosphere.

A platinum alloy powder is prepared by using plasma in a prepared platinum alloy ingot.

The plasma equipment used in the present invention is composed of a vacuum reaction chamber, a quenching part, and a filter part. In the vacuum reaction chamber, raw material input, decompression by a vacuum pump, reaction gas input and power plasma formation, and raw material after plasma formation It is characterized in that it is melted and vaporized and moved to the quenching portion by vacuum pump and cold gas induction to obtain fine powder in the filter portion.

A platinum alloy ingot is introduced into the plasma equipment chamber. Molybdenum (Mo), tungsten (W), copper (Cu), graphite, etc. may be used as the material of the mold, and it is preferable to minimize contamination by the mold. If contaminants remain, the purity of the final strengthened platinum material is lowered, which affects the quality. In order to form a plasma, after inputting raw materials, a vacuum apparatus is used to inject a plasma forming gas after depressurization, and a predetermined power is input to form a plasma. Plasma power application to produce the powder is advantageous to initially form a plasma with a low power of 10 kw or less to heat up and melt the platinum alloy ingot, and to increase the plasma power to vaporize and scatter the powder when melting is completed. This is because when the plasma power is increased from 10 to 10 kw or more, it is difficult to prepare fine and uniform powder due to the boiling of the molten metal due to the rapid temperature rise or the instability of the molten metal.

The prepared platinum alloy powder is used to prepare a molded body through a pressureless heat treatment and to prepare an oxide-treated platinum alloy molded body of an oxide element through queuing.

The size of the platinum alloy powder prepared by using plasma is variously distributed in the range of several tens of nm to several tens of micrometers. In order to show uniform physical properties of the final oxide dispersion-enhanced platinum material, the prepared powder is classified and a powder having a constant size It is preferable to use.

The platinum alloy molded body is manufactured by manufacturing a mold internal shape into a desired shape, and injecting a platinum alloy powder prepared by using a plasma into the mold and then performing heat treatment. In this case, the oxidized platinum alloy molded body may be manufactured by heat treatment in an atmosphere of vacuum or pressureless inert atmosphere.

At this time, the heat treatment conditions are preferably carried out for 1 to 5 hours at a temperature of 1000 ℃ to 1400 ℃, when the alloy is less than 1000 ℃ or less than 1 hour is easy to break the platinum alloy molded body is difficult to manufacture a healthy platinum alloy molded body and alloy The oxidation of the element may not be sufficient, and if the temperature is higher than 1400 ° C. and the time is longer than 5 hours, there is a disadvantage in that the dispersion strengthening effect due to coarsening of alloying elements is lowered.

In addition, since the mold is expensive and there is a possibility that the mold may be damaged or broken when used at high temperature in the air, firstly, a sound platinum alloy molded body is manufactured by using a carbon mold in a vacuum or in an inert atmosphere, and oxidation of the alloying element is performed in a post process. After removing the mold, only the platinum alloy molded article is heat-treated in air to prepare the oxidized platinum alloy molded article. When manufacturing a platinum alloy molded body, it is necessary to sufficiently oxidize the alloying element, which is easier to oxidize than platinum, and for this purpose, a low density platinum alloy molded body which is advantageous for oxidation should be manufactured. It is advantageous to produce a type platinum material.

The high-density sintered compact is manufactured through high temperature press molding on the oxidized platinum alloy compact.

High-density can be achieved by hot forging or hot rolling on the oxidized platinum alloy molded body.However, due to the low density of the molded body, it is often damaged during hot processing. The purpose is to facilitate the hot working and cold working after manufacturing.

Applicable hot press molding process can be hot press or hot isostatic press, and the hot press molding process condition is 1 to 5 hours in the temperature range of 1200 ° C to 1400 ° C. It is preferred to produce at a pressure of from 50 MPa. If the temperature is less than 1200 ℃ or the sintering time and pressure is low, it is disadvantageous to obtain a high density sintered body, if the temperature is 1400 ℃, the sintering time is more than 5 hours, there is a high possibility of deterioration of characteristics due to the coarsening of the oxide, when the pressure is high, This is undesirable because the risk of the application molds and equipment can be increased resulting in costly losses.

The final oxide dispersion-enhanced platinum material is produced by hot working and cold working on a sintered body densified by high temperature pressing.

The hot working process is a process applied to secure the density close to the theoretical density, and is preferably carried out by introducing a process that is easy to apply during hot rolling, hot forging or hammering. In the case of reinforced platinum manufactured by hot working, it is desirable to have a relative density of 98% or more. If a relative density of 98% or less is used, even if a relative density of 99% or more is secured after subsequent cold working, it remains during hot working. This is because the relative density due to the decrease in the cross-sectional area of one pore is increased, and the possibility of the occurrence of a blister due to the final recrystallization heat treatment is high. Relative density = (manufactured dispersion-enhanced platinum specific gravity / theoretical specific gravity) x 100 Therefore, the measurement specific gravity of the dispersion-reinforced platinum prepared by the present invention is 21.06, and the theoretical specific gravity of the dispersion-reinforced platinum is 21.39 gr / cm ³ , and in the present invention, the relative density of 98% or more means that the relative density of 98.5% = (21.06 /21.39) x 100. In the case of hot working, the processing temperature is appropriately carried out at 1100 ℃ to 1400 ℃. If it is lower than 1100 ℃, it is easy to cause cracks during hot working, and it is difficult to secure high density. This is because the characteristics of the oxide dispersion-enhanced platinum material may be deteriorated due to coarsening.

After hot working, it is also preferable to perform annealing and cold working in order to prevent the occurrence of cracking during cold working. At this time, the purpose of introducing the processing tissue is to recrystallize through the post-heat treatment to homogenize the tissue first, and also to increase the size through cold working. The reduction ratio is suitably 50 to 90% reduction ratio so that recrystallization can occur through subsequent heat treatment. This is because recrystallization may not occur when the processing stress is lower than 50%, and the breakage of the material is high due to the high processing stress when it is 90% or more.

It is preferable to heat-treat the cold worked material in the air at a temperature range of 1200 ° C. to 1400 ° C. for 1 to 5 hours. When the temperature is below 1200 ° C. or 1 hour or less, recrystallization of the microstructure may be suppressed. If the temperature is 1400 ° C. or more or 5 hours or more, grains and oxides are coarsened and high temperature strength may be lowered, which is not preferable.

[ Example ]

500 g of Pt-0.3 wt% Zr ingot were prepared using a vacuum high frequency induction furnace. For the prepared ingot, Pt-Zr powder was prepared by using a DC plasma equipment, the manufacturing process is as follows. After depressurization to 10 ^-3 torr using a vacuum pump attached to the plasma equipment, plasma was formed by using Ar as a reaction gas, thereby melting the ingot and further increasing the plasma power to prepare a powder. And the final Pt-Zr powder was collected by the quenching part and the like. Table 1 shows the process conditions for producing Pt using plasma.

Process item Process conditions - Examples Tier 1 (Low Power) Step 2 Applied plasma output 5 Kw 30 Kw Reaction gas for plasma Furtherance Ar Ar Gas flow rate 20 L / min 20 L / min Gas composition for cooling (flow rate) Ar + N ₂ (150L / min) Ar + N ₂ (150L / min)

The result of FESEM image analysis after classifying the Pt-Zr powder prepared by plasma below a certain size is shown in FIG. 1.

From Fig. 1, in the case of the platinum alloy powder produced by plasma, spherical powder of 1 mu m or less, which is a characteristic of the vaporized powder, is also observed.

Table 1 shows the results of ICP analysis to confirm the alloying element content of the platinum alloy powder prepared by plasma.

(Unit: wt%) element Example element Example element Example Al 0.0000 Fe 0.0010 Ru 0.0020 As 0.0001 Ir 0.0000 Sb 0.0000 Au 0.0001 Mg 0.0000 Si 0.0000 B 0.0001 Mn 0.0000 Sn 0.0029 Bi 0.0000 Mo 0.0010 Te 0.0000 Ca 0.0000 Ni 0.0000 Ti 0.0050 CD 0.0001 Os 0.0000 Wo 0.0000 Co 0.0001 Pb 0.0000 Zn 0.0070 Cr 0.0003 Pd 0.0020 Zr 0.2770 Cu 0.0007 Rh 0.0100

As shown in Table 2, in the case of the prepared platinum alloy powder, the Zr content, which is an alloying element, showed 0.28 wt% similar to the target composition, and exhibited a high purity of PN purity 3N5 except for the Zr content, thereby making it possible to manufacture a healthy platinum alloy powder. It was.

The prepared powder was placed in a square molded carbon mold and heat-treated at 1300 ° C. for 2 hours in an argon (Ar) atmosphere to prepare a molded product. The molded product was heat-treated at 1400 ° C. for 2 hours in air for oxidation treatment. It was. Oxidized specimens were subjected to high temperature pressing at 20 MPa pressure for 2 hours at 1300 ℃ to ensure high density, and final oxide dispersion strengthened platinum by hot rolling, cold rolling and heat treatment at 1300 ℃ for ultra high density. The material was prepared.

For comparison, after the reinforced platinum powder was manufactured by using the wet method, which is a conventional manufacturing method, an oxide dispersion-enhanced platinum material was prepared by manufacturing a molded body, oxidation treatment, pressure sintering, hot working, and cold working as described above. The characteristics were compared (Comparative Example 1). In addition, commercially available 0.3 wt% Pt-Zr-reinforced platinum material was analyzed and compared to improve the reliability of the physical property evaluation (Comparative Example 2).

The preparation time, relative density, purity, zirconium (Zr) content, and physical properties of the reinforced platinum material are shown in Table 3, and the Blister test results are shown in Table 4, respectively.

Item Example Comparative Example 1 Comparative Example 2 Manufacturing period (days) 2 10 - Relative density (%) 99 ↑ 99 ↑ 99 ↑ Zr content (wt%) 0.28 0.23 0.16 Purity (excluding Zr content) 3N5 2N9 3N2 Hardness (Hv) 89 87 78

Example Comparative Example 1 Comparative Example 2 1200 ℃ x1hr Blister None Blister None Blister None 1500 ℃ x1hr Blister None Blister None Blister None

It can be seen from Table 3 that the oxide dispersion-enhanced platinum material produced by the present invention significantly reduces the production period, and the platinum has the highest purity. In particular, it can be seen that the present invention is very advantageous to control the zirconium (Zr) content from the results of the Zr content similar to the target composition compared to the platinum material prepared by the wet method. In the thermal stability evaluation result, which is a major characteristic of the oxide dispersion strengthening (Table 4), the present invention showed thermal stability equivalent to that of the platinum material manufactured by the wet method and commercially available oxide dispersion-reinforced platinum.

2 shows the results of TEM analysis for analyzing the oxide of the oxide dispersion-enhanced platinum material prepared by the present invention. From the TEM analysis result (FIG. 2), the present invention enabled the production of platinum material in which Zr oxide of 100 nm size was distributed.

Claims (12)

In manufacturing the oxide dispersion-enhanced platinum material using plasma,
Adding an alloying element to platinum to produce a platinum alloy ingot;
Preparing a platinum alloy powder using a plasma on the prepared platinum alloy ingot;
Preparing a molded article through a pressureless heat treatment to the platinum alloy powder and a oxidized platinum alloy molded article of an oxide element through queuing;
Improving the density of the molded body subjected to the oxidative heat treatment through hot pressing; And
A method of producing an oxide dispersion-enhanced platinum material using plasma, comprising the steps of preparing a final material through hot working, cold working and recrystallization heat treatment. The method of claim 1,
The alloying element added in the step of manufacturing the platinum alloy ingot is any one selected from zirconium (Zr), samarium (Sm), yttrium (Y), europium (Eu), hafnium (Hf) using a plasma Method for producing oxide dispersion strengthened platinum material. 3. The method according to claim 1 or 2,
The method for producing an oxide dispersion-enhanced platinum material using a plasma, characterized in that the amount of alloying elements added in the step of producing the platinum alloy ingot is 0.02 wt% to 1 wt%. The method of claim 1,
The material of the mold used in the production of the platinum alloy powder using plasma is any one selected from graphite, copper (Cu), molybdenum (Mo), platinum (Pt) or tungsten (W). Method for producing an oxide dispersion-enhanced platinum material using a plasma. The method of claim 1,
The step of preparing the platinum alloy molded body is heat-treated for 1 to 5 hours at a temperature of 1000 ℃ to 1400 ℃ in a vacuum or inert atmosphere, followed by heat treatment for 1 to 5 hours at a temperature of 1000 ℃ to 1400 ℃ in air Method for producing an oxide dispersion-enhanced platinum material using a plasma. The method of claim 1,
The high pressure pressing molding the molded body is produced by hot pressing or high temperature isostatic molding. The method according to claim 6,
The high-temperature press molding to the molded body is carried out at a temperature of 1200 ℃ to 1400 ℃, 5 to 50 MPa pressure, 1 to 5 hours, characterized in that the production method of the oxide dispersion strengthening platinum material using plasma. The method of claim 1,
The hot working is a method of producing an oxide dispersion-enhanced platinum material using plasma, characterized in that any one selected from hot rolling, hot forging or hammering (Hamering) process. The method of claim 8,
The hot working is a method of producing an oxide dispersion-enhanced platinum material using a plasma, characterized in that carried out at a temperature of 1100 ℃ to 1400 ℃. The method of claim 1,
A method of producing an oxide dispersed strengthening platinum material using plasma, characterized in that the relative density of the hot worked platinum material is 98% or more. The method of claim 1,
The cold working method is a method of manufacturing an oxide dispersion-enhanced platinum material using a plasma, characterized in that the cold-worked platinum alloy molded body is cold worked at a reduction ratio of 50% to 90%. The method of claim 1,
The recrystallization heat treatment is a method of producing an oxide dispersion-enhanced platinum material using a plasma, characterized in that the cold-processed platinum material is heat-treated for 1 to 5 hours at a temperature of 1200 ℃ to 1400 ℃.

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