Al粒径对PTFE/Al活性材料动态力学性能的影响

Effect of Al Particle Size on the Dynamic Mechanical Properties of PTFE/Al Reactive Material

为探究Al粒径对PTFE/Al活性材料热化学反应特性和动态力学性能的影响,采用模压烧结成型法制备了4种含不同Al粒径的PTFE/Al活性材料试件,利用同步热分析仪和分离式霍普金森压杆实验系统对4种试件分别进行了相应的测试,得到了不同试件的热化学反应曲线以及不同应变率下的应力-应变曲线。结果表明,在10℃/min的升温速率下,纳米Al颗粒在500℃左右会与PTFE分解产物发生点火反应,而微米Al颗粒低于900℃未与PTFE分解产物发生反应;此外,成分为微米Al颗粒的PTFE/Al活性材料,其粒径越小,抗压强度越高;而纳米Al颗粒除因团聚导致的混合不均匀外,在相同质量下的颗粒数量大大增加,颗粒与颗粒之间的距离变小,颗粒周围基体的微小裂纹更容易汇聚成断裂裂纹,使抗压强度下降。研究结果可为PTFE/Al活性材料的工程应用提供重要参考。

In order to investigate the effect of Al particle size on the thermochemical reaction characteristics and dynamic mechanical properties of politetrafluoroethylene-aluminum(PTFE/Al),four types of PTFE/Al reactive material specimens with different Al particle sizes were prepared by molding sintering method and were tested using DTA/TG simultaneous thermal analyzer and SHPB experimental system.The thermochemical reaction curves and stress-strain curves of different specimens were obtained.Results show that at the heating rate of 10℃/min,the nano-Al particles ignite with PTFE decomposition products at about 500℃,while micro-Al particles don’t react with PTFE decomposition products below 900℃.In addition,the smaller the particle size,the higher the compressive strength of PTFE/Al active materials consisting of micro-Al particles.Except for uneven mixing caused by agglomeration of nano-Al powder,the number of nano-Al particles increases greatly at the same mass,the distance between particles and particles decreases,and the micro-cracks in matrix around particles are more likely to converge into fracture cracks,which in turn reduces the compressive strength.The research results can provide important reference for the engineering application of PTFE/Al active materials.