This work reports the appearance of iridescent spectral patterns in the form of coloured stripes on AISI 321 steel surfaces subjected to ultrasonic impact treatment (UIT). The possible reasons for the UIT-textured surface coloration are considered from the viewpoints of wave (diffraction and interference) optics. According to the XRD analysis, the phase composition of the AISI 321 steel surface layer after UIT is represented by the austenite and martensite iron phases. The chemical composition of the UIT-textured steel near-surface layer is identified using XPS, which includes iron and chromium in the oxidised and metallic states. The thickness of the oxygen-enriched layer after UIT is estimated to be approximately 15 nm. SEM and AFM analysis confirmed that UIT provides the formation of periodic surface structures with characteristic dimensions from several hundreds of nanometres to several micrometres coinciding in order of magnitude with wavelengths in the visible range. Applying different processing modes of AISI 321 steel surface leads to qualitative transformations in the spectral patterns: the position of the coloured stripes, its width, and the total number of the observed diffraction maxima change according to the equation of light diffraction. The obtained results indicate that diffraction of light is the main reason for the appearance of spectral patterns on the UIT-textured AISI 321 steel surface, which is analogous to a reflective diffraction grating. Structural diffraction coloration could be used as a possible basis for a non-destructive spectral control for UIT-textured steel surfaces and indirect monitoring of the performance of UIT equipment.

The development of mycotic colonization of the base surface with further biodegradation of acrylic plastics is currently of undoubted interest. The oral cavity is a favorable ecological niche for colonization by fungi and their subsequent possible invasion into the epithelium of the oral mucosa. The method of modulation interference laser microscopy is of considerable interest to researchers in medicine in the context of obtaining the necessary information about the morphological characteristics of microbial cells and the microbiome community as a whole during the colonization of a certain ecological niche in the human body. Purpose of the study: to analyze the microrelief of the biofilm of yeast-like fungi of the species Candida albicans of base plastics of the hot type of polymerization using the method of laser modulation interference microscopy. An experimental study was carried out in order to study biofilms of yeast-like fungi of the genus Candida on samples of basic plastics, an image of a biofilm of yeast-like fungi of the species Candida albicans was obtained on the surface of a plastic of a hot type of polymerization (polymethyl methacrylate) in the visualization of the phase portrait, a description of its horizontal and vertical bioprofile. As a result of the research, the heterogeneous structure of the biofilm was determined, due to the different density and accumulation of cells along the surface, the characteristics of the surface were established in accordance with the roughness criteria. The microrelief parameters on a separately arbitrarily selected section line allow one to determine the characteristics of the biofilm in the required area and make it possible to judge the nature of its formation in a certain biological niche.

The article considers the transfer of utilization technologies for detachable elements of the launch vehicle (LV) structures during the launch at the powered phase after their detachment at the unpowered phase of the descent trajectory to the utilization of tanks for fuel and lubrication materials (FLM) delivered to outlying regions of the Arctic. Opposed to detachable LV structures, utilization of FLM tanks is carried out under ground conditions by burning fuel elements prepared from FLM tank structures in conventional boilers and domestic heating furnaces. The research task has been set considering the possibility of implementing the requirements in the design and construction of polymeric composite material (PCM) to manufacture combustible tanks for the FLM storage. The requirements have been formulated for the production stages of combustible PCM and utilization system including the definition of design and construction parameters of PCM. The results of preliminary experimental studies in terms of determining the combustibility of the proposed PCM and their strength characteristics have shown the possibility of developing combustible structures.

Wire electrical discharge machining (WEDM) is widely used in various fields of production. Its disadvantages include a relatively low productivity rate caused by wire breakages among other factors. In this article, the method of fractographic analysis is used to study a wire that has undergone a breakage during machining. The results indicate that the tool–electrode is subjected to mechanical tension followed by a ductile fracture. The most probable reason of wire breakages is a decrease in the wire cross–section, which can be caused by an electrodes short circuit.

Проволочная электроэрозионная обработка широко (ПЭЭО) применяется в различных сферах производства. К ее недостаткам относится сравнительно невысокая производительность, обусловленная, помимо прочих факторов, обрывами проволоки. В данной статье методом фрактографического анализа проводится исследование проволоки, претерпевшей обрыв в ходе обработки. Полученные результаты свидетельствуют о том, что электрод-инструмент подвергается механическому растяжению, сопровождающемуся вязким изломом. Наиболее вероятной причиной обрывов является уменьшение поперечного сечения проволоки, которое может быть вызвано коротким замыканием между электродами.

Development of the composites based on substances with a high bioactivity potential is of current interest to medical materials science because composites' properties can be modified by varying the components ratios. Weakly crystallized calcium phosphates and calcium silicate hydrates, possessing higher chemical reactivity than their crystalline forms, are promising salts to be studied as biomaterials' constituents. In this study, precipitation from aqueous solutions was employed to obtain apatite and calcium silicate hydrate composites. Synthesized solids were examined without high-temperature thermal pretreatment using X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), laser diffraction, physical adsorption (BET method) and thermogravimetric analysis coupled with the mass spectrometry (TGA/MS). Compositions containing poorly crystallized carbonate-substituted hydroxyapatite, calcium silicate hydrate and calcite as an admixture were obtained by varying concentrations of the reagents. Soaking of the composite ceramics formed from freshly precipitated synthetic solids in simulated body fluid (SBF) at 37 degrees C for 14 days lead to formation of the surface layer of amorphous calcium phosphate. As the calcium silicate content in the composites increases, the coatings density and thickness also increase, because silicate ions act as active sites in the process of new phase nucleation. Furthermore, prismatic calcite crystals were identified to form on the lower side of ceramics. This may be caused by an increasing of local supersaturation with respect to calcium carbonate in small-volume confinement conditions during the experiment.

The paper studies the effect of parameters of a thin-layer copper-based coating applied by magnetron sputtering on the wear resistance of samples made of steel 18Cr2Ni4WA when working in a friction pair "18Cr2Ni4WA - cast iron GG 15". The rational values for the thickness of the applied copper coating are determined, at which the lowest friction torque during the burn-in period and the minimum burn-in time are achieved. Jeol JCM-5700 Scanning Electron Microscope is used to study the friction track of samples and counter bodies. It is found that in the process of friction, the coating is selectively transferred from copper to the surface of the counter body, which significantly reduces the wear of the counter body.

Probe device for electrical measurements of parameters thin doped films ZnO is considered. On the base of use of this probe device there is measured by the Hall E ffect method the concentration of electrons of the conductivity in indium doped thin films ZnO with thickness in the interval (0,065–0,3) μm concentration of electrons of the conductivity in the interval (2–3,4)∙1019 cm–3 and low mobility of electrons of the conductivity — (4–8,5) cm2 /B∙s. Dignity of probe device is a possibility of the reduction of the voltage asymmetry of hall probes.

Актуальной задачей современного биоматериаловедения является создание остеоиндуктивных препаратов на основе биосовместимых синтетических солей, с достаточно высокой прочностью и пористостью, форма которых позволяла бы заполнять костные дефекты различной формы и размеров. В данной работе по суспензионной технологии, основанной на принципе несмешивающихся жидкостей, из синтетических смесей с различными пропорциями гидроксиапатита и волластонита получена серия гранулированных препаратов, частицы которых имеют сферическую форму, микротвердость не менее 17 HV и открытую пористость порядка 50 %. Полученные материалы могут быть использованы для восполнения дефектов костных тканей различной локализации, формы и размеров в хирургической стоматологии, травматологии и ортопедии.

The paper presents the results of the investigation devoted to the influence of wire electrical discharge machining modes on crack formation and surface layer morphology of the titanium alloy. The aim of the paper is to obtain interrelation data about processing modes with depth of microcracks penetration, as well as on the influence of processing modes on the morphology of the surface layer, in particular, on the group of parameters Rk. It is shown by using scanning electron microscopy that the depth of microcracks depends of the number of passes and processing conditions. The maximum depth is 12 μm after the first pass, the minimum is 0,9 μm after the fourth pass. The groups of parameters Rk study by the method of profilometry made it possible to conclude that the most favorable oil-retaining microrelief is formed after the third pass.

The offered vacuum vaporizer can be used under the vacuum fabrication of films from Cr, Mg, Mn, SiO, GeO, MoO3 , WO3, ZnS, ZnSe, CdS, CdSe, CdTe by sublimations. Vacuum vaporizer containing tubular element with tightly closed by flat end areas, executed from Та (or Мо) foil by the thickness (0,05–0,1) mm with the high temperature of melting and evaporations and is kept a central region of the radial cross-section with the hole in the manner of the oval situated between flat end areas having variable area of the current section, which decreases toward from the centre of the tubular element to its ends. The offered vaporizer has broader field-performance and technological possibilities, since for the fabrication of the vaporizer use a metallic foil that allows under its fabrication to change amounts of the vaporizer. Herewith the vaporizer possible to use for fabrication of films repeatedly executing its recurrent boot without removing from the vacuum camera.

Task of studies is a development of the structure and way of the fabrication of the photocell capable to take a radiation or in near infrared region of the spectrum (1–1,4) microns, or in the field of (0,5–1,4) microns. Way of fabrication and results of studies of photoelectric features of two spectrum photocell based on two Schottky barrier contacts Al-p-Si and Ti-p-Si, situated on opposite parties Si plate are considered.

Task of studies is a development of the structure and way of fabrication of a photocell capable to take a radiation or in near infrared range of the spectrum (0,9–1,4) micron, or in the field of (0,5–1,4) micron. Way of fabrication and results of studies of photoelectric features of two spectrum photocells based on two Schottky barrier contacts PtSi-n-Si (or PdSi-nSi), situated on opposite parties silicon plate, are сonsidered. It is shown that the explored photocell can be used for the transformation of the energy of the radiation in the electrical energy at room temperature in two ranges: or in near infrared region of the spectrum (0,9–1,4) micron, or in the field of (0,5–1,4) micron. This characteristic of the designed photocell will allow to increase its application. Photocell possesses a simple structure and technology with a time of its fabrication in the interval (2,5–3) of the hour.

The paper provides the results of a short circuit impact on wire breakages during wire electrical discharge machining (WEDM) of AISI 9840 steel by the SODICK VZ300L machine. A method of scanning electron microscopy (SEM) is used for debris size, morphology and shape analysis. The carried out investigation led to the conclusion that the most probable reason of the welding bridge formation is due to the non-spherical (conglomerates) particles' presence with a large number of surface irregularities in a dielectric liquid. A classification of debris particles is proposed from the point of view of their dimensions and ability to overlap the spark gap - "effective" and "ineffective" particles.

Thermal decay of a metastable state is a useful model employed in many branches of natural sciences. The inertia parameter and friction coefficient, as well as the potential energy, might have quite a different scale in the different branches. However, the time evolution of quantities characterizing the decay process (or the Kramers problem) should be the same, e.g. the fission rate. Therefore, it is convenient to have a set of universal parameters for scaling the problem. Performing numerical modeling within the Langevin dynamics, we have managed to find such universal dimensionless parameters.

Calcium silicates are considered as promising components of materials for hard tissue repair. The main attention is paid to the crystalline forms of these substances. In the present study, a series of amorphous calcium silicate hydrates with molar coefficient Ca/Si = 0.65 - 1.45 was prepared by precipitation in aqueous solutions. The samples were analysed using X-ray diffraction, FT-IR spectroscopy, SEM, TGA, BET. The dynamics of calcium silicate hydrates dissolution in Tris-buffer solution with pH = 7.40, corresponding to the acidity of human plasma, was compared with wollastonite and apatite. It is shown that calcium silicate hydrates actively dissolve in a slightly alkaline medium, ensuring the appearance of calcium ions in the solution in amounts that exceed the cation concentrations in systems with beta-CaSiO3(sic)(10)(PO4)(6)(OH)(2).

Zirconium, niobium and vanadium are the high costly refractory metals that cause the topicality of economically processing and waste minimization during manufacture the products from such metals. The purpose of this work is to establish the quality of the surface layers after wire electrical discharge machining (WEDM) of Zr, Nb and V. The morphology and crack formation in the surface layers of zirconium, niobium. vanadium was investigated by SEM and profilometry methods. The results of the WEDM regimes influence on morphology, roughness and crack formation in the surface of Zr, Nb and V are presented. It is established that refractory metals are processed more difficult than steel, copper and aluminum alloys, although the morphology of the treated surfaces are practically no different.

Structure and strategy of the fabrication of the photocell on the base of the Schottky barrier contact Pd-n-GaAs are сonsidered. There is measured I(V)-features of photocells, their C-V-features, spectrums photovoltage and current of the short circuit, and determined height of the Schottky barrier contacts Pd-n-n+-GaAs by photoelectric method. There is shown that air annealing of structures n-n+-GaAs-AuGe under (200–210) C within 30 minutes before precipitating a film Pd on n-GaAs brings: to the reduction on two orders direct Idir and inverse Iinv currents (under 0,5 V), to reduction on three orders of density of the current of the saturation J0 , to reduction of capacities of photocells before values (241– 233) pF under inverse tensions (0,22–0,96) V, reduction of the current of the short circuit of photocells and to increase their photovoltage that connected with formation fine insulator film on n-GaAs under air annealing of structures n-n+-GaAs-AuGe.

Abstract Composites based on several biocompatible inorganic compounds present oneself a class of promising materials that can be used to repair damaged areas of hard tissue. Development of these composites and their bioactivity establishing is paid a significant attention. Investigation of processes occurring at composite powder materials soaking based on poorly crystallized carbonate substituted hydroxyapatite and calcium silicate hydrate in Tris-buffer was performed in this work. Chemical composition analysis of solutions contacted with composites with varying calcium phosphate and calcium silicate contents was carried out. Examination of undissolved solid phases was performed by SEM, FTIR and LDA. The obtained results indicate that materials components gradually dissolve in Tris-buffer. Moreover, the samples resorption rate increases with the growth of calcium silicate hydrate content in materials composition. Precipitation of the apatite was repeatedly detected in experimental conditions; it designates a potentially high bioactivity of investigated synthetic mixtures.