Microstructure, mechanical properties and high-speed dry-cutting performance of AlCrSiCN composite coatings

AlCrSiCN specimens with different carbon contents were fabricated by cathodic vacuum arc technique, and the microstructures, mechanical property, tribological and high-speed dry-cutting performance were investigated. The results show that the structural transformation from dense and fine nanocomposite to coarse columnar structures was found for the AlCrSiCN coatings when increasing the C content. The excess carbon was presented in the form of nanocrystalline graphite and/or amorphous carbon. Addition of C also reduces the surface roughness and the micro-hardness. The adhesive strengths of AlCrSiCN coatings (such as C10 and C20 coatings) with a low C content were enhanced, whereas it decreased to a value of Lc2 of 17.7 N when the C content increased to 5.58 at. % for C30 coating. Tribological experiments showed that C atoms reduced the coefficient of friction due to the lubricating effect of nanocrystalline graphite and/or amorphous carbon. The high-speed dry-cutting results also showed that AlCrSiCN-coated tools performed better than those with an AlCrSiN coating, and the coatings (C10) with a lower C content possessed the greatest wear resistance.