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Title: Optimising aluminium alloy surfaces for wear and corrosion controlled by plasma electrolytic oxidation (PEO)
Author: Algahtani, Ali Muhammad A.
Awarding Body: University of Leeds
Current Institution: University of Leeds
Date of Award: 2013
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Aluminium and its alloys are broadly used in a wide variety of applications. Aluminium's main advantages include: lightness, high specific strength, high thermal and electrical conductivities, good formability, excellent machinability, diversity of aluminium alloys, extensive range of forms and options (e.g. rolling, extrusions, stampings, forgings and castings), and suitability for a diverse range of joining techniques, surface treatment and recyclability. A number of surface treatment technologies are available. They produce thicker oxide coating layers that can be used to combat corrosion and wear of aluminium alloys under aggressive environments, such as petroleum extraction environments. Coating processes to surface modify e.g. with alumina include Plasma Electrolytic Oxidation (PEO), Plasma Spray Ceramic (PSC) and Hard Anodizing (HA). In this thesis, aqueous slurry erosive wear characteristics of oxide coatings produced using the aforesaid three processes have been compared and benchmarked against the uncoated aluminium substrate. This research investigates the extent of erosion resistance, in particular, the effect of sand concentration and temperature variations to the aqueous slurry impingement against material properties such as adhesion, ductility and roughness. Also, a series of electrochemistry tests has been conducted. Coatings properties have been characterised using various tools including optical microscopy, scanning electron microscopy (SEM), x-ray diffraction (XRD), surface profilometry and hardness indentations. The results indicate that PEO coating can offer the most effective barrier to the aluminium substrate as it has the lowest weight loss under erosion tests and the highest enhancement factor under electrochemistry tests compared to the other materials. Therefore, PEO surface treatment should be considered as one of generation materials and innovative problem-solving technologies to be introduced in oil and gas industry.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available