Stress and related mechanical properties of multilayer coatings deposited by vacuum arc method

Viorel Braic 1Victor Moagar-Poladian 3Alina Vladescu 1Mihai Balaceanu 1Corneliu Trisca-Rusu 2Mariana T. Braic 1Cosmin Cotrut 2

1. National Institute for Optoelectronics (INOE), 1 Atomistilor Str., Bucharest 77125, Romania
2. University Politehnica of Bucharest, Polizu 1-7, Bucharest, Romania
3. National Institute for Research and development in Microtechnologies (IMT-Buchares), P.O.Box 38-160, Bucharest 023573, Romania

Abstract

The multilayer coatings composed of different thin films with thicknesses in the nanometre range (1-20 nm), known as super lattices, have received considerable attention due to their increased hardness, wear and corrosion resistance. As it is known besides its composition and structure, the properties of a coating are also related to the induced stress during growth. The aim of this paper is to investigate - by computer simulation and experimental approach - the variation of the stress in different transitional metals nitrides MeN (Me=Ti,Zr,Nb) and in the related multilayered structures as Me1N/Me2N (e.g. TiN/NbN). We have performed finite element method simulation in order to observe the behaviour of the multilayered material under intrinsic stress and in order to achieve the response of the structure under different varying loads. The mesh was build with shell elements and we have used the initial stress commands to apply the right amount of stress into the layers. The simulations were performed for different thickness values of the individual layers in the superlattice structure. Films with a total thickness of 2 microns were deposited by the cathodic arc method on Si and HSS substrates; the stress was determined by XRD. The bilayer period was 500 nm for MeN/Me multilayered coatings and 50 nm, respectively 10 nm for Me1N/Me2N multilayer. Both theoretical and experimental results showed the decrease of the stress in the multilayered coatings. These results were also correlated with the observed increased microhardness, adhesion onto the substrate and the corrosion resistance of the deposited films.

 

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Presentation: Poster at E-MRS Fall Meeting 2006, Symposium A, by Mariana T. Braic
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-20 12:53
Revised:   2009-06-07 00:44