Abstract
Seven Cr-B-N films with various boron contents ranging from 3.7 to 20.6 at.% were deposited by a bipolar asymmetric pulsed DC reactive magnetron sputtering system. The structures of thin films were characterized by X-ray diffraction (XRD). The surface and cross-sectional morphologies of thin films were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The surface roughness of thin films was explored by atomic force microscopy (AFM). A nanoindenter was used to evaluate the hardness and properties of thin films, respectively. The phases of each Cr-B-N coating were mainly CrN and amorphous BN regardless the boron content. It was found that the grain size decreased with increasing boron content. The hardness and elastic modulus of Cr-B-N thin films decreased with increasing boron concentration, which were mainly attributed to the nanostructure configuration of small CrN nanograins and large intergranular amorphous BN phase.