Crack formation dynamics investigation of in a solid body under the surfactant influence

A method for estimating crack formation in a solid is proposed. The necessity the crack formation dynamics investigation is substantiated. Based on the Rebinder effect, a method for controlling the cracking nature using surfactants is proposed. The destruction by impact and explosion of samples pre-treated with water and surfactant is considered. It is established that pre-treatment of glass plates with surfactant solution shows a more uniform cracks distribution on impact, which may be the basis for the assumption that the surfactants use in blasting will significantly improve the crushing quality and reduce the oversized fractions yield. When examining the samples, which were saturated with surfactant solution, it is seen that the cracks system only increased after the explosion, small cracks appeared, which connect large ones. In the case of water use, we also see an increase in cracking, but it is not as intense and uniform as in the case of surfactants previous use. This result also confirms the fact that the pre-saturation of the medium with a surfactant solution before the pulse loads contributes to a more uniform crushing in the future and provides a basis for experiments on three-dimensional models in this direction.

Experimental research of shipbuilding steels at cathodic polarization

С целью определения корректных значений защитного потенциала, указываемых в системах катодной защиты морских судов и сооружений наложенным током для предотвращения локальных коррозионно-механических разрушений разработана методика определения потенциала корпусных сталей в отсутствии поверхностной пленки при катодной поляризации. Полученные значения потенциала могут быть рекомендованы для использования как защитного в системах катодной защиты, обеспечивая потенциал незаряженной поверхности стали, в том числе и на поверхности без оксидной пленки. В результате происходит подавление процесса адсорбции анионов и катионов; предотвращение процесса растрескивания стали; стабилизация процесса катодной поляризации при потенциале незаряженной поверхности, когда на поверхности стали заторможена электростатическая адсорбция и не наблюдается эффект Ребиндера. In order to determine the correct values of the protective potential indicated in the cathodic protection of marine vessels and structures by applied current to prevent local corrosion and mechanical damage, a method has been developed for determining the potential of hull steels during cathodic polarization on a surface without an oxide film. The obtained potential values can be recommended for use as protective in cathodic protection, providing the potential of an uncharged steel surface, including on a surface without an oxide film. As a result, the process of anions and cations adsorption is suppressed; prevention of steel cracking; stabilization of the cathodic polarization process at the potential of an uncharged surface, when electrostatic adsorption is inhibited on the steel surface and the Rebinder effect is not observed.

ENERGYEFFICIENT EQUIPMENT FOR DEHYDRATION THERMOBILE MATERIALS

The article substantiates the relevance of processing thermolabile materials into dried foods, as one of the alternative options for fresh fruits and vegetables. It is noted that drying, as a method of conservation, is characterized by high energy intensity and increased requirements for the quality and safety of the final product. The naturalness of the dried products and the environmental cleanliness of the process come to the fore. The criteria of quality and efficiency of the process are combined into a single task: increasing the efficiency of the drying process and creating energy-efficient equipment. The analysis of heat and mass transfer during convective drying allowed us to establish methods and ways to improve the energy efficiency of the process. Based on a synthesis of theoretical and experimental studies, the optimal heat and humidity parameters of dehydration were determined, according to which the temperature of the material during drying does not exceed the maximum permissible value. This contributes to the preservation of valuable nutrients in the final product. Prevention of excess material temperature above the acceptable level is confirmed by the nature of the change in the numerical value of the Rebinder effect and is provided by drying in multi-stage dehydration modes, including high-temperature high-moisture method using zone drying installations of tunnel and belt type, as well as heat-pump drying installations with low heat consumption. It was emphasized that the drying of thermolabile materials is carried out in an environment of pure hot air without the use of inert and chemically synthesized substances. Non-contact air heating is carried out using traditional fuels as well as secondary and renewable energy sources. It is noted that the design features of the drying equipment make it possible to distribute the intensity of the thermal effect on the material, depending on its moisture content into zones, and also automatically maintain and control these parameters for a specific type of raw material. The adopted recirculation system of the drying agent helps prevent emissions of waste coolant and reduces thermal pollution of the environment.