多升温速率法研究SiO2涂层/三维碳纤维编织体材料的微观氧化特征和机理

采用热重分析中的多升温速率法,从微观角度对SiO2涂层/三维碳纤维编织体材料氧化反应的特征和机理进行了系统研究。结果表明:非等温条件下,材料的氧化过程呈现自催化特征。材料的氧化失重过程是一个复杂过程,首先为化学反应控制(转化率α≤10%),反应的活化能为138.619kJmol-1;随失重的增加(α≤55%),逐渐变为化学反应和气体扩散共同控制,其活化能的最小值为54.524kJmol-1;当α>55%,随失重的增加,化学反应对总反应速率的影响逐渐增大,活化能逐渐增加。最后通过对材料微分热重曲线重叠峰的解析研究了升温速率对涂层/编织体材料热氧化稳定性的影响。

STUDY OF MICRO-OXIDATION PROPERTIES AND MECHANISM OF SIO_2 COATING/3-D CARBON FIBER BRAID THROUGH MULTI-HEATING RATES

The micro-oxidation properties and mechanism of SiO2 coating/3-D carbon fiber braid was studied through non-isothermal TGA with multi-heating rates systematically. The results showed that in non-isothermal condition,the oxidation properties of CB exhibited a self-catalytic characteristic. The oxidation process of composite was a complex stage: When α≤10%, oxidation stage of CB was mainly controlled by chemistry reaction, the corresponding Ea was 138.619kJ·mol-1; With the increase of α(55%≥α>10%), the oxidation process was controlled by chemical reaction and gas diffusion together, and the Ea was up to minimum 54.524 kJmol-1 when α equaled to 55%; When α>55%, the chemical reaction influence became greater, which led to the increase of Ea with the increase of α. The influence of heating rates on the thermal oxidation stability of CB was also studied through overlap peak solving.