Abstract
Hard coatings have been adopted in cutting and forming applications for nearly two decades. The major purpose of using hard coatings is to reduce the friction coefficient between contact surfaces, to increase strength, toughness and anti-wear performance of working tools and molds, and then to obtain a smooth work surface and an increase in service life of tools and molds. In this report, we deposited a composite CrTiSiN hard coating, and a traditional single-layered TiAlN coating as a reference. Then, the coatings were comparatively studied by a series of tests. A field emission SEM was used to characterize the microstructure. Hardness was measured using a nano-indentation tester. Adhesion of coatings was evaluated using a Rockwell C hardness indentation tester. A pin-on-disk wear tester with WC balls as sliding counterparts was used to determine the wear properties. A self-designed compression and friction tester, by combining a Universal Testing Machine and a wear tester, was used to evaluate the contact behavior of composite CrTiSiN coated dies in compressing of Mg alloy sheets under high pressure. The results indicated that the hardness of composite CrTiSiN coating was lower than that of the TiAlN coating. However, the CrTiSiN coating showed better anti-wear performance. The CrTiSiN coated dies achieved smooth surfaces on the Mg alloy sheet in the compressing test and lower friction coefficient in the friction test, as compared with the TiAlN coating.
Highlights
Mg alloys feature low density, high strength/weight ratio, good machinability, anti-shock performance and corrosion resistance and easy recycling
Industrial applications of hard coatings in a form of either single layer or multilayer synthesized by physical vapor deposition (PVD) have been increasing rapidly because they can be prepared relatively and provide improvements in tribological or corrosive properties [1,2], or high temperature oxidation resistance [3]
Particles were seen, which are common characteristics of coatings grown by cathodic arc deposition coating was relatively smooth than that of TiAlN coating
Summary
Mg alloys feature low density (pure Mg ~1.738 g/cm3 ), high strength/weight ratio, good machinability, anti-shock performance and corrosion resistance and easy recycling. Industrial applications of hard coatings in a form of either single layer or multilayer synthesized by physical vapor deposition (PVD) have been increasing rapidly because they can be prepared relatively and provide improvements in tribological or corrosive properties [1,2], or high temperature oxidation resistance [3]. Chromium nitride (CrN) coatings have been applied in molding and machining industries to prolong tool service life because they show excellent adhesion [7], corrosion resistance, and anti-wear and machining performance [8,9]. The addition of Si to the CrN coating to form amorphous Si3 N4 phase has been adopted to improve the mechanical properties and oxidation resistance [12,13,14,15]. The surface conditions of Mg sheets after compression and friction behavior during compressing were studied
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