Fabrication and characterization of plasma-sprayed HA / SiO2 coatings for biomedical application

Fused silica powder has been mixed with hydroxyapatite (HA) powder and plasma sprayed by using gas tunnel-type plasma jet. The influence of silica content (10 wt% and 20 wt%) on the microstructure and mechanical properties of HA–silica coatings was investigated. For investigating the microstructure and mechanical properties of HA–silica coatings, SUS 304 stainless steel was used as substrate material. The spraying was carried out on roughened substrate in an atmospheric chamber. Scanning electron microscope micrographs of cross-sectioned HA/SiO2 coatings showed that the sprayed HA coatings with 10 and 20 wt% SiO2 have dense structure with low porosity compared to the pure HA coatings. On the other hand, as the amount of silica was increased the coatings became denser, harder and exhibited high abrasive wear resistance. The presence of silica significantly improved the adhesive strength of HA/SiO2 coatings mainly due to the increase in bonding strength of the coating at the interface.