Advanced high-temperature-resistant silicate adhesive reinforced by intermetallic compounds for joining SiC/SiC composites

Abstract

In this study, an advanced high-temperature-resistant silicate adhesive, SA-AN, was developed by using Ni2SiO4, Ti, ZrO and Si powders modified silica sol as resin matrix, Al powder and ZnO as curing agents for jointing SiC/SiC composites. The thermal and mechanical properties of SA-AN were evaluated. The structural evolution of SA-AN, the reaction process at the interface, and the fracture mode of the joint were comprehensively investigated. The adhesive was transformed into Al–Ni-rich intermetallic compound-reinforced ceramic composites at high temperatures. Moreover, interfacial reaction of adhesive with SiC/SiC substrate occurred and the resulting diffusion reaction layer effectively relieved the thermal stress between the adhesive and the SiC/SiC substrate. Due to the formation of intermetallic compounds and the occurrence of interfacial reaction, the mechanical properties and heat resistance of the joints were considerably improved. Tensile shear strength of the adhesive was 18.7 MPa after calcination at 600 °C and 17.9 MPa after calcination at 900 °C, which was 65.5% and 94.6% higher compared to the conventional silicate adhesive SA-A, respectively. After 50 cycles of RT-900 °C, tensile shear strength of SA-AN still achieved 10.3 MPa with a retention rate of 61.5%. Furthermore, the mixed fracture pattern of the adhesive joint containing SiC/SiC substrate damage was attained even at 1200 °C of calcination, indicating the effective adhesion at this temperature. As first reported in this study, SA-AN is an efficient high-temperature-resistant adhesive applicable for bonding SiC/SiC composites, which has wide application prospects in aerospace domain.