METHOD FOR MAKING COATINGS OF BORON CARBIDES AND COATINGS OBTAINED THEREBY

摘要

The method according to the invention comprises the deposition of one of the crystalline phase or a mixture of the following crystalline phase: phase of quadratic structure B50C2, phase of rhombohedral structure B13C2, so that the atomic ratio C/B of the deposition is comprised between 0.04 and 0.22. Said atomic ratio is adjusted within this range to a value which is an increasing function of the hardness of the desired coating, which hardness is comprised within a range extending between 3200 and 5100 kg/mm<2> (micro-hardness HK0.1). According to a preferred embodiment, the coating is made by chemical deposition in vapour phase, consisting in the reduction of a gas mixture containing at least a boron compound, particularly boron trichloride, and a least a carbon compound, particularly methane, in the presence of hydrogen.