Bioactivity characterization and a full factorial design on the adhesive strength of air plasma sprayed HA-TiO2 Coated Ti

Series of Atmospheric Plasma Spray Coatings were made on titanium substrates based on a Full Factorial Design. Three parameters (number of pass of the bond coat, amount of TiO2 into coating powder precursor and the spray distance) with three levels were selected to investigate their effects on the bonding strength and bioactivity. The coatings were characterized in terms of adhesion and bioactivity. The results indicated that all parameters had a positive effect on the bonding strength of the coatings. R2 and R2adjusted values were found to be 98.9% and 96.9% respectively, which proved the reliability of the Regression and ANOVA analyses. After being immersed in simulated body fluid for 7 and 28 days, the surfaces of these coatings were completely covered by carbonate-containing apatite. Moreover, the microscopic analyses verified that TiO2 addition enhanced the formation of the apatite layer so did the bioactivity.