Key Engineering Materials Vol. 910

Abstract: In the presented study, changes in the wettability and corrosion properties of composite coatings formed on the MA8 magnesium alloy by plasma electrolytic oxidation (PEO) with subsequent treatment with organofluorine polymers were investigated after accelerated climatic tests in a salt spray chamber. It was found by the sessile drop method that after accelerated climatic tests the contact angle decreases by 2.5 times for PEO coatings, and by 15o for composite coatings. Evaluation of the electrochemical properties of the composite layers revealed an insignificant decrease in the value of the corrosion current density after 40 days of holding samples in a salt spray chamber.

Abstract: The article presents the results of silicon dioxide leaching from quarry waste dumps with silicon content of 50% and more. NaOH solution was used as a leaching agent and H2SO4 solution as a precipitant. The influence of basic parameters on the leaching process (concentration of leaching agent, operating temperature, ratio of liquid phase to solid phase, stirring speed) and on the precipitation process (concentration of the precipitant and temperature) was investigated. As a result of using the optimal parameters a high efficiency of silica powder production of 98.7 % was achieved. The powder is presented mainly in the form of particle agglomerates. The average particle size is 300-700 nm, the size of agglomerates is more than 700 nm. The structure is predominantly porous.

Abstract: The paper presents the results of research of influence of nanopowders of tungsten compounds obtained from hard-alloy waste on structure formation and kinetics of cement stone strength gain. The positive effect of additives on the mechanical and structural characteristics of the cement stone in the concentration range of 1...5 wt.% has been established.

Abstract: The paper considers principles of creating promising memristive structures based on composite oxides with agglomerates of nanoparticles. The proposed functional nanomaterial is promising for the formation of a composite structure of a memristor, consisting of two electrodes based on one or more nanoscale layers of metal oxides, which are separated by an active medium so that an insulating layer is applied between the electrodes at the periphery of the active medium region. A conductive layer is formed on top of the insulating layer, which is connected to the negative rail, which prevents leakage of negative oxygen ions through the insulating layer. The authors considered in detail technological process of integral production, which forms the necessary vertical profile of the memristive structure ensuring its greatest stability and repeatability of parameters. The implementation of a hardware-software complex for monitoring and diagnosing a memristive structure is proposed. As a result of the research, an original technical solution was created, which ensures formation of memristive structures with a high efficiency of impact on negative oxygen ions, which are charge carriers in this structure, which ensures their high productivity and stability of parameters.

Abstract: In this paper, it is proposed to use modern research AMD-methods to monitor the properties of the subsurface layers of materials subjected to innovative technological treatments. They are based on the analysis of the parameters of acoustic waves reflected from the subsurface layers of the studied materials. The technological processing leads to a change in the acoustic characteristics, the value of which is calculated by the values of the parameters of the material of the samples. The effectiveness of the application of methods of acoustic-microscopic flaw detection for the analysis of the state of materials after thermal, chemical, deformation, and diffusion effects is demonstrated.

Abstract: The article discusses a powdered material - carbidostal. Comparative characteristics of carbidostals, tool steels are given and hard alloys. Methods of producing and producing carbidostals are considered. Conditions for free separation of residues of impregnating material from the surface of the article are established. The reasons of volumetric change of amount of carbides and binding by height of impregnated press are studied.

Abstract: It is of great interest to be able to remove residues of impregnating material from the resulting article in order to reduce the cost of manufacturing such parts. To this end, a thermodynamic calculation allows you to obtain the necessary conditions for obtaining high-quality products.

Abstract: The given study is dedicated to optimization of dispersion-strengthened material based on copper powder of the Cu-Al-C-O system used for valve guides of internal combustion engines. The developed material containing 3 % wt aluminum, 0.6 % wt carbon and not more than 0.02 % wt oxygen has the recrystallization temperature of 1000^оС and exhibits higher tribotechnical properties comparing to the prototype. In particular, the wear out intensity of the developed material is 2.5 times lower. The material production technology is based on the method of reactionary mechanical alloying in the attritor and powder and granular metallurgy technologies.

Abstract: The paper discusses computer modeling of the temperature dependences of the dielectric constant of polymer composite materials. Issues of the combined radio wave and thermal methods of diagnostics of nondestructive inspection of the polymer composite materials in the laboratory conditions are considered. The paper offers a method for combining the measurement and heating processes. This method can be implemented, the way is to do the heating and the measurement at the same frequency with using a high-power sounding wave. As a result, the radiant material heating is obtained, and we judge about the substance parameters and a presence of defects in the substance by a reflected wave in an indirect method. A descriptive characteristic of such a problem boils down to describing all the processes in the sample by the electrodynamic theory. The heating process can also be described by the electrodynamics equations, but the process will be described by the thermal equations in the nonstationary heating conditions in the most accurate way.

Abstract: Equipment, pipelines, hydraulic structures located in the water are covered with a layer of fouling organisms, which is accompanied by a deterioration in operating parameters and increased corrosion of structural materials. Most anti-fouling coatings contain some type of toxins, the gradual release of which from the coating into the water should lead to the death of the fouling organisms. A promising antifouling coating intended for use in an aquatic environment is a combined metal-polymer coating, the composition and application technology of which were developed by the company LLC TSZP. On the studied coating, neither in the zone of variable wettability, nor in the zone of complete immersion, firmly fixed zebra mussels were not found, and single specimens on individual samples had very weak fixation.