A polysilazane coating protecting polyimide from atomic oxygen and vacuum ultraviolet radiation erosion

A polysilazane coating was prepared on polyimide substrate by the polymeric precursor method to protect space materials from attack of atomic oxygen (AO) and vacuum ultraviolet radiation (VUV) in low earth orbit (LEO) environment. Erosion kinetics, surface morphologies, and surface composition investigation indicate that this polysilazane coating possesses excellent AO resistance, and displays low shrinkage tendency in AO exposure. The erosion yield of the prepared polysilazane coating is 3.5 × and 2.1 × 10− 26 cm3/atom during AO exposure and simultaneous AO and VUV exposure, respectively. The low AO erosion yield of the polysilazane coating results from the formation of a SiO2-rich layer on its top surface during exposure, and the VUV radiation is able to create free radical sites on the exposed surface, promoting the formation of a uniform SiO2-rich surface layer.