The potential of fabric reinforcement in the thermoplastic polymers for enhancing the abrasive wear resistance has not been explored so far. Hence a series of seven composites of polyetherimide (PEI) reinforced with three types of fabrics viz. glass (with three different weaves), carbon and aramid (Kevlar 29) was fabricated and abrasive wear performance of these composites along with the neat polymer was evaluated. A polymer pin was abraded against silicon carbide (SiC) abrasive paper under various loads and two fabric orientations. It was observed that the aramid fabric (AF) revealed significant potential to improve abrasive the wear performance of PEI. When the fabric was perpendicular to the abrading surface, performance of the composites was substantially better than the case when it was in the parallel orientation. Carbon fabric (CF) and glass fabric also showed some potential for enhancing the wear resistance of PEI when the fabric was in the perpendicular orientation. The mechanical properties of the composites, however, could not be correlated with the wear performance. Worn surface analysis by SEM on the other hand, helped to correlate the performance of the composites with the surface topography, failure of fibres, resin and their interface. Difference in the failure mode of the fibres was thought to be mainly responsible for controlling the wear performance of the composites.
Recently commercialised polytetraflurotehylene (PTFE) composite reinforced with 25% chopped carbon fibres was selected for this study since details of the tribological behaviour were not available. The composite was evaluated for friction and wear performance in stringent operating conditions in adhesive as well as abrasive wear modes. The coefficient of friction (μ) and specific wear rate ( Ko) of the composite in the adhesive wear mode were measured under high speeds, loads, extended sliding duration, and elevated temperatures and are reported in this paper. At moderate loads, it was observed that though it exhibited a high μ (≅ 0.4) and low K (≅ 10-15 m3N-1m-1), it showed lower μ (≅ 0.15) and appreciably good wear performance at higher loads and moderate speeds. At higher speeds (more than 4 m/s) its performance, however, deteriorated. It was also revealed that the composite showed poor performance when tested at elevated temperatures beyond 150°C. A comparison with tribo-performance of neat PTFE indicated that CF reinforcement resulted in enhancement in wear behaviour very significantly. The friction coefficient, however, increased substantially. Moreover, abrasive wear performance also showed little deterioration due to carbon fibre reinforcement. Worn surface analysis by scanning electron microscope (SEM) was done to study wear mechanisms.
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