Synthesis and optimization of a new calcium phosphate ceramic using a design of experiments

Abstract

The main objective of this work is to understand the effects caused by particle size, temperature, and sintering time on ceramic formation and development of its surface hardness (Vickers hardness Vk) in order to extend its use in medical applications. The ceramic consists of a biphasic calcium phosphates mixture (beta-tricalcium phosphate and hydroxylapatite) to which we have added zinc oxide, silica, and zirconia in order to improve the biological and mechanical profiles of this ceramic. The ceramization process is made by partial melting, which the melt agent is an amorphous aluminum phosphate added by small quantities to the last mixture. In fact, when the aluminum phosphate is under high temperature, it causes the formation of a melt which facilitates the adhesion of particles during the solidification process. In this study, we adopted an experimental strategy such as central composite design. This plan lets us optimize the mechanical hardness of the ceramic, involving a polynomial form derived from the Taylor–Mac Lorrain equation. The isoresponses curves obtained give us the estimated responses and empirical possibilities for obtaining ceramics with an optimum hardness, which can then be used for each type or intervention place in reconstructive surgery.