JPS61270351A - Ornamental platinum alloy - Google Patents

Abstract

PURPOSE:To develop an ornamental platinum alloy excelling in mechanical strength and workability by adding Ga and W to Pt in a specific ratio and by carrying out alloying. CONSTITUTION:The ornamental platinum alloy consists of, by weight, 84-96% Pt, 2-10% Ga and 0.5-10% W and has age-hardening properties. The platinum alloy for ornaments such as rings, necklaces, etc., which, as compared with conventional ornamental platinum alloys, excels in hardness after solution heat treatment, hardness after ageing, mechanical strength and workability, hardly causes occurrence of blowholes at casting and has finer crystal grains can be obtained.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to rings, seven necklaces, brooches, tie pins,
This invention relates to the improvement of platinum alloys used as materials for cufflinks, watch frames, watch hands, lighters, writing utensils, eyeglass frames, earrings, etc.

(Prior Art and its Problems) Conventionally, platinum-palladium (5 to 15 weight percent) alloys have been widely used as materials for ornaments such as those mentioned above. This alloy has excellent workability and castability, but because of its low mechanical strength and particularly low hardness, it is easily scratched and stamped during polishing, and is difficult to produce gloss, and is used as a finished product. (Also, in the case of jeweled rings, the part that holds the jewels in place loosened and the jewels could fall off.)

(Object of the Invention) The present invention has been made to solve the above-mentioned drawbacks, and aims to provide a decorative platinum alloy with excellent mechanical strength and workability.

(Structure of the Invention) The decorative platinum alloy according to the present invention has 84 to 9 G of platinum by weight.
, gallium 2-10% by weight, tungsten 0.5-10
It has age hardening properties consisting of % Shigesato.

In the decorative platinum alloy according to the present invention, the reason for adding gallium is that, as is clear from the binary phase diagram of Pt-Ga, Ga has a maximum solid solution amount of 6 at 1361°C with respect to pt.
This is because the solid solubility limit gradually decreases as the temperature decreases, and when aged at an appropriate temperature after being subjected to solution treatment in which it is heated to the solid solution region and rapidly cooled, it exhibits remarkable age hardening properties. . If the amount added is less than 2% by weight, there will be little improvement in hardness, and if it exceeds 10% by weight, pt and Ga will form an intermetallic compound, resulting in poor workability.

The reason for adding tungsten is that tungsten has a deoxidizing effect, can suppress oxygen concentration during casting, improves castability, and prevents coarsening of crystal grains at high temperatures (for example, in brazing filler metal). This is to prevent a decline in the strength of
This is because if the amount added is less than 0.5% by weight, there is little improvement in hardness, and if it exceeds 10% by weight, the alloy becomes too hard and the workability deteriorates.

(Examples) Examples and conventional examples will be described below in order to clarify the effects of the decorative platinum alloy according to the present invention.

The hardness after solution treatment, the hardness after aging, and the cavities during casting of the platinum alloys for ornaments in Examples 1 to 5 and the platinum alloys for ornaments in Conventional Example 11hL'lt2 with the component compositions shown in Table 1. The degree of occurrence and the size of crystal grains were measured, and the results shown in Table 2 were obtained.

As is clear from Table 1, Table 2, and the above table, the platinum alloy for ornaments according to the present invention has superior hardness after aging treatment, has smaller crystal grains, and is easier to cast than conventional platinum alloys for ornaments. It can be seen that the incidence of nests is also low.

(Effects of the Invention) As detailed above, the platinum alloy for ornaments of the present invention has extremely excellent workability and mechanical strength, and has a low occurrence of cavities during casting, so it is superior to conventional platinum alloys for ornaments. It can be said to be an epoch-making product that can replace alloys.

Claims (1)

[Claims] A platinum alloy for ornaments consisting of 84 to 96% by weight of platinum, 2 to 10% by weight of gallium, and 0.5 to 10% by weight of tungsten.