Physical and tribological diagnostic of Ti-(Carbon Nitrides) and Ti-Nb-(Carbon Nitrides) coatings

Abstract

Electrochemical, mechanical and tribological properties of Ti-C-N and Ti-Nb-C-N coatings deposited onto Si (100) and AISI 4140 steel substrates were determined in this work. Introduction of Nb in the ternary Ti C-N film was evaluated via quantitative elemental concentration depth profile by glow discharge optical emission spectroscopy (GDOES) and the morphology via scanning electron microscopy (SEM) were observed for the layers before the tests. The morphological surface was analyzed via AFM. Mechanical and tribological properties for both coatings were obtained by mean of nanoindentation measurements throughload versus displacement method, and scratch test using the critical load criterion, respectively. The failure modes from scratch test were observed via optical microscopy. Nanoindentation results reaching the elastic-plastic behavior of the TiCN and Ti-Nb-C-N coatings with inclusion of Nb (TiNbCN), indicated not only the hardness and elastic modulus but also the critical load for the adhesive failure increase when increasing r.f negative bias voltage. An improvement of hardness and critical load around 60% and 28% for TiCN as well as 26% and 31% for TiNbCN, respectively, was associated to an increasing in the r.f negative bias voltage from 0 V to -100 V.