Vacuum synthesis of an intermediate layer of ZnO nanorods on brass for the formation of strong adhesive coatings

Abstract

The paper presents the research results of a new method of increasing the adhesion of coatings, by forming an intermediate layer of ZnO nanorods, which provides strong adhesion of almost any material with the surface of brass. The synthesis of ZnO nanorods is carried out in a vacuum chamber equipped with multifunctional devices, including plasma-arc accelerators and a gas plasma source based on a helicon-type radio-frequency (RF) discharge. Before the synthesis of ZnO nanorods, the surface of the brass substrate is treated with ions in a dense argon plasma flow of a helicon-type RF discharge. The layer of ZnO in the form of nanorods is synthesised on the substrate surface, which is uniformly distributed and randomly oriented relative to the surface. The ZnO synthesis uses zinc atoms that diffuse from the bulk of the substrate to its surface when the substrate is heated to 450–550 °C. The Zn atoms react with oxygen introduced into the vacuum chamber. The zinc atoms belong simultaneously to the ZnO nanostructure and the brass lattice. This provides cohesion between the nanostructures and the substrate. When any coating (metal, dielectric, etc.) is deposited on an intermediate layer of ZnO nanorods, strong coating adhesion to the nanorods is ensured due to the nanorods' mechanical bonding and the coating material's matrix. The adhesion value for the aluminium nitride layer, which was deposited on the intermediate layer of ZnO nanorods, increased seven times compared to the deposition of AlN on pure brass.