This study shows that the osteogenic abilities of calcium silicate based coatings can be improved through nanotopographical surface modifications and the addition of bioactive trace elements. CaSiO 3 powders were deposited on titanium substrates by atmospheric plasma spraying and the topography and composition of the resulting coatings were modified by hydrothermal treatments in deionized water and in aqueous solutions of Sr(NO 3 ) 2 . Bone marrow stem cells were cultured on treated and untreated coatings. The cells spread further on treated surfaces and were found to be relatively larger in size than the cells on untreated surfaces. Calcium silicate coatings treated in the strontium-containing solution showed the best overall improvement in terms of bone cell growth and differentiation.

In this work, finite element analysis is used to investigate the effect of pore size on the stress intensity factor (SIF) of plasma sprayed coatings. Test samples with different pore sizes were obtained by spraying wollastonite powders with particle sizes of 60-75 μm, 75-95 μm, and 95-150 μm onto Ti 6 Al 4 V coupons. The results show that coating stress varies in proportion to the length of 2D pores and to a lesser extent the diameter of 3D pores. This implies that reducing the length of 2D pores may be considered as a way to increase the fracture resistance of plasma sprayed coatings.

Wollastonite coatings were deposited on Ti6Al4V substrate at the substrate temperatures of room temperature, 200 °C, 400 °C and 600 °C by the atmosphere plasma spraying, respectively. The effect of substrate temperature on the microstructure, phase composition, mechanical properties and dissolution behavior of wollastonite coatings were investigated. The microstructure and phase composition of coatings were examined by SEM and XRD. The hardness and elastic modulus were obtained by the Knoop indentation tests. In addition, the dissolution behavior of coatings was evaluated by immersion in SBF solution. The results indicate that a slight decrement of porosity and an obvious increment of crystallinity were found with the substrate temperature. The hardness and elastic modulus of coatings increased with the substrate temperature up to 400 °C firstly, and then a decrement was observed with the temperature further increasing to 600 °C. The dissolution rate of coatings characterized by the pH changes and the released Ca, Si and P concentration in the SBF decrease with the substrate temperature, which is related to the porosity and crystallinity of coatings. It is revealed that through increasing the substrate temperature during plasma spraying is a feasible method to improve the mechanical properties and to decrease the dissolution of wollastonite coatings.