Taguchi grey relational analysis on the mechanical properties of natural hydroxyapatite: effect of sintering parameters

Previous studies have reported the synthesis and mechanical properties of natural hydroxyapatite (HA), but optimization of the measured hardness and compressive strength has not been examined. This paper presents optimization of HAp mechanical characteristics (hardness and compressive strength), using Taguchi grey relational analysis design. In the design, three factors with mixed levels (2 and 3) were employed with the consideration of sintering parameters (0 and 500 Pa compaction pressure, and 900, 1000, and 1100 degrees C sintering temperature), reported in the previous study. The orthogonal array L18 having 18 rows corresponding to the number of tests and the required columns was selected. Results obtained show that HA with better hardness and compressive strength is feasible with little or no compaction pressure. An optimum grey relational grade (GRG) of the synthesized HA is 0.7171 and has an experimental value within 95% confidence interval. The optimum sintering parameters are gotten to be 500 Pa compaction pressure and 1100 degrees C sintering temperature. The result shows that sintering temperature having 99.90 percentage of contribution is the most significant factor, while compaction pressure and residual error are insignificant on the overall hardness and compressive strength of the synthesized HA.