CHEMICAL BONDING IN HARD BORON HEXAGONAL BORON-NITRIDE MULTILAYERS

The oxides and nitrides of boron show great potential for use as hard, wear-resistant materials. However, large intrinsic stresses and poor adhesion often accompany the hard coatings as found for the cubic boro n nitride phase. These effects may be moderated through the use of a l ayered structure. Alternate stiff layers of boron (B) and compliant la yers of hexagonal baron nitride (hBN) are formed by modulating the spu tter gas composition during deposition from a pure B target. The B/hBN thin films are characterized with transmission electron microscopy to evaluate the microstructure, nanoindentation to measure hardness and X-ray absorption spectroscopy to determine chemical bonding. The effec ts of layer pair spacing on chemical bonding and hardness are evaluate d for the B/hBN films. (C) 1998 Published by Elsevier Science S.A.