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Microstructure and micro mechanical properties of multilayer Cr/CrN, PLD coatings
|Lukasz Major 1, Jerzy Morgiel 1, Zhiqing Yang 2, Jűrgen M. Lackner 3, Bogusław Major 1|
1. Polish Academy of Sciences, Institute of Metallurgy and Materials Sciences (IMIM PAN), Reymonta 25, Kraków 30-059, Poland
The CrN shows superior high temperature corrosion resistance over TiN. The paper describes investigation of possibilities of improving mechanical properties of wear resistant CrN coatings through their regular slicing with increasing number of Cr layers. It was realized by deposition of the Cr/CrN coatings built of 2, 4, 8, 16, 32 and 64 Cr/CrN bi-layers using reactive Pulsed Laser Deposition (PLD) technique. The application of transmission electron microscopy helped to determine coatings bi-layer super-lattice thickness at 1000 ,500 ,250 ,125 and 62 falling with increasing number of deposited bi-layers. The columnar microstructure for multi-layered Cr/CrN coatings was determined. The inter-crystallite defect density in multilayered coatings was otherwise comparable with that in CrN monolayer coating. The X-ray diffractometry measurements confirmed that the multilayer coatings are retaining main texture parameters of CrN once. The micro-mechanical properties were assessed by micro-hardness measurements and scratch test using Rockwell penetrator of 200mm diameter loaded from 0.03N up to 20N and finally by measuring their wear resistance through ball on disc test. The performed measurements indicated that switching from single layer to multi-layered metal/nitride coatings resulted in small hardness drop from 17 to 10 GPa. Simultaneously the it was noted that the scratch resistance rose from 4.4N for CrN mono-layer to a maximum of 7.7N for Cr/CrN- 8 layered one. The wear test showed advantage of multilayer coatings over mono-layer CrN as the 35% lowest wear was observed for Cr/CrN-8 layers. The present investigation confirmed that a significant improvement of mechanical properties of CrN type coatings by their sandwiching with Cr layers might be achieved.
Presentation: Poster at E-MRS Fall Meeting 2006, Symposium A, by Jerzy Morgiel
See On-line Journal of E-MRS Fall Meeting 2006
Submitted: 2006-05-17 06:05 Revised: 2009-06-07 00:44