CVD法制备B-C体系材料
Preparation of B-C system materials by CVD
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摘要: 以BCl3-C3H6-H2为反应体系, 采用化学气相沉积法(CVD)在炭纤维束上制备了B-C体系材料, 研究了沉积温度的影响。利用SEM和XPS对BC<em>x层的微结构、 元素含量和化学结构进行表征, 并结合化学反应过程, 探讨了导致沉积产物形貌、 成分和键结合状态的差异原因。结果表明, 沉积温度对B-C层生长速率和断面形貌均有较大影响: 900℃沉积时, 沉积较慢, 断面平整; 1000℃时, 沉积速度加快, 断面呈显著片层状结构; B-C层内B元素原子含量随沉积温度升高而降低; 沉积产物内B元素键结合状态有: B4C、 B替代C、 BC2O、 BCO2和B2O3。沉积温度不仅影响B元素键结合状态, 而且还影响各结合状态的含量。B4C在900℃时含量为0, 在1000℃时达到最大值32.5at%; B替代C在900℃时含量最高, 然后随温度升高而下降, 在1050℃时其含量又有所升高。Abstract: The B-C coating was prepared by CVD from BCl3-C3H6-H2 precursor mixtures on the carbon fiber. The effect of the depositing temperature on the coatings character was analyzed. The microstructure of the deposit was analyzed by SEM. The element content and the type of the chemical structure of the deposited coating were studied by X-ray photoelectron spectroscopy. The inducements of the microstructure, component and various types of the chemical structure were discussed with the consideration of the chemical reaction processes. SEM results show that with the depositing temperature rising from 900℃ to 1100℃, the growth rate increases and the cross section microstructure turns from amorphous into laminated structure. XPS results show that with the increasing of temperature, the content of boron increases. The boron accommodates five different chemical structures in the BCx coatings. The content of boron within these different chemical structures is also influenced by the depositing temperature.