Deposition and characterization of TiAlN and multi-layered TiN/TiAlN coatings using unbalanced magnetron sputtering

TiAlN coatings have been known to be superior to other coatings such as TiN and TiCN in protecting tools which may be damaged by high thermal load (high cutting speed). Unfortunately, these coatings normally suffer greater damage than TiN and TiCN in more mechanically influenced processes such as interrupted cutting or slow speed cutting. The present study aims at developing multi-layered TiN/TiAlN coatings which may offer a good compromise between the properties of TiN and TiAlN. Three approaches including shutter control, power supply control, and rotational stage control were used to deposit multi-layered TiN/TiAlN coatings using unbalanced magnetrons. These coatings were then characterized using SEM, GDOS, nano-indention system, and tribometer. It was found that, in general, these multi-layered TiN/TiAlN coatings had lower wear rate than single-layered TiAlN within the tested sliding speeds. At certain sliding speeds, these coatings also had lower wear rate than TiN. In some tests, a thin layer (0.1 mu m) of TiCN was coated on multi-layered coatings in an attempt to reduce frictional damage particularly during run-in stage. The result shows that the wear resistance of the TiCN-(TiN/TiAlN)coating was significantly improved especially at low sliding speed. (C) 1998 Elsevier Science S.A. All rights reserved.