Abstract
Chromium nitride coatings were deposited by reactive magnetron sputtering onto substrates made from Cr-ledeburitic steel 1.2379. Microstructures, phase constitution, mechanical and tribological properties of CrN-coatings were investigated. It has been found that the deposition at given combination of parameters gave dense, fine-grained coatings, having columnar structure and very smooth surface. The coatings were formed from Cr₂N when low N2:Ar ratio had been used while they contained CrN at higher nitrogen input into the processing chamber. The Young’s modulus of the coatings was influenced only slightly by the deposition conditions. On the other hand, the hardness of the CrN was higher than that of the Cr₂N. The adhesion of the CrN is better than that of Cr₂N. The principal explanation is that the Cr₂N is brittle in nature and exhibits a strong tendency to cracking and spallation when normally loaded. Generally, the friction coefficient measured against 100Cr6 ball bearing steel was lower than that determined against sintered alumina. Considerable material transfer (adhesion) has been recorded for 100Cr6-steel while no transfer but abrasion has been detected for alumina counterpart. For the alumina counterpart, better tribological behavior has been recorded for the CrN than that for Cr₂N, which is consistent with its good adhesion.

Key words
ledeburitic steel substrate, magnetron sputtering, CrN-coating, microstructure, mechanical properties, tribology

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