JPS59143032A - Surface hardened pt alloy member for decoration - Google Patents

Abstract

PURPOSE:To provide a titled alloy member having extremely high surface hardness and excellent wear resistance by forming a surface-hardened layer consisting of the texture dispersed therein with hard CrB on the surface of a Pt- Cr alloy member consisting of a specific compsn. CONSTITUTION:The surface of a Pt alloy member having the compsn. contg. 0.5-15wt% Cr, further contg. either one or both of 0.5-25% Pd and 0.5-15% >=1 kind among Cu, Ag, Ni, Co, Fe, Au and Ir according to need and the balance consisting of Pt and unavoidable impurities is subjected to a boriding treatment, then the B diffused and intruded from the surface reacts with the Cr solutionized mainly in the base, thereby forming hard CrB. A surface-hardened layer having extremely high hardness of about 1,000-1,500Hv dispersed with hard CrB is formed on the surface of the above-mentioned Pt alloy member and the beautiful decorative metallic gloss is maintained semipermanently.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to decorative PT alloy members such as rings and necklaces that have extremely high surface hardness and therefore exhibit excellent wear resistance in practical use.

As is well known, Pt, like Au, is the most stable metal among metals, retains a beautiful metallic luster for a long time, and is extremely flexible and malleable.
Coupled with the fact that it is easy to work with, it is widely used as a decorative material like Au.

Also, since PT is extremely soft, it is easily scratched.
Therefore, Cu, kg, Ni, Co, F
i'e, Au.

Alternatively, Pt alloys containing metals such as Ir as alloy components to give appropriate strength are 950 platinum and 85 platinum.
It is put into practical use as 0 platinum.

However, even when these PT gold alloys are worn as accessories, they are easily scratched and their metallic luster deteriorates relatively quickly.

Furthermore, in recent years, rings and necklaces with clear patterns created by sharp cuts called the diamond cutting method have become popular, but conventional PT gold alloys are soft and often wear out, causing the patterns to become unclear. In view of these points, the demand for hard PT gold alloys is increasing.

Generally, when wearing PT alloy members as accessories, K
In order to prevent scratches on the surface of the PT alloy member, it is said that the surface hardness of the PT alloy member should be Hv (Vickers hardness) of 4o○ or more, preferably Hv: 500 or more. Since the hardness of %Hv:500 is approximately Hv:500, if a PT gold alloy with a hardness of %Hv:500 or higher can be made, it will be possible to provide a PT alloy watch that will not be scratched even with this dial glass.

However, even if various PT gold alloys are subjected to thermal mechanics or work hardening is used, the hardness obtained is at most Hv: 350, and it is difficult to obtain a hard PT that satisfies the above requirements. Currently, alloy members are not available.

Therefore, from the above-mentioned viewpoint, the present inventors conducted research to obtain a PT alloy member having hardness, particularly high surface hardness.
, 5 to 15%, and optionally Pd, 05%.
~25%, Cu, Ag, Ni, Co, Fe
.

Au, and one or more of the rows, 05-1
5% contains one or both, and the remaining 9 consists of pt and unavoidable impurities, and this p
When the surface of the PT alloy member is subjected to boriding treatment, the B that has diffused into the surface reacts mainly with Cr dissolved in the base material to form extremely hard chromium boride. A hardened surface layer having a structure in which hard chromium boride is dispersed is formed on the surface of the It was discovered that the hardened PT alloy member exhibits extremely excellent wear resistance and retains a beautiful metallic luster semi-permanently.

This invention was made based on the above-mentioned knowledge, and includes: Cr: 0.5 to 15% by weight.

and, if necessary, Pd: 0.5 to 25%, Cu + Ag + N1+ Co + Fe + A
One or more of u + and k r゛o5
~15%.

A decorative surface formed by forming a hardened surface layer having a structure in which hard chromium boride is dispersed on the surface of a PT alloy member having a composition containing either or both of the above and the remainder consisting of PT and unavoidable impurities. This is characterized by a hardened PT alloy member.

Next, the reason why the composition range of the PT alloy of the present invention is limited as described above will be explained.

(a) Cr The Cr component has a solid solution in the base material to strengthen it.
When a material is subjected to boriding treatment, it forms hard chromium boride, which increases its surface hardness and significantly improves wear resistance. However, if the content is less than 0.5%, the desired high It is not possible to form a surface hardening layer with hardness, and on the other hand, if the content exceeds 15%, the plastic workability of the component itself tends to deteriorate, and furthermore, the hardness is further improved by the surface hardening layer. Since no effect could be expected, its content was set at 05 to 15%.

(b) pa The Pd component has the effect of improving the ductility of the PT alloy member, so it is included as necessary when particularly ductility is required, but if the content is less than 0.5%, the desired content cannot be achieved. The effect of improving toughness cannot be obtained, and if the content exceeds 25%, the corrosion resistance will decrease, so the content was set at 05 to 25%.

(c) Cu, Ag, Ni+ Co, Fe,
Au and Ir These components have the effect of strengthening the PT alloy member, so they are included as necessary when particularly strong strength is required, but if their content is less than 0.5%, the desired strengthening cannot be achieved. On the other hand, if the content exceeds 15%, the ductility decreases and plastic working becomes difficult, so the content was set at 05 to 15%.

Next, the PT alloy member of the present invention will be specifically explained with reference to Examples.

Example Using a TIG arc, necessary alloying metals and electrolytic PT were melted in a water-cooled copper crucible to prepare molten PT alloys (logs) each having the composition shown in Table 1. It is cast into a mold to form a button shape, and then its surface is polished to obtain a test piece having dimensions of flat surface: 1 OB x thickness: 1 m. Holds the molten flux (composition).

Weight: B4C: 80%, H3POs: 10
%.

The present invention's pt
Combined total members ~27 and comparative Pt alloy members 1~8 were manufactured, respectively.

Then, the maximum surface hardness (Vickers hardness) of the various members obtained as a result was measured. These results are shown in Table 1. Furthermore, Table 1 also shows the maximum surface hardness before the boriding treatment.

The comparative PTT gold members 1 to 8 were all subjected to a conventionally known PT gold alloy boriding treatment.

From the results shown in Table 1, the PTT gold member of the present invention]~2
In contrast to the comparative PTT gold members 1 to 8, which do not contain Cr, the surface hardness of PTT gold members 1 to 8, which do not contain Cr, has a much higher surface hardness of Hv: 500 or more. It is clear that even if the fertilizing treatment is carried out, the surface hardness remains almost unchanged since no hardened surface layer having a structure in which hard chromium boride is dispersed is formed.

As mentioned above, the PTT gold member of the present invention has a hardened surface layer with a structure in which hard chromium boride is dispersed, so when it is used for decoration, it retains its original shape for an extremely long period of time. It has industrially useful properties such as not impairing its aesthetic value.

Applicant: Mitsubishi Metals Corporation

Claims (4)

[Claims] (1) Cr: Contains 0.5 to 15%, the balance 9 is p
A surface hardened PT alloy member for decoration, comprising a surface hardened layer having a structure in which hard chromium boride is dispersed, on the surface of a PT alloy member having a composition (the above weight %) consisting of T and unavoidable impurities. (2) Cr: Contains 0.5 to 15%, and further contains P
A hardened surface layer having a structure in which hard chromium boride is dispersed is formed on the surface of a Pi alloy member having a composition (weight%) containing d05 to 25% and the remainder consisting of PT and unavoidable impurities. Decorative surface hardened PT alloy parts. (3) Cr: Contains 0.5 to 15 tyb, and further contains Cu and Ag. A PT alloy member containing 05 to 15% of one or more of Co, Fe, Au + and Ir, with the remainder consisting of PT and unavoidable impurities (weight %). A decorative surface-hardened PT alloy member formed with a surface-hardened layer having a structure in which hard chromium boride is dispersed. (4) Contains Cr: O, 5-15%, further contains Pd: 0.5-25%, Cu, Ag, Ni,
Contains one or more of Co, F'e, Au, and 05 to 5, and the rest is p.
A surface hardened PT alloy member for decoration, comprising a surface hardened layer having a structure in which hard chromium boride is dispersed, on the surface of a PT alloy member having a composition (the above weight %) consisting of T and unavoidable impurities.