Optimization of MWCNT – Metal Matrix Composites feedstocks

Abstract

Micro powder injection moulding-μPIM is a powder injection moulding-PIM variant for microparts/devices. This study is about the optimization and respective production of nanocomposites feedstocks suitable to μPIM process. The optimization of MWCNT content in metal matrix composites-MMC feedstock were performed using torque rheometry until achieve homogeneous feedstocks with suitable flowability to μPIM process (60:40 vol.%). During debinding step, it is likely loss of MWCNT, forcing a new stage where physical connection between powders and MWCNTs should be established. Mechanical milling seems the suitable technique to be adopted to overcome this major problem. In preliminary route, the binder M1 (with or without SA addition) is mixed with copper or 316L steel powder. Therefore, two different routes were selected: route 1 – the addition of different MWCNT contents is done during the preparation of feedstock; route 2 – a mechanical milling of metallic powders with MWCNT precedes the conventional production of feedstocks, but with SA addition to improve the nanoreinforced content. The first route impairing its processability by μPIM. The other route revealed to induce homogeneity mixing and torque values suitable to be used as feedstock for μPIM. The route 2 allowed to manufacture with high quality microparts up to 2% of MWCNT addition.