Abstract
Thin hard coatings in the thickness range of only a few micrometers
deposited by physical vapour deposition (PVD) on components or tools can
improve the friction and wear properties by several orders of
magnitude. A 2 μm thick TiN (E=300 GPa) coating on a high-speed
steel substrate with a bond layer at the interface between the coating
and the substrate was modelled by micro-level three-dimensional
finite-element method (3D FEM) in order to optimise a coated surface
with regard to coating fracture. Both compliant low modulus (E=100 GPa) and stiff high modulus (E=500 GPa) bond layers at the coating/substrate interface of 200 and 500 nm thickness were investigated. First principal stresses were simulated for scratch test geometry in the load range of 7.5–15 N. Very high stress concentrations of above 5700 MPa
tensile stresses were observed in the bond layer just behind the
contact zone for the stiffer bond layer. The stiff bond layer generated 5
times higher tensile stress maxima compared to the compliant bond
layer. There was approximately 3.5 times larger strain in the compliant
bond layer compared to the stiff bond layer. The general coating design
advice based on this exercise is that when a bond layer is used e.g. for
coating/substrate adhesion improvement should the bond layer be less
stiff than the coating not to generate high and critical tensile
stresses. The thickness of the bond layer may vary and is not critical
with respect to generated stresses in the surface.
Original language | English |
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Pages (from-to) | 137-148 |
Number of pages | 12 |
Journal | Tribology International |
Volume | 42 |
Issue number | 1 |
DOIs | |
Publication status | Published - 2009 |
MoE publication type | A1 Journal article-refereed |
Event | 34th Leeds-Lyon Symposium on Tribology - Lyon, France Duration: 4 Sept 2007 → 7 Sept 2007 |
Keywords
- Hard coating
- Finite-element method model
- Coating adhesion
- ProperTune