硅树脂/EPDM绝热材料的性能及陶瓷化机理

Property and ceramicization mechanism of siliconeresin-filled EPDM insulation

采用SEM、TG、DSC、拉伸试验和氧-乙炔烧蚀试验,研究了硅树脂对EPDM绝热材料力学性能、热稳定性以及耐烧蚀性能的影响,并分析了硅树脂/EPDM绝热材料在烧蚀过程中炭化层的陶瓷化机理。结果表明:随着硅树脂含量的增加,绝热层的抗拉强度和断裂伸长率均有所降低;在硅树脂含量为35 phr时,绝热层的热稳定性以及耐烧蚀性能最好,残炭率能达到30%左右,线烧蚀率最小为0.048 mm/s;观察形貌发现,含硅树脂绝热层烧蚀后形成的炭化层更致密坚硬,孔洞更小,耐冲刷性能更好。添加硅树脂能够有效提高EPDM绝热层的耐烧蚀性能,其作用机理主要是通过高温下分解产生的硅氧化物与碳进行碳热还原反应形成碳化硅和其熔融态将炭化层粘结在一起,最终形成一种类陶瓷结构的炭化层。

The influence of silicone resin on the mechanical properties,thermal stability,and ablation resistance of EPDM insulation materials was investigated through SEM,TG,DSC,tensile testing,and oxygen-acetylene ablation testing.Additionally,the ceramization mechanism of the carbonized layer in silicone resin/EPDM insulation materials was analyzed during the ablation process.The results show that with the increase of the silicone resin content,tensile strength and elongation at break of EPDM insulation decrease;When the content of silicone resin is 35 phr,the thermal stability and ablation resistance of the insulation are the best,the residual carbon rate can reach about 30%,and the minimum line ablation rate is 0.048 mm/s.The morphology observation shows that the char layer formed after the ablation of silicone insulation is more compact and hard,with smaller holes and better erosion resistance.The addition of silicone resin can effectively improve the ablative resistance of EPDM insulation.The action mechanism is mainly the formation of silicone carbide by carbothermal reduction reaction at high temperature and the adhesion of molten state after decomposition to form a kind of ceramic structure.