MWCNT reinforced SS 316L matrix composites

Abstract

The selection of appropriate reinforcement material is a critical problem in enhancing the mechanical properties of composites. This study is about the optimization and respective production of nanoreinforced composites feedstocks suitable to μPIM (micro powder injection moulding) process. The μPIM, a variant of PIM (powder injection moulding), is a potential method for mass producing near net-shape microcomponents. The selected materials were: powder (stainless steel 316L), binders (M1 with or without stearic acid – SA) and nanoreinforcement (multi wall carbon nanotube – MWCNT) because of their impressive properties. The first route (without SA addition) impairing its processability by μPIM. The variant with SA revealed feedstock homogeneity and torque values suitable to be used as feedstock in μPIM. The route 2 allowed manufacturing microparts with high quality, up to 2% vol. of MWCNT addition. The injection of MMC (Metal Matrix Composites) feedstock with higher nanoreinforcement content is difficult because lost elasticity and it is essential re-adjust the injection conditions, mainly the injection pressure and temperature. The debinding and sintering steps were tested in controlled atmosphere, as result the final microparts present good shape retention, without defects and shrinkage between 11 and 14%.

Keywords:

• SS 316L
• MWCNT
• binders
• debinding
• sintering
• μPIM
• MMC