硼系化合物对可瓷化硅橡胶复合材料性能的影响

Effect of Boron-based Compounds on Properties of Ceramizable Silicone Rubber Composites

研究硼系化合物B1(粒径为5~10μm)/B2(粒径为2~3μm)用量比对可瓷化硅橡胶复合材料物理性能和热稳定性的影响,以及不同烧蚀温度下可瓷化硅橡胶复合材料陶瓷体的微观形貌和物相演变。结果表明:当硼系化合物B1/B2用量比为30/20时,可瓷化硅橡胶复合材料的拉伸强度和拉断伸长率均最大,分别为4.11 MPa和255%;在较低烧蚀温度(600~800℃)下,随着硼系化合物B1/B2用量比的增大,可瓷化硅橡胶复合材料陶瓷体的弯曲强度增大、线性收缩率减小,但变化不大;在较高烧蚀温度(800~900℃)下,可瓷化硅橡胶复合材料陶瓷体的弯曲强度先减小后增大,体系中生成的液相物质较多,形成了致密的陶瓷层,从而减缓了热量传递,阻碍了氧气对内部材料的氧化,提高了复合材料的热稳定性,增大了陶瓷体的弯曲强度。

Effect of the dosage ratio of boron compound B1(particle size 5~10μm)/B2(particle size 2~3μm)on the physical properties and thermal stability of the ceramizable silicon rubber composite was studied.The micromorphology and phase evolution of the ceramic body of the ceramizable silicone rubber composite at different ablation temperatures were also studied.The results showed that,when the dosage ratio of boron compounds B1/B2 was 30/20,the tensile strength and elongation at break of the ceramizable silicone rubber composite were the highest,4.11 MPa and 255%respectively.At a lower ablation temperature(600~800℃),with the increase of the dosage ratio of boron compounds B1/B2,the flexural strength of the ceramic body of the ceramizable silicone rubber composite increased and the linear shrinkage decreased,but these changes were not significant.At a higher ablation temperature(800~900℃),the flexural strength of the ceramic body of the ceramizable silicone rubber composite initially decreased and then increased,and many liquid substances were generated in the system,forming a dense ceramic layer,which slowed down the heat transfer,hindered the oxidation of the internal materials by oxygen,improved the thermal stability of the composite,and increased the bending strength of the ceramic body.