The synthesis and characterization of CVD ZrB 2 coating from ZrCl 4 -BCl 3 -H 2 -Ar System
The synthesis and characterization of CVD ZrB 2 coating from ZrCl 4 -BCl 3 -H 2 -Ar System
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DOI：
10.1016/j.ceramint.2017.10.145
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发表时间：
2018-02
影响因子：
5.2
通讯作者：
Yan Zhu;Lai-fei Cheng;Mingxing Li;Baisheng Ma;Yongsheng Liu;Litong Zhang
中科院分区：
文献类型：
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作者：
Yan Zhu;Lai-fei Cheng;Mingxing Li;Baisheng Ma;Yongsheng Liu;Litong Zhang
通过热力学计算和化学气相沉积(CVD)实验，研究了在低压条件下，由ZrCl4-BCl3-H2-Ar体系合成和表征的化学气相沉积(CVD)ZrB2。在合适的工艺参数下，在石墨和碳纤维上成功地沉积了菜花状致密的ZrB2涂层。计算结果表明，随着温度的升高，ZrB2的产率增加。随着H_2流量的增加，ZrB_2的含量增加到一个较宽的极大值，当H_2流量超过40×10~(-6)Mol时，ZrB_2的含量保持不变。BCl3浓度显著影响CVD-ZrB_2的相组成。实验结果表明，温度、H_2和BCl3流量对涂层的表面粗糙度、生长速率和相组成有显著影响。随着温度的升高，涂层的厚度和颗粒尺寸增大。然而，在高温下，颗粒尺寸会减小，因为颗粒没有足够的时间在高反应速率下生长。随着H2流量的增加，涂层的形貌由疏松粗糙向致密光滑转变。当BCl3浓度较低时，BCl3还原反应占主导地位，当BCl3浓度较高时，沉积机制转变为B和ZrB2的共沉积。
By conducting thermodynamics calculations and chemical vapor deposition (CVD) experiments, the synthesis and characterization of CVD ZrB2from ZrCl4-BCl3-H2-Ar system at low pressure were investigated. Cauliflower-shaped, dense ZrB2coating was successfully deposited on graphite substrates and carbon fibers under appropriate parameters. Calculation results indicate that the yield of ZrB2increases with increasing temperature. The amount of ZrB2increases to a broad maximum with increasing H2flux and then remains constant when H2flux reaches above 40 mol. BCl3concentration significantly affects phase composition of CVD ZrB2. Three phases are involved, namely, Zr+ZrB2, ZrB2, and ZrB2+B. Experimental results show that the temperature and H2and BCl3fluxes significantly affect surface roughness, growth rate, and phase composition of ZrB2coating. The thickness and particle size of ZrB2coating increase with the increase in temperature. However, at high temperatures, particle size decreases because particles do not have enough time to grow at high reaction rate. Morphologies of ZrB2coating vary from porous and rough to dense and smooth with the increase in H2flux. BCl3reduction by H2dominates deposition process at low BCl3concentration, and deposition mechanism changes to the codeposition of B and ZrB2at high BCl3concentration.