Coating of Cr-V Ledeburitic Steel with CrN Containing 7% of Ag

Samples made from Vanadis 6 PM ledeburitic tool steel were surface machined, ground and mirror polished. Prior the deposition, they were heat treated to a hardness of 60 HRC. CrAg7N-coatings were deposited by magnetron sputtering technique, using pure Cr and Ag targets, in a composite low pressure nitrogen/argon atmosphere and at a temperature of 500 °C. The coatings have an average thickness of 4.3 μm. They grew in a very well visible columnar manner, but, individual silver agglomerates were visible along the columnar crystals, also. The average size of silver agglomerates lies well below 50 nm, e.g. one can suggest that they are capable to be solved and release the Ag atoms to be migrated to the free surface during thermal exposition. The coatings had a good adhesion on the surface - the first critical loads, established by scratch-testing method, ranged between 30 and 39 N.