Cross-sectional analysis on microstructure of plasma-sprayed HA+TiO2 composite coatings on titanium substrate
(1. School of Materials Science and Engineering;
2. School of Stomatology, Shandong University, Ji’nan 250062, China)
2. School of Stomatology, Shandong University, Ji’nan 250062, China)
Abstract: The cross-sectional analysis on hydroxyapatite (HA) coating and HA+TiO2 composite coating was conducted by using electron probe microanalyser (EPMA). The results reveal that annealing at 650℃ leads to the cracking within the HA coating or along the coating/substrate interface. The ribbon-like regions in HA coating are verified to contain less PO4-4 groups resulted from the high temperature melting of HA particles in plasma flame. From the viewpoint of microstructural observation, it can be concluded that the addition of TiO2 into HA coating can effectively strengthen and toughen the whole coating system with a shift of the well-bonded interface from the THA (top HA) coating/HTBC (HA+TiO2 bond coat) interface in the as-sprayed THBC (top HA-HTBC) coating to the HTBC/Ti substrate interface in the heat treated THBC coating. The THA coating bonds well to Ti substrate perhaps via its TiO2 hobnobbing with the Ti oxides formed on the Ti substrate.
Key words: cross-sectional analysis; hydroxyapatite; composite coating; plasma spraying