Abstract
In methods for multi-arc ion plating technology, the behavior and characteristics of the arc spot determine the physical characteristics of arc plasma and the properties of the subsequent deposited coatings. In this paper, the effect of arc currents on the hardness, friction coefficient, high temperature oxidation, and corrosion properties of the CrSiN coatings was studied. According to the XRD and SEM results, with the increase of arc currents, the coatings grew preferentially to the CrN (111) crystal direction, and the CrN (220) crystal phase appeared at high currents of 90 A. In addition, the number of large particles increased when the current exceeded 70 A. The HR-TEM results confirmed the formation of nanocomposite structure of nanocrystalline of CrN embedded into the amorphous phase of Si3N4 as explored by XRD. The maximum hardness was achieved at 3120 Hv when the coatings were deposited under currents around 70 A. However, the hardness values decreased with further increase of arc currents. From the contact of ceramic balls with the wear of coatings, the surface of coatings gradually produced friction marks, and the friction force increased from a steady friction force to a dynamic friction force. The high temperature oxidation results showed that fewer oxides were formed on the surface of the coatings when oxidized at 800 °C. It was also found that CrSiN nanocomposite coatings prepared at an arc current of 70 A had a larger corrosion potential and polarization impedance, which could effectively protect the tool matrix.
Highlights
CrN coatings can effectively improve work-piece processing performance and tool life due to their excellent properties such as their high hardness, wear resistance, and corrosion resistance
The substrate bias and deposition temperature were fixed, and the current applied to CrSi target (φ = 100 mm × 10 mm, 99.9 at.%, Cr:Si = 88:12) was taken as the only variable to study the influence of currents on coating deposition
For the deposition of CrSiN layer: When N2 was introduced, the working pressure was adjusted to 1.0 Pa, the substrate bias was further reduced to −60 V, the duty cycle was adjusted to 80%, and the deposition time was 40 min
Summary
CrN coatings can effectively improve work-piece processing performance and tool life due to their excellent properties such as their high hardness, wear resistance, and corrosion resistance. Compared with the previous technologies, multi-arc ion plating is widely used for its high deposition efficiency in the preparation of tool coatings [14]. The disadvantage of this method is the generation of large particles which have adverse effects on the friction and corrosion resistance properties. Some studies believe that the arc spot on the cathode has a very high temperature, which causes the target to boil [15] At this time, part of the target metal escapes in the form of vapor, and part of the target metal escapes in the form of droplets which will form large particles. The hardness, friction coefficient, high temperature resistance, and corrosion resistance of the CrSiN coatings were investigated
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