SIMULATION-BASED OPTIMAL DESIGN OF HFCVD EQUIPMENT ADOPTED FOR MASS PRODUCTION OF DIAMOND FILMS ON INNER-HOLE SURFACES

HFCVD diamond films have been extensively applied on inner-hole surfaces of some wear resistant components as protective coatings, the mass production of which puts forward a high request to the HFCVD equipment. In this paper, adopting a typical kind of drawing die as the substrate, several different substrate configurations are proposed to expand the capacity of the equipment. Temperature distributions on inner-hole surfaces of the substrates are respectively predicted and compared by the finite volume method (FVM) simulations. In summary, for parallel configurations, proper-designed auxiliary devices (e.g. the heat-insulated plate, the water-cooled plate and the heat-insulated cushion block) can provide sufficient effects on the uniformity of the substrate temperature distribution. Moreover, without any auxiliary devices, homogeneous substrate temperature distributions can also be obtained using circular pattern configurations (radial, hexagon and triangular). Accordingly, the HFCVD equipment referring to the design concept of the triangular configuration is trial-manufactured. In the verification experiments, similar substrate temperature values are detected in three different modules, and as-deposited microcrystalline diamond (MCD) and nanocrystalline diamond (NCD) films both present uniform grain size, thickness and quality, well validating the rationality and correctness of the simulation-based optimal design.