Paper SE-ThP8
A Comparative Study on the Mechanical Properties and Thermal Stability of Cr-Zr-N and CrSi-Zr-N Coatings Synthesized by Closed Field Unbalanced Magnetron Sputtering

Thursday, October 23, 2008, 6:00 pm, Room Hall D

Recently, the synthesis of Cr-Zr-N coatings by adding an heterogeneous atom, Zr into CrN film was successfully made using a closed field unbalanced magnetron sputtering and these Cr-Zr-N coatings are reported to have not only much improved mechanical properties, but also a very low surface roughness with increasing Zr content. Especially, the average friction coefficient against Al₂O₃ counterpart ball of the Cr_1-xZr_xN (X=0.34) coating was measured to be approximately 0.17 at room temperature and this value is approximately 3.5 times lower than that of CrN film (approximately 0.6). However, investigations on the high temperature characteristics of the Cr-Zr-N coatings revealed their mechanical properties are severely deteriorated at 500 ℃ due to the surface oxidation and the decrease of hardness by means of the residual stress relaxation. In this work, to improve the high temperature mechanical properties of the Cr-Zr-N films, the CrSi-Zr-N coatings were synthesized from CrSi(Si=10 and 20 at.%) and Zr targets by a closed field unbalanced magnetron sputtering and their chemical composition, crystal structure, morphology and mechanical properties were characterized by glow discharge optical emission spectroscopy (GDOES), X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and nanoindenter. Also, the thermal stability of the CrSi-Zr-N coatings was evaluated by annealing the thin films at temperatures between 300 and 900 ℃ for 30min in air. The experimental results showed the CrSi-Zr-N coatings exhibit higher thermal stability and mechanical properties compared to those of Cr-Zr-N coating with increasing Si content. Detailed experimental results included wear test at 500 ℃ will be presented.