Microstructure and mechanical properties of HA/ZrO2 coatings by gas tunnel plasma spraying

The gas tunnel plasma spraying method was employed to deposit HA/ZrO2 composite coatings on SUS 304 substrate in an atmospheric chamber. The design of the plasma torch allows for the external and internal feeding of the sprayed powder. Pure HA powder was fed externally and ZrO2 powder was fed internally. The feeding rate was controlled to deposit HA/ZrO2 coatings with difference zirconic contents. Two sprayed coatings with difference zirconia contents were obtained. The influence of ZrO2 and its volume fraction on the mircostructure and mechanical properties of HA/ZrO2 composite coatings was investigated. A comparison between the mircostructure and mechanical properties of pure HA and HA/ZrO2 composite coatings was made. Scanning electron micrographs of the coatings cross-sections showed good adhesion between the coatings and the substrate and also the dense structure of the coatings. The presence of ZrO2 imporved the hardness and abrasive wear resistance of the composite coatings compared with the pure HA coatings