Study On Spray Technique And Performance Of Solar Energy Selective Absorption Coatings Of Carbide Cermet

The problem of energy is the bottleneck hampering the development of social economy, so the research of renewable energy is a significant subject in human's researches. Among those researches of renewable energy, the solar energy develops the most rapidly. The solar collector plays an important role in the filed of heat use. Although a lot of progresses have been made in the research of selective coatings, some deficiencies still exist in the coatings that we have prepared. Thus, the research of selective coatings needs further development. The research of this subject appears particularly important in now days that energy is badly needed.In this paper, two kinds of cermet selective absorption coatings WC-Co and Cr3C2-NiCr were prepared by HVOF. Some related analyses have been made to the powders and coatings with equipments of electron microscope, X-ray diffractometer and infrared spectrometer. Also, how the spray distance and thickness affects the coatings have been discussed. At last, Climate resistance performance and High temperature resistance performance of the coatings have been tested.The researches showed that, the coatings made by HVOF are dense, with a low porosity. When spraying WC-Co powders, WC decarburization exists, and there's a little W2C phase in the coatings. The two kinds of cermet solar energy selective absorption coatings WC-Co and Cr3C2-NiCr prepared by HVOF demonstrate good optical performance.Also, the researches showed that, the increase of spray distance intensifies WC decarburization when spraying WC-Co powders, but some WC decarburization didn't affect the coatings obviously because of the coatings'absorption performance largely depending on the metal in cermet. When discussing the effect of thickness of the coatings on the performance of the coatings, the increase of the coatings'sickness increased the coatings' absorptivity, but the emissivity did not change at the same time.What's more, the researches showed that, Coatings made by HVOF combine well with the substrate. After two mouths'test under atmospheric environment, the coatings didn't fall off or break, which means the coatings are fit for use in normal environment. WC-Co and Cr3C2-NiCr cermet coatings not only demonstrate good absorptivity, but also good stability under high temperature. After high temperature resistance experiment, the main phase of the coating didn't change and the coating's absorptivity and emissivity attenuates little. The coatings show good stability.