Nanomechanical and electrochemical properties of ZrN coated NiTi shape memory alloy

Zirconium nitride (ZrN) thin films were deposited on NiTi and Si substrates in the 23-570 degrees C temperature range by direct current reactive magnetron sputtering using N-2/Ar gas mixture. The film hardness, corrosion behavior, phase composition, and texture were determined. The deposited films were composed mainly by the cubic ZrN phase, whose texture varies with substrate temperature, changing progressively from (111) to (200) texture as the temperature increases. The hardness of the films is influenced by the texture and has a linear relationship with the ratio of the texture coefficients P(111)/P(200). The higher hardness is obtained for ZrN thin films with (200) texture. Electrochemical tests show that NiTi coated with (200)oriented ZrN films has higher tendency to passivation and greater stability of the passive film as compared to (111)-oriented ZrN films, despite no abrupt changes was observed when the texture changes from (111) to (200). (c) 2012 Elsevier B.V. All rights reserved.