No abstract

The article describes the process of liquid-phase shear exfoliation of graphite in a rotary apparatus with moving blades, in water and I-20A oil (Rosneft, Russia) used as a liquid. The linear dependence of the process intensity on the shear rate and graphite concentration in the initial suspension are established in the paper. To increase the share of graphene converted into graphene plates, it has been proposed to reduce periodically the concentration of graphene plates in suspension by adding pure liquid. It was found that the exfoliation rate of graphite is directly proportional to the concentration of graphite in the initial suspension and the rotor speed. The resulting graphene-containing oil-based suspension was used to modify greases.

Исследовано влияние на кинетику процесса эксфолиации графита в стержневой барабанной мельнице следующих параметров: диаметра и скорости вращения барабана; концентрации графита в исходной суспензии. Установлено, что производительность мельницы прямопропорционально зависит от указанных параметров. Предложен экспресс-метод определения концентрации малослойного и многослойного графена в масляных суспензиях. Обоснована перспективность использования барабанных стержневых мельниц для получения графеновых суспензий на основе органических жидкостей в производстве пластичных смазок, модифицированных графеновыми структурами.

Lubricants modified with nanosized particles are of great interest to science and industry, since they have much better tribological characteristics compared to traditional lubricants. One of the most promising nanoparticles is graphene, which has an extremely low coefficient of friction, is very wear-resistant and environmentally friendly. Today, the main problem for the development of a new nano-lubricant is the creation of an environmentally friendly and cheap technology for the industrial production of graphene suspensions or graphene concentrates for the modification of traditional lubricants. The article describes the process of liquid-phase shear exfoliation of graphite in a rotary apparatus with moving blades, in synthetic oils. The kinetic dependences of the exfoliation process, i.e. the dependence of the concentration of graphene nanostructures in suspension over time at different values of the process parameters. It has been experimentally proved that using a stator-rotor mixer with moving blades, it is possible to obtain graphene nanostructure concentrations of at least 2 mg / ml.

Nanoparticles can accelerate cement hydration due to their high activity compacting microstructure, and consequently increase the strength. For the industrial production of concrete modified with nanoscale particles, it is necessary to develop an environmentally friendly and cheap technology for the industrial production of nanoparticles. The article presents the results of increasing the operational characteristics of concrete by adding graphene nanostructures obtained by liquid-phase shear exfoliation of graphite. This environmentally friendly technology requires energy costs, at least ten times less than technologies that use ultrasonic treatment of the suspension. Our industrial partner set a specific task: to find the minimum concentration of graphene structures in relation to cement, at which the compressive strength of cement-sand mix increases by 30%. It was experimentally established that at concentrations of graphene nanostructures with respect to cement not more than 0.02%, the compressive strength increases by at least 30%.

The article considers the calculation of a rotary apparatus with movable blades for the production of graphene-containing suspensions, which are used to modify structural and functional materials with improved performance characteristics. The rationale is given for the expediency of obtaining graphene plates by the method of shear exfoliation of graphite directly in liquids that are part of these materials. The kinetics of the exfoliation process in inorganic and organic liquids has been investigated, and according to the results of the analysis, dependences are proposed for calculating the main operating and geometric parameters of rotary apparatus with movable blades.

A method and device for obtaining graphene-containing suspensions by liquid-phase shear exfoliation of graphite in a continuous mode have been developed. The comparison of the intensities of the process of exfoliation of graphite in the periodic and continuous modes was carried out and it was found that the intensity of the exfoliation process in the continuous mode is higher than in the periodic one. The limiting concentration of graphene structures in a suspension is reached 1.5 times faster when using an apparatus operating in a continuous mode than in a periodic mode, and its numerical value is greater (by at least 25 %).