JPS62161951A - Surface treatment of ornamental parts - Google Patents

Abstract

PURPOSE:To form hardened layers of a sufficient thickness on ornamental titanium parts in a short time and to give a fine color tone to the surfaces of the parts by ion-nitriding the parts and forming titanium nitride films by ion plating. CONSTITUTION:The surfaces of ornamental titanium parts such as wrist watch cases are ion-nitrided at such a relatively low temp. as 400-600 deg.C to form hardened layers to several ten mum depth in a short time. Titanium nitride films are then formed by ion plating to provide fine finished appearance. By this method, ornamental parts each having a hardened layer of a sufficient thickness and assuming a fine surface color tone are easily obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for surface treatment of decorative items such as wristwatches.

[Summary of the invention]

The present invention hardens the surface of a titanium watch case or other decorative item by subjecting it to ion nitriding treatment.

This processing method further forms a titanium nitride film on the surface by ion plating.

[Conventional technology]

Stainless steel has traditionally been used as the material for watch cases.

BS etc. were used, but in recent years titanium has also come into use. Titanium is lightweight and has excellent corrosion resistance, but it has the disadvantage of having low surface hardness and being easily scratched.

Various methods have been used to harden the surface of titanium.

Among these, nitriding treatment is commonly performed.

When titanium is nitrided, it hardens to a depth of several tens of microns, giving it sufficient strength for decorative items such as watch cases.

However, normal nitriding treatment in a nitriding gas involves heating at a high temperature of 800° C. or higher for a long time, so there is a risk of deformation.

In addition, although the surface of 9 is golden, the color tone is dirty and one color is likely to be uneven.

On the other hand, when a titanium nitride film is formed on the surface of titanium etc. by ion plating, a beautiful color tone can be obtained, but the thickness of the treated film is usually as thin as about 1 μm, so when it is applied to a soft metal like titanium, it cannot be plated. It had the disadvantage of being uneven and prone to scratches.

[Problem that the invention seeks to solve]

The present invention aims to form a hardened film on titanium with an impregnable thickness in a short time at a moderate temperature, and to give the surface a beautiful color tone.

[Means for solving problems]

The present invention uses ion nitriding of titanium to create a hardened layer of tens of microns in a short time at a relatively low temperature, and then creates a titanium nitride layer on top of that using ion plating to create a beautiful exterior finish. That is.

The reason why the processing temperature was limited to 400 to 600°C is that 400°C
This is because the nitriding rate decreases rapidly below 600°C, and the surface condition deteriorates when the temperature exceeds 600°C.

Nitriding in a normal nitrogen atmosphere takes a long time at a temperature of 800°C or higher, but with ion nitriding, a hardened layer with a thickness of 20μ or more can be created in a relatively short period of several hours at a lower temperature. can get.

〔Example〕

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

A wristwatch case was formed from pure titanium (JI type 32) and subjected to ion nitriding treatment under the following conditions.

Nz flow rate Q, 51/m1n Hz flow N O, 71'/min Furnace pressure 5mmHg Temperature 550℃ Treatment time 5hr Discharge voltage 300■ Discharge current 0.8A This nitriding treatment reduces the surface hardness to I (V1200, hardening depth was 30μ.

Furthermore, a titanium nitride film is formed on the surface of this nitrided titanium by ion plating treatment.

After evacuation, nitrogen gas was introduced and ion plating was performed under the following conditions.

Nz flow t 120mj2/min substrate bias
150V Ionization voltage 40V (50A) Vacuum degree 4X10-'Torr EB gun 10KV 300mA processing time
By this treatment for 20 minutes, a titanium nitride film with a thickness of about 1 μm was formed.

In this way, the titanium case that was subjected to ion nitriding treatment and further ion plating treatment had a sufficiently thick hardened layer, was resistant to scratches, and had a beautiful surface color.

〔Effect of the invention〕

According to the method of the present invention, decorative parts having a sufficiently thick cured layer and beautiful surface color can be easily obtained.

that's all

Claims (1)

[Claims] A method for surface treatment of decorative parts, characterized by subjecting titanium to ion nitriding treatment at 400 to 600°C, and further forming a titanium nitride film by ion plating.