Influence of nano-TiO₂ filler additives on hardness and wear behaviour of boron-free glass reinforced polyimide composites

Fiber-reinforced polyimides were observed to exhibit high brittleness and friction coefficient, hence limit their use for mechanical friction component applications. Thus, in the present study, glass fiber-reinforced polyimide composite containing various nano-TiO ₂ additives (0, 2, 4, and 6 wt%) for better mechanical and tribological performance properties produced by spark plasma sintering processes were investigated. The microstructure, mechanical (hardness and elastic modulus), and tribological (coefficient of friction and wear) properties of the produced nanocomposites were studied using the scanning electron microscopy (SEM), nanoindentation test at an applied load of 200 mN, and pin-on-disc tribometer analyzer, respectively. For the wear test, a load of 10 N and sliding speed of 150 r/min was applied under 15 min for each sample test. The SEM results revealed that the fillers were evenly distributed within the polyimide matrix composites. Glass fiber/polyimide composites with 0 wt% nano-TiO ₂ depicted 123 HV hardness and 11.40 GPa elastic modulus. Comparatively to the neat glass-fiber/polyimide composite, an improvement of 21.9% in hardness and 9% in modulus were recorded for the composite filled with 4 wt% nano-TiO ₂ particles. Furthermore, characterizing the tribological behaviour of the nanocomposites, results show that the coefficient of friction and wear rate of the nanocomposites filled with 4 wt% nano-TiO ₂ were reduced by 32.2% and 76.9%, respectively, compared to pure glass fiber/polyimide composite. However, the findings suggest the facile and cost-effective means of producing polyimide nanocomposites and their potential application in mechanical load-bearing and mechanical friction components.