Plasma nitrided and TiCN coated AISI H13 steel by pulsed dc PECVD and its application for hot-working dies

Pulsed direct current (dc) plasma-enhanced chemical-vapor deposition (PECVD) holds great advantages such as plasma permeation and deposition in the inner wall of holes and narrow cracks usually encountered in complex components. In this work, plasma nitriding and TiCN coatings on H13 steel have been developed using pulsed dc PECVD. The composite layer has been characterized with respect to its microhardness, adhesion, and microstructure. The results indicate that with the assistance of plasma nitriding, the composite layer improves the surface microhardness and interfacial adhesion between the coating and substrate. The application of this duplex-plasma processing on a hot-working die made of AISI H13 steel provides a significant increase in lifetime for the steel. This is a more-successful processing technique than conventional techniques, which usually do not improve the surface properties of dies, with complex shapes and demanding performance requirement conditions. However, extra hardening of this composite layer is not always advantageous. Microhardness (related to layer's strength) and adhesion, as well as the toughness of the coating system, should all be considered together.