Study of Mechanical, Tribological and Thermal Stability Properties of TiAlN Coatings with Low Aluminum Content

Abstract

Ti-Al-N coatings have been widely studied especially those with high aluminum content for different industrial applications because they have high wear resistance and good thermal stability. For the present work TiAlN thin films were prepared by the simultaneous laser ablation of Ti and Al targets in a reactive atmosphere containing nitrogen. The structural characterization of the deposits was carried out using X-ray diffraction and it was found that the films were highly oriented in the (111) direction of TiN. The maximum coating hardness was 43 GPa for an aluminum concentration close to 11 at.%, whilst the coatings commonly used in industry with an aluminum content of about 25 at.% or greater, have hardness values between 25 and 30 GPa. The thermal stability of the films was studied by micro-Raman spectroscopy in the temperature range from 500 to 900 º C. This technique was used to detect the formation of the TiO 2 phase. The results indicated that the inclusion of relatively low aluminum contents up to 15 at.% led to an improved thermal stability up to 900 º C.