A composite structural high-temperature-resistant adhesive based on in-situ grown mullite whiskers

The effect of whisker growing catalyzed by different amounts of AlF3 on the various properties of an epoxy/silicone resin-based high-temperature-resistant adhesive was comprehensively investigated. Although the addition of AlF3 promoted the oxidation reactions, accelerated the premature formation of mullite whiskers, increased the production of SiC ceramic, and reduced the thermal expansion of bonding layer, the excessive use of AlF3 induced many more large holes in the bonding layer, caused the structural heterogeneity, and made mullite whiskers overgrow, thus finally led to the weaker mechanical properties of adhesives. The best dosage of AlF3 in this work was 3 % (mass fraction), a uniform composite structure that whisker weaved adhesive frame kept steady from 1100 °C to 1500 °C, and an impressive bonding strength of 63 MPa was achieved at 1100 °C, 80 % higher than that of the blank sample. Under the synergistic effect of whisker repair, whisker bridging, whisker drawing and crack deflection, a multi-stage fracture phenomenon happened during the shear test, and the fracture displacement of 1100 °C-calcined adhesive with 3 % AlF3 increased by 61 %, compared with that of the black sample.