Deposition of CVD diamond onto boron carbide substrates

Boron carbide (B4C) is a hard, lightweight ceramic used in the nuclear and aerospace industries. Depositing a CVD diamond coating onto its surface may increase its wear resistance and hence its value as a structural material in advanced applications, such as gyroscope rotors. Hot filament CVD has been used to deposit 2-4-mu m layers of polycrystalline diamond onto polished B4C blocks. Wie found that adhesion of the diamond coating was poor, with spontaneous delamination occurring. SEM and scanning Auger microscopy determined that boron from the surface of the B4C was diffusing into the CVD diamond to a depth of about 0.1 mu m. This left a B-depleted, C-rich layer al the diamond/B4C interface which caused the delamination of the doped diamond film. (C) 1997 Elsevier Science S.A.