JPH0280555A - Method for coating with black film - Google Patents

Abstract

PURPOSE:To form graphite films on the materials to be treated with superior adhesive strength by impressing negative bias voltage to cathodes at the time of forming black films on respective surfaces of the materials to be treated by using graphite target materials attached to cathodes, respectively, by a cathodic sputtering method. CONSTITUTION:Materials 5 to be treated attached to a holder 4 are disposed in a vacuum chamber 1, and also cathodes 2 to witch graphite targets 3 are attached, respectively, are disposed on both sides of the above materials 5 to be treated. A gas for plasma discharge, such as Ar, is introduced into the vacuum chamber 1 and a voltage for plasma discharge is impressed on the cathodes by means of an electric power source 6 to initiate plasma discharge. The above Ar gas is ionized by the above electric discharge and carbon is sputtered from the graphite targets 3, by which carbon films are formed on respective surfaces of the materials 5 to be treated. Since the powdered carbon is allowed to collide from the targets 3 against the materials 5 to be treated with high energy by impressing a negative bias voltage of 0 to -150V on the cathodes 2 by means of an electric power source 7 at this time, the carbon film excellent in adhesive strength can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention relates to a method of coating a surface of a treated article with a black film by means of cathodic sputtering.

[Conventional technology]

There is a known technique in which a target attached to a cathode is sputtered by plasma discharge generated in a working gas to coat the surface of a treated product with a substance liberated from the target by the sputtering.

[Problem to be solved by the invention]

In the above-mentioned conventional technology, titanium or other material is used as a target to coat the surface of the processed product with a film of gold color, deep purple color, or the like. However, these days, black products are often preferred, and in response to this, there is a demand for a technique for coating treated products with a black film using the above-mentioned cathode sputtering method.

The present invention has been made in view of the above points, and its purpose is to provide a method capable of coating the surface of a processed product with a black film that has high adhesion to the processed product. It is.

[Means to solve problems]

In order to achieve the above object, the present invention takes the measures as described in the claims above, and its effects are as follows.

[Effect]

By sputtering a graphite target while applying a bias voltage of 0 to -150V to the treated product, carbon released from the target forms a highly adhesive black film on the surface of the treated product. coated.

〔Example〕

The drawings showing the embodiments of the present application will be described below.

Fig. 1 shows an outline of a device for coating the surface of a processed product by cathode sputtering, which is similar to a known device. It is about 700 fl.

Reference numeral 2 denotes cathodes attached to the chamber 1, and although two are provided facing each other, it is also possible to provide only one cathode. Although a type cathode may be used, the former is preferable in that the film formation rate can be increased. Reference numeral 3 denotes a target attached to the cathode 2, and the target is connected to the cathode 2 in a good electrical manner. Achieving such a condition can be achieved by soldering,
The target 3 is made of graphite in order to form a black film on the processed product. The shape is, for example, a plate, and a plurality of locations around the plate are fixed to the cathode 2 by screws. 4 is a holder for the treated product, and 5 is a treated product (also called a base material) attached to the holder 4.This treated product 5 includes various articles that require a highly decorative black coating (for example, eyeglass frames). , knife, etc.), if only one cathode 2 is provided, use a holder 4 that can rotate the product 5 to form a coating on each part of the surface of the product 5. 6 is a power source for plasma discharge, for example, a DC power source with an output of 400 V or more is used, and the wires are connected as shown in the figure. 7 is processed product 5
This is a voltage divider shown as an example of a means for applying a bias to the product 5, and a voltage obtained by dividing the output (negative voltage) of the power supply 6 is applied to the processed product 5.

Although the figure shows an example in which the bias voltage is applied to a large number of processed items 5 through the holder 4, it may be applied directly to the processed items 5 without passing through the holder 4.

Next, the coating of the film on the processed product 5 using the above-mentioned apparatus will be explained. After the product 5 to be processed is placed in the vacuum chamber 1, the inside of the vacuum chamber 1 is first evacuated using a vacuum pump, and an inert gas (for example, argon) is introduced therein as a working gas for plasma discharge, that is, an ionized gas. be introduced. The pressure inside the chamber 1 is set at 10-" mbar to 5 x 10-" to ensure good plasma discharge.
It is made into mbar. In this state, a voltage for plasma discharge is applied to the cathode 2, and a bias voltage (0
A plasma discharge is generated in the chamber 1 by applying a voltage to the cathode 2 (selected from -150 V). High-speed particles (ions in the plasma) caused by the discharge collide with the target 3, and carbon in the target 3 is liberated. The liberated carbon flies toward the treated product 5, which is biased, and forms a highly adhesive black film on its surface. After a predetermined period of time has elapsed in the above state, the coating film has a predetermined thickness, for example, 0.5 mm, on the surface of the processed product 5. If it is coated to several μm to several μm,
The power source 6 is turned off, the pressure inside the chamber 1 is restored, and the coated product 5 is taken out.

When coating the processed product 5 by cathode sputtering as described above, the atoms of the sputtered substance deposited on the surface of the processed product 5 with low kinetic energy and the light gas atoms are exposed to the bias potential applied to the processed product 5. These atoms are not sufficiently firmly attached to the film to be removed again due to etching due to the bombardment of positive ions in the plasma caused by the plasma.

This results in the growth of a neat film deposited with high kinetic energy, free of gas adsorption.

Next, we will explain the results obtained through experiments on the relationship between the bias voltage and cathode current and the color, film formation rate, adhesion, hardness, etc. of the coating when coating the treated product 5 as described above. .

First, Figure 2 (A) shows the relationship between the bias voltage and the color of the coating obtained by a color difference meter.
In the bias voltage range of -150V, a coating that is recognized as normal "black" is obtained. (Cathode current at this time is 4.5A (cathode output density 7W/cd)
It was set to ) When the voltage exceeded -150V, peeling of the coating occurred.

FIG. 3(A) shows the film formation rate, adhesion, and hardness in the case of the above bias voltage and cathode current. As the bias voltage increases, the hardness similarly increases, but the adhesion strength shows a decreasing curve with a peak of -80V. Further, the film formation rate decreases from 10.0 to 9.0 (person/s), but powdery peeling occurs when the bias voltage exceeds 1150V. Therefore, the bias voltage is -150
It is preferable to set it to v or less.

Next, in Figures 2(B) and 3(B), the bias voltage is set to 18.
0V, and the cathode currents were 4.5A (cathode output density 7W/cj) and 6A (cathode output density 9.5W/cj).
cd), the hardness rapidly decreases from 1200 (HV) to 700 (IIV) or less as the cathode current increases. However, the adhesion strength and film-forming speed are on the rise, especially the film-forming speed has increased from 10 (people/s) to 15
The color 0, which extended to (person/S), was black with a yellowish tinge and did not change much.

The above is an example where the conditions during the film formation process are constant, but the conditions can also be changed sequentially during the formation process. It is also possible to carry out this process and then gradually change the bias voltage to increase the hardness of the coating.

The above embodiment is an example in which coating is performed with the processed product 5 stationary facing the target 3 (also referred to as static coating).

This static coating method can be used when you want to increase the adhesion by obtaining a film with a thickness of several μm or by raising the temperature of the treated product to 400 to 50°C. , tools, molds, etc.

On the other hand, instead of the static coating described above, coating may be performed intermittently by taking the treated product out from between and putting it in between two opposing targets (also called dynamic coating). Although this method takes time to obtain a thick film, it is best used for processed products where excessive temperature rises should be suppressed or where uneven coloring should be avoided. Examples of its uses include glasses, watch frames, etc. There are ornaments such as

Next, we will show the experimental results for dynamic coating.

(a) Data +11 When cathode current is 6A and bias voltage is -150V, L *
56.66 a*0.42, b*5.09 The color at this time was not pitch black but brown.

(b) Data (2) When cathode current is 6A and bias voltage Ov, L *47.
61 The color when a*0.05 and b*2.5 was yellowish but close to pitch black.

(c) Data (3) When cathode current is 7.5A and bias voltage is 0■, L *4
7.18 a * 0.02, b * 1.65 The color at this time was even closer to pure black than in (b) above.

By lowering the bias voltage (OV in the above case), a color close to pure black can be obtained. In this case, in order to prevent the film quality from deteriorating (low adhesion and hardness),
A method was adopted in which the bias voltage was gradually lowered and the voltage was set to 0 during the final coating stage.

As understood from the above results, the bias voltage (0 to
-150v), different shades of black can be obtained.

〔Effect of the invention〕

As described above, in the present invention, a graphite target attached to a cathode is sputtered by plasma discharge generated in a working gas, and
Since the surface of the treated article 5 placed under a bias voltage of -150V is coated with carbon released from the target by the sputtering, the surface of the treated article 5 has a decorative effect. It is possible to coat the treated product 5 with a coating having an excellent black color and a high degree of adhesion, which has the effect of making the treated product excellent as a commercial product.

[Brief explanation of the drawing]

The drawings show examples of the present application, and FIG. 1 is a schematic diagram of a coating apparatus using cathode sputtering, and FIGS. 2 and 3 are graphs showing experimental results. 2. Cathode, 3. Target, 5. Processed product. Figure 2 (Δ) (B) 3rd

Claims (1)

[Claims] A graphite target attached to the cathode is sputtered by plasma discharge generated in a working gas.
A black film coating method for coating carbon liberated from the target by the sputtering onto the surface of the workpiece placed in the working gas with a bias voltage of 0 to -150V applied.