碳纤维表面 h-BN 耐高温涂层的制备及表征

目的在碳纤维表面制备六方氮化硼涂层,以提高纤维的抗氧化、耐高温性能,拓宽其在高温领域的应用。方法以硼酸、尿素、氨气和氮气作为原始材料,先通过浸渍法在碳纤维表面涂覆硼酸和尿素的混合溶液,然后将其放置在氨气和氮气氛围中进行高温热解。采用电子显微镜分析涂层的形貌,观察涂层与碳纤维的结合是否良好;采用傅里叶红外光谱、X射线电子能谱及X射线衍射等测试技术对涂层的成分和结构进行表征。结果碳纤维表面的涂层连续,形貌良好。红外光谱中,在1399,799 cm-1处存在B—N键和B—N—B键的特征峰。X射线衍射图谱中,在43.64°和53.93°存在六方氮化硼(001)晶面和(004)晶面的特征峰。X射线电子能谱分析表明,涂层中存在O,B,C和N四种元素,且B与N的原子比接近1∶1。结论实验中成功制备了h-BN涂层碳纤维,且涂层和碳纤维结合较好。涂层中的h-BN结晶度良好,纯度较高,但少量氧化物的存在会对h-BN涂层碳纤维耐高温性的提升有所影响,如何进一步提高h-BN涂层的纯度有待研究。

Preparation and Characterization of h-BN High-temperature Resistant Coating on the Surface of Carbon Fibers

Objective Hexagonal boron nitride coatings were prepared on carbon fiber surface, in order to improve the oxidation resistance and high temperature resistant performance of the fiber, so as to broaden its application in the field of high temperature. Methods With boric acid, urea, ammonia and nitrogen gas as raw materials, a mixture of boric acid and urea solution was coated on the carbon fiber surface through impregnating method, and the coating was then placed in the ammonia and nitrogen atmosphere for high temperature pyrolysis. The morphology of the coating was observed by electronic microscope analysis to check whether the coating was well bonded with the carbon fiber. Fourier infrared spectra, X ray electronic energy spectrum and X-ray diffraction ( XRD) were used to characterize the composition and structure of the coating. Results The coating on the surface of the carbon fi-ber was continuous and had good appearance. In the infrared spectrum, B—N key and B—N—B key characteristic peaks occurred at 1399, 799 cm-1 . In the X-ray diffraction pattern, (001) crystal plane and (004) crystal plane characteristic peaks of hexagonal boron nitride appeared at 43. 64. and 53. 93., respectively. X-ray photoelectron analysis showed the existence of the four elements of O, B, C and N, and a B/N atom ratio of close to 1:1. Conclusion H-BN coated carbon fiber was successfully prepared, and the coating was well bonded with the carbon fiber. The h-BN in the coating had good crystallinity and high purity, but the existence of a small amount of oxide had influence on the thermostability improvement of h-BN coated carbon fiber. More works have to be done to study how to further improve the purity of h-BN coatings.