JPS609869A - External parts for timepiece - Google Patents

Abstract

PURPOSE:To obtain the titled external parts each having a surface film with improved adhesive strength by coating the surface of each body to be treated with Ti, Zr or the like and by subjecting the coated body to static isotropic treatment at high temp. and pressure in a nitrogen atmosphere to diffuse the metal in the body and to form a nitride film. CONSTITUTION:The surfaces of external parts of stainless steel, brass, German silver or the like for a timepiece are coated with one or more among Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, tritium, U, Np and Pu to about 1-200mum thickness. Each of the bodies to be treated is put in a pressure vessel and subjected to static isotropic treatment at high temp. and pressure in a nitrogen atmosphere to diffuse the coating in the body and to form a layer of the nitride of the coating. By this method, hard and rigid surface films can be formed on the external parts for a timepiece.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exterior part for a watch, in which a nitride layer having strong adhesion is formed on the surface of an object to be treated. Additionally, titanium and zirconium are applied to the surface of copper alloys such as stainless steel, brass, and nickel silver, which are commonly used as materials for watch exterior parts, using various wet and dry plating methods.

Tantalum, chromium, tungsten, etc.) II
After complete formation, various metals such as titanium, zirconium, chromium, etc. coated on the surface are diffused into the inside of the object by static isotropic high temperature and high pressure treatment in a high pressure container with a nitrogen atmosphere. At the same time, the present invention relates to an exterior part for a watch, characterized in that a strong nitride film is formed by a reaction between the film and a nitrogen atmosphere.

Currently, the main exterior parts for watches are made of stainless steel, brass, or nickel silver as base materials, with various plating applied as needed.In addition, materials such as cemented carbide, titanium, or plastic are also used. It is used in the department.

On the other hand, if we look at recent market trends, there is a growing trend toward smaller and more traceable shapes, and there is also a strong tendency to desire items with higher decorative effects, especially those with beautiful surfaces and the ability to maintain their beauty forever. Excellent point strength or abrasion resistance is required as an essential condition.

However, currently, stainless steel, brass, and plated nickel silver, which are the most commonly used watch cases, are soft and easily exposed to sunlight during use, making it difficult to maintain their original appearance. Things are difficult.

In addition, most of the surfaces coated with normal wet plating or dry plating are not satisfactory in terms of hardness, and the plating peels off or wears away during use, exposing the base material, which leads to further wear and tear. The reality is that they cannot withstand long-term use.

On the other hand, cemented carbide cases are extremely hard and do not hold up at all when used with regular mobile phones, and can maintain their initial mirror-like beauty semi-permanently, but they are manufactured using powder metallurgy and require polishing using diamonds. The reality is that it is not possible to take full advantage of its features because there are many restrictions on the shape.

The present invention was developed in view of these drawbacks, and uses stainless steel and brass, which have no restrictions on design shapes.

The material is made of nickel silver, but it also includes titanium, zirconium,
hafnium, vanadium, niobium, tantalum, chromium,
Films of molybdenum, tungsten, etc. can be deposited using PVD methods such as vacuum evaporation, sputtering, and ion blasting, or OVD.
After that, the object to be treated is inserted into a high-pressure container and subjected to static isotropic high-temperature, high-pressure treatment in a nitrogen atmosphere to form the surface. A watch having an extremely hard coating with excellent adhesion by diffusing the coating formed on the substrate into the object to be treated and integrating it with the base material, and simultaneously forming a nitride layer of the coating. We succeeded in obtaining exterior parts.

Next, the details and characteristics of the present invention will be described. First, the object to be treated used in the present invention may be any metal material such as stainless steel, brass, or nickel silver, but it is suitable for use as an exterior material for a watch. The above-mentioned materials are also effective in terms of processability, economy, etc. As a coating material, periodic table PE
A-group titanium.

Any one or more of zirconium, hafnium, Vα group vanadium, niobium, tantalum, α group chromium, molybdenum, tungsten, actinium tritium uranium, neptunium, and plutonium may be used, but for practical purposes, It is easy to use elements other than actinium, and coating methods include various PVD methods, c
vp method.

Wet plating is typical, but PvD and OVD methods are effective for coating materials other than chromium. The thickness of the film formed is preferably 1 μm to 200 μm. If it is less than 1μ, the hardness and adhesion after diffusion are excellent, but there is a risk of caving in due to external impact, and if it is more than 200μ, post-processing is required for dimensional accuracy and it is not economical. .

Next, we will talk about the simultaneous diffusion and nitriding treatment, which is the most important feature of the present invention.Firstly, gas is used as the pressure medium in order to apply pressure without direction.The gas at this time causes the nitriding reaction. Using nitrogen gas and gas pressure alone have some effect, but in order to make the effects of the present invention more noticeable and promote it, it is necessary to combine temperature, and the combination of pressure and temperature has a synergistic effect. The effect further improves the properties.The temperature varies depending on the material used, but for copper alloys it is 300°C to 1000°C.
For steel-related applications, temperatures of 500°C to 1600°C are effective.
If the temperature is too low, diffusion will proceed <<; if the temperature is too high, problems such as dimensional changes in melting will occur. Number 10 as pressure
0''/, , ) or more, preferably 1000 or more, is effective.

As described above, the main feature of the present invention is that diffusion and nitridation are simultaneously formed by processing under high temperature and high pressure in a nitrogen atmosphere, and many effects that cannot be obtained with conventional methods can be expected. be.

The present invention will be explained in detail below with reference to Examples.

Example 1 A 30μ thick chromium layer was formed on a case previously processed from 18-8 stainless steel by wet plating. After that, the case was inserted into a high-pressure container, and the pressure was increased to 15% by flowing nitrogen gas.
00'Cgf/. When the temperature reached 1050°C, it was held for 3 hours. After heating, it is cooled to room temperature, and when it reaches room temperature and pressure, it is taken out from the high-pressure container. The case treated in this way has an HV of 1200 to 11 on the surface! to.

A chromium nitride layer is formed, and when looking at the cross section, the diffusion layer is 10
μ was confirmed. By the way, the chrome plating layer before treatment is Hv.
It was about 600-700. In addition, pinholes in the plating layer were also removed by high-temperature and high-pressure treatment, and the properties of the coating itself were improved. Regarding corrosion resistance, the treatment temperature matched the solution temperature of stainless steel, and in addition, the corrosion resistance of chromium and chromium nitride was excellent, so it could be used as a case material without any problems.

Example-2 Titanium was formed to a thickness of 10 μm by vacuum evaporation on a case previously processed from 1B-8 stainless steel, and then the case was inserted into a high-pressure container and nitrogen gas was flowed to a pressure of 1400”.
/,! When the temperature reaches 870°C, hold it for 2 hours. After heating, cool it down to room temperature, and when it reaches room temperature and pressure, take it out of the high-pressure vessel. The surface of the case treated in this way is An extremely hard golden titanium nitride layer with a Hv of 1700 to 1800 was formed, and a 5 μm diffusion layer was observed in the cross section. Incidentally, the stainless steel provided with the titanium layer before treatment is soft with a Hv of about 150 to 250, and the coating left on by vacuum evaporation has poor adhesion and is not practical. On the other hand, the treated case became an exterior part with a beautiful golden color, high hardness, high adhesion, and excellent corrosion resistance that could not be obtained conventionally. Even when hafnium was used instead of titanium, a film with similar colors and excellent properties could be obtained.

In the above embodiments, chromium, titanium, and hafnium were used, but similar nitrided layers and diffusion layers could be simultaneously obtained using other coating materials. In addition, the same effect can be obtained by using brass, nickel silver, etc., which have good machinability, as the base material.Furthermore, it is possible to obtain the same effect by using brass, nickel silver, etc. as the base material. Similar effects could be obtained with the coatings in which two or more types of coatings were formed.

On the other hand, although the present invention has been described only regarding the watch case, 1. As for the scope of application, similar effects can be expected when used in functional parts such as molds and cutting tools other than decorative parts. Further, even if the materials of each coating material used in the present invention are used, the same effects can be obtained even at a natural age. However, in this case, there are problems with processability and economy, so it is necessary to use it in a way that has high added value.

that's all Applicant: Suwa Seikosha Co., Ltd. Agent Patent Attorney Mogami

Claims (1)

[Claims] Titanium and zirconium are preliminarily applied to the surface of the object to be treated. hafnium, vanadium, niobium, tantalum, chromium,
Molybdenum, tungsten, tritium. After forming a coating with one or more of uranium, neptunium, and plutonium, the object to be treated is inserted into a high-pressure container and subjected to static isotropic high-temperature treatment in a nitrogen atmosphere.
An exterior part for a watch, characterized in that the formed coating is diffused into the interior of the object to be treated and a nitride layer of the coating is simultaneously formed by performing high-pressure treatment.