NANOCRYSTALLINE HARD COATINGS WITHIN THE QUASI-BINARY SYSTEM TIN-TIB2

Ti-B-N films with a gradient in the chemical composition were deposite d onto austenitic stainless steel sheets by means of unbalanced DC mag netron co-sputtering using a segmented TiN/Tib(2) target. Film microst ructure was characterized by means of electron-probe microanalysis (EP MA), transmission electron microscopy (TEM), electron energy-loss spec troscopy (EELS), and X-ray diffraction (XRD) as well as glancing angle X-ray diffraction (GAXRD). The mechanical properties oft he coatings were measured using a depth-sensing nanoindenter. The composition of t he films was found to lie close to the quasi-binary section TiN-TiB2 w ithin the ternary system Ti-B-N. The grain size determined from TEM in vestigations range between 3 and 5 nm. Coatings consisted of a nanocry stalline fee TiN phase (with boron atoms and oxygen impurities dissolv ed), and TiB2, TiB and B2O3. Microstructure as well as chemical compos ition of the films were not influenced significantly by the deposition parameters used in this investigation. Contrary, the mechanical prope rties were strongly influenced varying the ion bombardment. Hardness v alues exceeding 50 GPa and elastic moduli close to 500 GPa were obtain ed. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.