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Title: Tribology of polymers and composites in unlubricated rolling and sliding contact
Author: Chen, Yong Kang
Awarding Body: University of Birmingham
Current Institution: University of Birmingham
Date of Award: 1996
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A reliable and simple twin-disc test rig has been designed and built and used for rolling-sliding tests. The real-time measurement system has allowed a detailed study of tribological behaviour of polymers and reinforced polymer composites under unlubricated, non-conformal and rolling-sliding contact. A mathematical model has been established to enable the disc surface temperature to be predicted. Both polyoxymethylene, polyamide 66 and short glass-fibre reinforced polyamide 66 composites have been investigated in the present work. A comprehensive set of results has been obtained for polyoxymethylene over a range of slip ratios, loads and speeds, and for polyamide 66 and short glass fibre reinforced polyamide 66 composites over a range of slip ratios and loads with a constant speed. This experimental information has revealed major differences in tribological behaviour between these materials. The predominant wear mechanisms were studied by surface and subsurface analysis and surface temperature characterisation. An attempt to apply the current results to engineering components made from these materials has been made. It is shown that friction-generated heat has a major influence on the performance of unreinforced POM and PA 66. The maximum surface temperature when these materials are in contact dominates their wear transitions. An attempt to establish an envelope for engineering applications has been made. POM appears to exhibit better wear resistance than P A 66 which was always inferior with higher wear rates and a tendency to form deep cracks in the surface. Experimental results show that the tribological behaviour of short glass-fibre reinforced polyamide 66 composites can be improved significantly by changing the crystallinity of the materials. The effects of moulding conditions have been investigated. The key is a thin film which exists on the contact surfaces when two discs run against each other under these test conditions. The film plays a dominant role in the "self-lubricating" property of the composite.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available