JPH02185932A - Blackened gold alloy products and their manufacturing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention provides a blackening gold alloy and a blackening treatment characterized in that a hard black carbide film of an additive element is formed on the surface of the gold alloy. It is about law.

<Conventional technology> Conventionally, gold! Au) alloy is gold-silver copper (Au-Ag-
Cu) system, gold-Ni-Cu (Au-Ni-Cu)
There are many types, and the degree of color development is varied by adjusting the blended amounts of Ag, Ni, and Cu, but the colors are red, yellow, and white.

Recently, Au-Al (aluminum) based, Au-
With the development of Cd (cadmium) based alloys, the color has also changed to purple.
Added yellow-green color.

<Problem to be solved by the invention> However, as mentioned above, the three colors of white, yellow, red, purple, and yellow-green have limitations in creating multicolor designs for decorative items, and colors other than those mentioned above have limitations. There was a demand for the development of gold alloys.

Means for Solving the Problems> The present invention was proposed in view of the above, and uses pure gold (Au),
Or Au- with a silver (Ag) content of 40% by weight or less
Ag alloy or Au-Ni alloy with nickel (Nil content of 40% by weight or less) and 99.9 to 55% by weight, boron (B), silicon (Si), iron (Fe), cobalt (Co), titanium Each element of (Ti), niobium (Nb), and molybdenum (Mo) alone or in combination is 0.1
A gold alloy containing ~45% by weight is melted, and the gold alloy is made into a processed product by casting or other processing techniques. Hydrogen (H2), carbon oxide (CO), and hydrocarbons (C , I, ), and charcoal or coke powder mixed with sodium carbonate (Na
*Carburizing is performed for 10 minutes or more at a temperature below the melting point of the gold alloy using a solid carburizing agent, which is a powder mixture containing CO:+) and barium carbonate (BaCOi), and the hard black color of the added element is formed on the surface of the processed product. The present invention relates to a blackening gold alloy and a blackening treatment method characterized by forming a carbide film.

In the present invention, B, Si and
, Fe, Co, Ti, Nb, Mo, each element alone or two or more added together in a proportion of 0.1 to 45% by weight, is added to the Au alloy in a vacuum or inert gas atmosphere in a water-cooled copper crucible. It is melted in an arc melting furnace or a high frequency melting furnace.

Normally, when melting the above-mentioned Au alloy, the amount of melting at one time is approximately 50 to 100 g.

The ingots of each Au alloy melted as described above are melted in a vacuum or in an inert gas atmosphere, such as argon gas, and cast into a mold made of magnesia, zircon, alumina, mullite, silica, etc., and decorative processed products are produced. shall be. In this case, it is desirable to use pressurization with an inert gas or centrifugal force during casting to improve filling of the cavity in the mold.

The processed product obtained after casting as described above is usually treated with a solid carburizing agent (charcoal or graphite powder and sodium carbonate (Na2cOs)) after surface treatment by sanding, scraping, grindstone polishing, puff polishing, etc. Barium (BaCO
, ) and ) and heated at 800 to 900℃ for 2 to 3 hours.
Perform carburizing process for an hour.

Note that the carburizing temperature can be arbitrarily set as long as it is below the melting point of the alloy, and the treatment time can also be arbitrarily set.

By the above-described treatment, a glossy hard blackened layer is formed on the surface layer of the processed product. Next, by applying puff polishing to the surface of the processed product again, a glossier black color can be obtained.

Incidentally, FIG. 1 shows a schematic process diagram of the method for blackening a gold alloy according to the present invention.

<Example> An example carried out using an Au alloy of 18 karat (Au = 75% by weight), which is the most common Au grade, is shown below.

Example I Composition of Au alloy Pure Au 75 g Pure Ag 23 g Boron 2 g The above-mentioned composition was melted in an arc melting furnace in an argon gas atmosphere. This alloy was centrifugally cast in an argon gas atmosphere, and the resulting cast product (ring) was sanded and puff-polished to finish the surface. Next, this was buried in a solid carburizing agent (graphite powder 20% BaC0-) and
Carburizing treatment was performed at ℃ for 2 hours. After cooling, the ring taken out from the solid carburizing agent was completely blackened. This is because 84C, which is a black carbide, was generated throughout the surface layer of the alloy.

Then, when the surface layer was again puff-polished, a shiny black ring was obtained.

Example 2 Blend of Au alloy 75 g of pure Au 22 g of electrolytic Fe 3 g of pure titanium An Au-Fe-Ti alloy was obtained from the above-mentioned components by the same melting method as in Example 1. After that, this alloy is melted in a high-frequency induction furnace, and cast products (rings) are produced by centrifugal casting.
And so. Add this ring to solid carburizing agent (graphite powder + 10% N82).
COn) and carburized at 900°C for 3 hours. When the ring was removed after cooling, the entire ring had turned black. This is because uniform TiC was generated throughout the surface layer of the ring by the carburizing process. Then, when the ring was again puff-polished, a glossy black ring was obtained.

Example 3 Mixing of Au alloy Pure Au 75 g Pure Ag 23 g Silicon 2 g A cast product obtained by melting and casting in the same manner as above (
After surface finishing the ring), it was heated to 80°C in a solid carburizing agent.
After processing at 0° C. for 2 hours and cooling, the ring was taken out and subjected to puff polishing, resulting in a glossy black ring.

This blackened layer is due to the formation of SiC on the surface layer of the alloy due to the carburizing treatment.

Example 4 Au alloy composition Pure Au 75 g Pure Ni 22 g Boron 3g The above-mentioned composition was melted to obtain an Au-N1-B alloy.

Next, after making a cast product (ring), a surface finish is applied,
It was buried in a solid carburizing agent and carburized at 900°C for 3 hours. After cooling, when the ring was taken out from the carburizing agent, the surface of the ring was blackened, and when it was puff-polished, a glossy black ring was obtained.

Example 5 Blend of Au alloy Pure Au 75 g Pure Ag 20 g Cobalt 5 g The above blend was melted to obtain an Au-Ag-Co alloy. This alloy was melted again in a high frequency induction furnace and cast into a cast product by centrifugal casting. After surface finishing of the casting, it was treated in a solid carburizing agent at 900° C. for 3 hours. After cooling, the ring taken out from the carburizing agent turned black, and when it was puff-polished again, a glossy black ring was obtained.

Example 6 Au alloy composition Pure Au 75 g Niobium 25g The above-mentioned composition was melted to obtain an Au-Nb alloy.

A cast product of this alloy was placed in a solid carburizing agent at 900℃ for 2 hours.
Time carburizing treatment was performed. After cooling, the cast product (ring) taken out from the carburizing agent turned black, and when the surface was finished by puff polishing, a shiny ring was obtained.

Above, examples have been described for 18K (carat) Au alloys, but Au grades other than 18, for example 20K, 22
It is also possible to produce a black-colored Au alloy processed product by carburizing an Au alloy such as , after blending the additive elements according to the constituent conditions of the present invention.

<Effects of the Invention> As explained above, according to the present invention, conventionally, red, yellow,
The addition of a blackened Au alloy to the five colors of yellow-green, white, and purple Au alloys will enable even more diverse designs for precious metal ornaments, and will lead to higher added value in ornaments. .

[Brief explanation of the drawing]

FIG. 1 is a schematic process diagram of a method for blackening a gold alloy according to the present invention.

Claims (2)

[Claims] (1) The content of pure gold (Au) or silver (Ag) is 4
Au-Ag alloy or nickel (N
i) Au-Ni alloy containing 40% by weight or less is 99%
．． 9 to 55% by weight and 0.1 to 45% of each element of boron, silicon, iron, cobalt, titanium, niobium, and molybdenum singly or in combination
% by weight, and a hard black carbide film of an additive element is formed on the surface of a processed product obtained by processing the gold alloy. (2) The content of pure gold (Au) or silver (Ag) is 4
Au-Ag alloy or nickel (N
i) Au-Ni alloy containing 40% by weight or less is 99%
．． 9 to 55% by weight and 0.1 to 45% of each element of boron, silicon, iron, cobalt, titanium, niobium, and molybdenum singly or in combination
After melting a gold alloy consisting of A solid carburizing agent, which is a powder mixture containing barium carbonate, is used to carburize the product at a temperature below the melting point of the gold alloy for 10 minutes or more to form a hard black carbide film of the added element on the surface of the processed product. A blackening treatment method for gold alloys characterized by: