Microstructure and Growth Kinetics of Silicide Coatings for TiAl Alloy
来源期刊：Journal Of Wuhan University Of Technology Materials Science Edition2017年第2期
论文作者：黄磊 吴向清 XIE Faqin WANG Su
文章页码：245 - 249
摘 要：In order to improve the oxidation resistance of Ti Al alloy, silicide coatings were prepared by pack cementation method at 1273, 1323, and 1373 K for 1-3 hours. Scanning electron microscopy（SEM）, energy dispersive spectrometry（EDS） and X-ray diffraction（XRD） were employed to investigate the microstructures and phase constitutions of the coatings. The experimental results show that all silicon deposition coatings have multi-layer structure. The microstructure and composition of silicide coatings strongly depend on siliconizing temperatures. In order to investigate the rate controlling step of pack siliconizing on Ti Al alloy, coating growth kinetics was analyzed by measuring the mass gains per unit area of silicided samples as a function of time and temperature. The results showed that the rate controlling step was gas-phase diffusion step and the growth rate constant（k） ranged from 1.53 mg2/（cm4·h2） to 2.3 mg2/（cm4·h2）. Activation energy（Q） for the process was calculated as 109 k J/mol, determined by Arrhenius’ equation: k = k0 exp[–Q/（RT）].
黄磊，吴向清，XIE Faqin，WANG Su
School of Aeronautics,Northwestern Polytechnical University
摘 要：In order to improve the oxidation resistance of Ti Al alloy, silicide coatings were prepared by pack cementation method at 1273, 1323, and 1373 K for 1-3 hours. Scanning electron microscopy（SEM）, energy dispersive spectrometry（EDS） and X-ray diffraction（XRD） were employed to investigate the microstructures and phase constitutions of the coatings. The experimental results show that all silicon deposition coatings have multi-layer structure. The microstructure and composition of silicide coatings strongly depend on siliconizing temperatures. In order to investigate the rate controlling step of pack siliconizing on Ti Al alloy, coating growth kinetics was analyzed by measuring the mass gains per unit area of silicided samples as a function of time and temperature. The results showed that the rate controlling step was gas-phase diffusion step and the growth rate constant（k） ranged from 1.53 mg2/（cm4·h2） to 2.3 mg2/（cm4·h2）. Activation energy（Q） for the process was calculated as 109 k J/mol, determined by Arrhenius’ equation: k = k0 exp[–Q/（RT）].
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