Study On IR Heat Reflecting Coatings

ER heat reflecting coating (HIC) is a kind of functional coating that can reflect most of the solar energy in the near-infrared region of the solar spectrum, moreover the coating itself has a high emittance in middle-far IR band, thereupon it can prevent the surface temperature of coatings as well as the enclosed interior surroundings from being heated up without the consumption of energy. HIC exhibits great potential in the application as coatings for ships, vehicles, exterior wall of buildings and oil containers to prevent excessive internal temperature rise by keeping the surface cool.According to the principles of heat reflecting coating, studies were concentrated on the basic influencing factors of HIC. Firstly the effects of refractive indices, content, particles size distribution and type of reflective materials on the heat-shielding properties were measured and discussed. Then the near IR reflective spectrum and IR absorptive spectrum curves of different kinds of materials were summarized and analyzed, and a HIC specimen was prepared. Attempts, including calcinations process and surface coating treatment, to improve the reflective ability of filler were also made. Finally the durability and energy saving effect of HIC were measured by means of a simulated model under direct sunshine.Diffuse reflectance spectrophotometry with an integrating sphere was used to determine the reflective index of HIC in regions of visible and near infrared light (0.4-2.5 u m). Emittance of HIC in the region of 5-40 u m is measured by Fourier-Transform Infra-Red (FTIR) Spectral Emissometer. The developed white HIC reflects 91.46% of near infrared radiation, and the half-sphere emittance of the white HIC is as high as 85%. The surface temperature was lowered by 10-15 癈, and the temperature of enclosed internal surrounding was reduced by 3-5 癈, in comparison with those structure not coated with HIC under sunshine.Based on the preliminary study and test results, the following concluding remarks can be drawn: HIC provides an effective way for controlling surface and internal surrounding excessive temperature rise of structures and containers; Wide uses of HIC in urban areas maybe a resolution to urban heat island problem, in addition to improving work environments and save energy.