The Process And Optical Analyses Of Solar Receiver Selective Coating W-AlN

Solar selective coating is an important technology of solar collector. Tungsten metal is choice as the metal ceramic components and aluminum nitride formed by the reaction of aluminum and nitrogen as dielectric material in metal-ceramic. Because tungsten metal shows good oxidation resistance and good heat resistance, tungsten is used in the metal-ceramic selective absorbing coating as reflective layer; and because it does not react with argon gas and nitrogen in any temperature, tungsten is also used as the metal components of absorption Layer, which contributes to the formation of high absorption, low emissivity of the metal-ceramics. The W-AIN film is widely used in medium temperature solar selective absorbing coating.This thesis reports such films deposited on stainless steel and on glass by the magnetron sputtering as pure Al, W-AIN film, the pure W film, A1N film and the W/high W-A1N/low W-WA1N/A1N film technology.The membrane surface Morphology, structure and composition of pure Al, W-AIN, the pure W, A1N and the W/W-WA1N/A1N films are analyses by X-ray diffraction (XRD), scanning electron microscopy (SEM) and other methods. The sputtering rate of W, the reflectivity, absorption rate and transmission rate of pure A1, pure W, A1N, W-AIN, and W/high W-AIN/low W-WA1N/A1N films obtained under different processes are measured.In this paper, the optical parameters (n and k) for the different metal composition mixture films are calculated by media theory with the W and A1N refractive index and extinction coefficient. By imputing optical parameters (n and k) for each layers to the optical simulation software TFC, and modifying the thickness parameters, the multilayer design is optimized. The results show that the solar selective absorbing coating has an important significance.