Hierarchically constructed metal foam/polymer composite for high thermal conductivity

Most polymeric tribological components are inherently insulative, resulting in susceptibility to failure from frictional heating at the PV limit, which is typically reported as a product of the heat flux terms pressure (P) and sliding speed (V). This letter reports on the design of a tribological composite for increased thermal conductivity and PV limit. The control sample is an unfilled compositionally graded sample, consisting of a PEEK bulk with an integral PEEK/PTFE tribological solid lubricant surface layer. One composite sample is a compositionally graded PEEK bulk containing 10 vol.% aluminum foam, and the other is a 10 vol.% indium filled PEEK/PTFE bulk sample. Tribological experiments are conducted on a thrust washer tribometer instrumented with 13 thermocouples. At failure, the unfilled sample had a temperature rise of 170 K. Under the same conditions, the aluminum and indium filled samples had temperature rises of 37 K and 115 K, respectively. They also had 250% and 40% higher PV limits, respectively than the unfilled sample. As designed, the continuity of the aluminum foam was found to be substantially more effective than the particle dispersion of the indium at dissipating thermal energy.