BORON-NITRIDE HARD COATINGS BY ION-BEAM AND VAPOR-DEPOSITION

Boron nitride (BN) thin films were synthesized by ion beam and vapor d eposition (IVD) process. Boron was deposited on substrates and nitroge n ions were simultaneously irradiated to the depositing film. The ener gies of nitrogen ions were 2.0 keV. The multilayered films were deposi ted to improve the film adhesion: B-rich BN films were formed on subst rates and stoichiometric films were deposited on the B-rich BN films. In order to evaluate the behaviour of the multilayered BN films at hig h temperatures, the heat treatments (from 500 to 800 degrees C) were p erformed in a nitrogen and air atmosphere. Crystalline structures of t he films were determined by IR analyses. The results indicated that th e main phases of the multilayered BN films were cubic, and the crystal line structures were unchanged up to 800 degrees C in a nitrogen atmos phere. In the case of the heat treatment in air, the crystalline struc ture of the film was changed at 750 degrees C. Compression moulding te sts by forming bolosilicate glass lenses were performed at 630 degrees C using the multilayered BN coated moulding die. The BN films prepare d by IVD process had a mirror finish, and the surface roughness of the moulding die was not changed after the glass moulding tests. XPS anal yses showed that the multilayered BN flim on the moulding die had exce llent corrosion resistance for applications of the glass-forming.