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Title: Microstructure, tribology and surface behaviour of electroless nickel composite coating with ceramic reinforcing particles on aluminium alloy substrate
Author: Mayanglambam, Franco
ISNI:       0000 0004 6057 1892
Awarding Body: Queen's University Belfast
Current Institution: Queen's University Belfast
Date of Award: 2016
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Electroless nickel composite coatings having silicon carbide (SiC) as reinforcing particles have been a surge of interest as protective layer for inferior materials by transforming the surface behaviour. In this research, phase changes during heat treatment showed NixSiy phases are independent of particles content in the coating from X-ray diffraction. Different heat treatment environments (air and vacuum) did not influence the formation of silicides. The content of SiC particles in the coating had a direct relationship with particle concentrations in the bath. Angular ceramics (SiC) had a higher degree of incorporation as compared to spherical ceramics as revealed by scanning electron microscopy. At the interface, zincating layer was found to be thermally affected and copper segregation from the bulk substrate was also detected from the elemental analysis by energy dispersive X-ray. The microhardness was controlled by specific reinforcing particles content in an effective matrix-ceramics system. Lower content of SiC in the coating results in a better wear resistance in as-deposited state during microabrasion test. Particles were seen to be pressed in the matrix. Dry sliding at elevated test temperature showed that wear behaviour had significant relationship with particle content in the coating. Propagation of microcracks was ceased by the reinforcing particles. Slight crystallisation and triboxidation were seen post-wear test. Overall, electroless nickel composite coatings developed by incorporating SiC and oxide based ceramics from the waste/surplus have unique properties potential for diverse engineering applications. However, the coating performance differs with the variation of parameters such as particle content, heat treatment environments and temperatures, sliding condition and test temperature. A well-tuned composite system is definitely a promising candidate required for surface engineering strategy. Therefore, it is highly useful to consider the aforementioned variable parameters in the decision processes for optimising an industrial process that utilises such nickel composite coatings, and vice versa.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available