Optimization of plasma-assisted chemical vapour deposition hard coatings for their application in aluminium die-casting

Within this work, different types of commercial hard coatings produced by p lasma-assisted chemical vapour deposition (PACVD) were tested in aluminium die-casting applications: TiN, Ti(C,N), Ti(B,N) and (Ti,Al)(C,N). All coati ngs tested on die-casting cores showed a significant increase in lifetime. To optimize the coating performance and to understand their different behav iour in die-casting, the soldering tendency was characterized employing an immersion test in liquid aluminium, the oxidation resistance was evaluated using thermo-gravimetric analysis, and the influence of thermal cycling on film stresses was investigated employing a cantilever method. In addition, coating topography was studied using atomic force microscopy. The results i ndicate that optimization of the performance of hard coatings in aluminium pressure die-casting is mainly achieved by reducing their soldering tendenc y and adjusting a suitable level of low compressive stress. (C) 2001 Elsevi er Science B.V. All rights reserved.