Research on Compound-Modified Self-hardening Phosphate Binder

Based on the use of the determined curing agent (a mixture of electromolten magnesium sand powder and microsilicon powder), an optimized modified phosphate adhesive component and process are proposed. Orthogonal test determined that the modified phosphate binder composition ratio is phosphoric acid:aluminum hydroxide:water:boric acid:citric acid:1% malic acid aqueous solution:triethanolamine = 300:60:80:4:1:5:5. In a laboratory environment of 40% RH × 25 °C, when the amount of binder added is 3.0% (accounting for sand) and the amount of curing agent added is 0.9% (accounting for sand), the 4 h tensile strength of the sample is 0.75 MPa, 24 h the tensile strength reaches 1.21 MPa. The gas volume of the sand sample (600 °C × 3 min) is 6.40 mL g −1 , and the high temperature residual strength of the sand sample (600 °C × 5 min) is 0.01 MPa. The modified phosphate binder has higher tensile strength, lower gas evolution and good collapsibility. The binder can meet general casting production requirements.