Dual-Action Calcium Monoaluminate Enabled Room-Temperature Curing of Inorganic Phosphate-Based High-Temperature Adhesive

High-temperature adhesives find extensive application in diverse domains, encompassing repairs, production processes, and material joining. However, achieving their curing at ambient temperatures remains a formidable challenge due to the inherent requirement of elevated temperatures, typically exceeding 500 °C, for the curing reaction. To overcome this limitation, in this study, we developed a distinctive inorganic phosphate-based composite adhesive by incorporating dual-functional calcium monoaluminate (CA) into a traditional adhesive blend comprising Al(H₂PO₄)₃ and MgO. This distinctive approach significantly diminishes the curing temperature, enabling it to occur at room temperature. Firstly, CA's facile hydration reaction effectively scavenges surrounding water molecules, thereby accelerating the dehydration curing process of Al(H₂PO₄)₃. Secondly, as hydration is an exothermic process, it locally generates heat around the Al(H₂PO₄)₃, fostering optimal conditions for its curing reaction. Moreover, the adhesive's strength is substantially bolstered through the strategic inclusion of Nano-Al₂O₃ (enhancing the availability of reaction sites) and Nano-SiO₂ (improving overall stability). As a demonstration, the adhesive formulation with added CA containing 2% Nano-Al₂O₃ and 2% Nano-SiO₂ achieved a remarkable tensile strength of 32.48 MPa at room temperature, underscoring its potential as an efficient solution for various practical adhesive applications. The adhesive prepared in this study harnesses the hydration properties of CA to absorb moisture and release substantial heat, introducing a novel method for ambient temperature curing. This development promises to broaden its applications in refractory materials, coatings, and equipment repair.