Ultrahard coatings from Ti-BN multilayers and by co-sputtering
Two new techniques for the preparation of very hard Ti-B-N coatings are presented. The first method is accomplished in two steps: (i) the deposition of a multilayer coating of the sequence Ti-BN by reactive or nonreactive sputtering from a titanium and a hexagonal BN target respectively; (ii) a subsequent thermal treatment of the multilayer to induce a diffusion-activated mixing process between the titanium and BN layers with consequent phase transformations. The coatings were characterised with respect to stoichiometry by X-ray photoelectron spectroscopy, with respect to structure by glancing angle X-ray diffractometry and with respect to hardness and residual stress by micro-indentation and the substrate-bending method respectively. Hardness values up to 6000 HV were observed at a concentration ratio [Ti]:[B]:[N]=1:0.5:0.4. The coating with this compositional ratio is assumed to comprise a mixture of two solid solutions of the type Ti(B(x),N(y)) and TiN(1-x)(B(y)). This new technique has the advantage that almost stress-free coatings with good adhesion to metallic and non-metallic substrates are obtained. The second method is a co-sputtering process from a titanium and BN target. With this method coatings of considerable compressive stress are obtained.
Bibliographic Reference: Article: Surface and Coatings Technology, Vol. 48 (1991) pp. 169-174
Record Number: 199210144 / Last updated on: 1994-12-02
Original language: en
Available languages: en