Effects of microwave heating in nanolaminated Nb₂GeC synthesis

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• 作者：Ausdinir D. Bortolozo ; ^{ausdinir.bortolozo@fca.unicamp.br" class="auth_mail" title="E-mail the corresponding author} ; Alessandra Cremasco ; Ricardo Floriano ; Rodrigo J. Contieri
• 关键词：M2AX phase ; Microwave sintering ; Nanolaminated
• 刊名：Ceramics International
• 出版年：2016
• 出版时间：1 November 2016
• 年：2016
• 卷：42
• 期：14
• 页码：16343-16348
• 全文大小：3811 K

文摘

MAX phases are a class of ternary compounds, known to exhibit combined properties of ceramics and metals. In this study, we have used the microwave (MW) and conventional (CV) heat treatments in order to synthesize the Nb₂GeC phase starting from the mixtures of raw materials (Nb, Ge and C). The results of a detailed microstructural characterization that includes X-ray diffraction (XRD) with Rietveld refinement and scanning electron microscopy (SEM) of MW and CV treated samples are reported. The XRD patterns followed by Rietveld analysis revealed that the MW sample presents 93 vol% of Nb₂GeC phase after 48 h of processing while the CV sample has taken 240 h to attain similar results. Rietveld analysis confirmed that the Nb₂GeC phase has a hexagonal structure with <em>P6em>_<em>3em><em>/mmcem> space group and lattice parameters of <em>aem>=0.323±0.005 nm and <em>cem>=1.256±0.005 nm. The crystallite size was estimated by using the <em>Williansom-Hallem> method being about 75 nm and 62.5 nm for the processed samples after 240 h to CV and MW sample, respectively. SEM analysis showed the presence of a more refined microstructure and relatively lowers porosity for MW sample in comparison with CV sample. These results have indicated the high potential of microwave heating to produce MAX phases in a shorter processing time when comparing with conventional processing routes.