The pyrolysis behavior of polycarbosilane （PCS） and chemical reaction mechanism during the pyrolysis process were studied by thermogravimetric-mass spectrometry （TG-MS） combined with X-ray diffraction and infrared...The pyrolysis behavior of polycarbosilane （PCS） and chemical reaction mechanism during the pyrolysis process were studied by thermogravimetric-mass spectrometry （TG-MS） combined with X-ray diffraction and infrared spectroscopic analysis methods. The experimental results indicate that the main gas phase products generated during pyrolysis of PCS in nitrogen atmosphere include H2, -CH3 and CH4. The heating rate has a large effect on the pyrolysis process of PCS, the lower heating rate releases more small molecule gases and gets bigger rate of pyrolysis mass loss, demonstrating that the lower heating rate is beneficial to fully pyrolysis of PCS and obtain ceramics products with better microstructure.展开更多
采用热重-质谱联用（TG-MS）研究了氮气气氛中花生壳在不同升温速率（5,10和20℃/min）下的热解行为,分析得到了花生壳热裂解过程产生的小分子气相产物（CO2,CH4,H2,CO）随温度和升温速率变化的释放规律.结果表明：花生壳热裂解过程分...采用热重-质谱联用（TG-MS）研究了氮气气氛中花生壳在不同升温速率（5,10和20℃/min）下的热解行为,分析得到了花生壳热裂解过程产生的小分子气相产物（CO2,CH4,H2,CO）随温度和升温速率变化的释放规律.结果表明：花生壳热裂解过程分为四个阶段,升温速率越大,花生壳热解的失重温度区间越宽,最大热解速率峰越陡峭.应用Flynn-Wall-Ozawa法得出花生壳热裂解过程不同转化率（0.2~0.8）下的活化能在57.3~88.6 k J/mol范围内.结合Achar微分法和Coats-Redfern积分法确定了该反应过程的机理函数表达式,将30种常用机理函数一一代入得出花生壳热裂解机理的最概然函数为球形对称的三维扩散Jander方程,反应级数为2级.展开更多
基金Funded by the Natural Science Foundation of Hubei Province(No.2013CFB340)
文摘The pyrolysis behavior of polycarbosilane （PCS） and chemical reaction mechanism during the pyrolysis process were studied by thermogravimetric-mass spectrometry （TG-MS） combined with X-ray diffraction and infrared spectroscopic analysis methods. The experimental results indicate that the main gas phase products generated during pyrolysis of PCS in nitrogen atmosphere include H2, -CH3 and CH4. The heating rate has a large effect on the pyrolysis process of PCS, the lower heating rate releases more small molecule gases and gets bigger rate of pyrolysis mass loss, demonstrating that the lower heating rate is beneficial to fully pyrolysis of PCS and obtain ceramics products with better microstructure.
文摘采用热重-质谱联用（TG-MS）研究了氮气气氛中花生壳在不同升温速率（5,10和20℃/min）下的热解行为,分析得到了花生壳热裂解过程产生的小分子气相产物（CO2,CH4,H2,CO）随温度和升温速率变化的释放规律.结果表明：花生壳热裂解过程分为四个阶段,升温速率越大,花生壳热解的失重温度区间越宽,最大热解速率峰越陡峭.应用Flynn-Wall-Ozawa法得出花生壳热裂解过程不同转化率（0.2~0.8）下的活化能在57.3~88.6 k J/mol范围内.结合Achar微分法和Coats-Redfern积分法确定了该反应过程的机理函数表达式,将30种常用机理函数一一代入得出花生壳热裂解机理的最概然函数为球形对称的三维扩散Jander方程,反应级数为2级.
