Preparation of an aluminium phosphate binder and its influence on the bonding strength of coating

Abstract

In this paper, aluminium phosphate binders were synthesized using Al(OH) 3 and H 3 PO 4 as the raw materials. These binders, with the curing agent MgO and filler ZrO 2 , were used to prepare coatings by brush painting on the carbon fibre-reinforced epoxy resin matrix composites. The influences of synthesis conditions such as the P/Al ratio, concentration of the reactant and reaction temperature on the viscosity of binders and the bonding strength of corresponding coatings were investigated by using a viscometer and a universal testing machine. The structures and compositions of aluminium phosphate binders were characterized by X-ray diffraction, Fourier transform infrared and Raman spectroscopy. The results show that with a decrease in the ratio of P/Al, the degree of polymerization of the aluminium phosphate binder increases, the viscosity increases, while the bonding strength of the coating decreases. When P/Al = 3:1, the reaction product is Al(H 2 PO 4) 3 with the best properties of bonding strength. As the concentration of phosphoric acid solution increases in the range of 60-80%, the viscosity increases on account of larger quantity of viscous molecules in a unit volume and higher extent of polymerization of the phosphorus oxygen tetrahedron. The compositions of aluminium phosphate binders are almost the same when the reaction temperature changes from 120 to 180 • C, so the viscosity of the binder and the bonding strength of the coating do not exhibit obvious changes along with temperature.

Preparation of acid aluminum phosphate solutions for metakaolin phosphate geopolymer binder

“…The role of the Al/P molar ratio on the type of monoaluminum phosphate obtained was reported in the literature. 19,20 Thus MAP will be used along this paper to dene the acid aluminum phosphate solution prepared. The phosphoric acid was rst diluted with distilled water to obtain the desired concentration, then the corresponding amount of aluminum hydroxide was added.…”

“…16,17 However, the reactivity of the MAP depends upon its form and dosage, knowing that aluminum phosphate exists in different forms according to the molar ratio Al/P. [18][19][20] Thus, this work aims at understanding the role of the types of monoaluminum phosphate compounds and their content for getting the optimum characteristics of the metakaolin phosphate geopolymer binder obtained at room temperature. To address this, two acid aluminum phosphate solutions were prepared by targeting specic molar concentrations Al/P that give different types and percentages of monoaluminum phosphate compounds.…”

Phase development of phosphate‐bonded Al2O3‐MgAl2O4 high‐temperature ceramics: XRD and solid‐state NMR investigations

“…[8][9] Most frequently, the aluminium phosphate Al(H 2 PO 4 ) 3 is applied, because it is well soluble in water and achieves a high initial strength. [10][11][12] However, the course of the reaction within the ceramic body is also difficult to control in this case, which justifies the necessity of developing alternative phosphate binders for ceramic materials. The phosphate compounds of the refractory oxides (e.g.…”

“…8,9 Most frequently, the aluminum phosphate Al(H 2 PO 4 ) 3 is applied, because it is well soluble in water and achieves a high initial strength. [10][11][12] However, the course of the reaction within the ceramic body is also difficult to control in this case, which justifies the necessity of developing alternative phosphate binders for ceramic materials. The phosphate compounds of the refractory oxides (e.g., CaO, MgO, ZrO 2 , Al 2 O 3 ) seem to be suitable for this purpose, especially in the field of high-temperature applications, since they promise excellent high-temperature properties and corrosion resistance.…”

“…Preceramic polycarbosilane polymers are commonly used as precursors to make ceramic fibers 10,39 and ceramic matrix. [7][8][9]40,41 The chemical and volume changes that accompany ceramization of the polymer during pyrolysis have been documented in several studies.…”