Fabrication and characterization of HA/SiO2 coatings by gas tunnel plasma spraying

Fused silica powder has been mixed with hydroxyapatite (HA) powder and plasma sprayed by using a gas tunnel-type plasma jet. The influence of silica content (10Wt. % and 20 Wt. %) on the microscope and mechanical properties of HA-silica coatings was investigated. The spraying was carried out on a SUS 304 substrate in an atmospheric chamber. Scanning electron microscope micrographs of corss-sectioned HA/SiO2 coatings showed that the sprayed samples of 10 and 20 et. % silica have dense structure with low porosity as well as higher abrasive wear resistance compared to pure HA coatings. As the amount of silica was increased, the coatings became denser, harder and exhibited higher abrasive wear resistance compared to the pure HA coatings

Influence of spray parameters on the features of gas tunnel type plasma sprayed hydroxyapatite coatings

Hydroxyapatite coatings were deposited on 304 stainles steel substrates by using the gass tunnel type plasma spraying process. The influences of spraying distances and arc currents on the microstructure, adhesion and hardness properties of HA coatings were investigated. The results showed that HA coatings sprayed at low power have a porous structure and poor hardness. HA coatings sprayed at high power and short spraying distance are characterized by good adhesion and low porosity with dense structure. The hardness of the HA coatings sprayed at short spraying distance and higher plasma power was increased, mainly due to the formation of dense coatings

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