부산대학교 도서관

In extreme environments such as aerospace, plasma, and nuclear reactor, a conventional super-alloy and ceramic have reached to their mechanical limits. Accordingly, studies on materials which can innovatively improve the performance in extreme environments have been widely done, which resulted in attracting many attentions related to silicon carbide techniques including the chemical vapor deposition (CVD) process. Silicon carbide which is well-known structural ceramics of high hardness and strength shows an excellent oxidation resistance at high temperature especially when the silicon carbide is coated on SiC ceramics using CVD process.Due to formation of silicon carbide directly from the gas containing Si and C precursor without adding a sintering aid required for the general carbide manufacturing process, the silicon carbide products manufactured by CVD can give the advantage of high purity to suppress the contamination from other impurities. And CVD SiC can be easily deposited on carbon products because the thermal expansion coefficient of SiC shows a good matching with isotropic carbons, which resulted in the suppression of the particle's generation from carbon products. The CVD process of silicon carbide proceeds via complex processes that include the decomposition of precursors, the gas flow in the reactor, the diffusion and the surface reaction on the substrates. Accordingly, the combination of gas flow on macro scale and the reactions on atomic scale should be combined to give a good understanding of the CVD process. It can be attained with the simulation of computational fluid dynamics (CFD) which includes thermodynamic calculation, thermo-fluidal analysis, and chemical reaction kinetics. The temperature distribution in the reactor can be deduced from the CFD results and the growth rate can be also simulated with the deposition variables such as the gas flow rate and the position, the gas composition, the pressure and the temperature in a reactor. This study is done with a CVD reactor using a MTS-H2 system and the temperature profile and the deposition rate were compared with experimental results. The main purpose of this study is the improvement of the uniformity in the deposition zone which would be directly related with an yield of the SiC products. The effects of deposition parameters and chamber shapes on the uniformity would be discussed, too.