Nano-composites with Al 2O 3 (alumina) nano-particles in a nickel metal matrix have recently been shown to give a considerable improvement in materials properties. So far, nano-particle coatings have not found many applications within surface modification by ion beams. The present paper reports on a duplex surface treatment, where a coating of nano-diamonds is electrodeposited on a substrate prior to conventional physical vapor deposition (PVD). Boron nitride is a PVD film material existing in a number of crystalline structures, where, for instance, the cubic form (c-BN) is ultra-hard but exhibits a mediocre adhesion to the substrate, while the h-BN material is a layer-structured material with limited cohesion. Ion bombardment during deposition is known to be essential for increasing the c-BN content and the film micro-hardness, and boron nitride on tungsten carbide appears to be a potential tribological system. The present communication reports on nitrogen sputtering from an elemental boron target. Adding heavier gases such as argon and krypton to the sputter gas does not change the sputter rate, but the mechanical properties are changed considerably. Reactively sputtered BN thin film performance has previously been tested by the acoustic emission scratch technique developed for adhesion measurements. It was possible from correlations between critical loads derived from various methods to assess the coating performance with an indentation and to select appropriate deposition conditions for an increased fatigue performance of a coating system. The objective of the present study was to deposit a model material of BN, and, as previously reported, a nanocrystalline BN film can be deposited on metals by nitrogen sputtering from an elemental boron metal target. The effect of a buffer layer of electrosprayed nano-diamonds on the mechanical properties of a BN coating has been studied. An attempt was also made to spray nano-particles onto the substrate and, after ion bombardment, to deposit BN by reactive sputtering.