Preparation And Performance Study Of Phosphate Glass Based On Aluminum Substrate Coating Application

Phosphate glass has a low transition temperature and a wide and adjustable range of thermal expansion coefficients,which is promising for application in the field of aluminum substrate coating.The traditional phosphate glass has the defect of poor chemical stability,which limits its application.Therefore,the development of new phosphate glasses with low transition temperature and good chemical stability is of great practical significance.In this paper,two series of P₂O₅-Sn F₂-SnO-WO₃-B₂O₃ base glasses were prepared by the conventional melt-cooling method,and the relationship between glass composition,structure and properties was investigated by means of infrared spectroscopy,Raman spectroscopy,X-ray diffraction,differential thermal analysis and X-ray photoelectron spectroscopy,and the effects of different sintering and heat treatment regimes on the coating using this base glass were discussed.The effects of different sintering and heat treatment regimes on the surface quality and properties of the coatings using this base glass were discussed.The following results were obtained.1.In the xP₂O₅-（70-x）Sn F₂-15SnO-10WO₃-5B₂O₃（x=40,35,30,25,20）series of glasses,as the P₂O₅/Sn F₂ decreases,the glass structure tends to loosen,the degree of cross-linking decreases,the thermal expansion coefficient of the glass increases,while the glass transition temperature and softening temperature become lower.As tin destroys the unstable P=O,the P-O-Sn structure is formed,increasing the degree of cross-linking of the glass network,which in turn decreases the coefficient of thermal expansion and slightly increases the transition and softening temperatures.W⁶⁺ions form P-O-W chains by linking non-bridging oxygen present as[WO₆].The glass exhibits good water resistance due to the increased number of shorter chain structures with better chemical stability and more stable P-O-Sn and P-O-W bonds than P-O-P bonds.At a P₂O₅ content of 20 mol%,the glass is the most chemically stable,with a weight loss of 0.28×10^-5g·cm^-2·min^-1after 24 h of corrosion in water.2.Based on the study of xP₂O₅-（70-x）Sn F₂-15SnO-10WO₃-5B₂O₃（x=40,35,30,25,20）series of glasses,the effects of WO₃ and B₂O₃ contents on 20P₂O₅-50Sn F₂-（30-x-y）SnO-x WO₃-y B₂O₃（x=0,y=0,5,10,15;x=10,5,y=5,10）glass organization and properties of the influence law.The results show that the network structure constituent units of all glasses are dominated by short-chain structures,and only a few long-chain structures are present.In glasses containing WO₃,W⁶⁺ions are located in the voids of the glass structure in the form of glass exosomes[WO₆]in the glass.The presence of B₂O₃ as a glass forming body with[BO₄]tetrahedra strengthens the network structure and improves the performance of the glass.However,with the increase of B₂O₃,some of the B³⁺ions exist as[BO₃],which decreases the cross-linkage of the glass structure and makes the performance of the glass anomalous.In the glass with the coexistence of WO₃ and B₂O₃,all properties performed well,especially the glass chemical stability was significantly improved and the glass weight loss rate was the lowest at 9.52×10^-7g·cm^-2·min^-1.3.Based on the analysis of the glass properties,20P₂O₅-50Sn F₂-15SnO-5WO₃-10B₂O₃ was used as the base glass composition to prepare the coating on the aluminum substrate,and the optimum sintering temperature of 400°C and the coating thickness of 110μm to meet the insulation requirements were determined.At the same time,the analysis of crystallization kinetics shows that the crystallization activation energy of the glass is E=54.71KJ/mol,and the crystallization mechanism is surface precipitation.The thermal conductivity of the coating can be increased to0.97-1.16 W·m^-1·K^-1 by heat treatment of the glass coating.