Effects of microwave heating in nanolaminated Nb2GeC synthesis
Effects of microwave heating in nanolaminated Nb2GeC synthesis
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DOI：
10.1016/j.ceramint.2016.06.190
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发表时间：
2016-11-01
影响因子：
5.2
通讯作者：
Contieri, Rodrigo J.
中科院分区：
文献类型：
--
作者：
Bortolozo, Ausdinir D.;Cremasco, Alessandra;Contieri, Rodrigo J.
MAX相是一类三元化合物，已知表现出陶瓷和金属的组合性质。在这项研究中，我们已经使用了微波（MW）和常规（CV）热处理，以合成Nb 2GeC相从原料（Nb，Ge和C）的混合物。详细的微观结构表征，包括X射线衍射（XRD）与Rietveld细化和扫描电子显微镜（SEM）的MW和CV处理的样品的结果报告。随后进行Rietveld分析的XRD图案显示，MW样品在处理48小时后呈现93体积%的Nb 2GeC相，而CV样品花费240小时才获得类似的结果。Rietveld分析证实Nb 2GeC相具有六方结构，空间群为P6（3）/mmc，晶格参数为a=0.323 +/- 0.005 nm和c=1.256 +/- 0.005 nm。通过使用Williansom-Hall方法估计，对于CV和MW样品，240小时后处理的样品的微晶尺寸分别为约75 nm和62.5 nm。SEM分析表明，与CV样品相比，MW样品存在更精细的微观结构和相对较低的孔隙率。这些结果表明，与传统的加工路线相比，微波加热在更短的加工时间内产生MAX相的潜力很大。(C)2016 Elsevier Ltd和Techna Group S.r.l. All rights reserved.
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 P6(3)/mmc space group and lattice parameters of a=0.323 +/- 0.005 nm and c=1.256 +/- 0.005 nm. The crystallite size was estimated by using the Williansom-Hall 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. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.