JPS60141867A - Method for joining gold alloy to stainless steel - Google Patents

Abstract

PURPOSE:To prevent the electric corrosion of a joined part by joining gold or a gold alloy to stainless steel with an Ni layer as an insert in-between, diffusing the Ni in the metals on both sides by heat treatment, and quenching the joined part to carry out soln. heat treatment. CONSTITUTION:A stainless steel base 3 for a wrist watch is coated with an Ni layer 2 of about 2mum thickness by plating, and a gold or gold alloy plate 1 is joined to the layer 2 by diffusion. The Ni 2 layer is diffused in the plate 1 and the base 3 by heat treatment, and the joined part is quenched from 700-1,200 deg.C to carry out soln. heat treatment. The surfaces of the plate 1 and the base 3 are then polished as one body to provide a mirror finished surface 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Eleventh Industrial Field] The present invention relates to a method for preventing electrolytic corrosion (also referred to as potential difference corrosion) of a joint between a gold alloy and stainless steel. Its usage includes decorative items such as watch cases, bands, and pendants.

[Conventional technology]

Conventionally, various methods have been used for decorative items such as watch cases and bands by bonding gold alloy and stainless steel to enhance the decorativeness. However, if the dissimilar metals come into contact, the metal at a low potential (on the anode side), ie, stainless steel in this case, corrodes.

Therefore, as a measure to prevent corrosion, measures such as ■ Adoption of low carbon, high nickel, high chromium stainless steel that belongs to a higher potential (cathode side)'1 and inserting an insert material between the two metals of the scale to reduce corrosion f. It has been done. However, this effect was not sufficient under the harsh conditions of carrying a wristwatch, and discoloration of the stainless steel applied near the contact area was unavoidable.

[Purpose of the invention]

The present invention was made in order to prevent corrosion caused by contact between gold alloy and stainless steel, and to improve the long-term reliability of ornaments placed in corrosive environments such as watch case bands. Structure] The present invention uses nickel, silver,
Uses nickel, which is relatively effective among copper and other materials! 2,
The aim is to increase the corrosion effect and obtain long-term reliability of decorative items such as watch cases and bands.

That is, the configuration of the present invention is as follows.

(1) Put nickel as an insert material between the full alloy and stainless steel.

(2) Diffuse the nickel with gold alloy and stainless steel.

(3) After finishing the spear, it is rapidly cooled from a temperature of 700 to 1200°C and subjected to solution treatment.

Originally, nickel is a metal with poor corrosion resistance, but by undergoing the above treatment, its corrosion resistance was significantly improved. 2 shows a cross-sectional view of an example of the present invention.

The arm pull pedestal 3 made of stainless steel (SUS 516 TJ) is coated with 2 μm of nickel plating, and the 18
The gold plate 1 is bonded to the metal plate 1 by diffusion [also.

Next, this joining 1. The sample was rapidly cooled from 800°C into water. Thereafter, the gold alloy and Nutenrenu steel surfaces were polished together to give a mirror surface 4.

A salt water spray test was conducted for 48 hours on the product of the present invention and a watch case prepared for comparison, which was slowly cooled after diffusion bonding, and the corrosion status near the joint was examined using a stereomicroscope with a magnification of 20 times.

No rust occurred on the product of the present invention, but red-brown rust occurred on the comparison product from the 2nd and 3rd place toward the 7th stainless steel.

Example 2 Figure 2 shows one frame of a watch band made from clad material.

Originally, nickel-in in gold-alloyed stainless steel cladding material → tote material was conventionally made to minimize diffusion as much as possible in order to avoid lowering the pure gold content due to nickel diffusion.
``The cans are made with care to make them look good.

Therefore, in the Chigi example, the cladding material was once diffused in a vacuum furnace, and then nitrogen gas was introduced into the vacuum furnace at 850°C to rapidly cool the cladding material. Ta.

Afterwards, it was machined and finished as shown in Figure 2. That is, 2
A nickel injected well material 7 of 10 .mu.m is inserted between the metal plate 5 and the 5Us304 plate 6, which has a thickness of 0 prn.

In Example 1, the present invention and a conventional cladding material made into a watch band frame for comparison were simultaneously manufactured.
It was evaluated using the same salt spray test. Although no rust occurred in the product of the present invention, the comparative product had a slightly larger area of reddish discoloration than the comparative product of Example 1.

As detailed above, the diffusion of nickel, which is the insert material, into the gold alloy and stainless steel and the subsequent solution treatment did not significantly improve electrolytic corrosion.This is thought to be due to the following reasons. Ru.

That is, the diffusion of Ni-Nokel into stainless steel can be fully explained because nickel has the effect of improving the corrosion resistance of stainless steel. On the other hand, diffusion of nickel into gold 14-M
As is clear from the i-phase diagram (Figure 3), a solid solution is formed throughout the region at high temperatures above about 840°C, but as the temperature decreases, α1+α2
Separates into solid solution. Among these, S has poor corrosion resistance because it is mainly composed of α2 nickel and contains only a small amount of gold as a solid solution. Incidentally, since α1 metal is the main component and only contains a small amount of nickel, it has good corrosion resistance.

Therefore, in the case of two-phase coexistence of α1+α2 at a low temperature, it is assumed that rust occurred in the comparative product taken up in the example because α2 lacks corrosion resistance. However, when it is rapidly cooled from a high temperature and brought to room temperature as a solid solution as in the present invention, the nickel concentration as a whole is lower than the nickel concentration in α2, so the poor corrosion resistance of 29 Kel is not strong. It is assumed that.

The reason why solution treatment is limited to -700 to 1200℃ is that below 700℃, the two-phase α1+α2 remains and solution treatment is impossible; This is because if the temperature exceeds this temperature, it enters a liquid region and problems such as dimensional changes and pinballing occur.

〔Effect of the invention〕

As detailed above, according to the present invention, it is possible to avoid electrolytic corrosion of gold alloy and stainless steel, and to provide decorative items such as watch cases and bands that have sufficient long-term reliability even under harsh environments. Ta.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a joint between gold alloy and stainless steel according to the present invention, FIG. 2 is a perspective view of a watch band piece according to the present invention, and FIG. 3 is an Au-N? : State diagram. 1...18 gold plate 2...nickel plating 3...stainless steel watch pedestal 4...
・Integrated polished mirror surface 5...18 and metal plate 6...SUB 304 plate 7-7...2.Sokel insert material and above Applicant: Seiko Electronics T Gyo Co., Ltd. company) = 8-

Claims (3)

[Claims] (1) A 29K layer is provided as an insert material at the joint between gold or a gold alloy (under LJ, gold alloy and stainless steel) and stainless steel, and this 29K layer is diffused into the gold alloy and stainless steel by heat treatment. 700-1200℃
A method for joining gold alloy and stainless steel, characterized by performing solution treatment by rapid cooling from a temperature of . (2) A method for joining gold alloy to stainless steel according to claim 1, wherein the joint part is formed by diffusion joining, soldering, or fusion joining. (3) The insert metal Ni Sogal is Haku Maroku. A method for joining a gold alloy and stainless steel according to claim 1, wherein the gold alloy is a stainless steel.