Study on the interface of CVD diamond film on molybdenum sheet
By means of metallographic microscope, SEM, EDAX of molybdenum piece of CVD diamond film on the interfacial morphology and composition were studied, compared with magnetic field and without magnetic field by the deposition of diamond film cross-sectional shape characteristic, the results show that the added magnetic field or not between the CVD diamond film and the molybdenum substrate Mo2C of several um thick layer, it is fine the way of the columnar crystal growth, the layer below the molybdenum matrix was happened recrystallization refinement; The diamond film deposited by magnetic field is more compact, has smaller (microscopic) void number, smaller diamond particle size, and more Mo2C aggregates adhered to the back of the diamond film. The results of indentation test show that the diamond films deposited with magnetic field have better adhesion properties. Since diamond films (80μm/h) have been successfully deposited by DC plasma jet CVD method for the first time, the method has been further improved, and the deposition rate of diamond films can reach 930μm/h. At present, it is considered to be the method with the highest deposition speed and good quality among all the methods of low-pressure vapor deposition of diamond film, and it is most likely to be used in mechanical parts (diamond thin-film coated tools, diamond thick film brazing tools, etc.) and heat sinking parts of electronic instruments to realize the earliest industrial application. However, its inherent deficiency Point: Due to large temperature gradient field and particle velocity gradient field, the deposition area is small, the spatial distribution of sediments is not uniform, and the purity and crystallization quality deteriorate along the radial direction, which will undoubtedly affect the high quality. Preparation of large area uniform diamond film. Therefore, people try to apply external magnetic field to improve the motion track and energy exchange process and behavior of charged (energy) particles such as electrons, ions, atoms and various active groups in the plasma arc, in order to obtain diamond films with high quality, high deposition rate, large area, low roughness and uniform film thickness. The bonding state of the diamond film/base interface directly affects the film/base adhesion properties, which also affects the preparation of diamond film coating products and thick diamond film products.
