Stolboviy V. Structure and physical-mechanical properties of vacuum-arc nanostructured TiN and Mo-N coatings

Object: superhard nanostructured vacuum-arc coatings Mo-N and Ti-N. The purpose: the determination of physical-technological laws of vacuum-arc hardening of the quenched surfaces with low tempering temperature by use of pulse ionic treatment for increase of products' durability and for optimization of conditions of the directed change of structure and physical-mechanical properties of coatings Mo-N and Tі-N. Methods: vacuum-arc film precipitation, x-ray analysis, raster electron microscopy, measurements of hardness and of elasticity modulus, estimation of the coatings adhesion to substrate and of coefficient of friction. Results: For the first time physical and technological regularities are determined and the processes of the synthesis of superhard Mo-N coatings with the use of low-energy pulse treatment during the deposition are realized. It is shown that the Mo-N superhard coatings consist of low-temperature phase beta-Mo2N with a tetragonal lattice and high-temperature gamma-Mo2N with fcc lattice and also from Mo3N2 phase. The crystallite size is 9...12nm for Mo2N coatings with hardness greater than 45 GPa. For the first time it is found that the increase of hardness is caused by the increased content of low-temperature beta-phase Mo2N in the coating. The processes of deposition of Mo-N superhard coatings under substrate temperatures of 150°C are developed and realized. Field of application: physics of solid state, physics of surfaces, nanophysics