JP2006045630A - Gold alloy - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gold alloy which has a low gold content, thus is inexpensive, also has a color tone similar to that of 18-carat gold, further has satisfactory workability, and is suitable as an alloy material for jewelry. <P>SOLUTION: The gold alloy comprises, by mass, 37.5 to <50% gold, 6 to 14% silver, 6 to 10% zinc, 0.02 to 3% indium, 0.02 to 3% germanium, and the balance copper. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a gold alloy having a color tone suitable for jewelry, excellent workability, and inexpensive.

Gold has been widely used in jewelry since ancient times due to its beautiful color, corrosion resistance and processability. However, pure gold is practically used as an alloy with other metals such as silver and copper because it is very soft and weak in mechanical strength.
As a gold alloy for decoration, those of 12 gold (gold content 50%) to 22 gold (gold content 92%) are known (see Patent Document 1).

18 gold is a typical gold alloy, which is composed of 75% gold and the balance of silver and copper, and is widely used for jewelry (see Patent Document 2).
18 gold is excellent in processability and has a color tone suitable for jewelry, and its unique color tone is called 18 gold. For example, a silver / copper ratio of 15:10 is called yellow gold, the most common gold color, and a silver / copper ratio of 10:15 is called pink gold, which is a little reddish. Presents a golden color.
JP 63-169345 A JP 2002-105558 A (paragraph [0002])

However, since 18 gold has a gold content of 75%, there is a problem that it is expensive.
An object of the present invention is to provide a gold alloy that has a low gold content, is inexpensive, has a color tone similar to 18 gold, has good workability, and is suitable for jewelry.

As a result of intensive studies to solve the problems, the present inventors have found that a gold alloy having a color tone similar to that of 18 gold can be obtained while the gold content is 37.5% by mass or more and less than 50% by mass. I found it.
That is, the gold alloy of the present invention is gold 37.5% by weight to less than 50% by weight, silver 6% by weight to 14% by weight, zinc 6% by weight to 10% by weight, indium 0.02% by weight to 3% by weight. % Or less, germanium 0.02 mass% or more and 3 mass% or less, and the balance is copper.

A gold alloy can change a color tone according to liking by changing the ratio of the compounding element with respect to gold | metal | money, zinc, and copper. For example, when the ratio of copper is increased, a reddish gold color is obtained, and when the ratio of silver and zinc is increased, a reddish and pale gold color can be obtained.
The proportion of gold is preferably as low as possible to reduce the price of the gold alloy, but it is difficult to obtain the same color tone as that of 18 gold when the gold content is lower than 37.5% by mass, and 50% by mass or more. If so, the price is increased, so that it is 37.5% by mass or more and less than 50% by mass.

Silver is blended in order to adjust the color tone and obtain alloy strength. If it is less than 6% by mass, it becomes too red, and if it exceeds 14% by mass, it becomes whitish and loses the color tone of 18 gold.
Zinc is blended to improve the color tone and processability, but if it is less than 6% by mass, it will become too red and if it exceeds 10% by mass it will become whitish and will not be able to obtain a color tone of 18 gold. Falls too much and the brazing processability deteriorates.

Germanium, an additive element, prevents molten metal fluidity from being occluded by occlusion of silver, zinc, and copper gases (especially oxygen), and is effective in reducing nests in the cast body, making crystals finer and improving hardness. Is also effective. The reason why the addition amount is set to 0.02% by mass or more and 3% by mass or less is that if the amount is less than 0.02% by mass, the above effect cannot be obtained, and if the amount exceeds 3% by mass, it becomes too hard and the workability deteriorates. is there.
Indium, like germanium, reduces gas occlusion and promotes the effect of germanium, as well as adjusting the hardness. Indium and germanium also have the effect of changing the color tone. The reason why the addition amount is set to 0.02% by mass or more and 3% by mass or less is that if the amount is less than 0.02% by mass, the above effect cannot be obtained, and if it exceeds 3% by mass, the melting point decreases and the workability decreases. is there.

  The gold alloy of the present invention has a low gold content and is inexpensive, has a color tone similar to 18 gold while being 10 gold, has good workability, and is suitable for jewelry.

The composition is gold 37.5% to less than 50%, silver 6% to 14%, zinc 6% to 10%, indium 0.02% to 3%, germanium 0.02 A gold alloy in which the mass is equal to or greater than 3 mass% and the balance is copper is cast.
By adjusting the composition ratio of silver, zinc, copper, indium, and germanium within the above range, color tone and workability according to preference can be obtained.

  Table 1 shows the compositions of Examples 1 to 9 and Comparative Examples 1 to 3 of the present invention, their hardness, workability, and color tone.

In Examples 1 to 9 and Comparative Examples 1 to 3, the alloys having the compositions shown in Table 1 were heated at high frequency in an argon atmosphere, and samples were produced by a continuous casting method. Comparative Examples 2 and 3 are common 18 gold.
The hardness Hv was measured using a Vickers hardness meter.
The workability was comprehensively judged based on the occurrence of cracks by bending by cross-sectional observation, the presence or absence of discoloration after brazing, and the like.

The color tone was compared with the color tone of Comparative Examples 2 and 3 which was 18 gold.
Examples 1 to 3 are examples in which the color tone was adjusted by changing the ratio of silver and copper when gold was 41.7% by mass. Example 1 was yellow, Example 2 was pink, and Example 3 was reddish gold. A beautiful color tone similar to 18 gold was obtained. The hardness was slightly lower than those of Comparative Examples 2 and 3 which were 18 gold, and the workability was extremely good.

In Examples 4 to 5, workability was confirmed by changing the ratio of germanium and indium. In Example 4, the beautiful color tone of pink gold was obtained as in Example 2. However, since germanium was 3% by mass, the hardness was high and the workability was slightly reduced.
In Example 5, a beautiful color tone of pink gold was obtained in the same manner as in Example 2. However, since the indium content was 3% by mass, the hardness was low and the workability was slightly reduced.
Examples 6 to 7 are examples in which the color tone was adjusted by changing the ratio of silver and copper when gold was 37.5% by mass. Compared with Examples 1 to 3, the examples were slightly reddish.
Examples 8 to 9 are examples in which the color tone was adjusted by changing the ratio of silver and copper when the gold content was 49.9% by mass. The color tone was the same as that of 18 gold and the workability was good.

Comparative Example 1 is an example in which the proportions of gold, silver, copper, and zinc are similar to Example 2, but germanium and indium are not added. Since germanium and indium are not added, gas occlusion cannot be reduced, the number of nests is increased, and workability is not good.
As is clear from Table 1, Examples 1 to 9 all have the same color tone as 18 gold, and are gold alloys with excellent workability.

Claims (1)

  Gold 37.5% to less than 50%, Silver 6% to 14%, Zinc 6% to 10%, Indium 0.02% to 3%, Germanium 0.02% A gold alloy characterized by being 3% by mass or less and the balance being copper.