A novel structured suspension plasma sprayed YSZ-PTFE composite coating with tribological performance improvement

Two kinds of cauliflower-like architecture yttria stabilized zirconia (YSZ) coatings with different amounts inter-columnar voids were prepared by suspension plasma spraying (SPS) under different spraying parameters. YSZ coatings with high and moderate porosity were infiltrated with polytetrafluoroethylene (PTFE) in order to form a novel structured ceramic-polymer composite coating. Subsequently, the composite coatings were tribologically evaluated. The tribology behavior of the denser as-sprayed YSZ coatings and pure PTFE coatings were also investigated as reference materials. The results indicated that the composite coatings exhibited a significantly improved wear resistance in terms of a remarkably reduced coefficient of friction and wear rate compared with the as-sprayed YSZ coatings because of the lubricating effect of PTFE. Additionally, it was noted that the existing YSZ framework in composite coatings reinforces PTFE contributing to an even higher wear resistance than that measured on pure PTFE.