The methodology and results of studying the main weathering processes of oil spilled in the marine environment are presented in this paper. Evaporation, dissolution, emulsification and natural dispersion were considered. The influence of oil weathering processes on the selection of oil spill response method (mechanical, physicochemical, or thermal) was estimated. The tests were carried out using various oil samples recovered in the Russian Federation taking into account the hydrometeorological conditions of the seas located in temperate latitudes. The low significance of natural dispersion for the fate of oil spill was established (especially under conditions of calm sea state and in the case of bituminous superviscous oil). Evaporation and emulsification were confirmed to be the most important oil weathering processes from the point of view of selecting an oil spill response method. The physicochemical properties of oil can change dramatically during these processes. It was shown that the evaporation losses for light low-viscosity oil were much greater than those for bituminous superviscous oil. This was reflected in the density and dynamic viscosity of the resulting residues. It was noted that evaporation of a significant proportion of light oil fractions can negatively affect the effectiveness of dispersant application and in situ burning. A high tendency to be emulsified (regardless of conditions) was revealed for bituminous superviscous oil. This led to obtaining emulsions with very high water content and dynamic viscosity. The necessity to take into account the physicochemical properties of residues formed as a result of oil evaporation and emulsification on the water surface when selecting oil spill response method or oil spill modeling method was noted. The compounds (alkanes, cycloalkanes, aromatic hydrocarbons and organic sulfides) capable of changing water toxicological characteristics were registered in the water samples taken after tests of studying the oil dissolution process.

UV-visible spectrophotometry is one of the methods widely used in pharmaceutical analysis. Difficulties that arise when analyzing systems containing components with overlapping absorption spectra can be overcome by differentiating the spectral data. In accordance with the principles of «green» analytical chemistry, the use of derivative spectrophotometry (DSP) in routine analysis is environmentally safer and more cost-effective than chromatography. The paper presents the results of assessing the possibility of determining papaverine hydrochloride (PPH) and dibazole (bendazole hydrochloride, BDH) without preliminary separation by the first-order DSP method at «zero-crossing». The zero-order absorption spectra of hydrochloric acid solutions of PPH and BDH and their first derivatives were studied, obtained using spectrophotometer software when scanning through 0.1, 0.2, 0.5, and 1.0 nm and differentiation (Δλ) from 1 to 80 nm. The influence of Δλ on the shape, dA/dλ values, position of extrema and «zero-crossing» with the wavelength axis of the derivative spectra has been established. The optimal differentiation parameters were determined for analysis of binary mixture: scanning the absorption spectrum through 0.2 nm, Δλ = 2 nm, scaling factor — 100. Analytical wavelengths at which the concentrations of components are directly proportional to the dA/dλ value were 247.2 and 212.6 nm for PPH and BDH respectively. The method was tested on model solutions; the accuracy of determination varied for BDH — from 97 to 105%, for PPH — from 96 to 103%. A simple and easily implemented method for determining PPH and BDH in one unit of dosage form has been developed, with the help of which «Papazol» tablets from two domestic manufacturers were analyzed. The relative standard deviation of the analysis results does not exceed 0.04. Checking the correctness of the methodology, carried out using the Vierordt method, confirmed the absence of systematic error.

Measurement of magnetic parameters is a method for express product quality control in processing of WC-Co tool hardmetals. The coercivity value is often used to estimate the WC grain size and the hardness of the hardmetal, whereas the nature of the WC grain size distribution is often disregarded. H_C – HV properties of WC-Co hardmetals with different microstructures were studied. For production samples of WC – 10 % Co hardmetals, it is shown that H_C does not depend on the width of the WC grain distribution and is a function of the average size d_1.0. The hardness HV30, which is affected by the width of the WC grain distribution, is a function of the d_3.2 value. Based on the obtained relations, a H_C – HV property map is plotted, taking into account the width of the WC grain size distribution. The map shows that measuring only the coercivity value will introduce uncertainty in the estimated hardness in the 100 – 120 HV range. However, joint measurement of H_C and HV makes it possible to estimate the width of the WC grain size distribution in the hardmetal. Based on the analysis of experimental hardmetal samples with a carbon content near the lower boundary of the carbon window and sintered at a relatively low temperature, the formation of an unusual structure was observed featuring the uniformly distributed large cobalt lakes. In such a structure, the size distribution of Co lakes is bimodal and the average size of the lakes is not proportional to the average size of WC grains. Moreover the formation of such a structure does not affect the hardness of the hardmetal, but leads to a significant decrease in the coercivity. The results obtained can be used for industrial inspection of the WC-Co hardmetals properties, as well as in the interpretation of experimental data.

Diffusible hydrogen (DH) in metals is a part of dissolved hydrogen with high diffusion mobility. It is the main cause of cold cracking of welds and deposited metal. The paper presents the results of technological testing of DH in steels. It has been found that due to low maximum permissible concentrations in high-strength steels, the measurement methods verified for weld metal may give multiple measurement errors. A DH measurement technique is proposed based on the vacuum heating method with mass spectrometric measurement of hydrogen flow from the sample during its analysis. It is proposed to separate the flows of DH and more strongly bound hydrogen during vacuum extraction from the sample using the extraction curve. It is shown that good convergence of results is observed when using this technique, and the measurement time can be significantly reduced compared to the recommendations of standards for weld metal. Based on the comparison of experimental data and standard requirements, it was found that the DH activation energy is no more than 0.3 eV. The extraction time of DH at a fixed analysis temperature depends significantly on the size of the steel sample from which hydrogen is extracted. This does not allow using only the extraction time and temperature when separating DH from bound hydrogen, as recommended by many existing methods for measuring the mass fraction of DH. The obtained results can be used in technological testing of DH in steels.

The mechanism and kinetics of surface layer destruction during friction, as well as tribotechnical characteristics (level of surface destruction, friction coefficient, ultimate load-bearing capacity) depend on the structure, phase composition and properties of the surface operational layer, which are formed as a result of intense contact elastic-plastic deformation. The paper presents the results of assessing the conditions of the surface layer performance during friction of structural steels and alloys subjected to nitriding. A tribological criterion for the quality of the surface nitrided layer has been developed, an integrated approach to assessing the tribological efficiency of chemical-thermal treatment of structural steels and alloys has been proposed. The studies of the nitrided surface included the following stages: 1) based on the developed tribological criterion containing micro- and macroscopic characteristics of the material of the contact deformation zone during friction, the choice of its processing modes to ensure an acceptable level of surface destruction under test conditions of a heavily loaded mating; 2) using the surface plastic deformation method, assessing the ability of the nitrided layer (formed as a result of processing according to the selected mode) to perceive surface plastic deformation without destruction, which serves as a justification for the modes of chemical-thermal treatment; 3) assessing the ultimate performance of the nitrided surface layer under friction and wear conditions (maximum permissible (at which the pair operates stably) and critical (after which the pair is inoperative, but its operation is possible under short-term overloads) pressures, the average total wear intensity of the sliding friction pair in contact under load as a whole, and friction losses). The results obtained can be used to optimize the technological process of chemical-thermal treatment of tribotechnical parts.

The techniques to measure elastic modulus and shear modulus of a material in bending tests are studied and improved. Assuming specimen has a symmetry plane and a material is homogeneous and isotropic (ice, ceramics, alloys, and dispersion-filled composites with metallic, ceramic or polymer matrices and so on) we examine the manifold of features and peculiarities of bending tests, the factors influencing force – deflection curve and moduli values extracted from its linear part, we examine error sources and capabilities to minimize them and to extend the feasibility range of bending tests. We analyze the theoretic force-deflection curve obtained in three-point bending test in the symmetry plane of a specimen and its dependence on the ratio l of a specimen to the height of its cross-section (of arbitrary shape) taking into account the influence of shear stress and strain on a beam deflection (it is significant for beams with l < 10). The analytical estimate of the systematic error of the standard method for elastic modulus evaluation, which does not account for shear deformations, is obtained as a function of a beam span l and its cross-section shape and size. It is shown that the error depends on the Poisson ratio rather than on shear modulus. For materials with a positive Poisson’s ratio, the error is 11 – 15 % for beams with l = 5 and about 5 % for beams with l = 10. For materials with a negative Poisson’s ratio, the error is significantly lower. The new accurate explicit formulas are derived for simple calculation of elastic modulus, shear modulus, and Poisson’s ratio of the material based on two tests with different span l, eliminating the systematic error of the standard method. The formula for elastic modulus is independent of specific shape and size of a specimen’s cross-section and require only seven arithmetic operations. The applicability and high accuracy of the new formula for the effective longitudinal elastic modulus of fibrous and layered composites are demonstrated using bending test data of three structurally different composites with varying degrees of anisotropy (unidirectional carbon fiber-reinforced plastic, woven carbon fiber-reinforced plastic, and woven glass fiber-reinforced plastic with a fiber volume fraction of 61 – 63 %). The error didn’t exceed 2 – 4 % in any case.

In order to apply the standard ply-by-ply method for calculation of composite structures, a complete set of elastic characteristics of the material must be determined, which involves a lot of methodological difficulties. In the present work some methods of elastic constants approximate estimations for composite monolayers and symmetric pairs of layers, used, in particular, for creation of pressure vessels, are considered. The error of restoring the material elastic constants on the basis of the known larger Young’s modulus is determined. It was found that this error, in addition to the degree of composite anisotropy, is significantly influenced by the variation of experimental data in the used sample of composites of this class (carbon fiber-reinforced plastics (CFRP), glass fiber-reinforced plastics (GFRP) or organic fiber-reinforced plastics (OFRP)), which should be taken into account in the calculations. These conclusions are illustrated on verification stress computations in the ply pairs of a composite wound pressure vessel. A comparison of the results of ply-by-ply calculations using the full set of elastic constants and using an approximate estimation of the elastic constants via elastic modulus transformation invariants is presented. It is shown that for strongly anisotropic composite materials such as carbon fiber-reinforced plastics, in which the modulus along the fibers significantly exceeds the other elastic constants, approximate methods make it possible to carry out calculations of composite structures with acceptable accuracy without resorting to complicated computational procedures.

To ensure the reliability of structural elements made of polymer composite materials operating under vibration conditions, it is necessary to have data on their resistance to destruction for a reason of high-cycle fatigue. The traditional approach to determining the fatigue strength characteristics of materials involves long-term expensive tests. The infrared thermography method for express estimation of the fatigue limit was actively developed in recent years. The method is based on the use of self-heating of the material under cyclic loads exceeding the fatigue limit. The purpose of this work is to develop, within the framework of the infrared thermography method, a technique for experimental rapid assessment of the fatigue limit of polymer composite materials using the example of laminated carbon fiber, substantiation of the choice of controlled parameters of the thermal state of samples and processing of the results. The technique was developed using the example of laminated carbon fiber. Standard samples were subjected to block cyclic loading in the «tension-tension» cycle on the resonance testing machine. The surface temperature of the samples was recorded during loading using a precision infrared camera. Four variants of processing the test results were compared. The first two options are based on the use of the maximum and averaged stabilization temperature over the sample surface in the loading blocks. The third and fourth options are based on the use of increase of the maximum and averaged temperature at the beginning of the loading block. The estimates of the fatigue limit obtained by named four variants of the thermogram processing method are in agree with each other and with the results of standard fatigue tests. The use of the infrared thermography method makes it possible to significantly reduce the number of tested samples, the labor intensity and duration of work compared with standard fatigue tests. This allows us to recommend the described methodology for obtaining an express estimation of the fatigue limit at the stage of development of products made of composite materials when choosing design and technological solutions.