Boron nitride hard coatings by ion beam and vapor deposition

Abstract

Boron nitride (BN) thin films were synthesized by ion beam and vapor deposition (IVD) process. Boron was deposited on substrates and nitrogen ions were simultaneously irradiated to the depositing film. The energies of nitrogen ions were 2.0 keV. The multilayercd films were deposited to improve the film adhesion: B-rich BN films were formed on substrates and stoichiometric films were deposited on the B-rich BN films. In order to evaluate the behaviour of the multilayered BN films at high temperatures, the heat treatments (from 500 to 800°C) were performed in a nitrogen and air atmosphere. Crystalline structures of the films were determined by IR analyses. The results indicated that the main phases of the multilayered BN films were cubic, and the crystalline structures were unchanged up to 800°C in a nitrogen atmosphere. In the case of the heat treatment in air, the crystalline structure of the film was changed at 750°C. Compression moulding tests by forming bolosilicate glass lenses were performed at 630°C using the multilayered BN coated moulding die. The BN films prepared by IVD process had a mirror finish, and the surface roughness of the moulding die was not changed after the glass moulding tests. XPS analyses showed that the multilayered BN film on the moulding die had excellent corrosion resistance for applications of the glass-forming.