Aspects of determining the surface activity of dispersed systems based on mineral powders

Shamanina, A. V.; Kononova, V. M.; Danilov, V. E.; Ayzenstadt, A. M.; Frolova, M. A.

doi:10.31044/1684-579x-2021-0-7-30-36

Cited by 3 publications

(4 citation statements)

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“…Поэтому понятен проявляемый интерес исследователей к вопросам, связанным с количественным определением данных параметров. В этом плане в последнее время получили широкое распространение методы, осно-ванные на измерении угла смачивания поверхности рабочими жидкостями (А. Зисмана, ОВРК [11,12,[14][15][16][17]), образованной анализируемыми системами, причем в случае исследования минеральных порошков пробоподготовка включает в себя процесс уплотнения дисперсной системы под избыточной нагрузкой [18]. Кроме того, можно отметить, что измерение краевых углов смачивания позволяет подойти к решению вопросов, связанных с оценкой структурообразующей способности по потенциалу притяжения Ван-Дер-Ваальса и совместимости компонентов смеси с учетом постоянной Гамакера, рассчитываемой по уравнению Дерягина [19][20][21].…”

Section: методические особенности определения удельной поверхностной ...unclassified

“…В работах [13,16,18,21] представлены важные результаты методических подходов при расчете энергетических параметров поверхности порошков (удельной величины поверхностной энергии, числено равной поверхностному натяжению) с использованием метода Оунса-Вендта-Рабеля-Кьельбле при использовании в качестве рабочих жидкостей декана, глицерина и воды, однако учитывая зависимость краевого угла смачивания от шероховатости поверхности (уравнение Венцеля-Дерягина [12]), в настоящее время остается неопределенным фактор выбора величины избыточного усилия прессования исходного порошка в процессе пробоподготовки (данный параметр для большинства работ составляет от 2 до16 тонн).…”

Section: методические особенности определения удельной поверхностной ...unclassified

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Methodological Features of Determination the Specific Surface Energy of Mineral Quartz-Containing Powders

Frolova

2022

Bulletin of Belgorod State Technological University Named After. V. G. Shukhov

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Methods for sample preparation of prototypes for the subsequent determination of the specific surface energy by the Owens, Wendt, Rabel and Kaelble (OWRK) method are worked out on the example of highly dispersed powders of quartz sand, characterized by a SiO2 content of 98.3%. For this purpose, dry grinding in a planetary ball mill disperses the raw material, the mechanical activation time is varied in the range of 15÷45 min. Five fractions of highly dispersed powders are obtained. They are characterized by the specific surface area. This parameter is changed in the following range: 1200÷3000 kg/m2. Prototypes for subsequent research by the OWRK method are made by pressing with a pressing force of 2 to 16 tons. As a criterion for optimizing sample preparation conditions, the coefficient of determination of the functional dependence of the cosine of the wetting angle of the surface of test samples with working fluids (decane, glycerin, water) on the dispersion component of their surface tension is proposed. It has been established that for the quartz sand used, the maximum value of the coefficient of determination (0.94) is noted at a pressing force of fine fractions equal to two tons. An increase in the specific surface area of powder materials over 2370 kg/m2, obtained by mechanical dispersion and an increase in pressing force up to 12÷16 tons, leads to additional errors in determining the surface tension of compacted prototypes by the OWRK method.

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Section: методические особенности определения удельной поверхностной ...unclassified

Methodological Features of Determination the Specific Surface Energy of Mineral Quartz-Containing Powders

Frolova

2022

Bulletin of Belgorod State Technological University Named After. V. G. Shukhov

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“…It is known that the effectiveness of CB depends not only on the nature of the components used, but also on their active ability to participate in the hydration reaction during concrete hardening, forming hydrosilicates of additional generation. In this regard, one of the key factors is the surface activity of the components associated with the preliminary mechanical activation of the raw material to the optimal values of the specific surface area, which provides the maximum possible transition of internal energy of the entire system to surface energy [6][7][8]. These provisions fully apply to the pulverized fraction that is formed when concrete is crushed during its secondary use.…”

Section: Introductionmentioning

confidence: 99%

“…The atomization energy is a macro parameter of the system and is calculated based on the chemical composition of the sample by the values of the enthalpy of formation of its main compounds (in terms of oxides) [19]. The parameter of the fine state of a substance is the free surface energy (ES), which is numerically equal to the product of the specific surface energy of a highly fragmented sample (critical surface tension, σc) and its specific surface area (Ssp) [8] (expression 2):…”

Section: Introductionmentioning

confidence: 99%

Effectiveness Evaluation Criteria of Using Fine Powders of Secondary Concrete as a Component of Composite Binder

Drozdyuk

Ayzenshtadt

Aksenov

2021

MSF

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The paper considers the possibility of using energy criteria (surface activity, free surface energy) to quantify the efficiency of a highly dispersed system consisting of fine particles of secondary concrete as a component of composite binder of the hydration type of hardening. Using the G.A. Zisman method, the value of the critical surface tension was determined for secondary concrete fractions with different degrees of dispersion, which gives an idea of the free surface energy of a surface area unit. Based on the experimental data for determining the specific surface area and critical surface tension, the free surface energy and surface activity of the studied concrete powder were calculated, which can serve as criteria for quantitative energy characteristics of raw materials for the production of composite binders. Calorimetric studies related to measurements of the thermal effects of the hydration reaction of highly dispersed samples of secondary concrete have shown that this process is exothermic, the enthalpy of hydration of which is comparable to a similar parameter for cement. It was experimentally shown that fine powders of secondary concrete are effective as components of a composite binder, but they need to be pre-activated to optimal parameters, one of which is surface activity. In addition, the symbasis of changes in surface activity, the specific heat of the hydration reaction of highly dispersed concrete fractions and the compressive strength of fine-grained concrete samples made by using a composite binder containing a highly dispersed fraction of secondary concrete was established.

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Features of determining the specific surface area of powdered quartz-containing systems

Shamanina

Ayzenshtadt

2022

Vestnik MGSU

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Introduction. Mineral raw materials, mechanically dispersed to a fine-grained condition, contribute to the effective use of the energy potential in the course of the structuring of composite materials. An important parameter, characterizing the dispersion ability and allowing to evaluate the ability of the system to transform is the specific surface of the substance. The experimental value of the specific surface depends on the measurement method and may differ for the same solids when different methods are applied. The purpose of the work is to study the morphological features of the surface of powdered quartz-containing systems having varying degrees of dispersion. The work represents the experimental identification of specific surface. Materials and methods. Filtration and adsorption methods were used to identify the specific surface of a mechanically activated sample of polymineral sand. Fine powders of sand were obtained by dry grinding in a planetary ball mill. The analysis of the obtained results was conducted taking into account the surface tension values of the powders as the characteristics of the surface energy of a surface area unit. Results. It is found that dimensions of the specific surface identified using the gas filtration method are smaller than those obtained using the nitrogen adsorption method. The authors have identified a linear functional dependence between the ratio of dispersion and polarization components of the surface tension and the ratio of specific surfaces obtained using different methods for one sample of sand. Conclusions. Despite a difference in the values obtained for the same material sample, specific surface area indicators, identified using different methods, allow to evaluate the extent of the surface maturity, the availability of active centres, and the energy potential of mineral powders. The ratio of specific surfaces can be used as a criterion for the rational choice of the operating parameters of mechanical activation of quartz-containing powder systems to increase the energy potential of the surface.

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Aspects of determining the surface activity of dispersed systems based on mineral powders

Cited by 3 publications

References 0 publications

Methodological Features of Determination the Specific Surface Energy of Mineral Quartz-Containing Powders

Methodological Features of Determination the Specific Surface Energy of Mineral Quartz-Containing Powders

Effectiveness Evaluation Criteria of Using Fine Powders of Secondary Concrete as a Component of Composite Binder

Features of determining the specific surface area of powdered quartz-containing systems

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