An investigation of phase transformations in Pt-V coating systems

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dc.contributor.advisorLang, Candyen_ZA
dc.contributor.advisorTopic, Miraen_ZA
dc.contributor.authorMakhetha, William Motsokoen_ZA
dc.date.accessioned2016-02-18T12:11:37Z
dc.date.available2016-02-18T12:11:37Z
dc.date.issued2012en_ZA
dc.descriptionIncludes bibliographical references.en_ZA
dc.description.abstractPhase transformations in Pt-V coatings after heat treatment have been investigated. Five Pt- V ordered phases (PtV, PtV 3 , Pt 2 V, Pt 3 V and Pt 8 V) have been previously observed in bulk platinum-vanadium alloys. Phase formation in coatings is expected to be sequential and controlled by the lowest temperature eutectic (liquidus) composition; this allows control of experimental parameters for formation of desired ordered phases. This investigation included fabrication of coatings, heat treatments, morphology characterization and phase analysis. Single and multilayer coatings ranging between 0.07 μm and 0.5 μm were deposited on vanadium and platinum substrates using E-beam deposition. The kinetics of phase transformation were studied by subjecting the coated layers to a variety of heat treatments in the temperature range 600°C to 900°C for 4 and 8 hours. Composition and morphology characterization was carried out using EDS and SEM respectively. XRD was used for phase analysis. Four (PtV, PtV 3 , Pt 2 V, Pt 3 V) out of the five Pt-V ordered phases exhibited in bulk alloys, were successfully formed from the coating system investigated in this project. The first phase formed, and the sequence of phase formation, was found to be different depending on which metal formed the substrate. The vanadium-rich ordered phase (PtV 3 ) was preferentially formed first on vanadium substrates and the sequence of phase formation progressed through ordered phases richer in platinum. The platinum-rich ordered phase (Pt 3 V) was preferentially formed first on platinum substrates and the sequence continued towards formation of ordered phases richer in vanadium. An increase in heat treatment temperature from 600°C to 900°C resulted in rapid kinetics of phase transformation but affected the morphology of the coatings. An increase in coating thickness, number of coating layers, heat treatment time, and temperature resulted in an increase in overall total number of ordered phases and volume of ordered phases.en_ZA
dc.identifier.apacitationMakhetha, W. M. (2012). <i>An investigation of phase transformations in Pt-V coating systems</i>. (Thesis). University of Cape Town ,Faculty of Engineering & the Built Environment ,Centre for Materials Engineering. Retrieved from http://hdl.handle.net/11427/17104en_ZA
dc.identifier.chicagocitationMakhetha, William Motsoko. <i>"An investigation of phase transformations in Pt-V coating systems."</i> Thesis., University of Cape Town ,Faculty of Engineering & the Built Environment ,Centre for Materials Engineering, 2012. http://hdl.handle.net/11427/17104en_ZA
dc.identifier.citationMakhetha, W. 2012. An investigation of phase transformations in Pt-V coating systems. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Makhetha, William Motsoko AB - Phase transformations in Pt-V coatings after heat treatment have been investigated. Five Pt- V ordered phases (PtV, PtV 3 , Pt 2 V, Pt 3 V and Pt 8 V) have been previously observed in bulk platinum-vanadium alloys. Phase formation in coatings is expected to be sequential and controlled by the lowest temperature eutectic (liquidus) composition; this allows control of experimental parameters for formation of desired ordered phases. This investigation included fabrication of coatings, heat treatments, morphology characterization and phase analysis. Single and multilayer coatings ranging between 0.07 μm and 0.5 μm were deposited on vanadium and platinum substrates using E-beam deposition. The kinetics of phase transformation were studied by subjecting the coated layers to a variety of heat treatments in the temperature range 600°C to 900°C for 4 and 8 hours. Composition and morphology characterization was carried out using EDS and SEM respectively. XRD was used for phase analysis. Four (PtV, PtV 3 , Pt 2 V, Pt 3 V) out of the five Pt-V ordered phases exhibited in bulk alloys, were successfully formed from the coating system investigated in this project. The first phase formed, and the sequence of phase formation, was found to be different depending on which metal formed the substrate. The vanadium-rich ordered phase (PtV 3 ) was preferentially formed first on vanadium substrates and the sequence of phase formation progressed through ordered phases richer in platinum. The platinum-rich ordered phase (Pt 3 V) was preferentially formed first on platinum substrates and the sequence continued towards formation of ordered phases richer in vanadium. An increase in heat treatment temperature from 600°C to 900°C resulted in rapid kinetics of phase transformation but affected the morphology of the coatings. An increase in coating thickness, number of coating layers, heat treatment time, and temperature resulted in an increase in overall total number of ordered phases and volume of ordered phases. DA - 2012 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2012 T1 - An investigation of phase transformations in Pt-V coating systems TI - An investigation of phase transformations in Pt-V coating systems UR - http://hdl.handle.net/11427/17104 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/17104
dc.identifier.vancouvercitationMakhetha WM. An investigation of phase transformations in Pt-V coating systems. [Thesis]. University of Cape Town ,Faculty of Engineering & the Built Environment ,Centre for Materials Engineering, 2012 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/17104en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentCentre for Materials Engineeringen_ZA
dc.publisher.facultyFaculty of Engineering and the Built Environment
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherMaterials Engineeringen_ZA
dc.titleAn investigation of phase transformations in Pt-V coating systemsen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMScen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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