A study of electron exposure effects on ZnO/K2SiO3 thermal control coatings

An experimental investigation was undertaken to study the electron exposure effects on ZnO/K2SiO3 thermal control coating. The samples were exposed to 10, 30, 50 and 70 keV electrons, respectively. The spectral reflectance of each sample was measured in situ before and after electron exposures. Optical microscope and infrared spectra were applied to investigate physical changes induced by electron exposures. After exposure to electrons, the samples suffer an optical degradation and the K2SiO3 surface layer is damaged. The increase in solar absorptance (Δαs) of the coating is electron energy dependent, with Δαs increasing as the electron energy increases. It is believed that the degradation mechanism may involve the irreversible loss of oxygen during electron exposures in vacuum.