In situ synthesis and fabrication of tricalcium phosphate bioceramic coating on commercially pure titanium by laser rapid forming

Titanium possesses good mechanical property, but a lack of bioactivity. Bioceramic is usually used to coat the surface of a titanium implant to enhance its bioactivity. Therefore, it is important for the coating to have a high bonding strength to the titanium substrate and contain bioactive phases. In this work, CaCO₃ and CaHPO₄·2H₂O powders were used to fabricate a bioceramic coating on commercially pure titanium (cp-Ti) by the laser rapid forming (LRF) technique. The phase composition of the coating contained 95 wt.% of β-TCP and 5 wt.% of α-TCP. Three layers were found in the coating: a ceramic layer, a transitional layer, and the substrate layer. In the transitional layer, interpenetration of phases was observed. The bonding strength between the coating and the cp-Ti substrate was in excess of 40.17 MPa. In addition, the elastic modulus and the micro-hardness of the coating were 117.61 GPa and 431.2 HV_0.1, respectively. Furthermore, the static immersion test has confirmed that the coating not only prevented the corrosion of cp-Ti, but also induced the redeposition of β-TCP in synthetic saliva.