JP2922230B2 - Decorative white gold alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION INDUSTRIAL APPLICATION The present invention relates to a decorative white metal alloy used for processing materials such as rings, necklaces, brooches, tie stoppers, plates and wires used as accessories, and castings. About.

[Conventional technology]

White gold alloy is mainly made of Ni or
Pd has been alloyed and used as a substitute for platinum for a long time. Ni-based alloys are Au-Ni (5 to 25%)-Cu (10 to 25%).
%)-Zn (1-5%), and the Pd-based alloy is Au
The structure range of -Pd (5 to 40%)-Ag (10 to 20%)-Ni (1 to 5%) is general.

[Problems to be solved by the invention]

According to the prior art as described above, Ni-based alloys have high hardness and excellent spring properties, but have a problem that they are unsuitable for chain processing or delicate work due to their excessively high hardness. In addition, there is also a problem that castability is poor due to a large amount of Ni added, and that cavities are easily generated inside the cast body.

On the other hand, Pd-based alloys are often used for chain processing and delicate work because they have good workability, but they may be inconvenient because the hardness of the cast itself is small. For example, when a jewel such as a diamond or ruby is to be stopped on a ring or a necklace, since the strength of the pawl is weak, the holding of the wand is likely to be loose and the jewel may be dropped.

In addition, when working on tie pins, brooches, eyeglass frames, etc., a brazing process will always be required.
In the case of a system alloy, this heating causes softening, and the strength of the brazing portion becomes a problem.

[Means for solving the problem]

In the present invention, 10 to 35% of Pd, 1 to 05% of Ag,
1 to 05%, Zn 0.5 to 10%, In 0.5 to 10%, P 0.00
It is characterized by being a decorative white gold alloy containing 1 to 0.35% and the balance being 50 to 83.5% of Au.

[Action]

According to the above configuration, by adding 0.001 to 0.35% by weight of P to the hexagonal alloy of Au-Pd-Ag-Cu-Zn-In, the occlusion gas in the molten metal is reduced to improve castability. , To increase the hardness by microcrystallizing the structure after casting,
The appropriate strength can be maintained even after a heating step such as brazing.

Here, the reason that Pd is limited to 10 to 35 wt% is that the addition of less than 10 wt% cannot completely remove the golden color of Au, and the addition of more than 35 wt% results in a dark gray color tone. Cannot obtain the desired color tone.

The reason why the lower limit of the addition amount of Ag and Cu was set to 1 wt% is as follows.
This is because the addition of less than wt% does not provide a synergistic effect with other elements, and the addition of more than 10 wt% may degrade the excellent corrosion resistance of the gold alloy.

Furthermore, the reason why the contents of Zn and In are each limited to 0.5 to 10 wt% is that if the content is less than 0.5 wt%, the degassing effect is insufficient and the castability cannot be improved. Is remarkably reduced, and the workability is adversely affected. The addition of Zn and In is for obtaining the effect of the synergistic action of both, and the addition of either one cannot obtain the effect intended by the present invention.

Further, if the lower limit of the addition amount of P is less than 0.001 wt%, the effect of suppressing the growth of crystal grains in the cast body is small and improvement of heat resistance cannot be expected, and if it exceeds 0.35 wt%, the workability is significantly reduced. However, this is also to deteriorate castability.

〔Example〕

Hereinafter, Examples 1 to 8 are shown in the table, and the workability, the hardness of the cast body, and the castability (fluidity, porosity, casting surface) were compared with the conventional example.

The workability was evaluated by melting 500 g of each sample in a Tamman furnace, casting it into a 10 mm thick and 25 mm wide plate,
After annealing at ℃, rolling was performed for comparison.

In the test after casting, the weight of one sample was 10 g, and the fluidity to the precision part, the degree of porosity, and the casting surface on the casting surface were observed by the lost wax casting method using a high frequency suction type precision casting machine. Went and compared. The hardness was measured on the surface of the casting.

[Effects of the Invention] From the test results in the table, it can be seen that Conventional Examples A, C, E, and F have high hardness but are extremely difficult to process, and have poor castability such as fluidity, a cavity, and a casting surface. Further, it can be seen that the conventional examples B, D, and G have extremely good workability but low hardness.

On the other hand, the thing of the present invention has good fluidity to a high-precision part with high hardness, and also has a beautiful casting surface on the surface of the casting.

In addition, there are few defects inside the ingot, the workability is good, and an excellent decorative white gold alloy is obtained.

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takashi Miyamoto 11-17 Kugahoncho, Fushimi-ku, Kyoto-shi, Kyoto Prefecture Inside the Kyoto Fushimi Office of Kyocera Corporation (58) Field surveyed (Int. Cl. ⁶ , DB name) C22C 5/02

Claims (1)

(57) [Claims] (1) Pd by weight: 10 to 35%, Ag: 1 to 10%, Cu
1-10%, Zn 0.5-10%, In 0.5-10%, P 0.00
Decorative white gold alloy containing 1-0.35%, the balance being 50-83.5% Au.