Properties of Flexible DLC Film Deposited by Amplitude-Modulated RF p-CVD.

Takahiro NAKAHIGASHI

Nippon ITF, Inc., 575 Kuze Tonoshiro-cyo, Minami-ku, Kyoto 601-8205 Japan

E-mail address:JDM04606@nifty.ne.jp,

TEL 81-75-931-6040, FAX 81-75-931-6166

Abstract

In recent years, DLC (Diamond-like-carbon) film is strongly expected to develop applications in tribological elements. Contributing to this expectation is the properties of DLC films such as high hardness, low friction coefficient, wear resistance, and chemical stability. DLC films have been mainly applied to substrates of hard metals and ceramics because of their peculiar high internal stress.

Oil and fat have so far been added to improve the surface lubricity of the polymer materials such as rubber and resin. When oil and fat run dry, however, drawbacks such as gradual increase in the friction coefficient arise. Components and products made of rubber also tend to cling to the other materials used together therein. We wondered if we could eliminate such oil and fat additives that cause such bad effects. We have proceeded to coating to the polymer materials such as rubber and resin while making the best use of the feature of DLC.

We thought that three issues have to be resolved. (1) Low heat resistance of the polymer materials such as rubber and resin. (2) Pollution of the polymer material surface by oil, fat, resin, and oxidation prevention agents, etc., and (3) Transformation of the polymer materials. To resolve these possible problems: (1) We have developed a processing method by using the Amplitude-Modulated RF Plasma Chemical Vapor Deposition method which enables coating at lower temperature (below 80 degree C) and does not allow the processing temperature to rise any higher. (2) To prevent the pollution, we decided to clean the polymer surface by plasma. (3) To prevent the transformation, the film should be flexible enough to absorb the polymer material transformation. We have modified the DLC film structure to permit expansion and contraction.

The flexible DLC film is one of the novel techniques to deposit the DLC film on polymer materials such as rubber and resin, which does not cause any peeling off of the film even with the deformation of the substrates. The flexible DLC technique is expected to expand itself and to create wider applications of DLC films.

Keywords: DLC, Plasma, CVD, low friction, polymer material