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Optical properties and corrosion behaviour of sputtered Zr-B and Zr-B-N coatings

Findings on the structure, optical properties and corrosion behavior of Zr-B and Zr-B-N coatings obtained by non-reactive and reactive d.c. magnetron sputter deposition are reported. The addition of nitrogen reduced the grain size-coatings deposited at N flow rate f(N sub 2 ) of < approx14 sccm (...

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Bibliographic Details
Published in:Surface & coatings technology 1992-10, Vol.60 (1-3), p.571-576
Main Authors: Ubleis, A, Mitterer, C
Format: Article
Language:English
Online Access:Get full text
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Summary:Findings on the structure, optical properties and corrosion behavior of Zr-B and Zr-B-N coatings obtained by non-reactive and reactive d.c. magnetron sputter deposition are reported. The addition of nitrogen reduced the grain size-coatings deposited at N flow rate f(N sub 2 ) of < approx14 sccm (standard cm exp 3 min exp -1 ) were extremely fine grained, while N flow rates of > 14 sccm led to fracture-amorphous coatings with a very smooth surface. The hardness and abrasion resistance decreased with the increase in N content. Pure Zr-B coatings are silver-grayish with metallic brilliance but N changes the color from dark grey or black at low contents to interference colors in the amorphous state. Ellipsometric measurements of the refractive index n and absorption coefficient k supported the results derived from electron microscopy, color measurements and mechanical testing. The transition point between the fine-grained and fracture-amorphous structure lies in the range of f(N sub 2 ) approx10 sccm. The black coatings deposited with such N content improved the corrosion resistance. In potentiodynamic experiments, more positive free corrosion and pitting potentials were demonstrated. However, in salt spray testing and immersion testing using an artificial sweat solution, no beneficial effect of high N additions was noticed. Zr-B-N coatings deposited with N flow values in the range 10-20 sccm offer an excellent choice for decorative purposes, owing to their dark grey or intense black color and good corrosion resistance. Coatings were deposited onto molybdenum sheets and samples of austenitic stainless steel grade 304 (X5CrNi18 10).
ISSN:0257-8972