KR20150028037A - Method for preparing of platinum-rodium-oxide based alloys materials - Google Patents

Abstract

The present invention is to provide a method of preparing platinum-rhodium-oxide based alloys. An embodiment of the present invention provides the method of preparing platinum-rhodium-oxide based alloys, which comprises the steps of: forming an alloy ingot; forming an alloy steel sheet; heat-treating and internally oxidizing the alloy steel sheet; laminating and grinding the internally oxidized alloy steel sheet and pressurizing and molding the same at high temperature; hot working the alloy steel sheet which is pressurized and molded at high temperature; cold working the alloy steel sheet which is hot worked; and heat-treating the alloy steel sheet which is cold worked.

Description

METHOD FOR PREPARING OF PLATINUM-RODIUM-OXIDE BASED ALLOYS MATERIALS [0002]

The present invention relates to a method for producing a high-density oxide dispersion strengthening type platinum-rhodium-oxide alloy.

Dispersion strengthening is a method of strengthening a metal material in which dispersed particles composed of carbides, nitrides and oxides of other metals are dispersed in a metal of a parent phase to improve the mechanical properties of the parent metal by the action of dispersed particles.

Despite its high cost, platinum is mainly used because platinum has a high melting point, is easy to process at room temperature and high temperature, and has excellent chemical resistance, corrosion resistance and volatility.

Conventionally, in order to improve the strength of platinum, platinum materials in which platinum is alloyed with elements such as gold (Au) and rhodium (Rh) have been mainly used. However, due to an increase in the price of alloy elements (for example, gold, rhodium, etc.) recently used as reinforcing elements, in order to replace alloy materials such as Pt-Au and Pt-Rh, A platinum alloy material formed and dispersed is being developed.

For example, there is a platinum alloy in which oxide particles of a metal such as zirconium are dispersed in platinum as a parent metal. The platinum alloy is known to have a high high-temperature creep strength because it has a small amount of crystal grain growth and small deformation even when used at a high temperature of 1200 ° C or higher for a long period of time, has crystallized grains while being interrupted by recrystallization due to metal oxides, It is cheaper.

Such a dispersion-strengthening alloy tends to be deformed by high temperature and high stress, and is excellent in high-temperature creep characteristics and is used as a material and material for a high-quality glass production material for LCD and an apparatus.

As a conventional method for producing an oxide dispersion strengthening type alloy, an alloy ingot having a desired composition was produced, and then platinum alloy powder was produced using plasma. The above method has an advantage in that the content of the oxide element can be easily controlled, but the yield is somewhat lowered due to the scattered powder, and the manufacturing time is increased, so that a high cost is consumed.

Korean Patent No. 1,288,592

It is an object of the present invention to provide a method for producing a high-density oxide dispersion strengthening type platinum-rhodium-oxide alloy having excellent high-temperature creep strength.

In order to achieve the above object, a suitable example of the present invention includes at least one metal for an oxide selected from the group consisting of (i) platinum, (ii) rhodium and (iii) zirconium, samarium, yttrium and hafnium To form an alloy ingot; Melt spinning the alloy ingot to form an alloy thin plate; Subjecting the alloy thin plate to internal oxidation by heat treatment in an atmospheric environment; Laminating or pulverizing an internal oxidized alloy thin plate and subjecting it to hot press forming; Hot working a hot rolled alloy thin plate; Cold working the hot worked alloy sheet; And a step of heat-treating the cold-rolled alloy thin plate.

The alloy ingot may include 5 to 20% by weight of rhodium, based on 100% by weight of the alloy ingot. 0.02 to 0.8% by weight of a metal for an oxide; And a balance of platinum.

The step of forming the alloy thin plate may include melting the alloy ingot under a high vacuum of 10 ^-4 to 10 ^-3 Torr to form a melt; And injecting the inert gas into the melt at a pressure of 0.1 to 1.0 MPa to spray the melt onto the surface of the rotating copper wheel at 500 to 3000 rpm.

Also, the internal oxidizing step may be performed by heat-treating at a temperature of 800 to 1000 ° C for 1 to 5 hours.

The hot pressing may be hot press or hot isostatic molding and may be performed at a pressure of 10 to 50 MPa for 1 to 5 hours at a temperature of 1200 to 1400 占 폚.

Further, the hot working is preferably performed at a temperature of 1000 to 1400 캜.

It is preferable that the cold working is performed at a reduction rate of 40 to 90%.

Also, the heat treatment step may be performed at a temperature of 1200 to 1400 ° C for 1 to 5 hours.

The method for producing a platinum-rhodium-oxide-based alloy according to the present invention is a method for manufacturing a platinum-rhodium-oxide alloy according to the present invention by manufacturing a thin metal plate using a melt spinning method and then oxidizing the metal sheet only by the atmospheric heat treatment, .

Further, the density of the platinum-rhodium-oxide-based alloy can be increased and the high-temperature creep strength can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a process flow chart of a conventional method for producing a platinum-rhodium-oxide-based alloy.
2 is a process flow chart of the method for producing the platinum-rhodium-oxide-based alloy of the present invention.
3 is a transmission electron microscope (TEM) photograph of the alloy thin plate produced in Example 1. Fig.
FIG. 4 is a graph showing relative density results of each step of the platinum-rhodium-oxide-based alloy manufactured in Example 1 and Comparative Example 1. FIG.
5 is an EBSD analysis photograph of the platinum-rhodium-oxide-based alloy produced in Example 1. Fig.
6 is an EBSD analysis photograph of the platinum-rhodium-oxide-based alloy produced in Comparative Example 1. FIG.

Hereinafter, the present invention will be described with reference to Fig.

The present invention relates to a method for producing an alloy ingot comprising: forming an alloy ingot comprising at least one metal selected from the group consisting of (i) platinum, (ii) rhodium and (iii) zirconium, samarium, yttrium and hafnium; Melt spinning the alloy ingot to form an alloy thin plate; Subjecting the alloy thin plate to internal oxidation by heat treatment in an atmospheric environment; Laminating or pulverizing an internal oxidized alloy thin plate and subjecting it to hot press forming; Hot working a hot rolled alloy thin plate; Cold working the hot worked alloy sheet; And a step of heat-treating the cold-rolled alloy thin plate.

Each step of the manufacturing method according to the present invention will be described below.

First, at least one metal selected from the group consisting of (i) platinum (Pt), (ii) rhodium (Rh) and (iii) zirconium (Zr), samarium (Sm), yttrium (Y), and hafnium To form an alloy ingot (Step S100).

For example, in step S100, at least one metal selected from the group consisting of platinum, rhodium, zirconium, samarium, yttrium, and hafnium is mixed and dissolved, and then the mixture is injected into a mold having a predetermined shape to form an alloy ingot.

The content of platinum is not particularly limited, but may be a residual amount such that the total weight of the alloy ingot is 100% by weight.

The rhodium is an element added for solid solution strengthening.

The content of rhodium is not particularly limited, but when it is in the range of 5 to 20% by weight, excellent solid solution strengthening effect can be obtained. If the content of rhodium is less than 5% by weight, solid solution strengthening effect by rhodium can not be obtained. If it exceeds 20% by weight, strength is increased by strengthening of solid solution by rhodium, The improvement in the high-temperature strength of the alloy may deteriorate.

The alloy ingot includes one metal selected from the group consisting of zirconium, samarium, yttrium, and hafnium.

The one or more kinds of metals do not deteriorate the corrosion resistance and can be easily converted into oxides because the degree of oxidation is larger than that of platinum and rhodium and are stable even at a high temperature of 1400 DEG C or more.

The content of the at least one kind of metal is not particularly limited, but when it is 0.02 to 0.8% by weight, excellent dispersion strengthening effect of the alloy can be obtained. When the content of the oxide-based alloy element is less than 0.02% by weight, the dispersion strengthening effect of the platinum-rhodium-oxide-based alloy can not be obtained. When the content is more than 0.8% by weight, the creep strength of the alloy is improved. The dispersion strengthening effect is increased and the workability may be lowered.

Therefore, it is preferable that the content of rhodium and at least one metal be selected within a range in which workability can be maximized while enhancing solid solution strengthening and dispersion strengthening effects.

In addition, in the step S100, since the oxide-based alloy element has superior oxidation resistance compared with platinum or rhodium, it is difficult to control the content of the oxide-based alloy element by oxidation and vaporization when dissolved in the air, desirable.

The melting temperature is not particularly limited, but is preferably performed at 1200 to 1400 占 폚.

Thereafter, the alloy ingot obtained in the step S100 is melt-spun to form an alloy thin plate (step S200).

Since the thin alloy thin plate is formed through step S200, oxidation can be sufficiently performed in a short time even if the heat treatment is performed in an atmospheric environment in step S300.

When the alloy ingot is charged into a nozzle provided in a melt spinning machine and completely melted in a high vacuum of 10 ^-4 to 10 ^-3 Torr to form a melt and then the inert gas is injected into the melt at a pressure of 0.1 to 1.0 MPa for injection, The molten material is spaced apart in the vertical lower portion, and is brought into contact with the surface of the rotating copper wheel (Cu wheel) to be rapidly cooled to form an alloy thin plate.

The inert gas is not particularly limited, but is preferably an argon gas.

Further, the rotation speed of the copper wheel is not particularly limited, but in the case of 500 to 3000 rpm, the melt contacting with the surface of the copper wheel is rapidly cooled and the formed alloy thickness can be adjusted. However, since the metal thin plate is thin, the thickness of the thin plate can be adjusted, preferably about 50 to 200 mu m, because the oxidation can be sufficiently performed in a short time in step S300, and the distance between the melts contacting the copper wheel is adjusted Whereby the thickness of the thin metal plate can be controlled.

Since platinum has a high melting point in the nozzle, quartz or graphite, which is a melting point material, can be used.

Thereafter, the alloy thin plate obtained in the step S200 is subjected to heat treatment in an atmospheric environment and internal oxidation (S300).

By performing the heat treatment in an atmospheric atmosphere, oxides of metals selected from the group consisting of zirconium, samarium, yttrium and hafnium can be uniformly formed in a short time.

The temperature and time of the heat treatment are not particularly limited, but the temperature is preferably 800 to 1200 ° C, and the time is preferably 1 to 12 hours. If the heat treatment temperature is less than 800 ° C or the time is less than 1 hour, the oxidation of the alloy element may not be sufficiently performed. If the temperature exceeds 1200 ° C or the time exceeds 12 hours, The dispersion effect may be deteriorated.

Thereafter, the internal oxidized alloy thin plate obtained in step S300 is laminated or crushed, and hot press-formed (S400).

Through the above step S400, the relative density of the internal oxidized alloy thin plate can be adjusted to 80% or more.

Examples of the hot press molding include, but are not limited to, a hot press (HP) or a hot isostatic press (HIP).

The temperature and time for the high-temperature press-molding are not particularly limited, but it is preferable that the pressure and the pressure are 10 to 50 MPa for 1 to 5 hours at a temperature in the range of 1200 to 1400 ° C. When the temperature of the high-temperature press-molding is 1200 占 폚, the time is 1 hour, or the pressure is less than 10 MPa, a high-density sintered body can not be obtained and when the temperature exceeds 1400 占 폚 or the time exceeds 5 hours, If the pressure exceeds 50 MPa, it may lead to danger of applied mold and equipment.

Thereafter, the alloy thin plate obtained in the step S400 is hot-worked (S500).

In step S500, hot working is a step for obtaining a high-density alloy. Through this, the relative density of the alloy thin plate obtained in step S400 can be adjusted to 98% or more. Examples of the hot working include hot rolling, hot forging, and the like, but are not limited thereto.

If the relative density is less than 98%, the remaining pores are not removed during the hot working even if the relative density is higher than 99% due to subsequent cold working, and the blisters There is a high possibility that a blister occurs or internal bonding occurs.

The temperature of the hot working is not particularly limited, but is preferably performed in a temperature range of 1000 to 1400 캜. When the temperature is less than 1000 ° C, cracks tend to occur during hot working, and it is difficult to ensure high density of the alloy. When the temperature exceeds 1400 ° C, the effect of strengthening dispersion of the alloy may be deteriorated due to coarsening of the alloy element for oxide .

Meanwhile, the alloy thin plate obtained in step S500 may be heat-treated before step S600. This makes it possible to prevent the occurrence of cracks during cold working.

After the hot working, cold working for thickness control is performed (step S600).

Examples of the cold working include, but are not limited to, cold rolling and cold forging. Cold rolling is preferably performed.

The reduction rate of the cold rolling is not particularly limited, but is preferably 40 to 90%. If the reduction rate is less than 40%, the processing stress is low and recrystallization may not occur even after the subsequent heat treatment. If the reduction rate exceeds 90%, the alloy may be broken due to high processing stress.

After the cold working, heat treatment is performed for recrystallization of the microstructure (step S700).

The conditions of the temperature and time of the heat treatment are not particularly limited, but it is preferable that the heat treatment is performed at a temperature in the range of 1200 to 1400 占 폚 for 1 to 5 hours. Recrystallization of microstructures can be suppressed when the temperature is 1200 占 폚 or less than 1 hour, and when the temperature exceeds 1400 占 폚 or the time exceeds 5 hours, the crystal grains and oxides can coarsen and the hardness can be lowered.

Hereinafter, the present invention will be described concretely with reference to Examples. However, the following Examples and Experimental Examples are merely illustrative of one form of the present invention, and the scope of the present invention is not limited by the following Examples and Experimental Examples .

Example  One

99.7% by weight of PtRh10 having a purity of 3N5 and 0.3% by weight of Zr having a purity of 3N were charged and dissolved in a vacuum high-frequency induction melting furnace, and solidified to obtain an alloy ingot. Then, the alloy ingot was charged into a nozzle of a melt-spinning machine, and then Ar gas was pressurized at 0.3 to 0.5 MPa to spray the melted material onto the surface of the copper wheel to obtain an alloy thin plate. At this time, the rotational speed of the copper wheel was set to 500 to 3000 rpm. The resulting alloy thin plate was heat-treated at 800 to 1000 ° C for 1 to 5 hours in an atmospheric environment to prepare an internally oxidized alloy thin plate.

Then, the internal oxidized alloy thin plate was laminated or crushed, and pressed and sintered at 1400 캜 for 2 hours under a pressure of 20 MPa. The relative density of the alloy sheet after pressure sintering was measured to be 86.5%. Then, hot forging was performed at a temperature of 1200 캜. The relative density of the alloy sheet after hot forging was measured to be 98.0%. Thereafter, cold rolling was performed at a reduction ratio of 40%. The relative density of the alloy sheet after cold rolling was measured to be 99.9%. Then, the resultant was subjected to a heat treatment at 1200 ° C for 1 hour in air to prepare a platinum-rhodium-oxide-based alloy.

A transmission electron microscope (TEM) photograph of the inner oxidized alloy thin plate is shown in FIG. It was found that Zr metal oxides having a size of about 200 nm were uniformly dispersed along the grain boundaries.

Comparative Example  One

99.7% by weight of PtRh10 having a purity of 3N5 and 0.3% by weight of Zr having a purity of 3N were charged and dissolved in a vacuum high-frequency induction melting furnace, and solidified to obtain an alloy ingot. Thereafter, the pressure was reduced to 10 ^-3 Torr by using a vacuum pump attached to the plasma equipment, and Ar gas was used as a reaction gas to form a plasma. The alloy ingot was melted and the plasma power was raised to produce a powder. The obtained powder was put into a square shaped carbon mold and heat-treated at 1300 ° C for 2 hours in an Ar atmosphere to prepare a molded body and then heat-treated at 1400 ° C for 2 hours in the air to prepare an internally oxidized molded body.

Thereafter, the internally oxidized shaped body was pressure-sintered at 1400 DEG C for 2 hours at a pressure of 20 MPa. The relative density of the compact after pressure sintering was measured to be 93.4%. Then, hot forging was performed at a temperature of 1200 캜. The relative density of the compact after hot forging was measured to be 97.6%. Thereafter, cold rolling was performed at a reduction ratio of 40%. The relative density of the compact after cold rolling was measured to be 99.2%. Then, the resultant was subjected to a heat treatment at 1200 ° C for 1 hour in air to prepare a platinum-rhodium-oxide-based alloy.

Experimental Example  1. Determination of the content of alloy elements

The elemental content of the ingot and alloy thin plate of Example 1 was confirmed by ICP analysis. The results are shown in Tables 1 and 2, respectively.

≪ Elemental Content of Ingot of Example 1 > element content
(weight%) element content
(weight%) element content
(weight%) Ag 0.0002 Fe 0.0027 Ru 0.0016 Al 0.0015 Ir 0.0026 Sb 0 As 0 Mg 0.0002 Si 0.0043 B 0 Mn 0.0001 Sn 0.0029 Bi 0 Mo 0 Te 0 Ca 0.0009 Ni 0.0002 Ti 0 CD 0 Os 0 W 0.0070 Co 0.0013 Pb 0 Zn 0.0001 Cr 0.0003 Cu 0.0011 Zr 0.2156

<Elemental Content of Alloy Sheet of Example 1> element content
(weight%) element content
(weight%) element content
(weight%) Ag 0.0001 Fe 0.0028 Ru 0.0006 Al 0.0018 Ir 0.0082 Sb 0 As 0 Mg 0.0002 Si 0.0017 B 0 Mn 0.0005 Sn 0.0047 Bi 0 Mo 0.0010 Te 0 Ca 0.0022 Ni 0.0017 Ti 0.0002 CD 0.0001 Os 0 W 0 Co 0.0001 Pb 0 Zn 0.0031 Cr 0.0009 Cu 0.221 Zr 0.2444

As shown in Table 1, in the case of the platinum-rhodium-oxide-based ingot, the zirconium content as the oxide alloy element is 0.2156 wt%, which is similar to the target composition. Also in the platinum-rhodium- And the content thereof is 0.2444% by weight.

Experimental Example  2. Relative density measurement

The relative densities of the platinum-rhodium-oxide-based alloys prepared in Example 1 and Comparative Example 1 were measured after pressure sintering, hot forging and cold rolling, respectively, and the results are shown in FIG.

As shown in Fig. 4, the alloy of Comparative Example 1 showed higher relative density than the alloy of Example 1 in the case of the pressure-sintered platinum-rhodium-oxide alloy, but the hot forging and cold rolling processes In one case, the relative density of the alloy of Example 1 was higher than that of the alloy of Comparative Example 1. The relative density of the alloy of Example 1 which was cold-rolled by using the Archimede method was 99.9%, which was considerably high.

Experimental Example  3. EBSD  analysis

EBSD analysis was performed on the cross section of the platinum-rhodium-oxide alloy prepared in Example 1 and Comparative Example 1, and the results are shown in FIGS. 5 and 6, respectively.

As shown in Fig. 5, when the structure of the alloy after cold rolling (Example 1) is observed, it can be seen that the crystal grains are arranged along the rolling direction. Further, even after the 1500 ℃ high temperature heat treatment, grain growth is suppressed by the distribution of fine ZrO ₂ oxide, equiaxed crystals crystal grains can be seen the remains. However, in the case of the alloy of Comparative Example 1, after the high-temperature heat treatment, it is found that the crystal grains are coarsened by recrystallization of the structure.

Claims (9)

(i) forming an alloy ingot comprising platinum, (ii) rhodium and (iii) at least one metal selected from the group consisting of zirconium, samarium, yttrium and hafnium;
Melt spinning the alloy ingot to form an alloy thin plate;
Subjecting the alloy thin plate to internal oxidation by heat treatment in an atmospheric environment;
Laminating or pulverizing an internal oxidized alloy thin plate and subjecting it to hot press forming;
Hot working a hot rolled alloy thin plate;
Cold working the hot worked alloy sheet; And
Step of heat-treating the cold-worked alloy thin plate
Rhodium-oxide-based alloy. The method according to claim 1,
The alloy ingot may comprise, based on the total 100 weight percent,
5 to 20% rhodium;
0.02-0. 8% by weight of one or more metals; And
A method for producing a platinum-rhodium-oxide-based alloy comprising a remaining amount of platinum. The method according to claim 1,
The step of forming the alloy thin plate
Melting the alloy ingot under a high vacuum of 10 ^-4 to 10 ^-3 Torr to form a melt;
Injecting inert gas into the melt at a pressure of 0.1 to 1.0 MPa to spray the melt onto the surface of a rotating copper wheel at 500 to 3000 rpm
Rhodium-oxide-based alloy. The method according to claim 1,
Wherein the internal oxidation step is performed at a temperature of 800 to 1000 DEG C for 1 to 5 hours. The method according to claim 1,
Wherein the high-temperature press-molding is a hot-press or high-temperature isostatic molding. The method according to claim 1,
Wherein the high-temperature press-molding is performed at a pressure of 10 to 50 MPa for 1 to 5 hours at a temperature of 1200 to 1400 占 폚. The method according to claim 1,
Wherein the hot working is performed at a temperature of 1000 to 1400 占 폚. The method according to claim 1,
Wherein the cold working is performed at a reduction ratio of 40 to 90%. The method according to claim 1,
Wherein the heat treatment is performed at a temperature of 1200 to 1400 占 폚 for 1 to 5 hours.

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