Preparation Of V-Al-Ta-N Quaternary Coating By Magnetron Sputtering And Its Properties

Transition metal nitride coatings have excellent mechanical properties and tribological performance, which have been widely used in industry.In this paper, we add the transition metal atom Ta into V-Al-N system, prepared (V,Al)1-xTaxN coatings with several Ta content by reactive magnetron sputtering. XANES、XRD、AFM、SEM and TEM were used to characterize the structure and surface morphology in order to investigate the effect of Ta content on coating structure. TRIM calculation was used to analysis the energy distribution of particles. Nanoindentation, Vickers indentation and scratch test were used to investigate mechanical properties and deformation behavior of the coatings with various Ta. Annealing test was carried out at 700 ℃ under vacuum conditions for a preliminary study of the thermal stability of the coatings. Tribological performance was test on UMT-3 multifunctional tribometer. Wear rates, friction, and the morphology of wear tracks were used to investigate the wear properties. The main results as follows:1) All the reflections could be assigned to the cubic B1-structured. Ta content has a significant impact on the grain orientation. Coating showed a (111) texture as Ta content was low. When Ta content was higher (x≥0.57), a sudden change in preferred orientation, from purely (111) to 100% (002) occurred. Also the Ta content has an effect on the growth structure. The columnar structure become denser as the Ta content increased. TRIM computation showed that the bombardment of energetic backscatterd Ar might increased the adatom mobility which would cause the increase of surface diffusion, and lead to the densification of the growth structure.2) The mechanical properties increased obviously with more Ta addition. The hardness of coating with 0.03 at.% Ta was only 13.8 GPa, while the x=0.57 coating was doubled reaching 29.8 GPa. The densification of the growth structure was probably one of the most important reasons for the large enhancement of hardness. In addition, the addition of some Ta was help to improve the toughness of the coating. The Vickers indentation and scratch test revealed that the (200) structured coatings (higher Ta content) have a better crack resistance. The coating with higher hardness and better toughness showed that the addition of some Ta was contributed to the increase of the mechanical properties of the coatings.3) Annealing test showed that the hardness of coatings which have a lower Ta addition (x≤0.18) were somewhat increased after annealing. Coatings with medium Ta content (x=0.3、x=0.57) have a relatively higher hardness and stayed stable after annealing. The higher Ta (x=0.68) may lead to a significant decrease of the hardness after annealing.4) Tribological test revealed that the increase of Ta can reduce the initial friction coefficient of the coatings, but the wear resistance would be decreased.