| TiB₂ coatings on graphite substrates were performed by chemical vapor deposition(CVD) process. The CVD process was carried out under low and atmospheric pressure using TiCl_4,-BCl₃-H₂ system. The deposition rate, microstructural morphologies, and microhardness of TiB₂ coated layer were investigated in terms of deposition parameters such as reaction temperature, mole fractions of Ti/(B+Ti) and H/Cl, total pressure, and the distance between induced cube and substrate. The optimum conditions far TiB₂ coatings were achieved with 1㎝ of the distance between tube and substrate, 1/6 of Ti/(B +Ti) mole fraction, 6 of H/Cl, mole fraction and 1100℃ of reaction temperature. The coated layer exhibited preferred orientation, and the preferred orientation in TiB₂ coatings was expanded by increasing H/Cl male fraction, and by decreasing Ti/(B+Ti) mole fraction. The microhardness value of coated layers was 3150 KHN under atmospheric pressure at the reaction temperature of 1200℃. |
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