Study On The Preparation And Properties Of Photothermal Conversion Coatings With Vanadium Tailings Fabricated Via Plasma Spraying

With the continuous growth of the human population and the rapid development of global economies,traditional fossil energies are increasingly exhausted.Environmental damage and climate change caused by fossil energy are challenging to human survival and economic development.Hence,active development of renewable energy and changing energy consumption patterns are inevitable.The photothermal conversion technology is widely used on the solar collector,and the photothermal conversion coating is the key part of the collector.At present,the materials and various of preparation methods of photothermal conversion coatings have some limitations on performance,cost,efficiency and environmental protection.So,it is very important to choose a material with low cost,good optical performance,mature coating technology,easy mass produce and environment friendly.In this study,vanadium tailings were taken as the main material,and spray drying mathod was employed to obtain agglomerated powder with good fluiditys.The vanadium tailings coatings were prepared on stainless steel using plasma spraying.The phase composition and microstructure of coatings were tested.The optical properties,high-temperature stability,thermal shock resistance,salt spray corrosion resistance,and the effects of the components on the optical properties were studied.The results were as follow:A large number of spinel structure phases were obtained by the reaction of various metal oxides in vanadium tailings powder during spraying,which had higher absorptivity.The surface morphology and roughness of the coating have a significant effect on the absorption and emissivity.The infrared emissivity of the coating was reduced from 66.86%to 49.63%by reducing the surface roughness of the coating.As a result,the selective absorption performance was significantly improved.After heat treatment at 500℃for 48h and 60 times of thermal shock tests,the coating still had a complete structure,stable phase,and only a small loss in optical performance,which indicated that the coating had a good high temperature stability.After 144 h of salt spray test,corrosion occurred at the interface between the coating and the substrate,and tiny holes in the edge of the coating caused the substrate to be oxidized.In this experiment,iron oxide and manganese oxide,which were the main components of vanadium tail slag powders,were also used to fabricate coating to analysis the influence of component to property,and Fe₂O₃,Mn O₂,Fe₂O₃+Mn O₂and 2Fe₂O₃+Mn O₂coatings were prepared by plasma spraying.Mn₃O₄and Mn Fe₂O₄spinel phases fabricated in the Fe₂O₃+Mn O₂and 2Fe₂O₃+Mn O₂coating,which resulted that their optical performance were significantly better than that of Fe₂O₃and Mn O₂single oxide coatings.The2Fe₂O₃+Mn O₂coating with the highest content of spinel phases had the best spectral selective absorption performance.The results show that the good optical properties of vanadium tailings coating are determined by more iron oxide,manganese oxide and spinel structure.