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Title: Laser-assisted cold spray
Author: Bray, M. J.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2010
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The aim of this research project was to develop a laser-assisted cold spray (LCS) system capable of applying well adhered, fully dense metal coatings to flat surfaces without melting the powder or substrate. It was necessary for the LCS process to retain the advantages of cold spray (CS) – namely solid state deposition and high build rate, but reduce operating costs by eliminating the gas heater and replacing helium with nitrogen as the process gas. Optimum deposition conditions were investigated and the deposits characterised in order to form comparisons with other spraying techniques and to identify the bonding process. Several objectives were set at the beginning of the project to define a possible route to developing a successful spraying technique. The project started with a literature review to gain an understanding of current spraying and cladding technologies, and coating properties that were sought after and achieved. A basic rig was designed and constructed to carry out proof of principle trials. The rig was then redesigned for better process capability, control, and data acquisition. A process optimisation study was carried out to identify key variables that needed to be controlled, and their effect on deposition. The process was found to be sensitive to deposition site temperature and particle velocity, and process parameters that affect these – such as laser power, gas pressure, traverse rate and powder feed rate. Materials analysis was carried out on samples produced using LCS under various conditions and compared to coatings produced using other spray techniques. By analysing single-particle impacts and coatings, and relating deposition conditions to existing theory, a deposition mechanism unique to LCS was proposed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available