AVS 46th International Symposium
    Vacuum Metallurgy Division Tuesday Sessions
       Session VM-TuP

Paper VM-TuP5
Friction Evaluation and Development of Vacuum Materials for Tribological System

Tuesday, October 26, 1999, 5:30 pm, Room 4C

Session: Poster Session
Presenter: M. Tosa, National Research Institute for Metals, Japan
Authors: M. Tosa, National Research Institute for Metals, Japan
A. Kasahara, National Research Institute for Metals, Japan
Y.S. Kim, National Research Institute for Metals, Japan
K. Yoshihara, National Research Institute for Metals, Japan
Correspondent: Click to Email
Vacuum materials for movement system requires small friction as well as low outgassing. Friction and outgassing strongly depends on the surface conditions and structures of the materials. It is therefore important to evaluate fiction accurately in-situ in a vacuum as controlling such surface layer structures as contaminates layer, adsorbed layer and oxide layer by changing load and vacuum pressure. We have developed a vacuum friction measurement apparatus to evaluate sliding friction under changing the load from 1N to 0.98 mN and under the vacuum pressure from 10@super5@ Pa to 10@super-8@ Pa. Two strain gauges measure the friction force occurred at the loaded pin on the substrate sheet. The measurement was carried out on the sheets for such vacuum materials as type 304 stainless steel, copper, hexagonal boron nitride (h-BN) segregated copper film on the stainless steel, sintered h-BN plate and titanium nitride (TiN) coated stainless steel. All steel sheets are polished mechanically with diamond powder of 0.3µm in grain size. Co-sputtering deposition of h-BN chips and a copper disc target prepared segregated h-BN film. Titanium nitride was coated on the stainless steel with magnetron sputtering deposition. The result of the measurement in decreasing the vacuum pressure shows that the friction coefficient of h-BN surface segregated copper film on steel keeps about 0.1, which is smaller than any other coefficient. The friction coefficient of copper and TiN coated steel decreased gradually but still larger than that of h-BN surface segregated copper film and the friction coefficient of stainless steel increases very much in decreasing the pressure. The result of the measurement in decreasing the load shows that the friction coefficient of h-BN surface segregated copper film on steel keeps smaller than that of copper and steel sheet. Hexagonal boron nitride segregated copper film can be therefore a good candidate material for vacuum tr! ibological system.