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dc.contributor.authorThirumalai, Sundararajan
dc.date.accessioned2022-01-26T00:34:23Z
dc.date.available2022-01-26T00:34:23Z
dc.date.submitted2021-08-31
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/332933
dc.description.abstractNovel nanocomposite coatings of the type Fe-Ti-N and Fe-Ti-O-N, having in-situ formed periodic multiphase nanocolumnar microstructures, have been developed by a two-target reactive magnetron sputter deposition and nanoparticle-assisted electro-co-deposition processes. Advanced thin-film characterisation techniques, such as scanning electron microscopy, transmission electron microscopy, X-ray diffraction, surface wettability, nanoindentation and nanowear testing, have been utilised effectively to study the coating structure and evaluate their performance. The origin of such a unique microstructure is attributed to the thermodynamic immiscibility of the phase constituents. The columnar width and tilt angle could be precisely tuned by modifying various deposition parameters, such as sputter gas pressure, target power, substrate tilt and rotation. A vector summation approach has been developed to derive the effective angle of incidence from the two sputter targets, and validate the classical tangent relationship between the said effective angle of incidence and the columnar tilt angle of the coatings. Moreover, a cosine relationship has been established to correlate the coating composition and angle of incidences of the sputtered species. Furthermore, a detailed structure-property correlation has been developed with due emphasis on understanding the mechanical and functional properties of the coatings. Preliminary finite-element modelling of the coating contact deformation have been performed, to explore the stress field distribution and crack healing potential of the innovative microstructures developed in this work. Understanding of the formation mechanism and microstructure control of such unique periodic nanostructures have been exploited, to develop dense biphase helical metal-nitride interpenetrating nanocomposite coating microstructures with an exceptional nanohardness of up to 17.1 GPa, despite having a high iron content of 59 %. Finally, nanoporous nanocomposite coating forms have also been fabricated using a high-pressure/power sputter deposition process in the classical Thornton zone-1 deposition regime, for potential niche applications such as photocatalyst/catalyst-support for dye-degradation and anti-bacterial surfaces. A modified-Wenzel equation has been proposed to effectively correlate the surface wettability of the porous films with their surface roughness.
dc.rightsAll Rights Reserved
dc.rights.urihttps://www.rioxx.net/licenses/all-rights-reserved/
dc.subjectAntimicrobial surfaces
dc.subjectCermets
dc.subjectElectro-co-deposition
dc.subjectNanocomposites
dc.subjectPVD/PE-CVD hard coatings
dc.subjectSurface engineering
dc.subjectThermal stability
dc.subjectThin film photocatalysis
dc.subjectTribology
dc.titleGrowth and characterisation of multifunctional nanocomposite coatings
dc.typeThesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationnameDoctor of Philosophy (PhD)
dc.publisher.institutionUniversity of Cambridge
dc.date.updated2022-01-24T17:33:12Z
dc.identifier.doi10.17863/CAM.80363
rioxxterms.licenseref.urihttps://www.rioxx.net/licenses/all-rights-reserved/
rioxxterms.typeThesis
dc.publisher.collegeSidney Sussex
pubs.funder-project-idEuropean Commission Horizon 2020 (H2020) Marie Sk?odowska-Curie actions (642642)
cam.supervisorGreer, Alan Lindsay
cam.depositDate2022-01-24
pubs.licence-identifierapollo-deposit-licence-2-1
pubs.licence-display-nameApollo Repository Deposit Licence Agreement


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