| Chemical vapor deposited (CVD) diamond film has the outstanding optical property. At present, diamond used for antireflection coating or protective coating in infrared windows becomes the hotspot. To develop the basic research for application of diamond coating for infrared windows and impel its industrialization process, study is carried out in this dissertation. The CVD deposition system, microwave-transparent mechanism, preparation technology, mechanical property and binding ability of the diamond coating are investigated in detail. To study how the factors influence the performance of diamond, modern analytical methods are carried out to analyze and evaluate the surface topography, microstructure and infrared transmittance. All the results of this research lay the foundation for the diamond coating's industrial production application in infrared windows.The main work and results obtained in this dissertation are as follows:1. Base on heat transfer theory and Energy conservation law, heat exchange process of electron assisted chemical vapor deposition(EACVD)system was analyzed, then the dynamic model of EACVD system was set up when the substrate sways without quick-return characteristics. To satisfy the requirement of temperature for diamond deposition, filament parameters and substrate swing parameters were optimized. Base on the geometric characteristics and process parameters, three-dimension finite element model of the flow field of EACVD was set up, and then the influence of substrate temperature, hunting period, filament parameters and inlet parameter in the uniformity of substrate surface was studied.2. Based on the finite element analysis of temperature and flow field, some parts of the EACVD system including the mechanical system and control system were redesigned and improved to meet the need for diamond deposition used in infrared windows. Then performance of the EACVD was studied by multi-point temperature measuring test and diamond deposition experiment. Results showed optimized system provides uniform temperature and flow field which was good for diamond deposition.3. Study of the microwave-transparent mechanism of infrared optical system was carried out, the transmittance model made of infrared windows and diamond film was set up to analyzed the optical antireflection mechanism and the relationship between reflectivity and refractive index of infrared windows and thickness of diamond film. Major factors influencing the transmittance were found out to provide the theoretical direction for preparation of high quality diamond coating. 4. Experimental study on the preparation of Nano-crystalline diamond (NCD) film and Micro-crystalline diamond (MCD) film was carried out on mono-crystalline silicon, and the key technologies in the process were investigated. The microstructure and infrared transmittance were characterized by Raman, SEM, XRD, Fourier transform infrared spectrometer (FTIR) and Three-dimensional topography instrμment. By studying the influence rules of process parameters on infrared transmittance, optimized parameters were obtained. The results showed that the highest infrared transmittivity of the MCD and NCD was below 50% at the range of 1000 cm-1 and 4000 cm-1.The diamond coating can not meet the demands of infrared window application.5. Base on the preparation of NCD and MCD, study of the composite diamond films was carried out by In situ deposition method and Alternating deposition method. The results showed that the diamond film obtained using alternating deposition method had high infrared transmittance. At the range of 1000cm-1 and 4000cm-1, the maximum transmission rate and antireflective rate arrived at 62% and 80% respectively. Binding ability of the diamond coating were analyzed to study how the process parameters influence the performance, and the results showed that the diamond film obtained using alternating deposition method had good binding ability. .
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