Grankin S. Phase composition, physical and mechanical properties of composite nanostructured coatings based on nitrides of refractory metals

The thesis is dedicated to the study of impact of physical and technological deposition parameters, in particular, partial pressure of working gas and bias potential, on formation of nanostructured coatings of systems TiN/ZrN, MоN/CrN, (TiCr)N, (TiAl)N, (TiZrNb)N, investigation of their structural and phase state, mechanical and tribological characteristics. Multilayered coatings TiN/ZrN, which contain TiN and ZrN phases, as well as coatings MoN/CrN, were formed by means of vacuum-arc deposition. Annealing of the coatings TiN/ZrN at Т = 700C in active atmosphere of nirtogen leads to changes only in surface layers. The highest hardness 42 GPa and the smallest abrasive wear of the coating with a value of 1.3*10-5 mm3*N-1*m-1 are inherent to the system TiN/ZrN with the smallest thickness of the layers of 20 nm. The hardness of the coatings MoN/CrN reaches values 38 GPa at conditions of the smallest by modulus bias potential and high pressure of nitrogen. The coatings (TiCr)N contain two phases. The average size of titanium crystallites is 15 nm, аnd the average size of nitride (TiCr)N crystallites is around 7.5 nm. The coatings (TiAl)N have cubic lattice of aluminium nitride of a structural type NaCl with a texture [111], the average size of crystallites is 15 nm. The basic forming phase of (TiZrNb)N coating has fcc-lattice. The coatings (TiZrNb)N obtained at the highest nitrogen pressure have the highest microhardness of 44.57 GPa and wear resistance.