Study On Preparation And Property Of Phosphate Binder

As a new material with some characteristics, such as high-temperature resistance, low pollution and environmental friendliness, phosphate binder has been emphasized by researchers all over the world. Phosphate binders not only can be used to bond metals, ceramics, but also can be used as a matrix of refractory, coating and composite. They play a very important role in advanced weapon development, promotion of the modernization of nationally defensive strategy weapon and industry and environment protection.In the paper, the solution prepared from H₃PO₄, H₃PO₄-Al₂O₃ and H₃PO₄-Al(OH)₃ was used as a matrix, Al₂O₃ as filler, ZnO, AlN and MgO as curing agents and Al(OH)₃ as a modifier to prepare a phosphate binder. Curing process and the effects of modifier and curing agent on the mechanical performance, high-temperature stability, crystal structure, microtopography of the binder were studied with Differential Scanning Calorimetry (DSC), Thermogravimetry Analysis (TGA), X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM) etc. The results showed that the addition of different curing agents and modifier into the binder could enhance the mechanical performance, accelerate the crosslinking of the binder to a defferent degree..The addition of Al(OH)₃ improved the shear strength and high temperature resistance of the binder, but do not lowered the curing temperature. The addition of AlN promoted the curing of the binder and enhanced the bonding strength. But because of the decomposition of AlN at high temperaturw, the temperature resistance property of the binder decreased quickly, so the binder had low shear strength, which was 0.3 MPa at 1000℃. Although MgO and ZnO promoted the reaction of the matrix with Al₂O₃, the binder became loose and had low strength because of the high activity of MgO, which reflected on the conglomeration of the binder. The addition of ZnO promoted the reaction of the matrix with Al₂O₃ enhanced the shear strength and the high temperature resistance of binder. Added with modifier and different curing agents and subjected to heat treatment, the binder produced aluminum phosphate with high-temperature resistance and became compact.