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Title: Amorphous carbon coating systems for pressurised water reactor tribological applications
Author: Cooper, Jack
ISNI:       0000 0004 7657 4246
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2018
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Pressurised water reactors provide a very challenging environment for material selection, especially when components also have tribological applications. The high temperature and pressure of the water can cause premature failures due to corrosion and degradation of material properties, with costly consequences. This Engineering Doctorate investigated the suitability of hard, wear resistant amorphous carbon coatings as one possible solution for Rolls-Royce to help meet the current demands of the nuclear industry to increase the lifetime, safety and reliability of components in PWR power systems, as long as the coatings can survive exposure to the extreme environment involved. The first aim of the project was to examine the effect of high-temperature high-pressure water on the hydrothermal stability of commercial and lab-deposited amorphous carbon coatings. Four types of amorphous carbon coatings of particular interest were selected and exposed to high temperature water in pressure vessels then characterised to help understand their thermal and chemical stability and degradation behaviour. The second aim of the EngD was to understand the effect of coating composition and architecture on the performance in high-temperature high-pressure water. Coatings were analysed in detail after hydrothermal exposure to determine possible failure modes and select promising coating features for future investigations. At relatively low temperatures below 240°C it was found that all the studied coatings survived with little change in their coating properties. When the autoclave temperature was increased to 280°C however, hydrogen-containing diamond-like amorphous carbon coatings in particular suffered severe spallation, whereas hydrogen-free, graphite-like amorphous carbon coatings remained intact, with most showing little change in their film properties. Following the characterisation, several material degradation mechanisms were discussed as the possible cause the observed film spallation, based on the observed changes.
Supervisor: Leyland, Adrian ; Matthews, Allan ; David, Stewart Sponsor: Not available
Qualification Name: Thesis (Eng.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available