Evaluation of the fracture resistance of DLC coatings on tool steel under dynamic loading

Nano-impact testing rapidly shows differences in coating performance that can be used to optimize coating design for improved durability. The technique can be used to find the optimum coating process parameters for enhanced fracture resistance under dynamic loading, and can differentiate between cohesive and adhesive failure modes. This paper presents results on a range of hydrogenated and hydrogen-free DLC coatings on steel substrates. A compositionally graded amorphous carbon coating with high sp2 fraction exhibited improved impact resistance compared to all the a-C:H coatings studied.