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Nanocrystalline Cr/CrN and Ti/TiN multilayer coatings produced
by pulsed laser deposition at room temperature |
J.M.
LACKNER, W. WALDHAUSER, L. MAJOR, J. MORGIEL, M. KOT, and B. MAJOR |
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Mechanical components and tools in modern industry are facing increasing performance requirements leading to the growing need for
advanced materials and thus, for modern frictional systems. In the last decades, the Pulsed Laser Deposition (PLD) has emerged as an unique
tool to grow high quality mono- as well as multilayers surfaces in metallic/ceramic systems. Building up a knowledge base of tribological
properties of industrially-scaled, room temperature deposited PLD hard coatings are the most important step for the application of these coatings
in engineering design. Although single-layer coatings find a range of applications, there are an increasing number of applications where the
properties of a single material are not sufficient. One way to surmount this problem is to use a multilayer coating. Application of metallic
interlayers improves adhesion of nitride hard layer in multilayer systems, which has been used in PVD processes for many years, however, the
PLD technique gives new possibilities to produce system comprising many bilayers at room temperature. Tribological coatings consisted of 2,
4 and 16 bilayers of Cr/CrN and Ti/TiN type were fabricated with the Pulsed Laser Deposition (PLD) technique in the presented work. It is
found in transmission electron examinations on thin foils prepared from cross-section that both nitride-based multilayer structures studied are
characterized by small columnar crystallite sizes and high defect density, what might rise their hardness but compromise coating adhesion. The
intermediate metallic layers contained larger sized and less defective columnar structure compared to the nitride layers, which should improve
the coatings toughness. Switching from single layer to multi-layer metal/nitride composition improved resistance to delamination. |
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Keywords: |
coatings, multilayers, laser ablation, deposition, microstructure TEM, tribology |