Sintered compact of noble metal with spotted pattern and its production

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Industrial application field]

The present invention relates to a precious metal sintered body having a spotted pattern such as a leopard pattern and a method for manufacturing the same, and the precious metal sintered body having this spotted pattern is used as a material for ornaments, arts and crafts, and the like. Is.

【0002】

[Conventional technology]

Traditionally, precious metal sintered bodies with a speckled pattern have been used as materials for ornaments or arts and crafts. In the precious metal sintered body having this speckled pattern, a precious metal ingot having a white color composed of Ag or Ag alloy, Pt alloy or the like is embedded in a colored precious metal powder such as Au or Au alloy, sintered, and then sintered. Manufactured by slicing the body as needed. The ratio of burying the noble metal ingot having a white color tone in a colored noble metal powder such as Au or Au alloy is said to be a volume ratio of colored noble metal powder: noble metal ingot having a white color tone = 70 to 80: 20 to 30. ..

【0003】

[Problems to be Solved by the Invention]

However, a noble metal ingot having a white tint has a melting point close to that of a colored noble metal powder such as Au or Au alloy (for example, Au has a melting point of 1063 ° C), such as Ag or Ag alloy ingot. When manufacturing a noble metal sintered body with a speckled pattern, even if it is sintered at the sintering temperature of a colored precious metal powder such as Au or Au alloy, the Ag or Ag alloy ingots of the noble metal ingot having a white color will be strong. There is no problem because it is joined, but the precious metal block with white color has a much higher melting point than colored precious metals such as Au or Au alloy, such as Pt900 (90% Pt-10% Pd, melting point: about 1700 ° C). When a noble metal sintered body with a speckled pattern is produced using a high noble metal ingot, the noble metal ingots having a white color tone such as Pt900, which has an extremely high melting point at the sintering temperature of a colored precious metal powder such as Au or Au alloy, are diffused bonded. However, the bonding strength between precious metal ingots having a white color is extremely weak. Therefore, when a precious metal sintered body having a speckled pattern with a high filling ratio of a precious metal ingot having a white color is processed by cutting, forging, rolling, bending, etc. to produce an ornament or an arts and crafts, the precious metal having a white color is produced. Cracks are generated from the joints between the lumps, and the cracks become more prominent as the density of the precious metal lumps having a white color increases. Conventionally, such cracks have been repaired by brazing or the like. For this reason, it is conceivable to heat the precious metal ingots having a white color and having an extremely high melting point to a temperature at which they are diffusively bonded to each other for sintering. The colored precious metal powder itself melts.

【0004】

[Means for solving problems]

Therefore, from this point of view, the present inventors have conducted research to obtain a precious metal sintered body having a speckled pattern in which cracks do not occur when manufacturing ornaments or arts and crafts. As a result, Au or A colored precious metal powder such as Au alloy and a precious metal mass having a high melting point white color with a colored precious metal layer such as Au or Au alloy coated on the surface are mixed and then sintered to prepare a sintered body, and then this baking is performed. The precious metal sintered body having a speckled pattern obtained by cutting the alloy into a plate shape can be processed by cutting, forging, rolling, bending, etc. even if the density of the precious metal ingot having a white color with a high melting point becomes high. Research has shown that cracks do not occur at the joints between precious metal ingots that have a high melting point of white color when they are applied to make ornaments or arts and crafts.

【0005】

The present invention has been made based on the above research results. (1) Surface spots in which a large number of precious metal lumps having a white color tone having a higher melting point than colored precious metals are dispersed in a colored precious metal sintered body base material. In the noble metal sintered body having a pattern, there is a speckled pattern in which a noble metal alloy diffusion layer having a lower melting point than the noble metal having a white color is always present in the gap between the noble metal ingot having a white color and the noble metal ingot having a white color. Precious metal sintered body, (2) Colored noble metal powder and precious metal ingot having a white color tone higher than that of colored noble metal are mixed and then sintered to prepare a sintered body, and then this sintered body is used as a plate. In the method for producing a noble metal sintered body having a speckled pattern by cutting into a shape, spots using a coated noble metal ingot coated with a noble metal layer having a lower melting point than the noble metal having a white tones as the noble metal ingot having a white color tone. It is characterized by a method for producing a precious metal sintered body having a pattern.

【0006】

The thickness of the coating layer of the coated noble metal mass used in producing the noble metal sintered body having the speckled pattern of the present invention is preferably in the range of 0.1 to 10 μm. The coating layer of this thickness is inconspicuous in the noble metal sintered body and contributes to adhesion.

【0007】

[Example]

Example 1 Obtained by cutting a Pt900 (90% Pt-10% Pd, melting point: about 1700 ° C) wire with a diameter of 1 mm and a pure Pd (melting point: 1552 ° C) wire with a diameter of 1 mm to a length of 1 mm. After surface-treating the white noble metal ingot, a pure gold film having the average thickness shown in Table 1 was formed by electroless plating, and a buried body composed of the white noble metal ingot having a pure gold film formed on the surface was prepared.

【0008】

On the other hand, as colored noble metal powders, K18Y gold alloy (75.0% Au-20.0% Ag-5.0% Cu, melting point: about 1000 ° C, yellowish) powder and K18R gold alloy (75.0%) having the average particle size shown in Table 1 % Au-5.0% Ag-25.0% Cu, melting point: about 900 ° C, reddish) Prepare powder and blend 30% by volume of buried material with respect to this K18Y gold alloy powder or K18R gold alloy powder: 70% by volume. Mix using, and put the mixture in a heat-resistant container casually, 10^-5Sintered in a torr vacuum atmosphere at 830 ° C for 3 hours, and sliced the obtained sintered body to a thickness of 2.0 mm to produce the speckled precious metal sintered bodies 1 to 5 of the present invention. Then, these speckled precious metal sintered bodies 1 to 5 of the present invention were bent by 180 °, the number of cracks generated on the surface was measured, and the results are shown in Table 1.

【0009】

Conventional example 1 The buried body made of the white noble metal ingot prepared in Example 1 is divided into the volume% of the colored noble metal powder made of K18Y gold alloy powder or K18R gold alloy powder, and the ratio of the colored noble metal powder: the white noble metal ingot = 70:30. The mixture was mixed, and the mixture was randomly placed in a heat-resistant container and sintered under the conditions shown in Table 1. The obtained sintered body was sliced to a thickness of 2.0 mm, and the conventional speckled precious metal sintered body 1 ~ 5 was manufactured, these conventional speckled precious metal sintered bodies 1 to 5 were bent 180 °, and the number of cracks generated on the surface was measured, and the results are shown in Table 1.

【0010】

<img file="JPH08239703A_D0001.tif" />【0011】

[Effect of the invention]

From the results shown in Table 1, the speckled pattern precious metal sintered bodies 1 to 5 of the present invention prepared by using a pure gold-coated white precious metal ingot as an embedded body do not cause cracks on the surface even when bent 180 °, whereas they are plated. It can be seen that the conventional speckled precious metal sintered bodies 1 to 5 obtained by mixing the white noble metal ingot itself with the K18 gold alloy powder and sintering the white noble metal ingots 1 to 5 are cracked by bending at 180 °. As described above, the precious metal sintered body having the speckled pattern of the present invention does not generate cracks even when processed, and can efficiently produce ornaments or arts and crafts having the speckled pattern in the decorative industry. It has an excellent effect.