JPH10179221A - White noble metal ornament and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an excellent ornament, which emits a bright white gloss, has high hardness, is rarely flawed is lightweight, and has nobility as a noble metal, by temporarily melting rhodium powder into a plate or rod shape, then casting it. SOLUTION: Rhodium powder having the grain size of 1-50μm is put in a die and compression-molded to form an ingot. The ingot is put in a high-frequency furnace, and it is melted, cast, and hot-rolled to form a sheet. The sheet is put in the high-frequency furnace and is again melted. The molten metal is poured into a precision casting die, e.g. a brooch casting die, heated to 600-900 deg.C in advance to manufacture a rhodium brooch. Or, the rhodium powder having the grain size of 1-50μm is put in the die and compression-molded to form the ingot. The ingot is put in a high-frequency furnace and is melted in vacuum. The molten metal is poured into the precision casting die, e.g. a medal casting die, heated to 600-900 deg.C in advance to form a rhodium medal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to white precious metal ornaments such as rings, earrings, earrings, necklaces, bracelets, brooches, pendants, tie pins, cufflinks, eyeglass frames, watch frames, watch bands, medals, and the like, and their manufacture. About the method.

[0002]

2. Description of the Related Art Conventionally, white precious metal ornaments are generally made of platinum or silver. Silver ornaments are relatively inexpensive, have a fresh white luster, and have a very beautiful appearance, but if left undisturbed in the atmosphere,
There was a problem that the color changed to black due to sulfuration. In addition, since platinum ornaments are high in purity and soft, they are easily scratched, and because of their high specific gravity, they have the disadvantage of being heavy as ornaments, and have the problem that they are darker white than silver. there were. White gold, which is a gold alloy, is also partially used as a white decorative material, but most of it is an alloy of about K14 to K18, and pure white one is hard to obtain.

[0003] In terms of "preciousness" required for precious metal ornaments, the above-mentioned alloys of silver and platinum (which are alloys for hardening), white gold, and the like are inferior to pure platinum. .

[0004] On the other hand, rhodium is much whiter than platinum, has a specific gravity of about half that of platinum, is hard to be scratched, and is more valuable than platinum in terms of "preciousness". Although it looked suitable as a material for decorative articles, it was hard and workability was poor. Therefore, there was no ornament made of pure rhodium. It is used only as a decorative product, and is used as a plating on the surface to prevent discoloration of silver and the like. However, since it is difficult to make a thick plating, a decorative product made of pure rhodium was not produced.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present invention provides an unprecedented white noble metal decorative article which exhibits a bright white luster, is hardly scratched, is light and has valuableness as a noble metal, and a method for producing the same. What you want to do.

[0006]

According to the present invention, there is provided a white noble metal decorative article made of a solid rhodium material. The term “pure rhodium material” as used herein refers to a material that does not contain anything other than rhodium and unavoidable impurities.

One of the production methods of the present invention for producing this white noble metal ornament is to first form rhodium powder by compression molding, then melt and hot-work to form a plate or bar, and then melt again. Thereafter, it is poured into a precision casting mold that has been heated to 600 to 900 ° C. in advance to obtain a rhodium decorative article.

Another method of the present invention for making white precious metal ornaments is a precision method in which rhodium powder is first compression molded, then melted in a vacuum and then heated to 600-900 ° C. It is characterized by being poured into a casting mold to obtain a rhodium decorative article.

Conventionally, powder has been generally used as a raw material of rhodium, but if the powder is dissolved as it is, it takes a long time to dissolve because the bulk specific gravity is small, and the pre-heated mold cools down and precision casting is performed. Did not do well. Therefore, in the method for producing a white precious metal decorative article of the present invention, the rhodium powder is once melted and formed into a plate and a rod, and then cast, so that the molten metal can be poured before the previously heated mold is cooled. Precision casting that faithfully captures the fine shape of the mold becomes possible.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a white noble metal ornament according to the present invention and a method for producing the same will be described. First, 1 of the manufacturing method
In one embodiment, rhodium powder having a particle size of 1 to 50 μm was first placed in a mold and compression-molded to produce an ingot. Next, the ingot was placed in a high-frequency furnace, melted, cast, and then hot-rolled into a sheet material. Then, the plate was put into a high-frequency furnace and melted again. 6
A molten metal was poured into a precision casting mold heated to 00 to 900 ° C., 800 ° C. in this example, and a broach casting mold in this example to obtain a rhodium broach.

Next, another embodiment of the manufacturing method will be described. Rhodium powder having a particle size of 1 to 50 μm is first placed in a mold and compression-molded to produce an ingot. Next, the ingot was put in a high-frequency furnace and melted in a vacuum. Next, a molten metal was poured into a precision casting mold previously heated to 600 to 900 ° C. and 850 ° C. in this example, and a medal casting mold in this example to obtain a rhodium medal.

As mentioned above, in the production method of the present invention, rhodium powder is melted after compression molding and processed into a plate or rod, and then melted again, or vacuum melted after compression molding to melt the molten metal. Is poured into a precision casting mold that has been heated to 600-900 ° C in advance, so that precision casting that faithfully captures the fine shape of the precision casting mold has been realized.

On the other hand, as an example of a conventional method for producing a white precious metal decorative article, a rod-shaped (sometimes plate-shaped) platinum material is put into a crucible and melted, and the molten metal is heated to 800 ° C. Pour into broach casting mold and medal casting mold,
A platinum brooch and a platinum medal were obtained.

When the rhodium broach and rhodium medal according to the embodiment of the present invention were compared with the above-mentioned conventional platinum broach and platinum medal, the results shown in Table 1 below were obtained. Was.

[0015]

[Table 1]

[0016]

As can be seen from the above description, the white noble metal ornament of the present invention has a bright white luster, is hard and hard to be scratched, is light, and has excellent precious metal precious metal value. It can be said that.

Further, according to the method for producing a white noble metal decorative article of the present invention, the above-mentioned excellent white noble metal decorative article can be stably and easily manufactured.

Claims (3)

[Claims] 1. A white noble metal ornament made of a pure rhodium material. 2. Rhodium powder is first compression molded, then melted and hot worked to form a plate or bar, then melted again, and then heated to 600-900 ° C. A method for producing white precious metal decorative articles, which is cast into a casting mold to obtain rhodium decorative articles. 3. Rhodium powder is first compression-molded, then melted in a vacuum, and then poured into a precision casting mold preheated to 600 to 900 ° C. to obtain a rhodium decorative article. Manufacturing method of white precious metal ornaments.