To improve the mechanical properties of self-lubricating chromium vanadium nitride(CrVN)coatings,vanadium nitride(VN)is combined with CrVN to form multilayered CrVN/VN coatings through an in-line magnetron sputtering system.The strengthening effect of the period thickness on the mechanical and tribological properties is studied.X-ray diffractometer,low-angle X-ray reflectivity,scanning electron microscopy,atomic force microscopy,electron probe micro-analyzer and X-ray photoelectron spectroscopy are employed to characterize the microstructures and chemical composition.Nanoindentation and ball-on-disc tribo-tester are used in characterization of the mechanical and tribological properties.The CrVN/VN multilayer coatings demonstrate good lubrication property with coefficient of friction down to 0.23.Multilayering with VN,the hardness of CrVN jumps to 27.6GPa with period thickness of 6nm,which has an improvement of 5.1GPa compared with that of 22.5GPa from rule-of-mixture.
CrAlVN coatings are of good intrinsic mechanical and tribological properties but lack of strength.Silicon can provide nitride coating high strength and excellent oxidation resistance.Logically,the combination of CrAlVN and Si should provide a good candidate for dry machining.The effect of silicon content on CrAlSiVN coating′s mechanical,tribological properties and oxidation resistance was investigated.The coatings were deposited on cemented tungsten carbide and Si wafer(100)substrates in an in-line magnetron sputtering system.Grazing incidence X-ray diffractometer,scanning electron microscopy,atomic force microscopy,transmission electron microscopy,electron probe micro-analyzer,X-ray photoelectron spectroscopy and Auger electron spectroscopy were employed to characterize the microstructure and chemistry.Nanoindentation and ball-on-disc tribo-tester were used in characterization of the mechanical and tribological properties.Incorporating with silicon,the CrAlVN coating was strengthened(hardness:21.2GPa up to 38.7GPa);even after 2hexposure to 700℃ in air,the hardness still maintains at 11.0GPa.
Qiang LIYue-xiu QIUBo LIDong-liang ZHAODe-en SUNDe-hui LI
