V. V. Shugurov

Influence of Plasma Assistance on Arc Deposited MoN Coatings

The paper reports on a study to optimize the modes of plasma-assisted vacuum arc deposition of molybdenum nitride (MoN) coatings. It is shown that the parameters of plasma assistance influence the coating properties and that varying the ion current ratio in the metal-gas plasma makes possible MoN coatings with high hardness and high wear resistance.

Modification of the surface layer of the system coating (TiCuN)/substrate (A7) by an intensive electron beam

In order to study the conditions of modification of the surface layer of the system coating (TiCuN)/substrate (A7) an analysis of processes occurring in the surface layer of the system wear-resistant coating/substrate irradiated by an intensive pulsed electron beam at a submillisecond exposure time has been carried out on the example of aluminum and titanium nitride. Irradiation has been carried out under conditions ensuring melting and crystallization of the surface layer of the material by a nonequilibrium phase diagram. It has been experimentally established that irradiation of the system coating (TiCuN)/substrate (A7) by an intensive electron beam is accompanied by changes in the phase composition of the material. It is evident that nanostructuring of the aluminum layer adjacent to the coating, and formation in it of nitride phase particles will contribute to hardening of the surface layer of the material, creating a transition sublayer between a solid coating and a relatively soft volume. The carried out analysis shows that binary nitrides based on TiN1-x are most likely to form under nonequilibrium conditions, since the homogeneity range of this compound is rather large. On the other hand, formation of the ternary compound Ti3CuN, which can be formed after an arc plasma-assisted deposition of titanium nitride of the composition TiCuN and by the subsequent intensive pulsed electron beam exposure, cannot be excluded.

Surface Doping of Steel with an Intense Pulsed Electron Beam

Surface doping of AISI420 steel is carried out in a single vacuum cycle, and consisted of spraying a thin (0.5 μm) film of Zr-Ti-Cu alloy by electric-arc sputtering of a cathode of the composition Zr-6 at.% Ti-6 at.% Cu, and the subsequent irradiation of the system “film (Zr-Ti-Cu alloy) / (AISI420 steel) substrate” with an intense pulsed electron beam. It is shown that the concentration of zirconium in the surface layer of steel decreases with an increase in the energy density of the electron beam (ES). It is established that formation of a surface alloy is accompanied by the following: formation of a cellular crystallization structure (the average cell size increases from 150 nm at ES = 20 J/cm2 to 370 nm at ES = 40 J/cm2); formation of a dendritic crystallization structure in the presence of refractory element particles (titanium or zirconium); decomposition of a solid solution with the release of zirconium carbide particles (particle sizes increase from (10-15) nm at ES = 20 J/cm2 to (30-40) nm at ES = 40 J/cm2). Particles of the carbide phase based on chromium of the composition Cr3C2, Cr7C3 and (Cr, Fe)23С6, along with zirconium carbide particles, are revealed upon the irradiation of the system “film (Zr-Ti-Cu alloy) / (AISI420 steel) substrate” with an intense pulsed electron beam (ES = 40 J/cm2). Chromium carbide particles have a round shape; their sizes vary from 40 nm to 60 nm. The analysis of phase transformation diagrams taking place under equilibrium conditions in systems Fe-Zr-C; Cr-Zr-C; Fe-Cr-Zr is carried out. It is established that ultra-high cooling rates that occur during the irradiation of the system “film (Zr-Ti-Cu alloy) / (AISI420 steel) substrate” with an intense pulsed electron beam impose restrictions on formation of phases of the intermetallic type. It is suggested that formation of predominantly carbide phases in the surface layer of the material is conditioned upon high mobility of carbon atoms in steel.

Combined surface modification of commercial aluminum

The paper analyzes research data on the structure and properties of surface layers of commercially pure A7-grade aluminum subjected to treatment that combines deposition of a thin metal film, intense pulsed electron beam irradiation, and nitriding in low-pressure arc plasma. The analysis shows that the combined method of surface modification provides the formation of a multilayer structure with submicro- and nano-sized phases in the material through a depth of up to 40 μm, allowing a manifold increase in its surface microhardness and wear resistance (up to 4 and 9 times, respectively) compared to the material core. The main factors responsible for the high surface strength are the saturation of the aluminum lattice with nitrogen atoms and the formation of nano-sized particles of aluminum nitride and iron aluminides.

Comparative evaluation of the sand blasting, acid etching and electron beam surface treatments of titanium for medical application

Modification of the surface topography and chemistry are commonly used to achieve the desired biological response to the implants. The influence of the different treatment methods on the physicochemical and mechanical properties of titanium is reported. All samples were divided into 2 groups. First group was sandblasted with 250–320 μm Al2O3 at two pressures 0.45 MPa and 0.61 MPa followed by the chemical etching in a fluorine-containing solution. The second group was acid-etched in the same solution followed by electron beam modification with the energy density 8 J/cm2. The samples were investigated by SEM, EDX, XRD, nanoindentation and sessile drop method. The studies revealed that all groups have nano/micro-patterned surfaces. The EDX analysis detected only titanium in all groups. The XRD results revealed the presence of diffraction peaks corresponding to titanium. The nanoindentation studies revealed significant differences in the mechanical properties between group 1 and 2. The elastic strain to failure and plastic deformation resistance of the group 2 were determined to be 0.035 and 5∗10−3, respectively, which were significantly higher than those of group 1. The obtained results of water contact angle for group 1 revealed moderately hydrophilic properties of treated surfaces. The water contact angle was increased up to 80.85 ± 8.3 ° for group 2.

Aluminum surface layer strengthening using intense pulsed beam radiation of substrate film system

The paper presents formation of the substrate film system (Zr-Ti-Cu/Al) by electric arc spraying of cathode having the appropriate composition. It is shown that the intense beam radiation of the substrate film system is accompanied by formation of the multi-phase state, the microhardness of which exceeds the one of pure A7 aluminum by ≈4.5 times.

Combined treatment of steel, including electrospark doping and subsequent irradiation with a high-intensity electron beam

A thermodynamic analysis of phase transformations taking place during doping of steel with tungsten and titanium has been performed. The studies on the surface layer of steel modified using the combined method (electrospark doping and the subsequent electron-beam treatment) have been carried out. Formation in the surface layer of a multi-phase submicrocrystalline structure with high strength properties has been revealed.

Electrospark doping of steel with tungsten

The paper is devoted to the numerical modeling of thermal processes and the analysis of the structure and properties of the surface layer of carbon steel subjected to electrospark doping with tungsten. The problem of finding the temperature field in the system film (tungsten) / substrate (iron) is reduced to the solution of the heat conductivity equation. A one-dimensional case of heating and cooling of a plate with the thickness d has been considered. Calculations of temperature fields formed in the system film / substrate synthesized using methods of electrospark doping have been carried out as a part of one-dimensional approximation. Calculations have been performed to select the mode of the subsequent treatment of the system film / substrate with a high-intensity pulsed electron beam. Authors revealed the conditions of irradiation allowing implementing processes of steel doping with tungsten. A thermodynamic analysis of phase transformations taking place during doping of iron with tungsten in equilibrium conditions has been performed. The studies have been carried out on the surface layer of the substrate modified using the method of electrospark doping. The results showed the formation in the surface layer of a structure with a highly developed relief and increased strength properties.

Arc plasma-assisted deposition of nanocrystalline coatings

The paper considers peculiarities of vacuum arc plasma-assisted deposition of multicomponent nanocrystalline coatings based on titanium nitride. Advantages and prospects of the modified ion plasma setup used for coating deposition are described. The effect of added elements on the structural phase state and characteristics of titanium nitride-based coatings is demonstrated.