The preparation and performance analysis of high-entropy phosphate high-temperature resistant adhesives

Abstract

In response to the weak bonding effect caused by the difference in thermal expansion between aluminum phosphate adhesive and alumina, a series of high-entropy phosphate adhesives (8.9 ×10⁻¹ K⁻¹) with high thermal expansion matching to alumina (9 ×10⁻⁶ K⁻¹) were developed and analyzed. The adhesive could cure at room temperature and evolve into a stable high-entropy ceramic structure during heat treatment. Among them, (La_0.2Ce_0.2Sm_0.2Nd_0.2Eu_0.2)PO₄ adhesive showed the best bonding performance since the generation of high-entropy ceramic. Without adding other additives, it provided a bonding strength of 14.8 MPa for alumina, 74 times that of aluminum phosphate. The strength retention rate remained at 40 % after 20 thermal cycles from room temperature to 1500 °C. The adhesion mechanism relied on the combination of mechanical interlocking, chemical bond adhesion and electrostatic interactions, and reinforced by the four core effects of high-entropy structure. High-entropy adhesives showed great prospects in aerospace, electronics, medical, and other fields.