Grain size evaluation of pulsed TiAlN nanocomposite coatings for cutting tools

Nowadays advanced TiAlN coatings enable high performance and high speed cutting. A side from excellent coating adhesion at the cutting edges and choice of material, a fine grained physical vapour deposition coating is the enabler for these high performance cutting operations. Isotropy and composition is of vital importance for the coating performance. On industrial scale equipment, composition (Ti–Al ratio), crystallite size and orientation are altered by changing pulse energy, duty cycle and cathode power. The synthesized coatings are then analyzed by common thin film and application oriented techniques, regarding the grain size and its influence on the coating properties. For the determination of the crystallite size, two methods, Debye Scherrer and Warren Averbach are compared. Finally, crystallite size is determined by using the Warren Averbach method and transmission electron microscopy for comparison reasons.