Thermal pyrolysis optimization for highest density of Ti-6Al-4V mix with Palm Stearin and Polyethylene

Abstract

Titanium metal injection molding (Ti-MIM) is coming ever closer to delivering its promise of high value markets, such as the aerospace and medical sectors. It is therefore an inspiration in this study to try to use palm stearin (PS) combined with backbone polyethylene (PE) for injection along with Ti-6Al-4V atomized powder. The uniqueness of PS is a potential binder system that can be used since it is very cheap material and highly available in Malaysia. The present work attempts to optimize the process parameters of thermal pyrolysis stage using Taguchi method of orthogonal array. Density is important characteristic in determine the quality of the brown part. Using these characteristics, the heating rate, temperature and soaking time are optimized in this study. The results show that no swelling or distortion was observed on the molded specimens on both binder systems. It was found that heating rate was the most significant factor followed by pyrolysis time and pyrolysis temperature. A verification test was also performed to prove the effectiveness of Taguchi technique after all the optimum parameters were determined. The optimization of thermal pyrolysis prepared in this study has enabled to improve the final density and mechanical properties of final part. Based on these results, sample displaying yield strength of 929.91 MPa and a plastic elongation of more than 12.15% were produced and meet the requirements of the ASTM B817-08.