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dc.contributor.advisorZerda, T. Waldek
dc.contributor.authorPantea, Cristianen_US
dc.date.accessioned2019-10-11T15:11:15Z
dc.date.available2019-10-11T15:11:15Z
dc.date.created2004en_US
dc.date.issued2004en_US
dc.identifieraleph-1059813en_US
dc.identifierMicrofilm Diss. 845.en_US
dc.identifier.urihttps://repository.tcu.edu/handle/116099117/34232
dc.description.abstractIn this dissertation work, the kinetics of the reaction between diamond and silicon at high pressure-high temperature conditions was investigated. This study was motivated by the extremely limited amount of information related to the kinetics of the reaction in diamond-silicon carbide composites formation. It was found that the reaction between diamond and melted silicon and the subsequent silicon carbide formation is a two-stage process. The initial stage is a result of direct reaction of melted silicon with carbon atoms from the diamond surface, the phase boundary reaction. Further growth of SiC is much more complicated and when the outer surfaces of diamond crystals are covered with the silicon carbide layer it involves diffusion of carbon and silicon atoms through the SiC layer. The reaction takes place differently for the two regions of stability of carbon. In the graphite-stable region, the reaction between diamond and melted silicon is associated with the diamond-to-graphite phase transition, while in the diamond-stable region there is no intermediary step for the reaction. The data obtained at HPHT were fitted by the Avrami-Erofeev equation. It was found that the reaction is isotropic, the ?-SiC grown on different faces of the diamond crystals showing the same reaction rate, and that the controlling mechanism for the reaction is the diffusion. In the graphite-stable region the activation energy, 402 kJ/mol is slightly higher than in the diamond-stable region, 260 kJ/mol, as the reaction between diamond and melted silicon is associated with the diamond-to-graphite phase transition, which has higher activation energy. In the diamond-stable region, the calculated activation energy is higher for micron size diamond powders (?260 kJ/mol), while for nanocrystalline diamond powders a lower value of 170 kJ/mol was obtained. This effect was attributed to nanocrystalline structure and strained bonds within grain boundaries in SiC formed from nanosize diamond. The ?-SiC started forming below the melting point in the case of nano-size diamond powders, due to the strained carbon atoms present on the diamond surface.
dc.format.extentxi, 119 leaves : illustrations (some color)en_US
dc.format.mediumFormat: Printen_US
dc.language.isoengen_US
dc.relation.ispartofTexas Christian University dissertationen_US
dc.relation.ispartofAS38.P364en_US
dc.subject.lcshDiamondsen_US
dc.subject.lcshSiliconen_US
dc.subject.lcshCarbonen_US
dc.subject.lcshChemical kineticsen_US
dc.titleKinetics of diamond-silicon reaction under high pressure-high temperature conditionsen_US
dc.typeTexten_US
etd.degree.departmentDepartment of Physics
etd.degree.levelDoctoral
local.collegeCollege of Science and Engineering
local.departmentPhysics and Astronomy
local.academicunitDepartment of Physics
dc.type.genreDissertation
local.subjectareaPhysics and Astronomy
dc.identifier.callnumberMain Stacks: AS38 .P364 (Regular Loan)
dc.identifier.callnumberSpecial Collections: AS38 .P364 (Non-Circulating)
etd.degree.nameDoctor of Philosophy
etd.degree.grantorTexas Christian University


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