The Preparation Of Aluminum Phosphate Adhesive And The Study Of Its Mechanical Properties

Aluminum phosphate adhesive has the advantages of low curing temperature, excellent dielectric properties, non-toxicity, high binding strength and high temperature structural stability, and it has broad application in architecture and aerospace. In this article, analysis of viscosity, TG-DTA, FT-IR, XRD, SEM and bending strength were done, self-curing reaction of the aluminum phosphate matrix, curing reaction of the adhesive. Impacts on mechanical properties and curing temperature of different mass ratio of aluminum phosphate matrix and different curing agents were studied.Tests of bending strength and viscosity and mechanical properties revealed the best performance of strength properties of Al(H₂PO₄)₃ matrix with different molar ratios of P and Al. Al(H₂PO₄)₃ matrix reacted with itself at the temperature of initial curing temperature, which resulted in AlH2P3O10 and its form containing crystalized water. A molecular of H2O was abstracted between every two moleculars of P-O-H, in which a bond of P-O-P was formed in the shape of line. A hexagonal structure of Al(PO₃)₃ with P-O-P bond in its circle shape formed under complete curing temperature, which provides adhension. Hexagonal structure of Al(PO₃)₃ transformed into its cubic state at about 550℃.Al(H₂PO₄)₃-Sintering Al(OH)₃ adhesive with the aluminum phosphate matrix and curing agent mass ratio of 5:1 transformed into Al(HP₂O₇)·2.5H₂O, under the complete curing temperature. Trigonal AlPO₄ transformed into the rhombic system at a certain temperature. Adhension was provided by inorganic macromolecular linked by Al-O-P-O-Al.Al(H₂PO₄)₃-Al(OH)₃, Al(H₂PO₄)₃-sintering Al(OH)₃ and Al(H₂PO₄)₃-Al2O3 adhesives with the matrix and curing agent mass ratios of 6:1, 7:1, 5:1 respectively transformed into AlPO₄ and Al(PO₃)₃. Al(H₂PO₄)₃-Fe₂O₃ adhesive with the matrix and curing agent mass ratios of 7:1 transformed into Fe(PO₃)₃, AlPO₄ and Al(PO₃)₃. Al(H₂PO₄)₃-CuO adhesive with the matrix and curing agent mass ratios of 6:1 transformed into Cu₂P₂O₇, AlPO₄ and Al(PO₃)₃.Al2O3, Al(OH)₃, Fe₂O₃ and CuO can all reduce the initial curing and complete curing temperature of adhesives, and they can all be used for adhesives to reduce the initial curing and complete curing temperature with the increase of the amount of curing agent. Fe₂O₃, as the curing agent, has the outstanding performance, which can reduce the curing temperature to 100℃. Although Al(OH)₃ can reduce the initial curing temperature, it can not be used as the curing agent for the reason that the complete curing temperature increases.