Effects of multilayer structure on the high-speed dry-cutting performance of AlCrBN/AlCrN multilayer coatings

To investigate the effects of different structures on the cutting performance of AlCrBN/AlCrN multilayer coatings, AlCrBN/AlCrN coatings with different multilayer structures (single layer, 10 bilayers, and 20 bilayers corresponding to T1 coating, T10 coating, and T20 coating) were synthesized using multi-arc ion plating technology. Grazing incidence X-ray diffraction (GIXRD) and transmission electron microscopy (TEM) results showed that the coatings were mainly composed of fcc-(Cr, Al) N phases located on the (111) and (200) crystal planes. All coatings exhibited a good indentation adhesion to the substrates. The hardness of the T10 coating (32.6 GPa) and T20 coating (31.2 GPa) was significantly higher than that of the T1 coating (28.0 GPa). Annealing experiments show that no phase composition evolution was revealed at 800 °C. High-speed milling tests imply that the milling life of the T10 coating (13 m) and the T20 coating (10 m) was increased by 62.5% and 25.0% compared to the T1 coating (8 m), respectively. In high-speed dry turning tests, the T10 coated tool also showed the longest lifetime (16 mins), an improvement of 23.1% over T1 or T20 coated tools (13 mins). SEM analyses of wear coated tools indicated that a multilayer structure enhanced their resistance to abrasion and adhesion wear, and led to better cutting performance, probably because of their excellent mechanical properties and thermal stability.