Specifications of radio-reflective coating on a sample of polymer composite materials, fabricated with transfer molding

The technique for preparing samples of composite materials for the subsequent application of radio-reflective coatings is described. The samples were fabricated by transfer molding using a specially developed industrial equipment. Samples were made with two types of binding: cold and hot curing. Radio-reflective coating was formed as a multilayer compositions based on alumina with an adhesive underlayer of nickel-chromium and the protective layer of silicon oxide. The coating was applied by magnetron sputtering in a vacuum. On the obtained coatings coefficients of radio reflection were measured. It was revealed that at 24 GHz radio reflection coefficients of both types of samples meet the requirements and is about 0,98. However, when the frequency of the radiation coefficients are about 0,95, which is insufficient for use in spacecraft antenna reflectors. To identify the causes of degradation of coatings were measured options gassing initial samples of carbon plastics and surface roughness of the samples with radio-reflective coating. Parameters of gassing compliant coatings that apply to this class are given. The roughness of the radio-reflective coating on carbon plastics is Ra = 363,8 nm with allowable roughness to 33 GHz - 600 microns is shown. Also thermoradiation characteristics resulting coating were measured. Measurements have shown the absorption coefficient of solar radiation of As somewhat high compared with the requirements of this class of coatings and emissivity En comply with these requirements. The work revealed that in order to set parameters coating is necessary to conduct operations on the preliminary preparation of carbon fiber: cleaning the surface of traces of release agent, increasing the duration of degassing prior to the deposition of carbon fiber, reducing the intensity during the deposition process.