JP2004360001A - Hardened high-purity platinum, and its product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a jewelry market with, as high-purity platinum for personal ornaments capable of gaining a Pt1,000 qualification, hardened pure platinum which is provided with a hardened surface-layer part and made scratch resistant by allowing, in order to obtain high-hardness high-purity platinum, hardening elements to diffuse and penetrate into a surface-layer part (up to about 100 μm) of high-purity platinum and alloying these hardening elements and the platinum. <P>SOLUTION: The hardened pure platinum can be obtained by coating the surface of Pt of 99.9% purity with one or more kinds among platinum-group elements other than platinum and metallic elements other than the platinum-group elements to 0.1 to 100 μm thickness by PVD, CVD, plating, etc., and then applying high-temperature heat treatment to the coated pure platinum for a long period of time to allow ≥98% of the above elements used in the coating treatment to diffuse and penetrate into the pure platinum and form a hardened layer in its part. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
Jewelry such as rings, pendants, earrings, brooches, and chains are made of gold, silver, platinum, and alloys based on these.Especially neat white, and platinum and its alloys that are heavy and luxurious Jewelry is preferred in Japan. Platinum jewelry is classified according to the purity of platinum. Pt = 99.9% or more pure platinum (denoted as Pt1000), platinum purity of 95% (Pt950), 90% (Pt900), 85% of ( Pt850) There are 4 grades. Among these four types of pure platinum and platinum alloy products, jewelry made of pure platinum, that is, Pt1000, has a pure platinum unique white color that is more favorable to consumers than platinum alloy. However, since pure platinum is soft (hardness is Hv = 40), the surface is easily damaged. If the surface of pure platinum jewelry is damaged, the shine of pure white of platinum will be impaired, which will lead to a reduction in aesthetics and commercial value. In order to improve this point, the present invention diffuses and penetrates a metal element effective for hardening platinum on the surface of pure platinum, forms a hardened layer on the surface of pure platinum, makes it difficult for scratches to be formed, and forms platinum. It is a new pure platinum jewelry that will keep the beautiful white shine for a long period of time.
[0002]
[Prior art]
Conventionally, pure platinum jewelry, that is, rhodium plating, ruthenium plating, or the like is applied to the jewelry surface of “Pt1000” to form a 0.2-0.5 μm hardened protective film to prevent damage to the surface of “Pt1000” jewelry. Was.
Further, recently, a hard intermetallic compound of platinum and boron (B) is formed on the surface of pure platinum, or zirconium (Zr), silicon (Si), magnesium (Mg), aluminum (AI), calcium A hardened surface layer is formed by alloying an element such as (Ca) with platinum or boron (B) contained in a trace amount, and is provided on the market as hardened “Pt1000” jewelry.
[0004]
[Problems to be solved by the invention]
The "Pt1000" jewelry with a platinum purity of 99.9% tends to be scratched when worn as a jewelry because the material itself is too soft. At one end, if the surface of the “Pt1000” jewelry is scratched, the part is easily stained, and diffused reflection of visible light occurs, reducing the shine of pure platinum pure white. The value will be impaired and the commercial value will drop significantly. The present invention has been made to overcome this problem, and has as its main purpose the manufacture of high-purity “Pt1000” jewelry, which is highly desired in the jewelry industry and is less likely to have scratches.
[0005]
[Means for Solving the Problems]
The nominal purity of platinum engraved with Pt1000 is 99.9%, so that 0.1% may contain other elements. Therefore, from the viewpoint of producing a hardened Pt1000 with 0.1%, a metal element for increasing hardness is diffused and infiltrated into the surface layer of pure platinum to solid-solution strengthen only the very surface of the Pt1000 jewelry, and the surface hardness is remarkable. It is characterized in that a cured layer is formed by ascending.
[0006] Among the platinum group elements, elements other than platinum (Pd, Rh, Ru, Ir, Os) or alloys thereof (including alloys with platinum) are used for PVD, CVD, plating, or powders of these elements. An organic solvent, a plasticizer, and the like are mixed to form a paste, and the paste is applied to the Pt1000 surface to coat the Pt1000 surface.
[0007] A single element or an alloy of tantalum (Ta), niobium (Nb), tungsten (W), zirconium (Zr), or the like, or an alloy of these metal elements and a platinum group element may be coated. Next, Pt1000 coated with these metals and alloys is coated in a vacuum, in an inert gas atmosphere, or in the case of a coated metal with low high-temperature oxidation at a temperature lower than the melting point of platinum for 2 to 60 hours in the atmosphere. The diffused metal element is diffused and penetrated into the surface layer portion of Pt1000 at 0.1 to 100 μm. At this time, the concentration of the permeated metal is 60 to 99% at the outermost surface of Pt1000 of 0.5 to 1 μm, and the concentration is gradually reduced to around 100 μm from here.
For diffusion and infiltration, HIP (high-temperature isostatic press) may be used to carry out treatment in an argon atmosphere at 600 to 1200 ° C. and 500 to 1000 kg / cm ² for 5 to 20 hours.
Alternatively, Pt1000 may be buried in a powder of Pd, Rh, Ru, Ir, Os or the like, and heated at a temperature lower than the melting point of platinum to diffuse and infiltrate these elements into Pt1000.
[0010] By the above-described method, the platinum group element having high hardness and the above-mentioned metal elements other than these and their alloys are penetrated into the surface layer of Pt1000, alloyed with platinum, and the part is hardened to thereby form a flaw. "Pt1000" jewelry that is difficult to attach.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in Examples 1 to 27.
[0012]
Embodiment 1
An 8 mm × 8 mm × 3 mm thick Pt1000 plate sample mirror-finished by buffing was buried in iridium (Ir) fine powder filled in an alumina container and lightly hardened. This was heated at 1200 ° C. for 20 hours in an argon atmosphere to perform a diffusion and infiltration treatment. After the treatment, a Pt1000 plate sample was taken out, rough-finished by magnetic polishing, and then mirror-polished with a buff until the original Pt1000 surface appeared. The polished sample was cut in the thickness direction, and the cut surface was analyzed by X-ray microanalyzer (XMA) from the treated surface to the inside. As a result, Ir had penetrated to 15.5 μm. The surface hardness was Vickers hardness, Hv = 150, and a Pt1000 plate having a surface hardness much higher than that of Ht = 40 of Pt1000 before the infiltration treatment was obtained.
[0013]
Embodiment 2
Rhodium (Rh) was coated by low-temperature and high-speed sputtering (argon 10 ⁻² Torr) on the surface of a plate-like pendant of Pt1000 manufactured by hand, which was mirror-finished by buffing. This was subjected to a diffusion and infiltration treatment by heat treatment at 1000 ° C. for 35 hours in an electric furnace in a vacuum. After buffing the surface of the sample after the infiltration treatment again, it was cut perpendicularly to the infiltration treatment surface, and the cut surface was examined for the infiltration state of Rh by XMA from the surface toward the inside. Rh was 23 μm from the surface. And the surface hardness was about Hv = 200.
After the diffusion and infiltration treatment, the surface of the sample was lightly buffed, and the results of measurement of the change in Rh concentration and the change in hardness in the surface layer are shown in FIGS. 1 and 2.
From FIG. 1, Rh has penetrated about 11 μm from the surface of Pt1000, and the hardness of the surface decreases with increasing Hv200 in sequence at the surface, but Hv = 105 to 60 μm from the surface to 20 μm.
[0014]
Embodiment 3
Ruthenium (Ru) was coated by electroplating on the surface of a Pt1000 plate-shaped pendant sample mirror-finished with a buff. This was heated in a vacuum at 1000 ° C. for 40 hours to perform a diffusion and infiltration treatment. The plating conditions are as follows.
<Ruthenium plating bath and operating conditions>
_{RuNOCl 3 · 5H 2 O 10g /} L
(As Ru) 3.5 to 4.5 g / L
NH ₂ SO ₃ H 10-20 g / L
Temperature 50-65 ° C
Current density 0.5-1.5 A / dm ²
Anode After the infiltration treatment of the Ti-Pt plate, the distribution of the Ru from the surface to the inside and the surface hardness of the cross section of the sample were measured. As a result, Ru was 6.8 μm in the surface layer portion, and the hardness of the portion was Hv = 140. The surface was more hardened.
[0015]
Embodiment 4
Rhodium (Rh) was coated by electroplating on the surface of a Pt1000 plate-like pendant sample having the same mirror finish as that used in Example 3. Rhodium plating bath and operating conditions are as follows.
<Rhodium plating bath and operating conditions>
Rhodium sulfate 1.5-2.0 g / L
Sulfuric acid (95-96%) 25-50 ml / L
Bath temperature 40-50 ° C
Current density 1 to 10 A / dm ²
Voltage 3-6V
Anode Pt
The sample after the plating coating was subjected to a diffusion infiltration treatment at 1200 ° C. for 25 hours in an argon atmosphere. When the surface hardness of the sample after the treatment was measured, it was Hv = 157.
[0016]
Embodiment 5
A paste obtained by dispersing iridium (Ir) powder in a cellulose solution was applied to the surface of a plate-like pendant sample of Pt1000 mirror-finished in the same manner as that used in the test of Example 3 with a brush, dried naturally, and then dried. Diffusion and infiltration treatment was performed by heating at 1000 ° C. for 30 hours in an argon atmosphere. Since the surface of the obtained sample was roughened due to the adhesion of undiffused Ir, the surface was first roughened by magnetic polishing, and then the surface was finished by buffing. A measurement was made. As a result, Ir had penetrated 9.3 μm from the surface to the inside, and the surface hardness was Hv = 187.
[0017]
Embodiment 6
Palladium (Pd) was coated on the surface of a mirror-finished Pt1000 plate-shaped pendant sample by electroplating. The composition of the plating solution and the operating conditions for plating are as follows.
<Palladium plating bath and operating conditions>
Pd (NH ₃ ) ₂ Cl ₂ 35g / L
Ammonium chloride 30-50g / L
Ammonium sulfate 20-30g / L
pH 9.0
Temperature 30 ° C
Current density 1A / dm ²
Pd content 15g / L
Then, the plate-shaped pendant after the plating was heat-treated at 900 ° C. for 15 hours in an argon atmosphere. After performing a secondary buffing finish on the plate-like sample, the penetration depth and surface hardness of Pd were measured. As a result, Pd had penetrated 7.2 μm from the surface of Pt1000 into the inside, and the surface hardness was also Hv = 100. .
[0018]
Embodiment 7
Iridium (Ir) was coated by electroplating on the surface of the Pt1000 plate-shaped pendant sample that had been mirror-finished. The composition of the plating solution and the operating conditions for plating are as follows.
<Iridium plating bath and operating conditions>
IrCl ₃ 15-20 g / L
Sulfamide 5-6g / L
Temperature 80 ° C
pH 2
Current density 1-3 A / dm ²
The plated pendant after the plating was heated at 1300 ° C. for 20 hours in an argon atmosphere. Ir penetrated 22.3 μm from the surface of Pt1000 into the inside, and the surface hardness was Hv = 160, and a sufficient surface hardness was obtained. The results of XMA analysis of the change in Ir concentration near the surface of this sample and the change in hardness are shown in FIGS.
[0019]
Embodiment 8
Tantalum (Ta) was coated by high-speed magnetron sputtering on the surface of a Pt1000 plate-like pendat sample mirror-finished by buff polishing. This was heat-treated at 1500 ° C. for 15 hours in an electric furnace. After secondary buffing of the treated sample, the distribution of Ta was examined by XMA from the surface to the inside of the cut surface in the thickness direction of the sample. As a result, tantalum was 34.2 μm inward from the surface. And the surface had a hardness of about Hv = 100.
[0020]
Embodiment 9
Zirconium (Zr) was coated by magnetron sputtering on the surface of a Pt1000 plate-like pendat sample mirror-finished by buff polishing. This was heat-treated at 1400 ° C. for 30 hours in an electric furnace. After secondary buffing of the sample after the treatment, the distribution of Zr was examined by XMA from the surface toward the inside of the cut surface of the sample, and Zr had penetrated about 10.6 μm from the surface to the inside, The surface had a hardness of Hv = 100.
[0021]
Embodiment 10
Rhodium was coated by electroplating on the surface of a Pt1000 plate-shaped pendant sample mirror-finished by buffing, and iridium was further coated thereon by electroplating. The composition of the plating solution and the operating conditions for each plating are as follows.
<Rhodium plating bath and operating conditions>
Rhodium sulfate 1.5-2.0 g / L
Sulfuric acid (95-96%) 25-50 ml / L
Bath temperature 40-50 ° C
Current density 1 to 10 A / dm ²
Voltage 3-6V
Anode Pt
<Iridium plating bath and operating conditions>
IrCl ₃ 15-20 g / L
Sulfamide 5-6g / L
Temperature 80 ° C
pH 2
Current density 1-3 A / dm ²
Then, the plated pendant after the plating was heat-treated at 1400 ° C. for 15 hours in an argon atmosphere. When the penetration depth of Ir and rhodium and the surface hardness of the sample after the treatment were measured, Ir was penetrated from the surface of Pt1000 to the inside by 16.1 μm and Rh was penetrated by 14.3 μm to form an alloy layer of Pt, Ir, and Rh. As a result, the surface hardness was as high as Hv = 140.
[0022]
Embodiment 11
The surface of the mirror-finished Pt1000 plate-shaped pendant sample was coated with iridium (Ir) by electroplating. The composition of the plating solution and the operating conditions for plating are as follows.
IrCl ₃ 15-20 g / L
Sulfamic acid 10-20 g / L
Temperature 80 ° C
pH 2
Current density 1-3 A / dm ²
Then, the plate-shaped pendant after plating was made to infiltrate Ir into the surface layer portion of Pt1000 by HIP. The HIP was performed at 1500 ° C. for 15 hours in an argon atmosphere. Ir penetrated 21.6 μm from the surface of Pt1000 into the inside, and the surface hardness was also Hv = 140. In the case of Pd, the hardness seemed to be slightly insufficient.
[0023]
Embodiment 12
Ruthenium (Ru) was coated by electroplating on the surface of a Pt1000 plate-shaped pendant sample which had been mirror-finished by buff polishing.
_{RuNOCl 3 · 5H 2 O 10g /} L
(As Ru) 3.5 to 4.5 g / L
NH ₂ SO ₃ H 10-20 g / L
Temperature 50-65 ° C
Current density 0.5-1.5 A / dm ²
Anode Ti-Pt plate This was heat-treated at 1000 ° C for 30 hours in an argon atmosphere. After the heat treatment, the distribution and surface hardness of Ru from the surface to the inside of the cross section of the sample were measured. As a result, Ru penetrated 6.4 μm into the surface layer, and the surface hardness was Hv = 130.
[0024]
Embodiment 13
An alloy of iridium (Ir) and platinum (Pt) was coated by electroplating on the surface of a Pt1000 plate-shaped pendant sample mirror-finished by buffing. The composition of the plating solution and the operating conditions for plating are as follows.
<Ir-Pt alloy plating bath and operating conditions>
IrCl ₃ 10 to 15 g / L
H ₂ PtCl ₆ 10-15 g / L
Sulfamic acid 10-20 g / L
Temperature 80 ° C
pH 2
Current density 1-3 A / dm ²
Then, the plate-like pendant after plating was infiltrated with an Ir-Pt alloy into the surface layer portion of Pt1000 by HIP. The HIP treatment was performed in an argon atmosphere at 1000 Kg / cm ² at 950 ° C. for 15 hours. Ir penetrated 8.9 μm from the surface of Pt1000 into the inside, and the surface hardness was also Hv = 150.
[0025]
Embodiment 14
The surface of a plate-like pendant sample of Pt1000, which was mirror-finished by buff polishing, was coated with iridium (Ir) by CVD at 1 atm and 1000 ° C. using IrCl ₃ as a raw material and argon (Ar) as a carrier gas. After coating, the sample was heat-treated at 1400 ° C. for 25 hours in an argon atmosphere. When the penetration depth and surface hardness of Ir were measured for the sample after the treatment, Ir penetrated 19.6 μm from the surface of Pt1000 into the inside, and the surface hardness was also Hv = 130.
[0026]
Embodiment 15
The surface of a Pt1000 plate-shaped pendant sample mirror-finished by buff polishing was coated with an Ir-Rh alloy by arc discharge ion plating using iridium (Ir) and rhodium (Rh) alloy as targets. After coating, this was subjected to a heat treatment at 1500 ° C. for 20 hours in an argon atmosphere, and thereafter, the surface of the sample was lightly buffed and then the surface hardness was measured. As a result, the penetration depth of Ir-Rh was 52.7 μm, and the surface hardness was Hv = 150.
[0027]
Embodiment 16
Iridium chloride (IrCl ₄ ) was dissolved in an ethisilicate hydrolyzed solution, and a Pt 1000 plate-shaped pendant sample mirror-finished by buffing was immersed in the solution to coat IrCl ₄ . The coated Pt1000 sample was heated at 900 ° C. for 1 hour to decompose IrCl ₄ to produce Ir on Pt1000, which was then heated at 1400 ° C. for 15 hours in a stream of argon. When the penetration depth and surface hardness of Ir were measured for Pt1000 after heating, the penetration depth was 23.5 μm and the hardness was 135.
[0028]
Embodiment 17
Niobium (Nb) powder was suspended in an ammonia-stabilized colloidal silica solution, and this solution was sprayed onto a Pt1000 plate-shaped pendant sample mirror-finished by buffing to apply Nb. The Pt sample coated with Nb was heated at 1400 ° C. for 5 hours in vacuum to diffuse Nb into the surface layer of Pt1000. As a result of measuring the penetration depth and surface hardness of Nb after the heat treatment, the penetration depth was 14 μm, and when the surface was analyzed by microfocal X-ray diffraction, Nb ₃ Pt was also generated and the hardness was Hv = 230. .
[0029]
Embodiment 18
Gold (Au) and copper (Cu) were plated on the surface of the Pt1000 plate-shaped pendant sample which had been mirror-finished by buffing, and the Pt surface was coated with Au and Cu. The coated Pt1000 was heat-treated at 1200 ° C. for 10 hours in a hydrogen stream to diffuse and infiltrate Au and Cu into the surface layer of Pt1000. Both elements of Cu and Au have penetrated to about 31.3 μm. When the surface was analyzed by microfocal X-ray diffraction, Cu ₃ PtAu ₃ Cu and the like were generated on the surface, and the surface hardness was about Hv = 256. there were.
[0030]
Embodiment 19
The surface of a plate-like pendant sample of Pt1000, which was mirror-finished by buff polishing, was coated by vacuum deposition with an electron beam at 10 ⁻⁶ Torr using germanium (Ge) as a Ge target. After coating, it was heated in a helium stream at 800 ° C. for 25 hours. As a result of measuring the penetration depth and surface hardness of Ge after heating, the penetration depth was 16 μm and the hardness was Hv = 157.
[0031]
Embodiment 20
Manganese (Mn) was coated on the surface of a Pt1000 plate-shaped pendant sample mirror-finished by buffing by sputtering at 10 ⁻² Torr. The coated sample was heat-treated at 1000 ° C. for 20 hours in a hydrogen stream. The Mn penetration depth and surface hardness of the heated sample were measured. As a result, the penetration depth was 35 μm, and the hardness was Hv = 223.
[0032]
Embodiment 21
Using a mixed gas of WF ₈ and H ₂ , tungsten (W) was coated on the surface of a plate-like pendant sample of Pt1000, which was mirror-finished by buff polishing. The coated sample was heat-treated at 1500 ° C. for 15 hours in a hydrogen stream. The W penetration depth and surface hardness of the sample after the treatment were measured. As a result, the penetration depth was 26 μm, and the surface hardness was Hv = 304.
[0033]
Embodiment 22
Osmium (Os) was vacuum-deposited with an electron beam under a vacuum of 10 ⁻⁶ Torr on the surface of a plate-like pendant sample of Pt1000, which had been mirror-finished by buff polishing, using an Os target. After the deposition coating, this was heat-treated at 1400 ° C. for 5 hours in the air. As a result of measuring the penetration depth of Os and the surface hardness of the sample after heating, the penetration depth was 6 μm and the hardness was Hv = 287.
[0034]
Embodiment 23
Powders of palladium (Pd) and copper (Cu) were simultaneously suspended in an ammonia-stabilized colloidal silica solution, and this solution was applied by spraying onto a Pt1000 plate-shaped pendant sample mirror-finished by buffing. The Pt1000 sample after application was heated in vacuum at 950 ° C. for 10 hours to simultaneously diffuse and infiltrate Pd and Cu into the surface layer of Pt1000. Heat treatment Determination of the palladium and copper penetration depth and surface hardness after, penetration depth of the palladium and copper have penetrated as 14～20Myuemu, the Cu 3 _Pt was analyzed surface with micro focus X-ray diffraction As a result, the hardness was Hv = 163.
[0035]
Embodiment 24
Pt1000 obtained by buffing a solution containing a small amount of carboxymethylcellulose and a small amount of a surfactant dissolved in an aqueous solution containing 10% of chloroplatinic acid (H ₂ PtCl ₆ ) and 30% of iridium chloride (IrCl ₃ ) by buff polishing. Was sprayed and applied onto the plate-shaped pendant sample. After the coated sample was dried, it was buried in alumina powder to prevent peeling of the coating film, and then this Pt1000 sample was heated at 1500 ° C. for 8 hours in an argon stream to alloy Ir and Pt simultaneously with Ir. Diffusion infiltration. After the heat treatment, Ir was diffused and penetrated into the surface portion of Pt1000 by 35.1 μm, and the surface hardness was Hv = 183.
[0036]
Embodiment 25
Indium and tin were supplied to the surface of the Pt1000 plate-shaped pendant sample which had been mirror-finished by buffing, and oxygen was sent to In (C ₁₁ H ₁₉ O ₂ ) ₃ and (C ₄ H ₉ ) Sn (C ₂ H ₃ O ₃ ) ₂ . Then, indium (In) and tin (Sn) were coated at 450 ° C. by CVD. The coated sample was heat-treated at 700 ° C. for 7 hours in a hydrogen stream. The W penetration depth and surface hardness of the sample after the treatment were measured. As a result, the penetration depth was 47.2 μm, and the surface hardness was Hv = 173.
[0037]
Embodiment 26
Using a target of an aluminum (Al) and palladium (Pd) alloy, a vacuum deposition was performed on the surface of a Pt1000 plate-shaped pendant sample mirror-finished by buff polishing with an electron beam under a vacuum of 10 ⁻⁶ Torr. The sample after the vapor deposition coating was heated at 850 ° C. for 20 hours under vacuum. As a result of measuring the penetration depth of Al and Pd and the surface hardness of the heated sample, the penetration depth was 52 μm, Al ₃ Pd was formed on the surface, and the hardness was Hv = 287.
[0038]
Embodiment 27
Using a chromium (Cr) target, a vacuum deposition was performed on the surface of a Pt1000 plate-shaped pendant sample that had been mirror-finished by buff polishing using an electron beam under a vacuum of 10 ⁻⁵ Torr. The sample after the vapor deposition coating was heat-treated at 1550 ° C. for 8 hours in a stream of argon. As a result of surface analysis and measurement of Cr penetration depth and surface hardness of the sample after heating, the penetration depth of Cr was 39.2 μm, CrPt ₃ was formed on the surface, and the surface hardness was Hv = 196. .
【The invention's effect】
As described above, the cured high-purity platinum according to the present invention is a high-purity platinum material that can replace conventional “Pt1000”, and can be certified as “Pt1000”, which has much higher hardness than conventional products. The hardened high-purity platinum produced by this method will be highly evaluated in the market.
[Brief description of the drawings]
FIG. 1 shows a result of XMA analysis of a change in Rh concentration from the sample surface to the inside when a permeation treatment is performed after rhodium (Rh) is sputter-coated on a Pt1000 sample in Example 2.
FIG. 2 shows the results of measuring the change in hardness (Hv) from the sample surface to the inside when performing a penetration treatment after rhodium (Rh) was applied to a Pt1000 sample by sputtering in Example 2 using a micro Vickers altimeter. It is a thing.
FIG. 3 shows the results of XMA analysis of a change in the concentration of Ir from the sample surface to the inside when the infiltration treatment is performed after coating the surface of the sample with iridium (Ir) by electroplating in Example 7; It is.
FIG. 4 is a micro-Vickers altimeter which measures the change in the hardness (Hv) of Ir from the sample surface to the inside when the infiltration treatment is performed after coating the surface of the Pt1000 sample with iridium (Ir) by electroplating in Example 7. 5 shows the results of the measurement.

Claims (2)

The hardened layer is formed by diffusing and penetrating a metal element effective for hardening into the surface layer of the high-purity platinum, and alloying the permeated element with platinum. The depth of the hardened layer is from 0.1 to 100 µm, and from the surface with a high content of hardening element to the inside of platinum, the content is continuously reduced to a maximum of 100 µm in depth, and the hardening element is alloyed with platinum. And a hardened layer is formed of the hardened layer, and the hardened surface layer is made of high-purity platinum having a higher hardness than the high-purity platinum of the matrix (base).
In forming the hardened layer, the surface of pure platinum (Pt1000) is coated in advance with a metal element to be diffused and infiltrated by one or more of the following methods.
{Circle around (1)} A metal or alloy to be diffused and infiltrated is coated on the Pt1000 surface by physical vapor deposition (PVD) or chemical vapor deposition (CVD).
{Circle around (2)} A metal or alloy to be diffused and infiltrated is coated on the Pt1000 surface by plating.
{Circle around (3)} A metal or alloy powder to be diffused and infiltrated is suspended in an appropriate solvent to be in a liquid or paste state and applied to the Pt1000 surface.
{Circle around (4)} Fine powder of metal or alloy to be diffused and infiltrated is dispersed in a dilute solution such as cellulose and brush-coated, or pure platinum is buried in the fine powder to cover the entire Pt1000.
{Circle around (5)} After immersing Pt1000 in a hydrolyzed ethyl silicate solution or colloidal silica solution, the Pt1000 surface is coated by sprinkling fine powder of a metal or an alloy into the undried solution while diffusing and penetrating it.
{Circle around (6)} A platinum group element halide other than platinum or a mixture of these and a platinum halide is dissolved in a diluted solution of cellulose or the like or colloidal silica, and the solution is brush-coated on Pt1000 or immersed in the solution. The metal that penetrates into is coated as chloride.
The coating process is performed once, or, if necessary, two or more times by any of the above methods or a combination thereof. The coated Pt1000 may be heated in air, in vacuum, in a stream of hydrogen, nitrogen, argon or helium at a temperature not higher than the melting point of platinum (1769 ° C.) for about 2 to 100 hours, or may be subjected to high-temperature hydrostatic pressure in an argon atmosphere. Hardened high-purity platinum (Pt1000), in which 95% by weight or more of the metal coated on the surface of Pt1000 is diffused into the surface layer of Pt1000 by pressing (HIP) to strengthen the surface layer portion and increase resistance to damage to the surface of Pt1000, and Product. Metal elements effective for forming a hardened surface layer of pure platinum (Pt = 99.9 wt%) are rhodium (Rh), ruthenium (Ru), iridium (Ir), and osmium (Os), which are platinum group elements other than platinum. , Palladium (Pd), and metal elements other than the platinum group, such as tantalum (Ta), zirconium (Zr), niobium (Nb), tungsten (W), germanium (Ge), manganese (Mn), and chromium (Cr) , Gold (Au), copper (Cu), tin (Sn), indium (In), and aluminum (Al). Usually, one of these elements is selected. 2. A hardened high-purity platinum formed by forming a hardened layer by diffusing and infiltrating a combination of two or more kinds of elements by the method according to claim 1.

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