Effect of bias voltage and nitrogen pressure on the structure and properties of vacuum-arc (Mo + Ti6%Si)N coatings

Abstract

Abstract-Effect of deposition conditions in reactive nitrogen atmosphere on the growth morphology, phase composition, structure, and mechanical characteristics (microhardness) of vacuum-arc multilayer coatings obtained using evaporation of the (Ti6%Si) and Mo cathodes is studied with the aid of raster electron microscopy, energy-dispersive elemental microanalysis, and microindentation. It is demonstrated that nitrogen atoms are redistributed to the region of the strongest nitride-forming element (Ti) in relatively thin layers (about 7 nm) consisting of substances with substantially different heats of formation (−336 kJ/mol for TiN and −34 kJ/mol for MoN). Such a process leads to lamination with the formation of nitride TiN and metal Mo (weaker nitride-forming element). Nitrogen-metal bonds are saturated in the layers of strong nitrideforming elements Ti(Si) when the nitrogen pressure increases from 6 × 10 -4 to 5 × 10 -3 Torr in the condensation procedure. Thus, the compound is filled with nitrogen to the stoichiometric composition and, then, the second system of layers based on molybdenum is saturated with nitrogen with the formation of the γ-Mo 2 N phase. An increase in bias potential U SP from -100 to -200 V stimulates mixing in thin layers with the formation of the (Ti, Si, Mo)N solid solution and leads to a decrease in microhardness from 37 to 32 GPa. DOI: 10.1134/S1063784217050073INTRODUCTION Additional requirements on the surface properties of components and structures emerge due to the development of modern technologies. The desired functional properties can be reached using deposition of relatively thin (with a thickness of up to 10 μm) multielement coatings [1][2][3]. When the vacuum-arc technology is employed, the best (primarily, mechanical) properties are obtained for multielement coatings based on nitrides of transition metals [4][5][6][7][8].Rapid recent progress in structural engineering is related to the study of the composition of multielement coatings, regularities of the formation of structure and stressed state, and the relation of the parameters and physicochemical characteristics [9][10][11]. The corresponding results are used to interpret physical processes of the formation of nanocrystalline solid coatings under strongly nonequilibrium conditions for deposition of vacuum-plasma fluxes [12][13][14]. In this regard, the method for formation of multilayer structures with nanosized periods is employed for efficient control of nanostructure state of coatings [15,16]. Crystallite structures with variable structural nonequilibrium, imperfection, and element distribution in volume and interfacial regions are formed when the composite structures are fabricated [17][18][19][20].

Structure and Properties of Cermet Coatings Produced by Vacuum-Arc Evaporation of a High-Entropy Alloy

“…The substrate material was made of a WC-8%Co hard alloy, selected to study physical, mechanical and tribological properties, elemental and phase analysis, and AISI 304 nonmagnetic stainless steel [(up to 0.08)C; (17,(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)Cr; (up to 2)Mn; (8)(9)(10)(11)Ni; (up to 0.045)P; (up to 0.03)S; (up to 1)Cu; (up to 0.8)Si; the rest Fe, wt.%] for transmission electron microscopy (TEM) analysis.…”

“…Less often, HEA-based nitride coatings were two-phase coatings. Thus, it was shown that AlCrTiZrNbY HEA coatings produced by vacuum-arc deposition consisted of two nanocrystalline phases [9]. One phase had a bcc lattice with an average crystallite size of 15 nm and a lattice period of 0.342 nm, and the other had an fcc lattice with an average crystallite size of 7 nm and a lattice period of 0.437 nm.…”