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

Hydroxyapatite coatings were deposited on 304 stainless steel substrates by using the gas 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.