By adding various concentrations of rare earth cerium into the acidic hypophosphite plating baths, electroless Ni-P-PTFE coatings have been successfully deposited on the surface of shaft made of mild steel. Surface morphology, microhardness and interfacial adhesion of the coatings were characterized by scanning electron microscope equipped with energy dispersive spectrometer, vicker microhardness meter and WS-92 scrape instrument, respectively. Ring-plate wear test was applied to study the friction coefficient and wear resistance of Ni-P-PTFE coating. Results revealed that Ni-P-PTFE coatings deposited with 10ppm or 20ppm cerium in the plating baths show low friction coefficient and high interfacial adhesion,leading to its perfect wear resistance. However, both the interfacial adhesion and wear resistance of the Ni-P-PTFE coatings were decreased drastically as the cerium concentration in the plating baths was exceeds 50ppm.

A band structure composed of a square array of parallel steel tube with narrow slits is presented.The propagation characteristic of acoustic waves in this structure is investigated theoretically by the finite element method. In particular the acoustic-solid coupling is taken into account for accurate results. The transmission coefficients of the band system with different angles of the square tubes and slits width are calculated. A large continuous band gap at a low frequency range in a compound structure is obtained due to the interaction of peaks and gaps fordifferent Structural parameters.