E. A. Levashov

Mechanical properties of Ti-B-C-N coatings deposited by magnetron sputtering

Abstract This work investigated structure, mechanical properties and tribological performance of the Ti–B–C–N thin films deposited using RF magnetron sputtering in different argon–nitrogen atmospheres from a TiB2–TiC composite target synthesized by a one-step SHS-consolidation technique. Quasi-amorphous nano-composite films were deposited using RF power density of 11.2 W/cm2 and a substrate bias of −50 V. In this paper, the mechanical properties of the composite films, including nanohardness, Youngs modulus, film adhesion and residual stress, are presented together with their tribological behavior. The best properties and performance were achieved by depositing the film with a 50-nm-thick titanium interlayer and using a substrate bias of 50 V. The nitrogen content in the deposition atmosphere changed the film properties and performance slightly. The Ti–B–C film and the Ti–B–C–N film deposited in an argon–nitrogen atmosphere with 10% nitrogen exhibited the best adhesion to substrate, lowest residual stress, and best tribological performance. In general, these Ti–B–C–N thin films appear to be a promising composite film system suitable for engineering wear applications.

The Structure and Properties of Ti–B–N, Ti–Si–B–N, Ti–Si–C–N, and Ti–Al–C–N Coatings Deposited by Magnetron Sputtering Using Composite Targets Produced by Self-Propagating High-Temperature Synthesis (SHS)

The microstructures and compositions of multicomponent Ti–B–N, Ti–Si–B–N, Ti–Si–C–N, and Ti–Al–C–N films deposited by reactive magnetron sputtering using composite targets and produced by self-propagating high-temperature synthesis (SHS) have been investigated by means of transmission electron microscopy. Auger spectroscopy, and X-ray diffraction. Depending on the chemical composition of the film deposited, different single-phase crystalline films were observed. The sputtering process included sputter cleaning prior to the DC magnetron sputter deposition of Ti and TiN interlayers prior to DC magnetron sputter deposition of the multicomponent films from multicomponent targets. The films produced were characterized in terms of their microhardness, wear resistance, high-temperature oxidation conducted in air. and corrosion resistance in a solution of 5NH2SO4 at room temperature.

Structure and Physical-Mechanical Properties of Nanostructured Thin Films

The structure and mechanical properties of nanostructured thin films based on carbides, nitrides, and borides of transition metals are described. The mechanisms of localized deformation of the films during indentation are compared. It is shown that the tendency of a material to form shear bands during deformation can be predicted using the parameter H3/E2, which describes the resistance of the material to plastic deformation. The columnar structure of the films is found to play an important role during deformation, which proceeds via slipping of columnar structural elements along the direction of an applied load.

Composition and oxidation resistance of Ti–B–C and Ti–B–C–N coatings deposited by magnetron sputtering

Abstract Nanocomposite Ti–B–C and Ti–B–C–N coatings were deposited from a TiB 2 –TiC target using RF magnetron sputtering. In this paper, the composition and oxidation kinetics of Ti–B–C and Ti–B–C–N coatings are presented. The film composition was characterized using XPS. Compared to the target composition, preferential sputtering of the carbon component was observed. Introducing nitrogen into the sputtering gas resulted in the formation of TiN, with nitrogen of approximately 30 at.%, and shifted the C 1s peak from the typical position for carbide to a higher binding energy position, which is typical of graphite. Both dynamic and isothermal oxidation kinetics were studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The oxide compositional depth profile, structure and morphology were characterized by Rutherford backscattering spectrometry (RBS), X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The results show that: (1) catastrophic oxidation started at 920 K; (2) TiB 2 and TiC in Ti–B–C coatings oxidized in sequence; (3) isothermal oxidation of Ti–B–C coatings in the temperature range from 1173 to 1323 K obeyed a parabolic rate law with an activation energy of 1.64 eV/atom, indicating a diffusion-controlled mechanism; and (4) well-crystallized oxide scales formed after oxidation in air at 1173 K for 2 h are mainly rutile TiO 2 , with XRD-detectable hexagonal B 2 O 3 and hematite Fe 2 O 3 resulting from iron outward diffusion.

Microstructure and mechanical properties of superhard Ti–B–C–N films deposited by dc unbalanced magnetron sputtering

Superhard quarternary Ti–B–C–N films were successfully deposited on AISI 304 stainless steel substrates by a dc unbalanced magnetron sputtering technique from a Ti–B–C composite target. The relationship between microstructures and mechanical properties was investigated in terms of the nanosized crystallites∕amorphous system. The synthesized Ti–B–C–N films were characterized using x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). These analyses revealed that our Ti–B–C–N films are composites of solid-solution (Ti,C,N)B2 and Ti(C,N) crystallites distributed in an amorphous boron nitride (BN) phase including some of carbon, CNx, B2O3 components. The hardness of the Ti–B–C–N films increased with the increase of N content up to a maximum value of approximately 45 GPa at 10 at. % N, with a subsequent decrease in hardness at higher N content. This value is considerably higher than the hardness measured in our Ti–B–C films (∼35GPa). The Ti–B–C–N(10 at .%)...

Optimization of PVD Parameters for the Deposition of Ultrahard Ti–Si–B–N Coatings

Multicomponent Ti–Si–B–N coatings were deposited on high-speed steel (HSS) substrates by reactive magnetron sputtering using a SHS TiB + 20 wt% Si target. The influences of the substrate temperature, bias voltage, and nitrogen partial pressure on the structure and the elemental compositions of the films were studied. The films were characterized by high-resolution transmission electron microscopy (HRTEM), Auger spectroscopy (AES), and X-ray diffraction (XRD). The results of HRTEM analysis indicated the formation of an ordered–disordered structure with fine crystalline grains of hexagonal Ti(B,N)x phase and amorphous integrain layers. The stoichiometry of the Ti(B,N)x phase was strongly affected by PVD process parameters. The films were characterized in terms of their microhardness and wear resistance. The reasons for the high value of microhardness appear to be the result of stoichiometric phase composition, compressive residual stress, and dense and fine microstructure of the Ti–Si–B–N coatings. The tribological wear test results indicated the superior wear-resistant properties of Ti–Si–B–N coatings compared to TiN and Ti(C,N) coatings.

Structure and Properties of Ti–B–N, Ti–Cr–B–(N), and Cr–B–(N) Coatings Deposited by Magnetron Sputtering of Targets Prepared by Self-Propagating High-Temperature Synthesis

Transmission and scanning electron microscopy, x-ray phase analysis, x-ray photoelectron spectroscopy, and atomic-force microscopy were used to study the structure and surface topography of Ti-B-N, Ti-Cr-B-(N), and Cr-B-(N) thin films. Physical, mechanical, and tribological characteristics of coatings were comparatively analyzed, including determination of the hardness, elastic modulus, elastic recovery, critical load, friction coefficient, and wear rate. It was shown that Ti-B-N and Ti-Cr-B-N coatings are superior to conventional TiN-and Ti-C-N-based coatings in terms of their physicomechanical and tribological properties. Ti-B-N and Ti-Cr-B-N coatings deposited under optimum conditions were characterized, accordingly, by a hardness of 31–34 and 40–47 GPa, an average elastic modulus of 378 and 506 GPa, a friction coefficient of 0.49–0.60 and 0.45–0.52, a dry-wear rate of (3.4–4.6) × 10−7 and (6.0–6.8) × 10−7 mm3 N−1 m−1, and a largest critical load of 50 and 22 N. Features in the determination of the physicomechanical properties of films during nanoindentation and their wear properties are discussed.

Adhesion, Friction, and Deformation Characteristics of Ti-(Ca,Zr)-(C,N,O,P) Coatings for Orthopedic and Dental Implants

This paper reports on the results of a comparative investigation into the physical, mechanical, and tribological characteristics of Ti-(Ca,Zr)-(C,N,O,P) coatings. The hardness, elastic modulus, elastic recovery, adhesion strength, friction coefficient, and wear rate of the coatings are determined. The specific features revealed in the deformation and fracture of the coatings deposited on various substrates in the course of adhesion tests are described. It is shown that the critical loads responsible for different types of adhesion and cohesion failure of the coatings can be determined from a set of parameters obtained during their scratching. The features observed in the behavior of the friction characteristics of the coatings during tribological tests in air and in a physiological solution are discussed.

Structure and properties of Ti-C-B composite thin films produced by sputtering of composite TiC-TiB2 targets

Abstract This work demonstrates the use of self propagating high temperature synthesis (SHS) for the production of dense, TiC-TiB 2 composite targets for magnetron sputtering of Ti-C-B composite thin films. The measured electrical resistance data of the composite thin films produced from the TiC-TiB 2 composite targets are presented and the microstructures of the composite thin films are characterized. Films with the composition 60%TiC+40%TiB 2 were the most thermally stable. However, there was noticeable oxidation when these composite thin films were heated in air at temperatures above 400 °C. Heat treatment of the films in vacuum indicated that recrystallization began at approximately 40 °C. The absolute value of the temperature coefficient of resistivity decreased noticeably with increase in annealing temperature, reaching a value of −2 × 10 −5 K −1 at 600 °C.

Characteristic properties of combustion and structure formation in the Ti-Ta-C system

Macrokinetic characteristics of the combustion of mixtures in the (100% − X)(Ti + 0.5C) + X(Ta + C) system with a variable mixing parameter X and initial temperature T0 of charge heating are considered. For compositions with X = 10 and 30%, an abrupt increase in the velocity Uc and temperature Tc of combustion as a result of passing two parallel chemical reactions of titanium and tantalum carbide formation is established. The Uc (T0) and Tc (T0) dependencies are linear for the mixture with X = 50%. By hardening the combustion wave, it is revealed that the primary structure formation in the combustion region starts from the selection of submicron grains of nonstoichiometric titanium carbide from the supersaturated titanium melt. In the investigated range of parameter X, synthetic products are single-phase and represent titanium-tantalum carbide. An increase in X results in a decrease in the size and microhardness of (Ti, Ta) C grains and a reduction of the relative density of compact synthetic products. The kinetics of high-temperature oxidation of alloys on the basis of carbide (Ti, Ta) C is studied. Ceramics produced at X = 10% are most heat-resistant.