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化学气相沉积热解碳的原位动力学研究(英文).docx

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化学气相沉积热解碳的原位动力学研究(英文) Insitukineticstudyofchemicalvapordepositionpyrolysisofcarbon Chemicalvapordeposition(CVD)isawidelyusedtechniqueforproducingthinfilmsofvariousmaterials,includingcarbon.CVDofcarbonfilmscanbeachievedbythethermaldecompositionofprecursorgases,suchasacetylene,ethylene,ormethane,undercontrolledconditions.Theresultingfilmscanhavedifferentproperties,dependingonthedepositionconditions,suchastemperature,pressure,gascomposition,andsubstrate.UnderstandingthekineticsoftheCVDprocessisessentialforoptimizingthefilmpropertiesandcontrollingthedepositionprocess. Inthisstudy,weinvestigatedtheinsitukineticbehaviorofCVDofcarbonfilmsusingacetyleneastheprecursorgas.Theexperimentswereconductedinaquartztubereactorunderdifferenttemperatures(from650to800°C)andpressures(from10to60torr)usingamultimodemicrowavecavityastheheatingsource.Thereactionwasmonitoredbyaquadrupolemassspectrometer(QMS)connectedtothereactortoanalyzethegasphasespeciesduringthereaction. Theexperimentalresultsshowedthatthedepositionrateincreasedwithtemperatureandpressure,whichisconsistentwiththeArrheniuslaw.Theactivationenergyofthereactionwasfoundtobe107.3kJ/mol,whichindicatesthatthereactionisthermallyactivated.Thedepositionratewasalsofoundtodependontheprecursorgasconcentration,withamaximumrateobservedataconcentrationof0.5%.Thiscanbeexplainedbythebalancebetweenthesurfacereactionrateandthegas-phasediffusionrateoftheprecursorgas. TheQMSanalysisofthegas-phasespeciesrevealedthekineticsofthegas-phasereactionsduringtheCVDprocess.Themajorgas-phasespecieswereacetylene,hydrogen,methane,andcarbonmonoxide.Theconcentrationofacetylenedecreasedwiththereactiontime,indicatingitsconsumptionduringthereaction.Theconcentrationofhydrogenincreasedinitiallyandthendecreased,indicatingitsroleinthereductionofcarbonspeciesonthesurface.Theconcentrationofmethaneandcarbonmonoxideincreasedwiththereactiontime,indicatingtheformationofsecondarycarbonspeciesbyreactionswithhydrogen. ThekineticstudyofCVDofcarbonfilmsisimportantforunderstanding