JP6728528B2 - Gold alloy - Google Patents

Description

The present invention relates to a gold alloy that can be mainly used for jewelry such as rings, necklaces, and broaches, and can also be used as an industrial gold alloy material.

Generally, gold materials of various grades such as 24 gold, 18 gold, 12 gold, and 10 gold have been developed as gold materials for jewelry, and as for color tone, jewelry of various colors such as yellow gold, white gold, and pink gold. Gold alloys for use have been developed and put into practical use.

Among them, yellow gold has a yellow color, but since it has a golden color close to that of pure gold, materials with various compounding values have been developed and put into practical use in various grades (for example, Patent Document 1).

JP, 9-13132, A

However, in a low-grade Au alloy such as 12 gold or 10 gold, which is inexpensive and easily obtainable with 50% by mass or less, an element other than Au must be added in a large amount. Is difficult to express.

In addition, when an element that easily volatilizes during dissolution is contained, there is a problem that if the element is redissolved for jewelry, the constituent element volatilizes and the color tone changes.

Therefore, an object of the present invention is to obtain yellow gold capable of developing a color tone close to the golden color of pure gold, in an Au alloy such as 12 gold or 10 gold containing 50% by mass or less of Au.

The gold alloy according to the present invention is composed of Au, Cu, Ag, Zn, In , 40 to 50 mass% of Au, 35 to 45 mass% of Cu, 8 to 20 mass% of Ag, and 1 to 8 mass% of Zn. , characterized in that a 1 to 10 wt% of In.

In the above-described structure of the present invention, Au is the main component and has a role of giving the original golden color of Au.

Ag, Cu and Zn are additive elements for maintaining the original golden color of Au, and by combining these three elements while controlling the compounding ratio, it is possible to provide yellow gold having the original golden color of gold. Made possible

In addition, by adding 1 to 10% by mass of In to the above composition, other constituent elements are less likely to volatilize even after repeated redissolution for jewelry, and as a result, the color tone changes even after repeated redissolution. It will be possible to use yellow gold without.

The elements constituting the above are blended in desired amounts, melted at a temperature of about 1100° C., and subjected to a casting process such as the lost wax method to process into jewelry such as rings, necklaces and pendants.

Here, the amount of Au is 40% by mass or more for obtaining a golden color peculiar to Au, and the amount of 50% by mass or less is for forming a low-grade Au alloy.

This is because Cu has an effect of imparting a red color tone, and if it is less than 35% by mass, the silver color tone due to Ag added at the same time becomes too strong, and if it exceeds 45% by mass, the red color tone becomes too strong. In addition, Ag added at the same time improves the mechanical strength, and can prevent the occurrence of scratches during use as a jewelery product and suppress the deterioration of the appearance quality.

This is because Ag has an effect of giving a silver color tone, and when it is 8% by mass or less, the red color tone due to Cu becomes too strong, and when it exceeds 20% by mass, the silver color tone becomes too strong. Is.

Zn can produce a golden color tone when combined with Au and Cu, and its effect is low at 1% by mass or less, and when 8% by mass or more, volatilization at the time of re-dissolution becomes large to reproduce the color tone. Is difficult.

Further, addition of Zn also has effects of improving castability and as a deoxidizing material during melting.

Next, In has an effect of suppressing volatilization of constituent elements and suppressing a composition change before and after remelting of the alloy. In particular, it is extremely effective in suppressing the volatilization of Zn. Due to this effect, yellow gold having no difference in color tone before and after redissolution can be obtained. If it is less than 1% by mass, the effect is low, and if it exceeds 10% by mass, it becomes white. Further, by adding at the same time as Zn, the castability can be further improved.

Table 1 shows comparative examples together with the examples.

In addition, the evaluation sample of the color tone was prepared by mixing the materials and melt-casting at about 1100° C. to prepare an ingot, rolling the ingot into a plate, and buffing the surface, and then evaluating the color tone with the naked eye and a color difference meter. did.

As a color tone evaluation standard, a representative K18 yellow gold consisting of 75% by mass Au, 12.5% by mass Ag, and 12.5% by mass Cu was produced under the same conditions as above, and the relative evaluation with the example was performed. .. When there is no difference compared with the color tone of K18 yellow gold, "yellow" is shown, and when there is a difference, that color tone is shown.

After the evaluation, these various alloys were again melted and processed under the same conditions, and whether or not there was a difference in the color tone was evaluated again in the same manner.

In addition, ICP emission spectroscopic analysis is performed to check whether there is a difference in alloy composition before and after remelting. When there is a difference in color tone and alloy composition before and after remelting, “X” is given, and when there is no difference, “X” is given. ○” was evaluated.

According to the invention of the present application, it is possible to obtain yellow gold for jewelry which has a low tone of 50% by mass or less of Au and has a color tone close to the golden color that pure gold originally has.

Further, by adding In, these constituent elements do not volatilize even when remelting, and there is no difference in color tone and alloy composition before and after remelting.

Claims (1)

A gold alloy composed of Au, Cu, Ag, Zn and In, where Au is 40 to 50% by mass, Cu is 35 to 45% by mass, Ag is 8 to 20% by mass, and Zn is 1 to 8%. The gold alloy is characterized by mass% and In of 1 to 10 mass %.