Reduced delamination and improved cutting performance of TiAlSiN multilayer coated cutter by tailoring the adhesion layers and intermediate layers

Abstract

Adhesion layers and intermediate layers exert important effects on the adhesion and cutting performance of PVD multilayer coatings. In this work, TiAlSiN multilayer coatings with different combinations of adhesion layers and intermediate layers were deposited, and their microstructure, adhesion and milling performance were assessed. Rockwell indentation and scratch results showed that delamination from the interfaces between the adhesion layers and intermediate layers occurred both for the T1 coating (TiN adhesion layer + Al17.5Ti80Si2.5N intermediate layer) and T2 coating (Al33Ti67N adhesion layer + Al43Ti54Si3N intermediate layer). Synchrotron radiation glancing incidence X-ray diffraction (SR-GIXRD) investigation on T2 coating revealed the discontinuities in lattice constant a and micro-strain at the interfaces between intermediate layer and adhesion layer, which resulted in poor cohesion of them. The T3 coating (Al67Ti33N adhesion layer + Al64Ti34Si2N intermediate layer) exhibited the lower residual stress (−3.7 GPa), and better cohesion and adhesion (Lc2 = 72 N). The T3 coating also had the longer milling life corresponding to a cut length 1700 m, due to its better cohesion and adhesion increased the “steady wear” stage. This improved cohesion and cutting performance of the multilayer coatings could be achieved by using proper combinations of adhesion layers and intermediate layers.