In-situ synthesis of ultra-fine ZrB2-ZrC-SIC nanopowders by sol-gel method
In-situ synthesis of ultra-fine ZrB2-ZrC-SIC nanopowders by sol-gel method
复制标题
溶胶-凝胶法原位合成超细ZrB2-ZrC-SIC纳米粉体
DOI：
10.1016/j.ceramint.2019.11.202
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发表时间：
2020
影响因子：
5.2
通讯作者：
Hou Xianghui
中科院分区：
文献类型：
--
作者：
Liu Changqing;Chang Xiaojing;Wu Yuanting;Li Xu;Xue Yunlong;Wang Xiufeng;Hou Xianghui
以经济实惠的ZrOCl2·8H2O为原料，采用简单的溶胶-凝胶法制备了相分布均匀的纳米粉末。研究了纳米粉末的合成路线、陶瓷化机理和形貌演变。通过原料之间的水解和缩合反应，成功地制备出了ZrB2-ZRC-SiC陶瓷前驱体。前驱体在650℃下热解完成，在1300℃时生成了ZrO2、SiO_2、B_2O_3和无定形碳，产率为39%。经1500℃热处理2h后，得到了尺寸分布窄、结晶度高的ZrB_2-ZRC-SiC陶瓷。保温时间为2小时时，晶粒度和粒度均可细化。进一步延长保温时间会导致严重的颗粒粗化。对陶瓷转化过程中生成碳的微观结构演变的研究表明，陶瓷的形成对碳的结构有序性的改善有负面影响，这是由于硼/碳热还原反应在其内部产生了大量的缺陷。
ZrB2–ZrC–SiC nanopowders with uniform phase distribution were prepared from cost-effective ZrOCl2·8H2O by a simple sol-gel method. The synthesis route, ceramization mechanism and morphology evolution of the nanopowders were investigated. ZrB2–ZrC–SiC ceramic precursor can be successfully obtained through hydrolysis and condensation reactions between the raw materials. Pyrolysis of the precursor was completed at 650 °C, and it produced ZrO2, SiO2, B2O3and amorphous carbon with a yield of 39% at 1300 °C. By heat-treated at 1500 °C for 2 h, highly crystallized ZrB2–ZrC–SiC ceramics with narrow size distribution were obtained. With the holding time of 2 h, both the crystal size and the particle size can be refined. Further prolonging the holding time can lead to serious particles coarsening. Studies on the microstructure evolution of the generated carbon during the ceramic conversion demonstrates the negative effect of the ceramic formation on the structure order improvement of the carbon, due to the large amount of defects generated in it by the boro/carbothermal reduction reactions.