Carbon fabric reinforced polyetherimide composites: Optimization of fabric content for best combination of strength and adhesive wear performance

Polyacrylonitrile (PAN) based high strength carbon fabric (plain weave) reinforced polyetherimide (PEI) composites were fabricated using impregnation technique by selecting five different contents of carbon fabric, viz. 85, 75, 65, 55 and 40 vol.%. These bidirectional (BD) composites were evaluated for their mechanical strength as well as tribological behavior in adhesive wear mode. Dry adhesive wear studies were conducted on a custom designed wear tester in which high PV conditions can be simulated. Tests were conducted at various operating parameters such as load, temperature and orientation of fabric with respect to the sliding plane. Two important results were observed; firstly the moderate CF contents (75, 65 and 55 vol.%) proved to be the most effective in manifold increase in mechanical strength of PEI and secondly, the composites with fabric in the direction normal to sliding plane led to very high coefficient of friction (μ). When fabric was parallel to the sliding plane, significant improvement in the tribo-properties of PEI in terms of very high tribo-utility (up to 600 N), appreciably low μ and enhanced wear resistance (WR) (in the range of 10−16 m3/N m) was achieved. The extent of improvement, however, strongly depended on the operating parameters and fabric content. A fairly good correlation was obtained between WR and combination of mechanical properties such as ultimate tensile strength (S), and interlaminar shear strength (ILSS). Wear mechanism studies by SEM supported the observed wear performance of composites.