Structural and mechanical properties of boron nitride thin films deposited on steel substrates by pulsed laser deposition

The article presents preliminary results of investigation on structure, morphology and mechanical properties of boron nitride thin films prepared by pulsed laser deposition on various steel substrates. In order to improve adhesion and reduce internal stresses, substrates were subjected to gas nitriding. To increase gas ionization in the chamber and provide the deposited particles with higher energy RF discharge generator was used. Structure and morphology of coatings were examined by atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR). Mechanical properties like nanohardness (sclerometric) and elastic modulus (using approach curves) were characterized by UNMT. Adhesion of coatings was measured by scratch tests; critical load was determined on the basis of microscopic observation and friction force and acoustic emission runs. On the basis of obtained results, possibility of using steel as substrate for BN thin films deposition was confirmed. Stable, crystalline, multiphase coatings with good adhesion to the steel substrate were obtained. It was also proved that mechanical properties of prepared coatings and their adhesion to the substrates strongly depend on the type of the substrate. In the next stage tribological properties of BN, coatings will be examined in particular in terms of wear resistance and friction coefficient between coatings and steel.