Wear and thermal behaviour of CVD alpha-Al2O3 and MTCVD Ti(C,N) coatings during machining

The wear properties of CVD alpha-Al2O3 layers with (10 (1) over bar2), (10 (1) over bar4) and (0001) growth textures were compared with MTCVD Ti(C,N) layers in single point turning of AISI 4140 steel. The experimental coatings were investigated with respect to thermal behaviour, deformation and wear. Substantial texture effects on wear performance of the alpha-Al2O3 layers were observed. A clearly enhanced ability of (0001) textured layer to undergo uniform plastic deformation was confirmed. The Ti(C,N) layer exhibited a more uniform plastic deformation than the alpha-Al2O3 layers. The observations were interpreted in the light of thermal, mechanical and frictional conditions occurring at the tool-chip contact interface. (C) 2009 CIRP.