Tribological investigation of TiAlCrN and TiAlN/CrN coatings grown by combined steered-arc/unbalanced magnetron deposition

The dry sliding wear of monolayer TiAlCrN and multilayer TiAlN/CrN coatings has been investigated against a BM2 tool steel counterface. The coatings were deposited on a BM2 tool steel substrate by combined steered-arc/unbalanced-magnetron deposition. Increasing either contact load or sliding speed led to a reduction in friction coefficient, typically from 1.1 to 0.2. Increasing load resulted in an increase in wear rate for both TiAlCrN and TiAlN/CrN (e.g. from 7 × 10-6 mm3/m at 22 N to 4 × 10-5 mm3/m at 189 N for the TiAlCrN monolayer coating, and from 7 × 10-6 mm3/m at 22 N to 2.5 × 10-5 mm3/m at 189 N for TiAlN/CrN multilayer). The wear rate for all coatings was at least an order of magnitude lower than the uncoated BM2 steel. The wear rate of the TiAlCrN coating tended to decrease with an increase in sliding speed (from 7.4 × 10-5 mm3/m at 0.2 m/s to 1.3 × 10-5 mm3 m at 1.1m/s) while the wear rate of the TiAlN/CrN was approximately constant as a function of sliding speed (approx. 1.5 × 10-5 mm3m).