The study of electroless codeposite composite coatings of PTFE and graphite particles with Ni - P matrix
Mao Zhiyuang Huang Langzheng Li Jiang Cheng Siyuang Liu Chunling(Dept. of Materials Science and Engineering)
Five kinds of self- lubricating composite coating have been obtained by electroless deposition, i. e. , PTFE, Graphite, Fluorinated graphite, MoS2and CaF were codeposited in Ni- P matrix. The triobological properties of the coatings were tested on ring- on-block and pin-on-disk machines. It was found that their friction coefficients and wear resistances vary with load, partical content and heat-treatment. Comparing with Ni -Pcoating, nitriding layer of steel, and quenched steel GCr15, self- lubricating compostie coatings possess lower friction coefficient.The worn surfaces were analyzed by AES and SEM. It was observed that as the surface was slowly worn away, more solid lubricant particles in the matrix were exposed. Fine particles (as PTFE particles 2μm) came off constantly and formed a transfer film on the surface of the friction couple. Coarse particles (as graphite particles30μm) shed partly or fragmented and finally transferred to the opposite surface. It was concluded that such transfers can provide continuous and constant supply of solid lubrication , and thus reduce the friction coefficient.