A. A. Klopotov

Instability of the crystal lattice of CuPd alloy

The results of structural investigations (x-ray structural analysis, small-angle scattering and electron microscopy) of the B2→Al deformation phase transition and the kinetics of the recovery processes of deformed CuPd alloy are presented. It is established that the phase transition occurs in regions of local plastic deformation and the B2→Al deformation transition helps to enrich these regions with palladium.

Structure and properties of surface alloys synthesized by pulsed electron-beam treatment of a coating-substrate system

Nanostructured multiphase Al-Ti-Cu surface alloys are synthesized by pulsed electron-beam treatment of the coating-substrate system. In certain conditions, the strength and tribological characteristics of the initial material may be greatly improved.

Surface of high-chromium steel modified by an intense pulsed electron beam

The formation of nanostructural multiphase surface layers in high-chromium 12Х18Н10Т and 20Х13 stainless steel under the action of an intense pulsed electron beam in a SOLO system is studied. The Fe–Cr–C system is thermodynamically analyzed. Alloying Fe–Cr alloys with carbon considerably changes their structural and phase state and determines the regions of existence of the carbides M23C6, M7C3, M3C2, and M3C with α and γ phases. The temperature field formed in the surface layer of the steel under the action of the electron beam is numerically calculated. When the energy density of the electron beam is 10 J/cm2, regardless of the pulse length of the electron beam (50–200 μs), the maximum temperature at the sample surface corresponding to the end of the pulse is less than the melting point of the steel. The structure and the mechanical and tribological properties of the surface layer of high-chromium 12Х18Н10Т and 20Х13 steel formed under the action of the intense pulsed electron beam are investigated. It is found that electron-beam treatment of the steel with melting and subsequent high-speed crystallization is accompanied by solution of the initial carbide particles of composition M23C6—specifically, (Cr, Fe)23C6—and hence saturation of the crystal lattice in the surface layer with carbon and chromium atoms. In addition, submicronic cells of dendritic crystallization are formed, and nanoparticles of titanium carbide and chromium carbide are deposited. Overall, electron-beam treatment improves the surface and tribological properties of the materials. For 12Х18Н10Т steel, the hardness of the surface layer is increased by a factor of 1.5 and the wear resistance by a factor of 1.5, while the frictional coefficient is decreased by a factor of 1.6. For 20Х13 steel, the microhardness is increased by a factor of 1.5 and the wear resistance by a factor of 3.2, while the frictional coefficient is decreased by a factor of 2.3.

ADHESIVE COMPOUND FOR PRODUCTION OF WOOD CHIPBOARD COMPOSITE MATERIALS

В настоящее время производство древесно-стружечных плит является приоритетным направлением развития деревообрабатывающей промышленности. Помимо чисто технологических аспектов, вопросы экологической безопасности изготовления древесностружечных плит являются наиболее актуальными, и это находит отражение в современной патентной и научно-технической литературе. Одним из основных путей повышения экологической безопасности и эффективности производства древесно-стружечных плит является направленное модифицирование основного связующего материала – карбамидоформальдегидной смолы – с целью существенного изменения эмиссии свободного формальдегида из готовых конструкций. Эта задача решалась путем модифицирования как связующего, так и отвердителя. В качестве отвердителя использовали хлористый аммоний, щавелевую кислоту, соляную кислоту, кремнефтористый аммоний, комбинированный отвердитель в составе хлористого аммония и аммиачной воды и другие, а в качестве модификатора смолы – раствор полиакриламида. В работе представлены результаты исследований газовой фазы древесно-стружечных плит, выдержанных при температуре 110 °С в течение 30 мин, методом парофазного газового хроматографического анализа с масс-спектрометрическим детектированием. Результаты приведенных испытаний показали, что наименьшим количеством выделяющихся компонентов в газовой фазе обладает образец на основе полиакриламида с модифицирующими добавками. Относительно газовыделения все исследуемые образцы древесно-стружечной плиты в целом удовлетворяют требованиям СанПин 6027 А-91 «Санитарные правила по применению полимерных материалов в строительстве и производстве мебели. Гигиенические требования» и МУ 2.1.2.1829-04 «Санитарногигиеническая оценка полимерных и полимерсодержащих строительных материалов и конструкций, предназначенных для применения в строительстве жилых, общественных и промышленных зданий».

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.

Weakly Stable Structural-Phase States of a Submicrocrystalline Alloy Grade 2 in the Weld Zone Obtained Using Electron-Beam Welding

The structural-phase state of weld joints of the samples of Grade 2 alloys with micro- and submicrocrystalline structure is studied using methods of X-ray diffraction analysis. The weld joint was obtained by joining plates with a thickness of 2 mm using the electron-beam welding method. It is established that the transfer of the titanium alloy Grade 2 from the microcrystalline state into the submicrocrystalline state during the process of gradual grinding of grains in the samples by the abc-pressing method at a parallel stepwise decrease of the temperature in the range of 750-500 °C leads to an intensive introduction of oxygen atoms into the crystalline lattice of the solid solution a-Ti. The presence of an increased content of oxygen atoms in the crystalline lattice of the solid solution a-Ti in the submicrocrystalline state in the Grade 2 alloy in the weld zone and in the heat-affected zone promotes the formation of metastable phases w-Ti and α-Ti. The obtained results made it possible to assume that in the process of electron-beam welding in the Grade 2 alloy in the submicrocrystalline state, an increased concentration of interstitial oxygen atoms in the crystalline lattice of the solid solution based on a–Ti plays a significant role in the formation of a wide range of structural-phase states in the weld zone and in the heat-affected zone.

Electron-Beam Welding - Structural-Phase State and Microhardnes in the Weld Zone in a Submicrocrystalline Titanium Alloy Grade2

The paper presents the results of the X-ray diffraction analysis of structural-phase states in the weld zone of a titanium alloy Grade2 in micro-and submicrocrystalline states. It is established that the structural-phase state in the weld zone and in the heat-affected zone depends on the state of samples of the alloy Grade2 before welding. It is shown that formation process of metastable phases ω-Ti and α′′-Ti occurs in the submicrocrystalline state in the alloy Grade2 in the weld zone and in the heat-affected zone. Investigations of the features of the microhardness distribution in the weld zone in alloys Grade2 in micro-and submicrocrystalline states are carried out. Different character of microhardness distributions in the weld zone in the samples depending on the structural-phase state of welded plates made of alloy Grade2 is determined.

Modification of Silumin Using the Electroexplosive Method

Surface modification of silumin of the grade AK12 with plasma formed during an electrical explosion of aluminum foil with a sample of yttrium oxide powder placed in the explosion region (the electroexplosive doping method) is carried out. The thermodynamic analysis of the system Al-Si-Y-O is carried out. The phases formed in this system under equilibrium conditions are revealed. Investigations of the elemental and phase composition and the defective substructure are carried out. Mechanical (microhardness) and tribological (wear resistance and friction coefficient) tests of the modified material are performed. The physical mechanisms responsible for multiple enhancement of surface properties of the modified silumin samples are revealed.

Dilatation Changes in the Phase Transition Region in TiNi-based Al-loys

The paper presents the data obtained as a result of the X-ray diffraction in situ study of the parameter structure of a thin crystalline structure in the of phase transition region in alloys based on titanium nickelide depending on the deformation influence. It has been shown that dilatation changes during the transition B2-R(w) depend on the arrangement of atoms in the doping element.

Structural and Phase Changes in the System Al-Si-Ti-B, Synthesized Using the Electron-Ion-Plasma Treatment Method

The results of surface modification of silumin samples of the eutectic composition using the combined method, which includes the irradiation with plasma formed during an electric explosion of the conductive material and the subsequent processing with a highintensity pulsed electron beam, are presented. Formation of a multilayer multiphase submicron and nanoscale structure with high mechanical and tribological properties is established. The results of the structural phase analysis of the material are discussed from the standpoint of