JPH03130336A - White gold alloy for ornament - Google Patents

Abstract

PURPOSE:To manufacture the white gold alloy for ornament improved in castability and having good workability by adding specified amounts of Zn, In and P to a gold alloy contg. specified ratios of Pd, Ag and Cu. CONSTITUTION:By weight, 0.5 to 10% Zn and 0.5 to 10% In and, furthermore, 0.001 to 0.35% P are added to an alloy essentially consisting of Au and contg. 10 to 35% Pd, 1 to 10% Ag and 1 to 10% Cu. In this way, the white gold alloy for ornament of 12 to 20K (50 to 83.5%) by which the casting skin on the surface of a cast body is made beautiful and having less defects on the inside of an ingot as well as having good workability can be obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to decorative white gold used for processed materials such as plates and wires used as rings, necklaces, brooches, tie holders, and other devices, or for cast bodies. Regarding alloys.

[Prior art] White gold alloys are mainly alloyed with Ni and Pd and have been used as a substitute for platinum for a long time in order to bleach the golden color of gold. 25χ)C
The structure range is u(10~25χ)-Zn(1~5χ), and the Pd-based alloy is Au-Pd(5~40''A)-Ag
(10~20χ)-Ni(1~5X) Mi woven range is common.

[Problem to be solved by the invention]

According to the above-mentioned conventional technology, Ni-based alloys have a high hardness and excellent spring properties, but on the other hand, their excessive hardness makes them unsuitable for chain processing or delicate craftwork. Further, due to the large amount of Ni added, castability is poor, and there is also the problem that cavities are likely to occur inside the cast body.

On the other hand, Pd-based alloys have good workability and are often used for chain processing and delicate craftwork, but they are sometimes inconvenient because the hardness of the cast body itself is low. For example, when securing a jewel such as a diamond or ruby to a ring or necklace, the strength of the retaining claw is weak, so the grip on the cane tends to loosen and the jewel may fall off.

In addition, when crafting items such as tie pins, brooches, and eyeglass frames, brazing must go through a process, but Pd
In the case of alloys, this heating causes softening, and the strength of the brazing parts becomes an issue.

[Means to solve problems]

The present invention has Au as the main component, and Pd1O to 35% by weight.
%, Agl~IOX, Cul~10'&, Zn0.5~10χ and In0.5 in weight ratio
~10% P is further added in a weight ratio of 0.001~0.35χ to obtain a white gold alloy of [12~X20 (50~83.5 wtX).

[For production]

According to the above configuration, Au-Pd-Ag-Cu-Zn-
The weight ratio of P to the six-element alloy of In is o, oot ~ 0.35X
By adding it, the occluded gas in the molten metal is destroyed and castability is improved, and the structure after casting is microcrystallized to increase hardness, and it maintains appropriate strength even after heating processes such as brazing. can be maintained.

Here, the reason why Pd is limited to 10-35w LX is as follows.
If less than 10wtX is added, the golden color of Au cannot be completely decolorized, and if more than 35wtX is added, the color tone becomes dark gray and the color tone desired by the present invention cannot be obtained.

Also, the lower limit addition amount of Ag and Cu is 1wt! The reason for this is that if each element is added less than 1wtχ, a synergistic effect with other elements cannot be obtained, and if each element is added more than 10wt2, there is a risk that the excellent corrosion resistance of the gold alloy will be degraded.

Furthermore, the contents of Zn and In are each 0.5 to 10-tX.
The reason why it is limited to 0.5 wtX is that if it is less than 0.5 wt
If the amount exceeds 0 wtχ, the melting point will drop significantly and workability will be adversely affected. In addition, Zn and In
The purpose of the addition is to obtain the effect of the synergistic action of both, and the intended effect of the present invention cannot be obtained by adding either one.

Furthermore, if the lower limit of the amount of P added is less than 0.001wt%, the effect of suppressing grain growth in the cast body is small and no improvement in heat resistance strength can be expected.
This is because adding more than tX significantly reduces workability and also deteriorates castability.

〔Example〕

Examples 1 to 8 are shown in the table below, and compared with conventional examples in terms of workability, hardness of cast bodies, and castability (fluidity, porosity, and cast surface).

For evaluation of workability, a sample of 500 g based on weight was melted in a Tamman furnace, cast into a plate shape with a thickness of 10 ann and a width of 25 mm, which was annealed at 750° C. and then rolled and compared.

In the post-casting test, the weight of one sample was set to Log, and a high-frequency suction type precision casting machine was used to observe the fluidity of the precision part, the degree of occurrence of casting cavities, and the casting surface on the surface of the cast body using the lost wax casting method. I went and compared. In addition, hardness was measured on the surface of the cast body.

〔Effect of the invention〕

From the test results in the table, it can be seen that conventional examples A, C, E, and I have high hardness, but are very difficult to process and have poor casting properties such as fluidity, cavities, and casting surface. Furthermore, it can be seen that conventional examples No. 2 and No. 3 have extremely good workability but low hardness.

On the other hand, the material of the present invention has high hardness, good flowability to precision parts, and beautiful casting surface.

Furthermore, the ingot has few internal defects and has good workability, making it an excellent decorative white gold alloy.

Claims (1)

[Claims] 1. Main component is Au, 10 to 35% Pd by weight, A
It is characterized by adding 0.5-10% of Zn and 0.5-10% of In by weight and 0.001-0.35% of P by weight to an alloy containing 1-10% of g and 1-10% of Cu. A decorative white gold alloy of K12 to K20 (50 to 83.5 wt%).