Synthesis of a novel preceramic polymer (V-PMS) and its performance in heat-resistant organic adhesives for joining SiC ceramic

摘要

Heat-resistant organic adhesives are urgently needed for aeronautical and astronautical applications, and there have been only a few successful studies in this ield. In this work, a novel preceramic polymer (V-PMS) has been synthesized by modifying polymethylsilane with 1,3,5,7-tetramethyl-l,3,5,7-tetravinylcyclotetrasiloxane, [CH_3(CH2=CH)SiO]4, and this has been used as a heat-resistant adhesive. The obtained adhesive was found to exhibit outstanding thermal and bonding properties. The ceramic yield was about 81% (in Ar) and 90.6% (in air) at 1200 °C. The shear strength was 14.9 MPa at room temperature, and this increased to a maximum of 31.7 MPa after treatment at 1000 °C for 2 h in air. Moreover, it was interesting to find that on addition of B4C powder to the preceramic polymer, its shear strength was surprisingly enhanced up to 50.8 MPa after annealing at 1200 °C under air atmosphere. Their excellent performances make the obtained adhesives promising candidates for joining SiC ceramics in high-temperature applications.