Laser processing of Ti composite coatings reinforced with hydroxyapatite and bioglass

Composite coatings of titanium reinforced separately with hydroxyapatite (HAp) and bioglass (BG) were deposited on titanium substrate using Laser Engineered Net Shaping (LENS™). The microstructure, phase constituents, in vitro electrochemical, tribological and biological properties of these composite coatings deposited using different laser powers was studied. The composite coatings showed several reaction products such as Ca2P2O7, CaTiO3, Na2Ca2Si3O9 due to high temperature interaction of HAp and BG with Ti. The average top surface hardness of the Ti substrate was 148 ± 5 HV and that of the composite coatings was between 720 and 740 HV. As a result, the composite coatings exhibited significant increase in the in vitro wear resistance. The incorporation of HAp and BG in Ti increased the corrosion current, possibly due to the presence of residual stresses, but shifted the corrosion potential towards noble direction due bioactive reinforcements. In vitro proliferation of mouse embryonic fibroblast cells (NIH3T3) was found to be more on composite coatings than on titanium substrate demonstrating their superior cell-materials interactions.