Growth and characterisation of boron–carbon–nitrogen coatings obtained by ion beam assisted evaporation

Ion beam assisted deposition (IBAD)techniques have been employed to produce thin films composed of boron, carbon, and nitrogen atoms, including amorphous carbon (a-C), carbon nitride (CNx) and ternary compounds (BCxNy). The films were deposited by evaporating either graphite or boron carbide (B4C) targets, with simultaneous ion bombardment from a precursor N2 +CH4+Ar gas mixture. The composition and bonding structure of the films have been carefully studied, including the analysis with time of flight elastic recoil detection analysis (TOF-ERDA) and X-ray absorption near-edge spectroscopy (XANES). Mechanical characterisation of the films has been also performed, including measurements of hardness, elastic modulus, and friction coefficients. The optimal values encountered are hardness of B35 GPa, and friction coeffivients of B0.05. Also, the thermal stability of the films has been examined by annealing under vacuum conditions. The applicability of the coatings is discussed in terms of all these parameters.