Effect of forming condition on compressive strength of hydroxyapatite-bioactive glass compact rod

¹ Advanced Manufacturing Technology Research Center, Department of Industrial Engineering, Faculty of Engineering, Chiang Mai University, Chiang Mai, Thailand
² Department of Tools and Die Engineering, Faculty of Engineering, Rajamangala University of Technology Lanna, Chiang Mai, Thailand

^* Corresponding author: wassanai@eng.cmu.ac.th

Abstract

With rising concerns regarding alloy implants, alternative biomaterials are currently studied, to avoid the adverse effects of metal on the human body such as irritation and inflammation. Hydroxyapatite (HA) and Bioactive glass (BG) are two bio-ceramics, which have been implemented in medical applications such as bone implants and fixation parts due to their biocompatibility and close resemblance to the mineralized phase of human bone. Furthermore, these materials can be synthesized from natural sources. In this study, M8 screws rod which are commonly implemented for bone fixation was selected as a case study to investigate an effect of forming conditions on the mechanical property of the composite structure. HA and BG were synthesized and formed into a composite specimen using a hydraulic pressing machine. Full factorial experimental design was employed to solve for an optimal forming condition. 3 factors consisting of mixing ratio, pressure and holding time for pressing were investigated for their impacts on the specimen’s compressive strength. The result revealed that the BG ratio and pressure have a significant effect on the structural strength. The maximum compressive strength of 32.20 MPa was obtained from the specimen with 7.5 wt% of BG, 120 kg/cm² of pressure and 30 second of holding time.