Structure and Micromorphology of Wear Debris of MC Nylon 6 under Dry Sliding: Correlation with Wear Mechanisms

The structure and micromorphology of wear debris of MC nylon 6 under dry sliding were investigated by FTIR, XRD, DSC, and FESEM, and the 3D surface topographies of friction materials before and after the friction test were observed, which will be helpful in understanding the friction and wear processes. The primary crystalline phase of both the unworn MC nylon 6 and the wear debris were α crystal, but the crystallinity of the latter was higher than that of the former. The proportion of α ₂ (002 + 202) planes increased and the reflection from the α ₁ (200) planes was suppressed in the wear debris, indicating a preferential arrangement of α ₂ (002 + 202) on the surface of the wear debris. The transition in structure of the wear debris originated from the activation of the chain segments due to the thermodynamic effects. The thermodynamic effects and high chain segment mobility resulted in the hydrogen bonding whose interchain distance is a larger rupture or even chain scission. MC nylon 6 was severely worn due to the contribution of the tearing force that resulted from the combined action of the tribo-interface adhesion and the shearing effect during friction, whereas no damage happened on the worn surface of the counterpart steel pin even if under severe sliding conditions.