Tribological properties of high temperature self-lubrication metal ceramics with an interpenetrating network

FeCrWMoV/TiC metal ceramic preforms with three-dimensionally interpenetrated micropores were fabricated using the mixture of stearic acid, TiH2 and CaCO3 as pore-forming agent. A self-made vacuum high pressure infiltration furnace was used to infiltrate the preforms with Pb–Sn based solid lubricants to create almost fully dense self-lubrication composites where both solid lubricant phase and matrix phase were interpenetrating throughout the microstructure. By means of scanning electron microscope (SEM) and energy dispersive spectrometer (EDS), it was found that solid lubricants were well dispersed and embedded in the metal ceramic matrix. The friction and wear behaviors of the composites were investigated using a pin-on-disk wear tester over a load range of 30–250 N. The experimental results indicated that by adding 15% silver in mass into the three-element Pb–Sn–RE compound lubricants, the sliding friction behavior of the composites upper 400 °C could be improved markedly, especially under high loads. It was considered that the micropores on friction surface would be the crucial factors determining the self-lubricating properties of the self-lubrication composites. The addition of silver could facilitate the breaking and moving of the wear debris hold on the friction surface, and thus to preserve the open pores at the surface and the further supply of the lubricant to the contact surface. The research also showed that, even the molten metallic lubricating film on the frictional surface was broken under the heavy load, the friction coefficient of the composite infiltrated with Pb–Sn–15Ag–0.7RE did not increase dramatically because of the micro-lubricating cellular structure in the composites.