JP2987314B2 - Method for hardening platinum or platinum alloy, and method for hardening palladium or palladium alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to platinum or a platinum alloy of a noble metal material used as jewelry, and a method of hardening palladium or a palladium alloy.

[0002]

2. Description of the Related Art Platinum (Pt), a precious metal material used as jewelry, is soft and easily scratched. For example, pure platinum having a content of 99.95% or more has a Vickers hardness (Hv) of only about 50 to 55 when annealed, and is easily scratched and may be deformed by a light impact. In this state, it cannot be actually used as jewelry.

[0003] For this purpose, platinum is processed into jewelry and the like in a cured state. How to cure platinum
Alloying with other metals, processing such as rolling and forging, or plating is common.

Similarly, palladium, which is a metal of a white metal element, or an alloy of palladium with gold, silver or the like also has a problem that it is soft and easily scratched.

[0005] Platinum (Pt) usually has a purity of 99.
If it is 8% or more, it is called pure platinum. In such pure platinum, it is attempted to increase the hardness by adding trace amounts of various metal elements of about 0.1%. However, in the case of pure platinum, only a Vickers hardness (Hv) of about 80 to 90 is obtained in consideration of the occurrence of cracks and cavities during casting.

On the other hand, in a platinum alloy having a platinum (Pt) content of 95%, 90%, and 85%, palladium (Pd), cobalt (Co), tungsten (W), copper (Cu), By mixing a metal such as iridium (Ir) and ruthenium (Ru), the hardness can be increased. However, when the hardness is high, castability is reduced, and during casting, shrinkage cavities due to solidification shrinkage, pinholes due to gas absorption, cracks, etc. may occur, and the fluidity is poor and it is not cast into a predetermined shape. There is a risk.

For example, a platinum alloy in which 10% of palladium (Pd) is blended with 90% of platinum (Pt) has good castability, but has a Vickers hardness (Hv) of 70%.
The hardness is insufficient for use as jewelry.

[0008] Further, for platinum (Pt) 90%,
5% palladium (Pt), 5% tungsten (W)
Although the blended platinum alloy has a high hardness of about Vickers hardness (Hv) 230 even when annealed, it can hardly be cast into a predetermined shape because tungsten is oxidized, and becomes brittle by casting. Problem.

Further, palladium (Pt) is 7% and cobalt (Co) is 3% with respect to 90% of platinum (Pt).
The platinum alloy blended in% has good castability, but has a Vickers hardness (Hv) of about 120, and has a problem that it is easily scratched and easily deformed as jewelry.

[0010] Such a platinum alloy can be used as a decorative article if its thickness, thickness and the like are increased in order to prevent deformation. However, decorative items with increased thickness, thickness, etc., require a lot of ingots, so they are not only expensive but also heavy, and when worn directly on the body like rings, earrings, etc. May cause stiff shoulders. In addition, there is a problem that the clothes are easily damaged in the broach directly attached to the clothes.

In the work hardening method in which the hardness is increased by forming into a predetermined shape by rolling or forging, unlike the casting method which is a usual method for forming jewelry, it cannot be processed into a fine shape. , Design, etc. are limited.
Although the hardness of the platinum alloy can also be increased by forming by spatula processing, there is a problem that uniform hardness cannot be obtained over the whole and that it takes much time and labor. A ring with a simple structure such as a marriage ring can be manufactured by molding, grinding, and polishing by machining after increasing the hardness by rolling or forging, instead of casting. It cannot be processed into a sophisticated design, shape, etc. as in the case.

As described above, there is a problem that it is not easy to form platinum or a platinum alloy formed by rolling or forging into a complicated shape as jewelry.
Further, tableware such as knives and forks manufactured by rolling or forging cannot be practically used with platinum or a platinum alloy and has not been put to practical use.

If the surface of a platinum alloy processed into a predetermined shape by casting is plated, the hardness of the surface increases, but a metal different from the base material of the platinum alloy adheres to the surface. For this reason, there is a possibility of peeling over time.

Since similar problems also occur in the case of palladium and alloys of gold and silver containing palladium, the range of use of palladium and alloys containing palladium is limited as jewelry.

JP-A-6-346222 discloses an article in which the surfaces of platinum and palladium are cured with boron and a method for producing the same. The method disclosed in this publication specifically describes a mixture of boron and potassium borofluoride, or a mixture of this mixture with polyproisobutylene and light benzene, or a mixture of these with aluminum oxide, and platinum or the like. By heating at a temperature of 750 ° C. or higher,
The surface such as platinum is hardened.

[0016]

However, in such a curing method, although the surface of platinum or the like can be cured, the surface of the surface is severely roughened, and polishing work for giving luster as jewelry is required. There is a problem that it is not easy.

Further, when fluoride is used, there is a risk of adversely affecting the environment. Therefore, it is necessary to purify wastewater after hardening platinum and the like, and equipment and the like for that purpose are used. Is necessary.

The present invention has been made to solve such a problem, and can significantly improve the hardness.
It is an object of the present invention to provide a method for hardening platinum or a platinum alloy and a method for hardening palladium and an alloy containing palladium, which make it possible to extremely easily obtain the luster required for jewelry with less rough skin.

[0019]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a method for producing platinum or a platinum alloy or palladium or a palladium alloy for a predetermined time together with a mixture of boron carbide, borax and salts. It is characterized by heating to a temperature.

As the salts, a mixture of sodium chloride and potassium chloride is preferred.

In this case, specifically, when the mixing ratio of boron carbide and borax to sodium chloride and potassium chloride is% by weight, platinum or a platinum alloy is used.
10:90 to 50:50, palladium or palladium
In the case of a platinum alloy, it should be 10:90 to 60:40.
No. More specifically, in each case, the mixing ratio of boron carbide and borax is 95: 5 to 60: 4 by weight%.
0 and the mixing ratio of sodium chloride and potassium chloride is 40:60 to 60:40 in weight%.

[0022]

Embodiments of the present invention will be described below.

Platinum or a platinum alloy, or palladium or an alloy containing palladium, is heated together with boron carbide, borax, and salts of sodium chloride and potassium chloride at a temperature of 600 to 800 ° C. for about 30 minutes to 4 hours. . As a result, boron enters the surface of platinum, a platinum alloy, or palladium or a palladium alloy, and the surface hardness of platinum, a platinum alloy, or an alloy containing palladium or palladium is significantly improved. In addition, the surface roughness of platinum or a platinum alloy, or palladium or the surface of palladium is small, and polishing work for obtaining luster required for jewelry is significantly reduced.

The mixture of boron carbide and borax that is heated with platinum or a platinum alloy, or palladium or an alloy containing palladium, increases the amount thereof, increases the heating time, increases the platinum or platinum alloy surface, or The penetration amount of boron on the surface of palladium or an alloy containing palladium increases, and the surface hardness increases.

Further, by using salts together with boron and borax, platinum or a platinum alloy,
Alternatively, while accelerating the hardening of palladium or an alloy containing palladium, platinum or a platinum alloy,
Alternatively, roughening of the surface of palladium or an alloy containing palladium is suppressed. As the salts, a mixture of sodium chloride (NaCl) and potassium chloride (KCl) is particularly suitable. However, sodium chloride (NaCl) or potassium chloride (KCl) alone may be used, and other salts may be individually added one by one. Alternatively, a plurality can be used simultaneously.

Boron carbide and borax become liquid by heating together with salts, and it is considered that roughening of the surface of platinum, a platinum alloy, or palladium or an alloy containing palladium is suppressed.

Platinum or a platinum alloy heated with a mixture of boron carbide, borax and salts, or palladium or an alloy containing palladium has almost no surface roughening and is not subjected to hardening treatment. Or, it is almost inferior to the surface condition of the alloy containing palladium. Therefore, by performing simple barrel polishing, buff polishing, or the like, excellent luster that can be used as jewelry is obtained, and the polishing operation is significantly reduced.

Platinum, a platinum alloy, or palladium or an alloy containing palladium may be cast in advance into a predetermined shape, or may be forged or rolled into a predetermined shape. Cast platinum or a platinum alloy, or palladium or an alloy containing palladium, can be formed into a complex shape such as an ornament, but the surface of boron or a boron compound is platinum or a platinum alloy, or an alloy containing palladium or palladium. Hardness increases over the entire surface due to penetration throughout. Platinum or a platinum alloy preformed into a plate shape by forging or rolling, or palladium or an alloy containing palladium has a hardness that can prevent deformation, so that it can be practically used as tableware such as knives and forks. Can be used.

As an alloy containing palladium, not only an alloy mainly containing palladium, but also a gold alloy, a silver alloy, a copper alloy or the like in which the addition ratio of palladium is less than half, without roughening the surface, Hardening of the surface is observed.

[0030]

Embodiments of the present invention will be described below.

Example 1 Boron Carbide (B ₄ C) 36
%, Borax (Na ₂ B ₄ O ₇ ) 4%, sodium chloride (NaCl) 30%, potassium chloride (KCl) 30%
Was mixed in a stainless steel crucible, and a plate material of 99.95% platinum (Pt) and a round shell were embedded in the mixed powder. The plate material is 10 mm square, thickness 1.
2 mm. Then, the crucible was housed in an electric furnace while being covered with a stainless steel plate, and heated at 750 ° C. for 3 hours. After the heating was completed, the plate and the Komaru ring were taken out of the crucible and washed with hot water to remove a mixture of boron carbide and the like adhering to the surface of the plate.

The Vickers hardness (Hv) of the surface of the thus obtained plate material was 50 before the treatment, but changed to 167 after the treatment.

The surface roughness of the obtained plate was measured using a surface roughness measuring device (trade name “Sarkoff 5” manufactured by Tosei Engineering Co., Ltd.).
50A "), the center line average roughness Ra is 0.
It was 16 μm. FIG. 1 shows a measurement graph of the surface roughness.

FIG. 2 shows a micrograph (× 100) of the surface of the obtained Komaru ring. The surface of this Komaru ring had almost no rough skin. Table 1 shows the results.

<Example 2> In Example 1, the purity was 9
9. Platinum (Pt) 90 instead of 9.95% platinum
%, Palladium (Pd), a 10 mm square plate material and a 1.2 mm thick plate member made of a platinum alloy of 10%, and a round shell were used. Except for this, curing was performed under the same conditions as in Example 1. The Vickers hardness (Hv) of the surface of the hardened plate material was 70 before the treatment, but 230 after the treatment.

The center line average roughness Ra of the obtained plate material is:
It was 0.10 μm. FIG. 3 shows a measurement graph of the surface roughness. FIG. 4 shows a micrograph (× 100) of the surface of the obtained Komaru ring. For comparison, FIG. 5 shows a micrograph (100 times) of the surface of the Komaru ring before the curing treatment. The surface of the Koumaru ring was hardly rough. The results are also shown in Table 1.

Example 3 Boron Carbide (B ₄ C) 21
%, Borax (Na ₂ B ₄ O ₇ ) 9%, sodium chloride (NaCl) 35%, potassium chloride (KCl) 35%
Was mixed in a stainless steel crucible, and a plate material of 99.95% platinum (Pt) and a Komaru ring similar to that of Example 1 were embedded in the mixed powder. Heated at 750 ° C. for 3 hours in an electric furnace.

The Vickers hardness (Hv) of the surface of the obtained plate material and the surface of the round shell was 50 before the treatment, but 156 after the treatment.

The center line average roughness Ra of the obtained plate material is:
It was 0.40 μm. FIG. 6 shows a measurement graph of the surface roughness.

FIG. 7 shows a micrograph (× 100) of the surface of the obtained Komaru ring. The surface of this Komaru ring had almost no rough skin. The results are also shown in Table 1.

<Embodiment 4> In Embodiment 3, the purity was 9%.
9. Platinum (Pt) 90 instead of 9.95% platinum
%, Palladium (Pd) made of a platinum alloy of 10%, a plate material having a thickness of about 10 mm square and a thickness of 1.2 mm and an instep ring were used. Except for this, curing was performed under the same conditions as in Example 3. The Vickers hardness (Hv) of the surface of the hardened plate material was 70 before the treatment, but was 313 after the treatment.

The center line average roughness Ra of the obtained plate material is:
0.29 μm. FIG. 8 shows a measurement graph of the surface roughness. FIG. 9 shows a micrograph (100 times) of the surface of the obtained Komaru ring. The surface of the Koumaru ring had almost no skin roughness. The results are also shown in Table 1.

Example 5 Boron Carbide (B ₄ C) 40
%, Borax (Na ₂ B ₄ O ₇ ) 20%, sodium chloride (NaCl) 20%, and potassium chloride (KCl) 20% were charged into a stainless steel crucible and mixed, and the mixture was purified to a purity of 99. 95% platinum (Pt) was cast into the Komaru ring and charged. Then, the crucible was placed in an electric furnace and heated at 800 ° C. for 4 hours. After the heating was completed, the ring was taken out of the crucible and washed with hot water to remove a mixture such as boron carbide attached to the ring surface.

The Vickers hardness (Hv) of the surface of the ring thus obtained was 350, and the surface was hardly rough. When the obtained ring was subjected to buffing, which is a normal ring finishing process, it became a glossy ring in a short time. The results are also shown in Table 1.

<Embodiment 6> In Embodiment 5, the purity was 9%.
9. Platinum (Pt) 90 instead of 9.95% platinum
%, A 10% palladium (Pd) platinum alloy cast on a round shell was used. Otherwise, Example 1
Curing treatment was performed under the same conditions as described above. The Vickers hardness (Hv) of the cured ring was 560, and the surface of the obtained ring had almost no roughening. The results are also shown in Table 1.

<Example 7> Boron carbide (B ₄ C) 7%,
Borax (Na ₂ B ₄ O ₇ ) 3%, sodium chloride (Na
Cl) and potassium chloride (KCl) 45% were mixed in a stainless steel crucible, and 99.95% pure platinum (P) cast into a standing claw ring was added to the mixture.
t) was charged. Then, place the crucible in an electric furnace at 80
Heated at 0 ° C. for 4 hours. After the heating was completed, the ring was taken out of the crucible and washed with hot water to remove a mixture such as boron carbide attached to the ring surface.

The surface of the ring thus obtained had a Vickers hardness (Hv) of 172, and almost no roughening was observed. When the obtained standing nail ring was subjected to buffing, which is a normal finishing step, a glossy ring was obtained in a short time. When this standing nail ring was stone-fixed, it was firmly stone-fixed as compared with the conventional standing nail ring, and the gloss was the same as before. The results are also shown in Table 1.

<Embodiment 8> In Embodiment 7, instead of the platinum having a purity of 99.95%, which was cast into a standing claw ring,
A platinum alloy of 90% platinum (Pt) and 10% palladium (Pd) was cast into a standing nail ring and used. Except for this, curing was performed under the same conditions as in Example 7. The cured nail had a Vickers hardness (Hv) of 157, and the surface of the product ring had almost no rough surface. Also, the ring was firmly stoned. The results are also shown in Table 1.

Example 9 Boron carbide (B ₄ C) 34
%, Borax (Na ₂ B ₄ O ₇ ) 16%, Sodium chloride (NaCl) 25%, Potassium chloride (KCl) 25%
Are mixed in a stainless steel crucible, and the mixture is mixed with 90% platinum (Pt) and 5% palladium (Pd).
%, Tungsten (W) 5% platinum alloy was pressed into a clip-type earring using a leaf spring and then charged. Then, place the crucible in an electric furnace at 800 ° C. for 30 minutes.
Heated for minutes. After the heat treatment was completed, the earring was taken out of the crucible and washed with hot water to remove the mixture adhering to the earring.

The Vickers hardness (Hv) of the surface of the earring thus obtained was 424, and the surface was hardly roughened. The platinum alloy of this embodiment has a Vickers hardness (Hv) of 23 before press working.
0, the Vickers hardness (Hv) at the time of press working was about 360, and the hardness was significantly improved by the curing treatment for 30 minutes. When the obtained earring was subjected to buff polishing, which is a finishing step of a normal product, the earring became glossy in a short time. Further, the clip has a pressing pressure of 35.4 gf because the hardness of the plate material constituting the leaf spring is high, which is remarkably lower than the pressing pressure of the earring clip of 25.2 gf when the hardening treatment is not performed. Was higher. The results are also shown in Table 1.

Example 10 Boron carbide (B ₄ C) 34
%, Borax (Na ₂ B ₄ O ₇ ) 16%, Sodium chloride (NaCl) 25%, Potassium chloride (KCl) 25%
Was mixed in a stainless steel crucible, and a plate material obtained by casting platinum having a purity of 99.95% was put into the mixture. Then, place the crucible in an electric furnace at 80
Heated at 0 ° C. for 4 hours. After the heat treatment, the platinum alloy plate was taken out of the crucible and washed with hot water to remove a mixture of boron carbide and the like attached to the surface of the platinum alloy plate.

The surface of the platinum plate material thus obtained had a Vickers hardness (Hv) of 50 before curing.
However, after the curing treatment, the Vickers hardness (H
v) 367. In addition, there was almost no rough surface. The results are also shown in Table 1.

<Example 11> In Example 10, the plate material was subjected to hardening treatment by forging before the hardening treatment.
The Vickers hardness (Hv) was 144. Then, when heat-treated with the boron compound under the same conditions as in Example 11, the Vickers hardness (H
v) became 346. In addition, there was almost no rough surface. The results are also shown in Table 1.

<Example 12> In Example 10, platinum (Pt) 9 was used instead of platinum having a purity of 99.95%.
A cast plate of a platinum alloy of 0% and 10% of palladium (Pd) was used. Except for this, curing was performed under the same conditions as in Example 10. The Vickers hardness (Hv) before the hardening treatment was 70, but the Vickers hardness (Hv) of the hardened plate material was 495. In addition, there was almost no rough surface. The results are also shown in Table 1.

<Example 13> In Example 12, the plate material was subjected to a hardening process by forging before the hardening process.
Vickers hardness (Hv) was 156. Then, when heat-treated with a boron compound under the same conditions as in Example 10, the Vickers hardness (Hv) of the platinum alloy plate material became 508. In addition, there was almost no rough surface. The results are also shown in Table 1.

<Example 14> In Example 10, a cast plate of a platinum alloy of 90% platinum (Pt), 7% palladium (Pd), and 3% cobalt (Co) was used. Except for this, curing was performed under the same conditions as in Example 10. The Vickers hardness (Hv) of the platinum alloy plate before the hardening treatment was 112, while the Vickers hardness (Hv) of the hardened platinum alloy plate was 327. In addition, there was almost no rough surface. The results are also shown in Table 1.

<Example 15> In Example 14, when a plate material of a platinum alloy was subjected to a hardening treatment by forging before the hardening treatment, the Vickers hardness (Hv) became 248. Thereafter, when heat treatment was performed together with the boron compound under the same conditions as in Example 13, the Vickers hardness (Hv) of the platinum alloy plate material became 314. In addition, there was almost no rough surface. The results are also shown in Table 1.

Example 16 Boron carbide (B ₄ C) 40
%, Borax (Na ₂ B ₄ O ₇ ) 20%, sodium chloride (NaCl) 20%, potassium chloride (KCl) 20%
Was mixed in a stainless steel crucible, and a 10 mm square, 1 mm thick plate material of palladium (Pd) was charged into the mixture. Then, place the crucible in an electric furnace at 80
Heated at 0 ° C. for 4 hours. After the heat treatment, the palladium plate was taken out of the crucible and washed with hot water to remove a mixture of boron carbide and the like attached to the surface of the plate.

The thus obtained palladium (P
The surface of the plate material of d) had a Vickers hardness (Hv) of 254. In addition, there was almost no rough surface. The results are also shown in Table 1.

[0060]

[0061]

<Comparative Example 1> For comparison, refer to JP-A-6-3
According to the method described in Example 1 of Japanese Patent No. 46222, the platinum (Pt) used in Example 1 was 99.95.
% Of the board and the shell ring were treated. That is, a mixture of 85% of boron (B) and 15% of potassium borofluoride (KBF ₄ ) is put into a crucible, and a plate material and a round shell are embedded in the mixture. Heated for hours.

The center line average roughness Ra of the obtained plate material is as follows:
1.58. FIG. 10 shows a measurement graph of the surface roughness.

A micrograph (1) of the surface of the Komaru ring
FIG. 11). Thus, the surface of the Komaru ring was severely rough and had poor gloss. Table 2 shows the results.

<Comparative Example 2>
9. Platinum (Pt) 90 instead of 9.95% platinum
%, Palladium (Pd), a 10 mm square plate material and a 1.2 mm thick plate member made of a platinum alloy of 10%, and a round shell were used. Except for this, curing was performed under the same conditions as in Comparative Example 1.

The center line average roughness Ra of the obtained plate material is:
1.21 μm. FIG. 12 shows a measurement graph of the surface roughness.
Shown in FIG. 13 shows a micrograph (× 100) of the surface of the obtained Komaru ring. Thus, the surface of the Komaru ring was severely rough and had poor gloss. The results are also shown in Table 2.

<Comparative Example 3> According to the method described in Example 8 of JP-A-6-346222, a plate (99.95%) of platinum (Pt) used in Example 1 and the same material as the former round ring were used. The board and Komaru ring were processed. That is, boron (B) 20%, boron carbide (B ₄ C) 4
A mixture of 0%, boron nitride (BN) 30%, and potassium borofluoride (KBF ₄ ) 10% is put into a crucible, and a plate and a round shell are embedded in the mixture. For 3 hours.

The center line average roughness Ra of the obtained plate material is:
It was 2.48. FIG. 14 shows a measurement graph of the surface roughness.

Further, a micrograph (1) of the surface of the Koumaru ring
00) is shown in FIG. Thus, the surface of the Komaru ring was severely rough and had poor gloss. The results are also shown in Table 2.

<Comparative Example 4> In Comparative Example 3, the purity was 9
9. Platinum (Pt) 90 instead of 9.95% platinum
%, Palladium (Pd), a 10 mm square plate material and a 1.2 mm thick plate member made of a platinum alloy of 10%, and a round shell were used. Except for this, curing was performed under the same conditions as in Comparative Example 3.

The center line average roughness Ra of the obtained plate material is as follows:
It was 1.04 μm. FIG. 16 shows a measurement graph of the surface roughness.
Shown in FIG. 17 shows a micrograph (100 times) of the surface of the obtained Komaru ring. Thus, the surface of the Komaru ring was severely rough and had poor gloss. The results are also shown in Table 2.

[0072]

[Table 1]

[0073]

[Table 2]

[0074]

As described above, the method for hardening platinum or a platinum alloy and the method for hardening palladium or an alloy containing palladium according to the present invention are described above. As described above, boron invades the entire surface of platinum or a platinum alloy, palladium or an alloy containing palladium. As a result, the hardness of the surface is remarkably improved, and the surface is hardly roughened. Therefore, the polishing work for obtaining luster as jewelry is remarkably reduced.

[Brief description of the drawings]

FIG. 1 is a graph showing a measurement result of a surface roughness of a plate material obtained by a curing method in Example 1 of the present invention.

FIG. 2 is a micrograph (magnification: 100) of a surface of a round shell obtained by a curing method in Example 1 of the present invention.

FIG. 3 is a graph showing a measurement result of a surface roughness of a plate material obtained by a curing method in Example 2 of the present invention.

FIG. 4 is a micrograph (magnification: 100) of a surface of a round shell in Example 2 of the present invention.

FIG. 5 is a photomicrograph (magnification: 100) of a surface of a round shell before hardening treatment in Example 1 of the present invention.

FIG. 6 is a graph showing a measurement result of a surface roughness of a plate material obtained by a curing method in Example 3 of the present invention.

FIG. 7 is a photomicrograph (magnification: 100) of the surface of a round shell in Example 3 of the present invention.

FIG. 8 is a graph showing a measurement result of surface roughness of a plate material obtained by a curing method in Example 4 of the present invention.

FIG. 9 is a photomicrograph (magnification: 100) of a surface of a round shell in Example 4 of the present invention.

FIG. 10 is a graph showing the measurement results of the surface roughness of a plate material obtained by the curing method in Comparative Example 1.

FIG. 11 is a micrograph (magnification: 100) of the surface of a Komaru ring obtained by a curing method in Comparative Example 1.

FIG. 12 is a graph showing a measurement result of surface roughness of a plate material obtained by a curing method in Comparative Example 2.

FIG. 13 is a micrograph (magnification: 100) of the surface of a round shell in Comparative Example 2.

FIG. 14 is a graph showing a measurement result of surface roughness of a plate material obtained by a curing method in Comparative Example 3.

FIG. 15 is a micrograph (magnification: 100) of the surface of a round shell in Comparative Example 3.

FIG. 16 is a graph showing a measurement result of surface roughness of a plate material obtained by a curing method in Comparative Example 4.

FIG. 17 is a micrograph (magnification: 100) of the surface of a round shell in Comparative Example 4.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C23C 8/40-8/42 C23C 8/68-8/70

Claims (6)

(57) [Claims] 1. Platinum or jewelry used as jewelry
Platinum alloys alloyed for use as jewelry are combined with a mixture of boron carbide and borax and a salt blended in an amount of 50% by weight or more with respect to the boron carbide and borax. Alternatively, a method of hardening platinum or a platinum alloy, comprising heating to a predetermined temperature for a predetermined time so that boron penetrates the entire surface of the platinum alloy. 2. The method for hardening platinum or a platinum alloy according to claim 1, wherein said salts are a mixture of sodium chloride and potassium chloride. 3. The mixing ratio of boron carbide and borax is 95: 5 to 60:40 in weight%, and the mixing ratio of sodium chloride and potassium chloride is 40:60 to 40 weight%.
The method according to claim 2, wherein the ratio is 60:40. 4. The method of claim 1 wherein the palladium used as a jewelry or the palladium alloy alloyed for use as a jewelry is treated with boron carbide and borax, and the boron carbide and borax. , Palladium or a palladium alloy characterized by being heated to a predetermined temperature for a predetermined time so that boron penetrates the entire surface of the palladium or palladium alloy together with a mixture with salts blended in a proportion of 40% by weight or more . Curing method. 5. The method according to claim 4, wherein the salts are a mixture of sodium chloride and potassium chloride. 6. The mixing ratio of boron carbide and borax is 95: 5 to 60:40 in weight%, and the mixing ratio of sodium chloride and potassium chloride is 40:60 in weight%.
The method for curing palladium or a palladium alloy according to claim 5, wherein the ratio is up to 60:40.