Abrasive wear performance of SiC-UHMWPE nano-composites – Influence of amount and size

Abstract

Ultra-high-molecular-weight-polyethylene (UHMWPE) is extensively researched tribo-material since it shows very low coefficient of friction (µ) apart from excellent wear resistance in various wear modes viz. adhesive, abrasive, erosive, reciprocating, fretting etc. Most of the times inclusion of right type of fillers/fibres shows excellent improvement in adhesive wear mode. However, it is extremely difficult to further improve the performance of a base matrix significantly in abrasive wear mode.Nano-fillers are reported as more efficient for performance enhancement as compared to their micro-counterparts. Hence two series of composites were developed by using very hard filler viz. silicon carbide (SiC) in different amounts and sizes. Micro-series contained six composites filled with micro-SiC (wt%; 0, 2, 4, 6, 8 and 10) while the nano-series contained eight composites filled with nano-SiC (wt%; 0, 1, 1.5, 2, 2.5, 3, 3.5 and 4). Both the series were characterized for physical and mechanical properties. With increase in SiC contents for both the series scratch hardness increased. Abrasive wear studies were conducted by sliding a pin of composite against the SiC abrasive paper in single-pass linear motion with fixed speed under different loads. It was observed that inclusion of SiC proved beneficial for enhancing wear resistance (approximately 15%) and optimum amount for micro-filler was around 8%. In case of nano-composites 3.5% was observed as an optimum amount to get the lowest wear rate. Nano-fillers proved to be approximately two times more effective than the micro-fillers. Increase in hardness of composite was responsible for increase in abrasive wear resistance. SEM studies indicated that inclusion of hard fillers mainly reduced the severity of micro-cutting mechanism leading to more wear resistance.