A CONCEPT FOR THE DESIGN OF NOVEL SUPERHARD COATINGS

Based on recent theoretical and experimental results regarding the app earance of supermodulus phenomena in composition-modulated layered het erostructures and on a simple thermodynamic criterion for segregation in ternary nitride systems, a concept for the design of novel nanocrys talline/amorphous composites is suggested. Experimental results on the nc-TiN/a-Si3N4 system are presented to support this concept. A Vicker s hardness of 5000 kg mm(-2) and an elastic modulus in excess of 500 G Pa combined with a stability against oxidation up to 800 degrees C are reported for such films. Further ternary systems in which similar enh ancement of mechanical strength, hardness and elastic modulus is expec ted, are suggested and briefly discussed with respect to their suitabi lity as protective tribological coatings.