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

Ibrahim Ibrahim

doi:10.3844/ajassp.2010.811.814

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.

Highlights

Titanium and its alloys have become very popular materials because of their low density, high corrosion resistance and excellent mechanical properties (Randall and Animesh, 1997; Liu et al, 2005)
Rheological study of titanium alloy: Figure 3 shows the viscosity versus shear rate at different temperature of titanium alloy
The results show that the sintered specimen titanium alloy part have achieved the minimum requirement for sintered Powder Injection Molding (PIM) parts compared with Standard Metal Powder Industries Federation (MPIF) 35 for the titanium alloy except for the tensile strength and elongation

Summary

Introduction

Titanium and its alloys have become very popular materials because of their low density, high corrosion resistance and excellent mechanical properties (Randall and Animesh, 1997; Liu et al, 2005). Titanium parts are still expensive because of high raw materials prices and because of difficulty forming, machining and welding. This is why the near net shape forming of titanium is very advantageous. Metal Injection Molding (MIM) as a near net shape process for high production number of small intricate parts is a desirable alternative (Rack and Qazi, 2005). In the MIM process, the binder is a key component, which provides the powder with the flowability and formability necessary for molding even though it is temporary (Scott Weil et al, 2006). The palm oil derivative which is palm stearin has been formulated

Results

Discussion

Conclusion