典型飞机线缆绝缘材料老化热解特性研究

Study on Aging and Pyrolysis Characteristics of Typical Aircraft Cable Insulation Materials

线缆绝缘材料老化是造成飞机电气系统故障的主要因素。以飞机上实际使用的轻型同轴电缆绝缘层聚四氟乙烯(PTFE)为研究对象,采用换气式老化实验箱对材料进行加速热老化处理。利用热重分析仪对N2气氛中不同升温速率下材料热分解参数进行测定,研究材料老化前后热解特性变化情况。结果表明:N_(2)气氛下PTFE老化后的初始热分解温度有所降低,说明老化后的绝缘材料更容易发生热解。采用Kissinger法与Starink法进行热解动力学分析,相比于未老化试样,老化试样在热分解初期活化能发生明显变化,呈现由低到高的变化趋势,说明老化试样热解过程中进行多步反应。老化试样的活化能整体上低于未老化试样的活化能,表明线缆绝缘材料老化后热稳定性下降。

The aging of cable insulation materials are the main factor causing the failure of aircraft electrical system.The polytetrafluoroethylene(PTFE)insulation layer of light coaxial cable actually used in aircraft is selected as the research object,and the materials are accelerated thermal aging by using a ventilated aging test box.The thermal decomposition parameters of the materials under different heating rates in N2 atmosphere are measured by a thermogravimetric analyzer,and the changes of pyrolysis characteristics before and after aging are studied.The results show that the initial thermal decomposition temperatures of PTFE after aging in N_(2) atmosphere are decreased,indicating that the aged insulating materials are more prone to pyrolysis.The Kissinger method and Starink method are used to analyze the pyrolysis kinetics.Compared with the unaged sample,the activation energy of the aged samples change significantly at the initial stage of thermal decomposition,showing a trend of change from low to high,indicating that there are multi-step reactions in the pyrolysis process of the aged sample.The activation energy of the aged sample is generally lower than that of the unaged sample,indicating that the thermal stability of the cable insulation materials decrease after aging.K.