JPH0723530B2 - Decorative Au alloy member having surface hardened layer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention has a surface hardened layer by nitriding treatment, which has excellent surface hardness and is particularly suitable for use as a decorative article such as a ring or a necklace. It relates to an Au alloy member.

[Conventional technology]

As is well known, gold is the most chemically stable metal of all metals, retains a beautiful golden color for a long time, is physically very flexible, and has the best malleability in all metals Since it is easy, gold and Au alloys have been widely used as decorative materials since ancient times.

Pure gold is extremely soft and easily damaged, so Ag, C
So-called 18K, 14 with appropriate hardness by adding u, etc.
Au alloys such as K are generally used as a decorative material, but even such an Au alloy has a drawback that it is still easily scratched when worn as a decorative article.

In recent years, Au alloy rings, necklaces, etc. that have a sharp pattern called a diamond cut method with a sharp cut have become popular, but in conventional Au alloy, the edge is worn and the pattern becomes unclear due to its softness. This is often a problem, and various attempts have been made to harden the Au alloy in order to overcome such problems.

[Problems to be solved by the invention]

On the other hand, when the Au alloy is worn as a decorative item, the hardness of the Au alloy member is usually Hv so that the surface is not scratched.
(Vickers hardness): 350 or more, preferably Hv: 500 or more is said to be good, for example, the hardness of the watch face glass is about Hv: 500, so if Hv: 500 or more Au alloy can be made, A hard decorative piece that won't get scratched even with this dial glass
Au alloy members can be provided.

However, at present, even if various Au alloys are subjected to heat treatment or further work hardening, the hardness is at most Hv: 300, which satisfies the above requirements.
At present, the development of Au alloys has not been successful.

[Means for solving problems]

Therefore, the present inventors, from the above viewpoint, hard,
As a result of research to obtain an Au alloy member having a particularly high surface hardness, as a result, it contains Mn in an amount of 5 to 25% by weight and, if necessary, Ni, Co, and Fe (hereinafter, these Are collectively referred to as iron group metals), 0.5 to 20%, and 1 or 2 or more of Ag, Cu, and Pd: 3 to 35%. Or both are contained and the rest is made of an Au alloy having a composition of Au and inevitable impurities, and when the surface of the base member is subjected to nitriding treatment, N diffused and infiltrated from the surface becomes Mn as an alloy component. Manganese nitride,
They have found that a complex nitride is formed with Mn and an iron group metal to form a surface hardened layer having a Vickers hardness of 500 or more.

The present invention has been made based on the above findings, and the reason why the component composition range of the Au alloy substrate is limited as described above will be described below.

(A) Mn Mn component forms a composite nitride together with manganese nitride and an iron group metal which is also contained as an alloy component if necessary during the nitriding treatment, and thus, on the surface of the Au alloy substrate,
It is an essential component for forming a nitriding surface-hardened layer with a Vickers hardness of 500 or higher, but if the content is less than 5%, a surface-hardened layer with the desired high hardness should be formed. However, if the content exceeds 25%, a peeling phenomenon will appear in the nitriding surface-hardened layer, so the content was defined as 5 to 25%.

(B) Iron group metal These components have the function of forming a composite nitride with Mn to form a high-hardness nitriding surface-hardened layer and also improving the strength of the Au alloy substrate. If required, it is contained as necessary, but the content is 0.5
If it is less than 20%, not only the desired high strength cannot be secured, but also the desired hardness improvement effect cannot be obtained, while 20%
If it is contained in excess of 10%, it will not be possible to fully exhibit the excellent properties of Au, so its content should be 0.
It was set at 5 to 20%.

(C) Ag, Cu, and Pd These components have the action of forming a solid solution in the base material and strengthening the solid solution, so if further strength is required, they are contained as necessary. However, if the content is less than 3%, the desired strength-improving effect cannot be obtained. On the other hand, if the content exceeds 35%, the characteristics possessed by Au cannot be fully exhibited, so the content is It was set at 3 to 35%.

When melting the Au alloy substrate of the present invention, Cd, Zn or the like may be used as a deoxidizing agent.
The following contents do not impair the characteristics of the substrate.

The nitriding treatment applied in the production of the Au alloy member of the present invention, particularly the ion nitriding treatment, is carried out as follows.
That is, an Au alloy substrate to be subjected to nitriding treatment is enclosed as a cathode in a closed container into which a mixed gas of H ₂ and N ₂ or NH ₃ gas is introduced so that the internal pressure is 0.5 to 10 Torr. By applying a voltage of 100 to 1500 V between the separately enclosed anode and the anode, a glow discharge is generated,
As a result, the nitrogen in the atmosphere ionized by the discharge collides with the Au alloy substrate (cathode), and the high kinetic energy of the ions heats the Au alloy substrate so that the surface is ion-nitrided. It becomes.

〔Example〕

Next, the Au alloy member of the present invention will be described with reference to examples.

Using a TIG arc, in a copper water-cooled crucible, the required additional metals and electrolytic Au are melted to prepare 10 g of Au alloy melt having the composition shown in Table 1, respectively, and then gold is placed on the button ingot. Die casting, surface polishing this ingot and dimensions: As a test piece (Au alloy substrate) having a size of 10 mm ^□ × 1 mm, after measuring the transverse rupture force for the purpose of evaluating the strength using a part of this test piece, after measuring the micro Vickers hardness,
Furthermore, the Au alloy member of the present invention is subjected to an ion nitriding treatment in a mixed gas atmosphere (mixing ratio 1: 1) of N ₂ and H ₂ having a pressure of 5 Torr at a temperature of 830 ° C. for 5 hours. 1 to 16 and comparative Au alloy members 1 to 3 each having a composition of the substrate corresponding to that of the conventional Au alloy were manufactured.

Then, the maximum surface hardness of each of the various members obtained as a result was measured by micro-Vickers. The results of these measurements are also shown in Table 1.

[Effects of the Invention] From the results shown in Table 1, the Au alloy members 1 to 16 of the present invention were obtained.
In both cases, the surface hardness was significantly improved by nitriding treatment, while the comparative Au alloy members 1, 2 (18K alloy and 14K alloy
It is clear that the surface hardness of (K alloy) is hardly changed by the nitriding treatment, and that the hardness of the comparative Au alloy member 3 made of the hard Au alloy is hardly improved. .

As described above, since the Au alloy member of the present invention has a remarkably hard surface-hardened layer formed by the nitriding treatment,
When used as a decorative member that requires these properties, it exhibits excellent performance for an extremely long period of time.

Continued Front Page (72) Inventor Kazuhiro Nakata 1-35-16 Hannan-cho, Abeno-ku, Osaka-shi, Osaka

Claims (4)

[Claims] 1. A nitriding surface-hardened layer which is hardened by manganese nitride on the surface of an Au alloy substrate containing Mu: 5 to 25%, and the balance of which is a composition of Au and unavoidable impurities (above wt%). A decorative Au alloy member formed by forming. 2. Mu: 5 to 25%, one or more of Ni, Co, and Fe (hereinafter referred to as iron group metals): 0.5 to 20%, with the balance being Au and inevitable impurities. An Au alloy member for decoration, which is formed by forming a nitriding surface hardened layer which is hardened by a composite nitride of an iron group metal and Mu on the surface of an Au alloy substrate having a composition (at least by weight). 3. A glass containing Mu: 5 to 25%, further containing one or more of Ag, Cu, and Pd: 3 to 35%, and the rest containing Au and inevitable impurities. An Au alloy member for decoration, comprising a surface of an Au alloy substrate having the following composition (at least by weight) and a nitriding surface hardened layer hardened by manganese nitride. 4. Mu: 5 to 25%, one or more of Ni, Co, and Fe (hereinafter referred to as iron group metal): 0.5 to 20%, further containing Ag, Cu, One or more of Pd and Pd: 3 to 35%, and the balance of Au and unavoidable impurities in the composition of the Au alloy substrate. A decorative Au alloy member formed by forming a nitriding surface-hardened layer hardened by a composite nitride.