JPH0238596A - Coating method for surface - Google Patents

Abstract

PURPOSE:To thoroughly eliminate a hole perforating a film by performing anodic-oxidation treatment which is performed for the purpose of sealing a pinhole generated on a coated surface layer in an initial stage while giving ultrasonic vibration to electrolytic liquid. CONSTITUTION:An Nb film is formed on Al alloy by high-frequency magnetron sputtering in a vacuum vessel. Then anodic-oxidation treatment is performed while giving ultrasonic vibration to electrolytic liquid. The oxide film formed on the surface of the Nb film is polished and removed and the Nb film is relaminated by sputtering. When this is immersed in hydrochloric acid at room temp., erosion is not caused on the surface of the Nb film even after the elapse of 24 hours. When ultrasonic vibration is not given) an eroded part is generated on the surface of the Nb film in about 3-6 hours. When ultrasonic vibration is given, anodic-oxidation treatment is performed while discharging gaseous H2 incorporated in a pinhole to the outside and therefore filling-up of the pinhole is completely performed and surface coating thoroughly free from the pinhole perforating the film is enabled.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to physical vapor deposition (PVD), chemical vapor deposition (CVD), etc.
Method D), when coating the surface of a material to be coated (base material or substrate) with a film using methods such as plating, there are no holes that occur in the film that penetrate from the material to be coated to the surface of the film. The present invention relates to a surface coating method.

[Conventional technology and its issues]

PVI) method, CVD on the surface of coated materials such as metals
A commonly used method is to coat metal, ceramic, or the like with a film to improve corrosion resistance, electrical conductivity, abrasion resistance, and other properties by methods such as electroplating and plating. For example, coating copper with silver, gold, etc. to improve conductivity and electrical connectivity, coating aluminum with titanium to improve corrosion resistance, and coating the surface of carbon steel with Nb to improve corrosion resistance. Alternatively, there is a method of coating one side of an insulating ceramic with a metal to impart conductivity.

In these surface coating methods, pinholes occur in the film due to pinholes inherent in the material to be coated, contamination of the material to be coated, the influence of dust such as the presence of foreign substances throughout the entire process of film formation, and the above-mentioned problems occur. There was a problem that the film characteristics could not be fully exhibited.

Conventional basic measures to suppress or eliminate the occurrence of pinholes include improving the precision of the cleaning process for the coating material, maintaining ideal conditions such as the cleanliness of the film forming equipment (equipment), and the degree of high vacuum attainment. In order to obtain a highly clean environment, methods such as introducing clean rooms and making the environment dust-free are being implemented to prevent the generation of dust.

In addition to these environmental measures, pinholes can be reduced or eliminated by increasing the thickness of the film or modifying the surface of the film by laser or ion beam irradiation, etc., within the required characteristics of the product. methods are also being used.

However, when the film is made thicker, distortion occurs due to differences in thermal expansion coefficients between the material to be coated and the film, and the film peels off. Furthermore, cleaning the environment requires enormous equipment costs, and it is difficult to employ it for surface modification of general industrial materials due to cost. Furthermore, surface modification methods such as laser and ion beam irradiation,
There were still problems in terms of cost and large area.

In order to solve these problems, the inventors of the present invention have conducted intensive studies and found that the material to be coated (base material or substrate) can be coated using surface coating methods such as physical plate deposition, chemical deposition, and plating. ), pinholes that occur in the initial layer applied to the material to be coated are removed by anodic oxidation treatment in one layer or each layer, using reaction products (oxides) with the material to be coated and the film. He discovered that by sealing the film, it was possible to eliminate the pores that penetrate from the material to be coated to the surface of the film, and filed a patent application (Japanese Patent Application No. 1227-1981).
(See No. 98).

However, by means of the anodic oxidation treatment, a reaction product (oxide) between the electrolyte and the coated material or film is generated inside the pinhole to seal the pinhole. When a certain amount of the reaction products (oxides) are generated inside the pinhole, the H2 gas generated by the reaction accumulates inside the pinhole, making it difficult for the electrolyte to penetrate inside the pinhole, resulting in oxidation. The reaction does not proceed sufficiently, and the inside of the pinhole is not completely filled with the reaction product. Therefore, even if a film is further laminated on top of the second layer, the film may not grow sufficiently in the pinhole area, and some pinholes will remain in the form of through holes, making it impossible to obtain sufficient corrosion resistance. There were cases where it was not possible.

[Means to solve problems]

The present invention was made as a result of intensive studies in view of the above points, and its purpose is to provide a surface coating method for sealing pinholes generated when coating a surface film on a material to be coated by anodizing treatment. Another object of the present invention is to provide an anodizing method that completely seals pinholes and provides a surface film with excellent corrosion resistance.

The present inventors used anodizing treatment to seal pinholes that occur when coating a surface film on a material to be coated, by performing anodizing treatment while applying ultrasonic vibration to the electrolytic solution, thereby sealing the inside of the pinholes. The present invention was completed by discovering that the anodic oxidation process can be performed while discharging H2 gas generated by the reaction between the electrolytic solution and the material to be coated or the film to the outside of the pinhole.

That is, the present invention aims at eliminating pinholes that occur in the initial layer applied to the material to be coated when coating the material with a film using a surface coating method such as physical vapor deposition, chemical vapor deposition, or plating. This surface coating method is characterized in that the anodic oxidation treatment is performed while applying ultrasonic vibration to the electrolytic solution.

When coating a material to be coated with a film by a surface coating method such as a PVD method, a CVD method, or a plating method, the present invention provides an anode for the initial layer coated on the material to be coated, that is, the first layer of the coating layer or each layer. The pinholes are filled in by filling them with oxidation treatment, and the pinholes sealed in this way in the first layer or each layer of the film are covered by several layers above it. Even when the film is coated, pinholes do not penetrate into the coating layer on the upper surface, and the properties of the film can be maintained without being impaired.

As the means for the anodizing treatment in the present invention, for example, A! When using a plate and coating the surface with a Nb film, first the Nb film is formed by high-frequency magnetron puncture, then the A2 surface is anodized by anodizing treatment, and an oxide (Nb205) film is applied to the Nb film surface. The pinhole is sealed, and the transferred oxide film is removed by polishing to expose the Nb film.

Encapsulation by means of the above-mentioned anodic oxidation treatment is possible by applying it to the first layer film, but
If the confinement of the layer seems incomplete, the 2N and 3
It is also possible to achieve more complete containment by applying it to each layer. The film with the pinholes sealed in this way has the desired properties, and no matter how many layers of film are coated on the surface if necessary, the pinholes are already blocked, so they can be continuously penetrated. A good film can be obtained without any pinholes.

In addition, when a thick film is created by such lamination, the internal strain in each layer (mainly thermal strain due to heating and cooling during film formation) is alleviated between each layer, so when a single layer is made thick, It is also possible to avoid problems such as deterioration of adhesion and peeling.

In the present invention, inorganic substances such as metals or ceramics can be used as the material to be coated, and inorganic substances such as metals or ceramics can be used as the coating.

[Effect]

In the method of the present invention, when sealing pinholes generated when coating a surface film on a material to be coated by anodizing, the anodizing is performed while applying ultrasonic vibration to the electrolyte. H2 gas generated by the reaction between the electrolytic solution and the coated material or film inside the pinhole is quickly discharged from the pinhole. Therefore, the electrolytic solution always permeates into the pinhole, and the oxidation reaction progresses sufficiently to completely fill the pinhole with the reaction product. In addition, when it is desired to further layer a film on top of this, the evaporated particles that fly onto the substrate surface by the PVD method etc. do not fill the pinholes and can adhere to the reaction product and grow as a film. The pinhole filled with the product is completely shielded from the outside world, ensuring the inherent corrosion resistance of the coating.

[Example] Next, the present invention will be explained in more detail with reference to Examples. The material to be coated was a 30mm square plate with a thickness of 1.24mm (
5086AI of square)! , using alloy, back pressure 5X10
The Nb film was heated to 200°C in a vacuum chamber kept at -7 Torr or less, and the Nb film was formed by high-frequency magnetron sputtering.
It was formed to have a thickness of 5 μm. Next, this sample was anodized under the following conditions to anodize the A2 surface and N
An oxide (Nb205) film was formed on the surface of the b film.

Electrolyte: 15%H2SO4 Liquid temperature: 20±0.5''C Current density: 0.83A/dm2 Time: 30min At this time, the electrolytic cell was immersed in an ultrasonic bath, and the oscillation frequency was 50KH.
Anodizing treatment was performed while applying ultrasonic vibration of z. After the anodic oxidation treatment, the oxide film formed on the surface of the Nb film was removed by polishing with #2000 emery paper, and an approximately 7.5 μm thick Nb film was deposited again by sputtering in the same manner as described above. Thereafter, the surface of the sample other than the coated surface was masked with an epoxy resin adhesive, and the sample was immersed in hydrochloric acid at room temperature. No abnormalities such as erosion occurred on the Nb film surface even after 24 hours of immersion.

On the other hand, when ultrasonic vibration was not applied during the anodizing treatment, erosion spots occurred on the Nb film surface when immersed in hydrochloric acid at room temperature for about 3 to 6 hours.

〔Effect of the invention〕

According to the method of the present invention, when forming a surface film by a method such as a physical vapor deposition method, a chemical vapor deposition method, or a plating method, it is possible to eliminate holes penetrating from the material to be coated to the surface of the film. It has remarkable industrial effects, such as the ability to obtain coatings with excellent corrosion resistance that have the same characteristics as those of previous generations.

Claims (3)

[Claims] (1) When coating the material to be coated with a film using a surface coating method such as physical vapor deposition, chemical vapor deposition, or plating, pinholes that occur in the initial layer coated on the material to be coated can be removed in one layer or in each layer. 1. A surface coating method for sealing by anodic oxidation treatment, characterized in that the anodic oxidation treatment is performed while applying ultrasonic vibration to an electrolytic solution. (2) The surface coating method according to claim 1, wherein the material to be coated is an inorganic substance such as metal or ceramics. (3) The surface coating method according to claim 1 or 2, wherein the coating is made of an inorganic material such as metal or ceramics.