Silicon Strengthened CrAlVN Coatings

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; 21.2 GPa up to 38.7 GPa); even after 2 h exposure to 700 degrees C in air, the hardness still maintains at 11.0 GPa.