Performance of AlTiBN and AlTiTaN coatings during milling of titanium

AlTiN, AlTiBN, and AlTiTaN coatings were deposited on cemented carbide substrate by cathodic arc evaporation. Scanning electron microscopy, X-ray diffraction, nanohardness testing, and scratch testing were used to examine the coating thickness, microstructure, hardness, adhesion strength, and oxidation resistance. The incorporation of B and Ta into the AlTiN coatings increased their hardness and oxidation resistance. In titanium-milling experiments using these three coatings, AlTiBN-coated carbide tools had the longest lifetime at cutting speed of 60 m/min. This is attributed to less delamination and chipping at the cutting edge, due to the coating's high hardness, good oxidation resistance, and sufficient adhesion strength. The major wear mechanisms of these coated tools are adhesive wear, oxidation, and chipping.