JPS62130238A - Hard platinum alloy for ornamentation - Google Patents

Abstract

PURPOSE:To improve the mechanical properties, castability and corrosion resistance by using prescribed percentages of Pt, Si and Pd, Cu, Ir, Rh or the like. CONSTITUTION:This hard platinum alloy for ornamentation consists of 85-95wt% Pt, 1.5-6.5wt% Si and the balance one or more among Pd, Cu, Ir, Rh, Au, Ag, Ni and Co. The alloy has high mechanical strength, especially hardness, satisfactory castability and superior corrosion resistance. The color tone of the alloy is comparable to that of platinum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a platinum alloy used for ornaments such as rings, tie bins, watch cases, earrings, and the like.

[Background of the invention and drawbacks of the prior art]

Pt-Pd alloy is widely used as a platinum alloy for decoration. Although this alloy has excellent workability, it is easily scratched or deformed when used.

On the other hand, as platinum alloys aimed at improving mechanical strength, Pt-Ir alloys, Pt-Pd-Co alloys (for example, Japanese Patent Application Laid-open No. 15-856-15) are known, but approximately Even if the drawbacks mentioned above can be overcome, it is still insufficient.

In addition, all of the platinum alloys mentioned above have high melting points, and there are considerable problems with castability such as flowability, and melting and casting of conventional platinum alloys requires particularly high-capacity melting equipment. Met.

[Purpose of the invention]

Therefore, the purpose of the present invention is to dramatically increase mechanical strength (
The object of the present invention is to provide a platinum alloy having excellent castability such as a low melting point and good flowability.

[Structure of the invention]

For the above purpose, in the present invention, 85 to 95% of pt
Add an appropriate amount of Si that forms an intermetallic compound with Pt,
The remainder is P d , Cu , A u , A g , R
It was supplemented with h-Ni-Co, Ir, etc.

As a result, regardless of the type of the remaining added elements (Pd, Cu, etc.), when the Si content is in the range of 1.5 to 6.5%, the hardness is high and the castability, color tone, and contact resistance are good. There was found.

〔Example〕

Pt with 1-7% of 81 and pd, Cu, Au, Ag,
Ninety types of alloys containing 1 to 14% of one or two elements selected from Rh, Ni, Co, Ir, etc. were melted.

During casting, centrifugal casting was performed using lost wax in the mold. The sample shape is a thin plate of 20x20xl (mm). At this time, the flowability of the metal was determined, and the transferability of the mold and the reactivity with the mold were also examined. Furthermore, the melting point was later measured, and the castability was determined from these results.

The cast samples were polished with waterproof paper and puff polished.
It was mirror-finished and used for hardness measurement, color tone measurement, and touch resistance test (after annealing at 650°C to 850°C).

When measuring hardness, Vickers hardness was measured. Regarding color tone measurement, use a spectrophotometer to measure L* a* B
*Performed by color difference ΔE*ab using a colorimeter (CIE1976). The evaluation measures the color difference with Pt, and ΔE*
a When b≦3, ◎, 3; When ΔE*ab≦6, ○, 6
When ΔE*a b≦9, ΔE*a b > 9
When , it was set as ×. In addition, the contact resistance was determined by the Cath spray test (49°
144 hours at 40'C), artificial sweat immersion test (40'C at 40'C)
8 hours) and 50% ammonium sulfide aeration test (144 hours at 25°C), and the presence or absence of corrosion was determined visually. Concerning the contact resistance, all samples showed good contact resistance without corrosion, so no entries were made in the evaluation column of Table 1.

Representative examples of the above results are shown in Table 1. Table 1 also shows Pt-10%Pd, Pt-10%Ir alloys, etc. prepared as comparative examples.

An alloy of Pt, Si, and Cu will be explained based on Table 1 as an example.

When the pt amount is fixed at 90%, (N[13~6)S1
As the amount of Si increases, the hardness increases and the buildability improves. However, the color tone deteriorates and when the amount of Si exceeds 6.5%, it no longer exhibits platinum color. Evaluations of Vickers hardness, color tone, and castability are as follows.

◎・・・・・・Very good.

○・・・Good.

△...Slightly inferior.

×・・・・・・Inferior.

The maximum amount of added Si was set to 65%. When the amount of Si decreases, the hardness also decreases and the castability deteriorates. On the contrary, the color tone improves and approaches pure platinum. Hardness is 40 even if SI is 1%
It exhibits a high hardness of FI II v, but its castability is
If the degree of deterioration is greater (if the Sl content is less than 1.5%), the flowability of the metal will be poor, and many cavities will occur, making it unusable. , the lower limit of the amount of Si was set to 1.5%.

The same results as above were obtained when the Pt amount was 95% and 85%. (1.2.7-9) Furthermore, the alloying elements added as the balance are changed from Cu to P.
d, Ni, Ir, Rh, Au, Ag.

The same result was obtained even when the material was changed to Co. Typical examples are shown in boxes 10-17.

Comparing these inventive alloys with comparative alloys (Nα18 to 21), the present alloy has a hardness of 3 to 3 that of conventional alloys.
It is clear that it is 6 times easier to cast and the color tone is not inferior. Furthermore, it has comparable contact resistance.

〔Effect of the invention〕

From the above results, the alloy of the present invention has extremely high mechanical properties (particularly hardness), good castability, the same platinum color tone, and excellent corrosion resistance compared to conventional platinum alloys. Be prepared.

Therefore, the alloy of the present invention is a platinum alloy that can be used for jewelry that can be molded by casting, such as rings, tie bins, earrings, and watch cases.

゛order°0　・ノ ↓゛〆

Claims (1)

[Claims] Platinum (Pt) 85-95% (wt%, same hereinafter), silicon (Si) 1.5-6.5%, balance palladium (Pt)
d), copper (Cu), iridium (Ir), rhodium (R
h) A decorative hard platinum alloy comprising at least one element selected from gold (Au), silver (Ag), nickel (Ni), and cobalt (Co).