Injection Molding of Titanium Alloy Implant For Biomedical Application Using Novel Binder System Based on Palm Oil Derivatives

Abstract

Problem statement: Titanium alloy (Ti6Al4V) has been widely used as an implant for biomedical application. In this study, the implant had been fabricated using high technology of Powder Injection Molding (PIM) process due to the cost effective technique for producing small, complex and precision parts in high volume compared with conventional method through machining. Approach: Through PIM, the binder system is one of the most important criteria in order to successfully fabricate the implants. Even though, the binder system is a temporary, but failure in the selection and removal of the binder system will affect on the final properties of the sintered parts. Therefore, the binder system based on palm oil derivative which is palm stearin had been formulated and developed to replace the conventional binder system. Results: The rheological studies of the mixture between the powder and binders system had been determined properly in order to be successful during injection into injection molding machine. After molding, the binder held the particles in place. The binder system had to be removed completely through debinding step. During debinding step, solvent debinding and thermal pyrolysis had been used to remove completely of the binder system. The debound part was then sintered to give the required physical and mechanical properties. The in vitro biocompatibility also was tested using Neutral Red (NR) and mouse fibroblast cell lines L-929 for the direct contact assay. Conclusion: The results showed that the properties of the final sintered parts fulfill the Standard Metal Powder Industries Federation (MPIF) 35 for PIM parts except for tensile strength and elongation due to the formation of titanium carbide. The in vitro biocompatibility on the extraction using mouse fibroblast cell line L-929 by means of NR assays showed non toxic for the sintered specimen titanium alloy parts.