JP2705947B2 - Manufacturing method of gold magnet accessories - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for adjusting the color tone of a surface of a personal accessory using a gold magnet alloy, and more particularly to a method for changing an alloy composition near a surface by selective oxidation treatment.

[Prior Art] Since the therapeutic effect of magnetism on the human body has been recognized by public institutions, various types of magnetic health appliances have been commercialized.
Among magnetic health appliances, there are so-called magnetic ornaments such as necklaces and bracelets, and the present inventors have used a gold-platinum-cobalt-based permanent magnet alloy as a material for composing this with a noble metal, particularly a gold alloy (Japanese Unexamined Patent Publication No. 62-185846).

This alloy is a two-phase dispersion type alloy composed of an α-phase mainly composed of gold and a β-phase mainly composed of a platinum-cobalt alloy. The accessory can be formed into a shape by casting.

The solubility of platinum or cobalt in gold is 900 ℃
At about 28% or about 5%, respectively.
On the other hand, when platinum and cobalt are added simultaneously, the mutual solubility is drastically reduced, and the total solubility of platinum and cobalt in gold is 1% or less, while the solubility of gold in the platinum-cobalt alloy is 0.5%. It is as follows.

Accordingly, the α phase has a composition close to pure gold and has a golden color, and the β phase is a platinum-cobalt alloy itself and has a dark platinum.

[Problems to be solved by the invention]

The color tone of this alloy is a mixed color of both phases exposed on the surface, but the color tone changes depending on the surface processing method. For example, when a swaging process or a roll rolling process is performed, a soft α-phase spreads on the surface and a hard β-phase is buried inside, so that the gold color of the α-phase is enhanced. On the other hand, when a grinding process, a diacut, or the like is performed, the soft α phase is preferentially removed, so that the β phase white color is emphasized.

Changing the color tone by the processing means in this way is a fate of the two-phase dispersion type alloy, but is often a drawback in the manufacture of accessories.

Therefore, an object of the present invention is to provide a gold magnet accessory that prevents a change in color tone depending on the above-mentioned surface processing method and exhibits a vivid golden color.

[Means for solving the problem]

For the above purpose, in the present invention, an accessory material made of a gold magnet alloy in a two-phase dispersion state of a phase containing gold as a main component and a phase containing a platinum cobalt alloy as a main component in an atmosphere containing oxygen. After heating to form a cobalt oxide layer on the surface, removing it reduces the cobalt content on the pole surface, and further heat-diffuses the remaining platinum which is unevenly distributed to form an alloy on the pole surface. The single phase was mainly composed of gold.

 Hereinafter, an embodiment will be described with reference to the drawings.

〔Example〕

A gold magnet alloy equivalent to 18 carats consisting of 75% gold (% by weight, hereinafter the same), 19% platinum and 6% cobalt was subjected to high frequency melting, casting, forging and wire drawing to obtain a wire having a diameter of 2 mm.

The wire rod was set on a chain knitting machine to make a kihei chain for a bracelet as a jewelry material. In this state, the material had a golden color close to pure gold, but had a slightly reddish dark color.

I tried to apply a surface treatment such as electrolytic polishing, buff polishing, barrel polishing, etc. to a part of the material, but it was observed that the golden color faded and whitened by any of the treatments. No color was obtained.

Therefore, in the present invention, the surface treatment was performed in the following steps.

FIG. 1 is a schematic cross-sectional view of an accessory material surface portion for explaining the manufacturing method of the present invention.

As shown in FIG. 1 (a), the material is in a two-phase dispersion state in which a β phase 12 mainly composed of platinum cobalt is dispersed in an α phase 11 mainly composed of gold. The diameter is around a few microns.

Since a golden α phase and a dark white β phase are exposed on the surface 1 of the material, the material has a dark golden color with a strong reddish color as a whole.

When the accessory material after chain knitting is heated in an atmosphere containing oxygen at a temperature of 900 ° C. for 10 minutes, a cobalt oxide layer 13 is formed on the surface of the material as shown in FIG. 1 (b).
Is formed.

This oxidation treatment removes cobalt that is slightly dissolved in the α phase on the very surface within a few microns from the surface of the material, so that the solubility of platinum in the α phase recovers and expands, Of cobalt is selectively removed, after which platinum 14 becomes β as shown in FIG. 1 (b).
It remains unevenly distributed in the phase position.

Next, the cobalt oxide layer 13 is removed by an acid pickling treatment and heated at a temperature of 900 ° C. for 60 minutes in a non-oxidizing atmosphere. As a result, the platinum 14 remaining unevenly distributed as shown in FIG. It is almost uniformly diffused to the pole surface 15 of the material and completely dissolved in the α phase, so the pole surface 15 of the material is a single phase of α phase mainly composed of gold with a small amount of platinum dissolved therein. .

By this treatment, the surface of the material showed a bright and bright golden color, which is the standard color of 18 carat gold alloy, and its gloss was further improved by barrel finishing. Further, the color tone did not change even by buffing, and the finishing treatment could be performed in the same manner as a normal gold alloy.

〔The invention's effect〕

According to the method of the present invention, a bright golden color, which is a standard color of a decorative gold alloy, can be obtained by using a gold-platinum-cobalt-based two-phase dispersed gold magnet alloy.

Further, the color tone is not deteriorated even by finishing treatment such as barrel polishing and buff polishing, which is extremely advantageous in production technology.

Furthermore, since the content of cobalt on the very surface is extremely small, even when brazing in air, discoloration due to oxidation is scarcely observed, and since the surface is a single phase, electric corrosion Corrosion resistance is further improved without causing a surface potential difference which causes the above.

Since the change in the alloy composition according to the method of the present invention is limited to the very surface of the accessory material, the effect on the magnetic properties is negligible, and the noble metal magnetic accessory using the gold alloy according to the present invention is used. The decorative function can be significantly enhanced.

[Brief description of the drawings]

1 (a), 1 (b) and 1 (c) are schematic cross-sectional views of the surface material of an accessory for explaining the manufacturing method of the present invention. 10: Material surface, 11: α phase, 12: β phase, 13: Oxide layer, 14: Platinum remaining.

Claims (1)

(57) [Claims] An accessory material made of a gold magnet alloy in a two-phase dispersion state of a phase containing gold as a main component and a phase containing a platinum-cobalt alloy as a main component is heated in an oxygen-containing atmosphere to obtain a surface. After forming an oxide layer of cobalt on the surface, it is removed to reduce the content of cobalt on the surface of the pole, and the platinum on the surface of the pole is mainly composed by heating and diffusing the platinum remaining unevenly distributed. A method for producing a gold magnet accessory, which is a single phase.