Development And Application Of New Weatherability Flat-plate Solar Selective Absorber Coating

People began to use solar energy to replace part of fossil fuels for the sustainabledevelopment of the human living environment. In China, the solar water heater is the fastestgrowing field in solar energy utilization. Flat plate solar collectors have an growing trend inrecent years.The solar selective absorbing coatings have a great influence on flat plate solarcollectors’ efficiency solar-thermal conversion. The solar selective absorbing coating used inthe flat plate solar collectors absorbs solar energy and converts it into thermal energy. A goodsolar selective absorbing coating should have high absorptance （α） and low thermal emittance（ε）. How to effectively increase the absorption rate reduce emissivity coating becomes thekey to optimize the coating problem.Based on the above background, the TiAlN-TiAlSiN-Si₃N₄tandem absorbing coatingswere deposited on SS （stainless steel） substrate using reactive DC magnetron sputteringsystem in this paper. TiAlN acts as the main absorber layer, TiAlSiN acts as the semi-absorberlayer and Si₃N₄acts as the antireflection coating in this tandem absorbing coatings.By studying the influence of the current of coating deposition, sputtering time, thereaction gas flow, deposition temperature on coating performance, I have got the optimumpreparation parameters of the TiAlN-TiAlSiN-Si₃N₄flat plate solar selective absorptioncoating after trial and error. The optimal coating parameters: base pressure was5.0×10-4Pa,sputtering pressure was5.0×10-1Pa, the gas flow of Ar was40sccm, sputtering bias was-100V,sputtering current was0.3A, and the coating was sputtered at room temperature, thesputtering time of high absorption layer, low absorption layer, antireflection layer were10min,10min,20min respectively, the gas flow of N2were respectively3sccm,20sccm,20sccm. Inthis condition, the performance of solar-thermal conversion coating was better.The optimized absorbing coatings exhibited an absorptance of0.945and an emittance of0.094. XRD showed that the coatings were amorphous. The absorptance of the coatings decreased from0.937to0.910and the emittance increased from0.106to0.150after heattreated600℃for2h in air. There was no significant change in the scanning electronmicroscope pictures and Roman data, and this confirmed the microstructure stability of thecoatings in air.