B_4C改性酚醛树脂对Si_3N_4的高温粘接性能

Adhesive properties of B_4C-modified phenol-formaldehyde(PF)resin adhesive for the high-temperature bonding of Si_3N_4

以酚醛树脂为基体，加入B4c作为改性填料制备出高温粘结剂，并对si3N4陶瓷进行粘接。在300～800℃温度范围内对Si3N4陶瓷粘接试样进行热处理，并测试了不同温度热处理后的室温剪切强度。结果表明，经过700～800℃热处理后，粘结剂表现出较为理想的粘接性能，剪切强度测试结果为Si3N4陶瓷基体破坏。利用扫描电镜研究了粘接试样的断面形貌及胶层结构特征。研究表明，在高温热处理过程中，B4C改性填料发生了复杂的物理、化学变化，通过B4C与树脂挥发分之间的改性反应，有效提高了酚醛树脂热解后的残炭值，进而改善了粘接胶层结构的高温稳定性；纤维状物质的形成与B2O3颗粒的细化，有助于提高粘接胶层的连接强度。

High-temperature adhesive was prepared using phenol-formaldehyde resin （PF） as matrix and boron carbide （B4C） as modifier, silicon nitride （Si3N4） ceramics were bonded by the adhesive, and the bonded specimens were heat-treated within 300--800℃ subsequently. The adhesive properties of the high-temperature adhesive were tested. The results indicate that the adhesive has outstanding high-temperature bonding properties for Si3N4 at high temperature. The failure of bonded joints treated at 700 and 800 ℃ were due to the broken of Si3N4 matrix. The micro-morphologies at bonding interfaces were also investigated by SEM. It is shown that complex physical and chemical changes occurred during the heat-treatment process. By means of the modification reaction between B4C and the volatiles of PF resin, the value of carbon residue was prompted effectively; and the formation of fibers and the nanocrystallization of B2O3 benefit the achievement of satisfactory high-temperature bonding properties.