Nanotribology and surface chemistry of reactively sputtered Ti-B-N hard coatings

The nanotribological performance of Ti-B-N protective coatings, 500 nm thic k, have been studied in the range of 0-38.5 at.% N. A correlation was estab lished amongst the chemical state, structure, mechanical properties, and na nowear resistance as a function of atomic percent nitrogen. The mechanical properties, elastic modulus and hardness, of the films were tested using a Hysitron Triboscope nanomechanical test instrument. The nanotribological pe rformance of the films was evaluated using a Nanoindenter II with scratch c apability. Single and reciprocating nanowear scratches, 10 mum in length, w ere performed at normal loads ranging from 50 to 750 muN. An atomic force m icroscope (AFM) was utilized to characterize the nanowear tracks with respe ct to depth and amount of plowing of material. The AFM images revealed that the reciprocating nanowear test caused grooving of the films with little t o no material removal. Chemical and structural information was obtained by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction. Increasing N content correlated with increasing number of B-N bends, structural disorder , and decreasing hardness, modulus, and wear resistance. (C) 2000 Elsevier Science B.V. All rights reserved.