Hydrolysis Mechanism of Borazine-derived Boron Nitride Pyrolysized below 1200 ℃

作者：Feng Cao; Kun Liu; Zhenyu Fang and Siqing Wang National Key Laboratory of Advanced Ceramic Fibers and Composites; College of Aerospace and Materials Engineering; National University of Defense Technology; Changsha; China

来源：Journal of Materials Science & Technology, 2012, (10): 956-960.

• Borazine
• Pyrolysis
• Boron nitride
• Hydrolysis
• Stability

Boron nitride(BN) powders were synthesized by pyrolysis at various temperatures to investigate the hydrolysis mechanism of borazine-derived BN pyrolysized below 1200 C.The BN was hydrolysized near room temperature at 65% or 90% relative humidity(RH) over 45 days.The long-term hydrolysis mechanism and structure evolution were investigated by a measurement of mass growth and by X-ray diffraction(XRD),Fourier-transform infrared(FT-IR) spectroscopy,and scanning electron microscopy(SEM) analyses.The samples pyrolysized below 1200 C were very sensitive to moisture,and their mass growth was closely related to the pyrolysis temperature.At 25 C and 65% RH,the sample pyrolysized at 400 C exhibited almost 100 wt% mass growth within 8 days,while the sample pyrolysized at 1200 C exhibited about 20 wt% mass growth.The XRD analysis suggested a hydrolysis mechanism that corresponded to the interlayer spacing in the BN,which was consistent with the results reported.On the other hand,the instability of borazine-derived BN should be directly due to the residual N-H bonds in the compound,as suggested by FT-IR analysis.