Abstract :
Sliding wear behaviour of some leaded-tin and aluminium bronzes has been studied over a wide range of applied pressures and speeds using a pin-on-disc machine. Wear rate, frictional heating and surface roughness of the samples were monitored during the tests. The wear response of specimens has been correlated with the features of their wear surfaces, subsurface regions and debris particles, and explained in terms of varying elemental concentrations and specific characteristics of various microconstituents in terms of thermal stability, cracking and lubricating tendency, and load bearing capability.
The study suggests that there is no direct correlation between mechanical properties (like hardness, tensile strength and elongation) and wear response of the samples. Rather the wear behaviour is better understood in terms of microstructural features. Furthermore, irrespective of material composition and microstructure there exists a specific set of test conditions (e.g. load and speed) leading to best wear performance wherein the positive effects of load bearing capability, thermal stability and lubricating tendency of various phases predominate over the negative influence of cracking and vice versa. The study also indicates that mere presence of a (solid) lubricating phase (like lead in leaded-tin bronzes) does not always ensure improved wear performance of materials and that appropriate sliding conditions are needed to realise the benefits of the lubricating agent in true sense.
