Substrate modification for high performance CrAl/CrAlBN multilayers coated TiCN-based cermet through plasma nitriding

Abstract

The plasma nitriding process was conducted on a TiCN-based cermet that had been coated with a multilayer CrAl/CrAlBN coating deposited via cathodic arc. The intensity of the plasma nitriding was modified by adjusting the anode current of the ionization source. To investigate the interface conditions, techniques such as electron probe X-ray microanalysis, electron backscatter diffraction, and transmission electron microscopy were employed. The results indicated that increasing the anode current led to the formation of a thicker nitrided layer and an increase in the texture coefficient of the (111) plane. Specifically, at an anode current of 200 A, the lattice mismatch degree at the TiCN/CrAlN interface decreased from 16.4 % to 3.7 %, resulting in the formation of a nearly coherent interface. The hardness, adhesion strength, and H/E ratio of the coating reached their peak values, and the coated cutting tool exhibited optimal cutting performance when machining the GH4149 superalloy.