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Title: Evaluating properties of corrosion resistance in thermal-sprayed (HVOF) coatings
Author: Abdollah, Sabrina
ISNI:       0000 0001 3389 7051
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2008
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Thermal sprayed coatings had increased interest in surface engineering for applications in aggressive aqueous corrosive environments. With the advent of the high-velocity oxy-fuel (HVOF) spray process, thermal-sprayed coatings have gained popularity and are being studied extensively for their corrosion-resistant properties. It is a technique for enhancing the components and aircraft landing gear systems. The main aim of this research project is to improve the anti-corrosion (barrier) properties of hard thermal-sprayed coatings. X The coatings provided by the research project's partner, Greenhey Industrial Services, Skelmersdale, UK, are high performance coatings, which offer high hardness, non-sacrificial nature and tend to accelerate substrate corrosion at local defects. >< Over the duration of this 3-year research project, several experimental work were carried out to study those characteristics that impact upon coating porosity and determine whether these experime!ltal methods can be used as a tool to determine the coating porosity of thermal sprayed coatings on a metal substrate. Initial experimental work carried out to investigate the properties of the thermal sprayed coatings in 3 different solutions, both in aerated & deaerated conditions. Different compositions of the coatings WClOC04Cr, WCl7Co and WCl2Co have been carried out in these solutions in both AC impedance & DC polarisation experimental work produced an inconclusive results. Similar experimental methods were carried out in a controlled environment only on \V'ClOC04Cr coating with different coating thicknesses (that is 2thous, 6thou, lOthou & l5thou) on both mild steel and stainless steel substrates in deaerated buffer acetate solution at pH - 4.5. Scanning electron microscopy (SEM) work was also been carried out on crosssectioned as-sprayed and ground finishing coatings and their respective salt sprayed specImens. Many parameters can be considered to improve the corrosion resistance of thermal sprayed coatings such as the powder particles size, type of gun used for the thermal sprayed process, the composition of the powder particles and the type of substrate used. All these process alterations can influence upon the barrier (anticorrosion) performance of the coatings. Although initially, it was envisaged to carry out a comprehensive research work, the limited as-received samples deter the progress. Nevertheless, various attempts were made to rank the coatings' corrosion performance in identifying the optimal condition.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available