Corrosion Condition and Protection of High Reflective Ag Coating for Radiation Cooling Film

The highly reflective Ag film is easy to age in air. The corrosion behavior of the Ag film was studied by changing the three conditions of humidity, temperature and reaction gas concentration in the environment. The results showed that the yellow edge ratio of the Ag film sample was 7.2% after 12 d in the atmosphere of 60℃ and 90% RH. Humidity had the most significant effect on the corrosion of Ag film, by followed temperature. When the concentration of reaction gas was reduced to the solubility in water, the corrosion inhibition effect on the Ag film was obvious. The SiNx/Ag-Cu/SiNx film structure could reduce water vapor adsorption, delay the diffusion of reactive gases in the film and block water vapor, so as to protect the Ag film. No corrosion was observed on the surface of SiNx/Ag-Cu/SiNx reflective film after 12 d in 60℃, 90% RH atmosphere.