JPS58199894A - Coating method of external parts for wristwatch consisting of ti or ti alloy - Google Patents

Abstract

PURPOSE:To improve the adhesion of a plating film in the stage of applying metallic plating of Au or the like for decorative purposes on the surface of external parts made of Ti metal for wristwatches by activating the surface of the Ti metal beforehand with a hydrochloric acid soln. CONSTITUTION:External parts made of Ti or a Ti alloy having high corrosion resistance for wristwatches are subjected to honing, according to need, then to pretreatments such as electrolytic degreasing, rinsing or the like. Such parts are dipped in a treating soln. of 60-95 deg.C, which is an aq. soln. of 6N-12N concn. of HCl, whereby the surface is activated. Plating layers of Ni and Au having extremely high adhesive strength are formed with strike plating solns. of Ni and Au contg. HCl without rinsing. The metallic plating layer provided with high adhesion is formed directly on the Ti metal which is heretofore considered to be impossible to be formed with the plating layer having high adhesive strength.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of directly plating the surface of a component.

As is well known, TI metals have excellent corrosion resistance, but
Due to the presence of a passivated film on the surface, it is difficult to obtain a film with strong adhesion using normal wet plating alone. Therefore, after activating the metal surface with a fluoride such as hydrotunic acid or a mixed acid thereof, plating is performed, and the T1 base material is coated with a metal having the desired color tone on the surface. It was customary to obtain strong adhesion by heating in an active gas or vacuum atmosphere.

However, these methods use fluoride,
Dedicated wastewater treatment equipment and heat treatment installation li! However, the disadvantage is that it requires the installation of a 100% carbon dioxide film, and the cost associated with film formation is high.

The purpose of the present invention is to eliminate the above-mentioned drawbacks and obtain a film with strong accumulating properties. A special feature that is characterized by applying activation treatment and immediately coating with Au or Ni.In order to obtain even stronger adhesion, watch exterior parts made of T+ or T1 alloy are honed before the pre-plating process. It is characterized by the introduction of processing.

The important point of the present invention is to treat watch exterior parts made of T+ or T1 alloy with hydrochloric acid or an activating solution containing hydrochloric acid, thereby improving adhesion without the need for post-process heat treatment. Excellent coatings can be created. The activating solution preferably ranges from 6N hydrochloric acid to 2N hydrochloric acid. Additives include nitric acid, sulfuric acid and inhibitors.
It has a good concentration range of 10% or less, and its addition is effective in preventing bits, acid stains, smut, etc. Good inhibitors include commonly known thiourea and mercaptan.

The temperature of the activation liquid is within the range of 60 to 95°C, but higher temperatures are preferred. If the temperature is less than 60"C, poor adhesion will occur, and if it reaches 95C, a large amount of gas will be generated, resulting in a decrease in workability, so this is not recommended.

The next important point is the strike plating solution containing hydrochloric acid, which is the main component of the activation solution.Usually, strike plating can be performed directly from the activation solution without washing with water. It is possible to prevent the metal surface activated with the activating liquid from becoming repassivated in the subsequent water washing process.

Even if a part of the activation solution is trapped in the strike plating solution, there is no effect because both contain hydrochloric acid. The type of strike plating solution may be one containing Au or Ni with general hydrochloric acid, and commercially available products are also sufficient.

The present invention will be explained below using examples.

Example 1 First, a watch case made of pure T1 metal was cleaned with Triclean, and then subjected to the usual plating pretreatment process, that is, degreasing, degreasing, and washing with water.
After performing 5% KCN - water washing - 5% H2S04 - water washing, it is immersed in a 90'C12N hydrochloric acid solution for 2 minutes, and an N+ strike is performed without immediately washing with water. Next, after washing with water, it was transferred to a Watts bath and N1 plating was applied to 2μ. The N1 coating thus rubbed had strong adhesion to the T+gold metal, and no abnormality was observed even when subjected to a tape test and a 90' bending test.

In addition, when N+ plating was performed after activation with fluoride using the conventional method, peeling occurred in the tape test and the desired force (
It was.

Example 2 Liquid honing was applied to the surface of a watch case made of pure Ti metal under the following conditions, and the watch case was activated in the same manner as in Example 1, and instead of the Ni strike plating and Watt bath, Immediately Au strike plating and Pd-
2μ of N1 alloy plating was applied. P obtained in this way
The d-N+ alloy coating has strong adhesion to TI gold metal,
Even after performing a tape test and a 90° bending test,
No abnormalities such as peeling were observed.

The composition and conditions of liquid honing for seedlings and this example are shown below.

d) Liquid Honing Composition White Alundum #80 12. "5% wt glass peas #120 125% wt water
75%wt ■Liquid honing conditions 15Kg/i Example 3 Partial masking was applied to the watch case made of pure TI metal and the In-type back cover, and only the threaded parts of the watch case and back cover were masked. Leave it exposed.

Next, activation treatment is performed under the following conditions, and Au strike plating is immediately performed. Next, water-washed tPd-NI alloy plating is performed for 2 μm, and a film is carved.

■Activation liquid composition 6N hydrochloric acid 98% Sulfuric acid 1.8% Inhibitor 02% ■Activation condition temperature 70℃ time
After removing the masking for 5 minutes, this Pd
When the adhesion of the -N+ alloy film was tested under the above test conditions, no problems were found. Furthermore, when the completed watch case and case back were screwed together and repeatedly engaged and disengaged, the result was 30.
No chips were generated even after repeated testing. Therefore, conventionally, the mechanical engagement part (threaded engagement) of the watch case was made of T1.
However, according to the method of the present invention, this problem can be solved.

As described above, according to the method of the present invention, a film with good adhesion can be formed at T1 or T+ without performing a heat diffusion treatment in a post-process.
Gold alloy watch exterior parts can be formed. Further, if the above-mentioned coating is formed on a fitting portion of a screw or the like of a watch exterior part, the practical effect will be even greater, and if the above-mentioned coating is used decoratively on a watch exterior part, it will contribute to the expansion of the design.

Claims (2)

[Claims] (1) Activate a watch exterior part made of T+ or T+ gold alloy with hydrochloric acid or a solution containing it at 60 to 95°C, and transfer the watch exterior part to the strike plating bath containing hydrochloric acid. , Au or Ni. (2) Honing a watch exterior part made of T+ or T1 alloy, then activating the watch exterior part with hydrochloric acid or a solution containing hydrochloric acid at 60 to 95"C; A method for coating a watch exterior part made of a T+ or 'TI alloy, characterized in that it is transferred to the above-mentioned strike plating bath containing hydrochloric acid and coated with Au or N1.