Effects of crystallinity, transcrystallinity and crystal phases of GF/PA on friction and wear mechanisms

Relationships between manufacturing processes, microstructures, mechanical and tribological properties of GF/PA6 composite were revealed in this paper by experimental investigations and theoretical analysis. The study indicated that the wear resistance was significantly influenced by the thermal history of the composite. Decreasing cooling rate during the components thermal moulding would result in enhancing approximate 28% of wear resistance and reducing almost 14% of friction in the GF/PA6 composites. A slow cooling gives the PA6 a high crystallinity and high ratio of α/γ phases which resulted in higher thermal stabilities, higher density and harder matrix in the composites than that of fast cooling. It also improves the interfacial properties and the composite hardness. Due to the thermal decomposition, abrasion and adhesion dominated the wear mechanisms, these improvements led to a higher wear resistance and higher pv service limit in the slow cooled GF/PA6 samples than that of fast cooled samples. Interfacial debonding dominated the friction mechanisms in the unlubricated pin-on-disk tests. A poor interfacial bond led to more glass fragments falling off from the GF/PA6 pins which scratched the sliding surfaces, damaged the oxidative film and resulted in severe abrasion and adhesion in the fast cooled samples, hence leading to a high friction coefficient.