Search

Influence of surface pretreatment on adhesion properties of TiZrN/TiSiN vacuum-arc coatings on steel substrates 12Х18Н9Т has been studied. Multilayer coatings were obtained by spraying two cathodes of compositions (mass %) 75 Ti + 25 Zr and 94 Ti + 6 Si in the same technological cycle with pretreatment, which could include cleaning of samples with gas plasma in the two-stage gas discharge or ion bombardment at arc spraying of cathodes, deposition on the substrate at arc spraying of cathodes, as well as combinations of these variants of cleaning with substrates. X-ray analysis, electron microscopy, sclerometry and micro-hardness measurements were used to study the composition, structure and properties of the obtained "coatingsubstrate" composites. The features of deformation and degradation of coatings formed after different variants of preliminary preparation of samples were revealed. Values of critical loads at dynamic indentation of coatings, changes in friction coefficient and level of acoustic emission signal testify to high adhesive strength of (TiZr)N/(TiSi)N coatings, which allows recommending them to increase cutting tool performance. The presence of an intermediate layer does not increase the resistance of these coatings to breakage, but it slows down the process of degradation of coatings and smooths sharp jump changes in properties. [ABSTRACT FROM AUTHOR]

The tribotechnical characteristics of (TiZr)N/(TiSi)N nitride multilayer coatings obtained by the method of vacuum-arc deposition at room temperature were investigated. The analysis of the influence of the deposition conditions on the mechanical and tribological properties of coatings with different modulation periods (total bilayer thickness) of this structure was carried out: in the 1st series λ about 20.4 nm, in the 2nd series with λ ≈ 43.9 nm, and in the 3d series of samples the coating was formed with a thickness of λ ≈ 137 nm. The results of wear were investigated, and they indicate that multi-element nitride coatings wear out by abrasive mechanism. The intensity of wear in coatings with the number of layers 360 (period λ = 20.4 nm) is 2 times lower than in coatings of 89 layers (period λ = 137 nm). The values of the friction coefficient were 0.79-0.82 during tests. Coating hardness was HV0.05 = 37.6 GPa for the samples of series 1, HV0.05 λ 31.2 GPa for the second series, and HV0.05 = 26.5 GPa for the samples of series 3. [ABSTRACT FROM AUTHOR]

Effect of pressure of the reaction gas on the texture, structural stress state and mechanical properties (hardness and resistance to abrasive wear) in vacuum-arc coatings based on Ti-V-Zr-Nb-Hf-Ta nitrides of high entropy alloys were investigated in this work. At a bias potential of – 200V, an increase in nitrogen pressure during deposition from 2.5·10 – 4 to 4.5·10 – 3 Torr leads to an increase in the content of nitrogen atoms in the coating, and the formation of a bittexture state [111] + [311] is established. The formation of a biaxial texture occurs due to the presence in alloys of atoms with very different masses (Ti, V and Hf, Ta). The use of a multi-element composition in a single-phase state with a simple cubic lattice allows to achieve high values of microstrain (up to 1.4 %) with a low deposition pressure. It is determined that the increase of nitrogen pressure during deposition leads to an increase in macrostresses. The highest hardness of 53 GPa is achieved in coatings obtained at a pressure of 2·10 – 3 Torr. It has been established that coatings with high resistance to abrasive wear are found to be: crystallite grain size 12-25 nm, absent of texture (or a low level of texture perfection), and also rather high microstrain in crystallites. [ABSTRACT FROM AUTHOR]

The influence of the main physical and technological factors of structural engineering (layer thickness, nitrogen atmosphere pressure and bias potential) on the structural-phase state of the NbN/Cu coatings was studied. It was established that with an increase in the thickness of niobium nitride layers from 8 to 40 nm (in the NbN/Cu multilayer composition), the phase composition changes from the metastable ε-NbN (cubic crystal lattice, NaCl structural type) to the equilibrium ε-NbN phase with a hexagonal crystal lattice. At low pressure PN = 7·10 -4 Torr in thin layers (about 8 nm thick), regardless of the Ub, the ε-NbN phase is formed. The reason for the stabilization of this phase can be the uniformity of the metallic fcc crystal lattice of the δ-NbN phase with the Cu crystal lattice. As the pressure increases from РN = 7·10 -4 Torr to 3·10-3 Torr, a more equilibrium ε-NbN phase with a hexagonal crystal lattice is formed. An increase in the bias potential during deposition from - 50 V to - 200 V mainly affects the change in the preferred orientation of crystallite growth. In thin layers of the ε-NbN phase (about 8 nm), a crystallite texture with the [100] axis is formed. In layers with a thickness of 40-120 nm, crystallites of the ε-NbN phase are predominantly formed with a hexagonal (004) plane parallel to the growth plane. At the greatest layer thickness (more than 250 nm), the ε-NbN phase crystallites are predominantly formed with a (110) hexagonal lattice plane parallel to the growth plane. The results obtained show great potential for structural engineering in niobium nitride when it is used as a constituent layer of the NbN/Cu multilayer periodic system. [ABSTRACT FROM AUTHOR]

The effect of negative bias potential (Ub =– 40, – 110, and – 200 V) upon the deposition of multielement coatings on their composition, structure, and mechanical properties was studied. It is shown that when using a high-entropy multi-element (of 7 elements) FeCoNiCuAlCrV alloy, it is possible to obtain a single-phase nitride (FeCoNiCuAlCrV)N. Nitride has an fcc crystal lattice (structural type NaCl). It has been established that with an increase in Ub in the structural state occurs transition from practically nontextured (polycrystalline) to the preferential orientation of the growth of crystallites with the [111] texture axis (at Ub=– 110 V) and [110] (at Ub =– 200 V). This is accompanied by a decrease in the lattice period, as well as a decrease in hardness and modulus of elasticity. For coatings (FeCoNiCuAlCrV) N, the highest hardness of 38 GPa is achieved by using the smallest (– 40 V) bias potential during the deposition process. It is shown that to achieve high hardness at high Ub it is necessary to increase the content in the highentropy alloy of elements with high nitride-forming ability. [ABSTRACT FROM AUTHOR]

uThe paper investigates the structure and properties of nanoscale multilayer coatings based on (TiZr)N and (TiSi)N produced by vacuum arc technique. Also, it provides an analysis of the impact of partial pressure of nitrogen on structural and phase state of coatings. The nitride phases are strongly textured, crystallographic planes (111) of most grains are oriented parallel to the surface. Dimensions of the coherent scattering regions and values of micro-distortions of the lattice have been calculated. The hardness of coatings reached 37.1 GPa, and the adhesion fracture load exceeds 150 N. The process technology ensures high uniformity of and a low defect rate in obtained coatings. [ABSTRACT FROM AUTHOR]

The effect of the constant bias potential (Ub) supplied to the substrate upon condensation and pressure of the nitrogen atmosphere (PN) on the elemental composition, growth morphology, texture, and physicalmechanical characteristics of vacuum-arc (AlCrTiVZrNb)Nx coatings is studied. It is established that with increasing Ub from – 110V to – 200V, the axis of preferential growth of crystallites of the fcc phase from [100] to [110] changes. Such a change is accompanied by a decrease in the hardness (H) and the ratio H/E (where E is the modulus of elasticity). The conditions for the formation of the preferential orientation of the crystallites (axial texture) of vacuum-arc (AlCrTiVZrNb)Nx coatings and the influence of texture on mechanical properties are discussed. It was established that the change in PN in the range (1.7-5)·10 –3 Torr basically allows to vary the degree of filling of the coating with nitrogen atoms. Based on the revealed regularities, the conditions for achieving high hardness for vacuum-arc coatings of nitrides AlCrTiVZrNb high-entropy alloy are substantiated. Because of the presence in the alloy of elements with a relatively low heat of nitride formation, in order to achieve high hardness, it is necessary to use deposition conditions with relatively low energy of bombarding atoms. The use of a low Ub = –110 V at the highest pressure PN = 5·10 –3 Torr allows achieving an superhard state with a hardness of 44 GPa. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Nano- & Electronic Physics is the property of Sumy State University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Nano- & Electronic Physics is the property of Sumy State University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Nano- & Electronic Physics is the property of Sumy State University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Nano- & Electronic Physics is the property of Sumy State University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Nano- & Electronic Physics is the property of Sumy State University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Nano- & Electronic Physics is the property of Sumy State University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Nano- & Electronic Physics is the property of Sumy State University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Nano- & Electronic Physics is the property of Sumy State University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Nano- & Electronic Physics is the property of Sumy State University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A comprehensive study of the influence of the thickness of the layers, Us and PN on the structural engineering to obtain high mechanical properties in multilayer composite MoN / CrN vacuum-arc coatings has been conducted by means of scanning electron microscopy with energy analysis, X-ray diffraction studies microindentation and scratch testing methods. It has been determined that in the studied PN = (2- 30) x 10 -4 Torr, the content of nitrogen in the coatings varies from 6.3 to 33 at. %, which leads even at the greatest nitrogen content to the formation of lower phase by nitrogen, y-Mo2N and isostructural CrN with the vacant sites in the nitrogen sublattice. The increase of thickness of the layers applied on the substrate in a stationary state promotes the increase of nitrogen content. Along with this, the lowest microdeformation and the average size of crystallites are formed at Ub = - 300 V, which defines the achievement of greater hardness of 35 GPa and high adhesion strength, which resists the destruction, Lc5 = 187.6 N. [ABSTRACT FROM AUTHOR]

Influence of constant and pulsed negative bias potential applied to the substrate during the deposition on the phase composition, structure, substructure and mechanical properties of multilayer ZrN / TiN coatings with a bilayer thickness of 50-200 nm was studied. Two-phase coating obtained from ZrN and TiN phases of the fcc structure of NaCl type without a significant loss of planarity and mixing layers is established. The use of high-voltage pulses would greatly change the structure and properties at Ub < 100 V. At larger value of Ub, constant potential becomes crucial for the structural engineering of the coating. It is shown that the greatest hardness is inherent to the coatings obtained by Ub = - 140...- 150 V, and H/E reaches a large value of 0.14, which is difficult to obtain in the single-layer coatings. [ABSTRACT FROM AUTHOR]

By the X-ray diffraction, electron microscopy, and microindentation methods we have investigated the phase composition, structure, substructure and hardness of vacuum arc multilayer coatings of TiN / CrN system obtained in the range of nitrogen pressure of 1·10-5 ... 5·10-3 Torr when applying continuous and pulsed negative bias potential. Formation of two-phase state with a preferred orientation of the crystallite growth was established at high pressure of (1 ... 5)·10-3 Torr and feeding of negative DC bias potential: Ub = - 20 V - texture axis [100], at - 230 V - texture axis [111]. Based on the studies of substructural state, connection of the transition to the superhard (57 GPa) state with decrease in the crystallite size and microstrain in TiN layers was established. [ABSTRACT FROM AUTHOR]

The questions of structural engineering of Cr-N system coatings produced by vacuum arc evaporation of Cr cathode in a nitrogen atmosphere are considered. As the variable physical and technological parameters we have used the following ones: pressure of nitrogen atmosphere (3.5-48) 10-4 Torr and negative bias potential applied to the substrate in constant (Ub= - 120 V) and pulse (Uip= - 1200 V) modes. Increase in the pressure without pulse action allows to transfer from Cr + Cr2N phase to phase of textured CrN crystallites with [111] axis. The transition from the metallic phase to the mechanical nitride is accompanied by a decrease in the average size of crystallites. Additional supply of impulse capacity allows to intensify the process of formation of nitrides and stimulates formation at high pressure of radiation resistant texture units with the [110] axis. [ABSTRACT FROM AUTHOR]

In order to develop the direction of "structural engineering nitride coatings" in the work conducted systematic analysis of the impact of the negative bias potential (direct and high-voltage pulse) on the structure, substructure and mechanical properties of ZrN coatings obtained by vacuum arc evaporation. Defined boundary value of (– 100 V) DC potential applied to the substrate, below which a high-voltage pulse potential (– 1200 ... – 2000 V quantity that allows to form peaks bias) makes a decisive contribution to the formation of preferred orientation of the crystallites with the [110] axis. The highest values of hardness 43 GPa are achieved at a constant potential -70 V. Supply high-voltage pulse shifts the maximum hardness in the direction of a greater value of the constant potential. [ABSTRACT FROM AUTHOR]