Effect Of Mechanical Activation Research Articles

The effect of cobalt content and mechanical activation on combustion in the Ni + Al + Co system

The effect of mechanical activation (MA) and cobalt content on the combustion velocity and maximum combustion temperature, elongation of samples during synthesis, the size of composite particles of the mixture after MA, phase composition and morphology of combustion products in the Ni + Al + Co system is investigated in this work. Activation of the Ni + Al + xCo mixture allowed the samples to burn at room temperature, with a cobalt content of up to 50 wt. %. An increase in the cobalt content in Ni + Al + xCo mixtures led to a decrease in the size of composite particles after MA, elongation of product samples and the maximum synthesis temperature. After MA, the elongation of the product samples and combustion velocity increased many times, the maximum synthesis temperature increased. With an increase in the cobalt content in the Ni + Al + Co mixture, combustion velocity first increases (at 10% Co), then decreases. Solid solutions based on NiAl and Ni3Al intermetallides were synthesized by the SHS method.

ВЛИЯНИЕ ПРОДОЛЖИТЕЛЬНОСТИ МЕХАНИЧЕСКОЙ АКТИВАЦИИ МЕТАЛЛИЧЕСКИХ ПОРОШКОВ ПРИ ИХ СМЕШИВАНИИ НА ПРОЧНОСТЬ ПЛАЗМЕННОГО ПОКРЫТИЯ

The article considers the effect of the duration of mixing the components of the FeCoCrAlTiCuMo coating in a special mixer-activator on the strength of the resulting coating. Indirect confirmation of the effect of mechanical activation during mixing on the formation of the plasma coating was obtained and a rational mixing time was determined. Based on the data obtained, it is possible to judge the possibility of creating a HES coating by mixing the components in an inert atmosphere, which allows increasing the strength of the coating by more than 2 times, in comparison with mixing powders by the traditional method in an air atmosphere.

Mechanical (ball milling) activation to regulate microstructure of κ-carrageenan and improve freeze-thaw stability of κ-carrageenan gels and κ-carrageenan-based emulsion gels

To expand the wide range of applications of κ-carrageenan in the food and biomedical fields, we have physically modified the carrageenan and focused on its freeze-thaw stability. In this study, κ-carrageenan (KC) was modified by mechanically activated to prepare wet ball milling κ-carrageenan (WMKC), and its properties were determined. The research results indicate that mechanical activation helps improve the freeze-thaw stability of KC gels and enables KC to better maintain its gel network structure during the freeze-thaw process. These phenomena are related to the effects of mechanical activation on the particle morphology, molecular structure, molecular interactions, and moisture migration of κ-carrageenan. The particle morphology images demonstrated that the WMKC particles exhibited a more irregular surface, which facilitated greater penetration of water molecules into the interior of the κ-carrageenan particles. Furthermore, the results of molecular structure and molecular interaction analyses showed that mechanical activation resulted in the removal of sulfate groups from the κ-carrageenan molecular chain. This resulted in more free -OH being exposed on the molecular chain, which in turn provided more binding sites for KC molecules with water molecules. Low-field nuclear magnetic resonance (LF-NMR) results also proved that WMKC could better maintain the binding with water molecules during the freeze-thaw process. A better combination of WMKC molecules and water molecules can significantly diminish the irreversible damage to the gel network structure of WMKC during the freeze-thaw process, thereby effectively enhancing the freeze-thaw stability of WMKC. In addition, we further used WMKC as the gel matrix and investigated that the freeze-thaw stability of the WMKC-based emulsion gel was optimal when the mechanical activation duration was 3h, which well meets the demand of κ-carrageenan emulsion gels in the frozen food industry.

Synthesis of high purity Ti2AlC MAX phase by combustion method through thermal explosion mode: Optimization of process parameters & evaluation of microstructure

Obtaining high-purity MAX-phase powders is a challenging issue. Therefore, in this article, the effects of two key parameters, including mechanical activation time (1, 2, and 3 h), and preheating temperature (800 and 1000 °C) were investigated on the formation mechanism of Ti2AlC MAX phase using mechanically activated (assisted) self-propagating high-temperature synthesis (MA-SHS) combustion method through thermal explosion mode. For this aim, a powder mixture of titanium, aluminum, and carbon with a stoichiometry ratio of (2:1:1) was used. Differential thermal analysis (DTA) was carried out to evaluate the effect of mechanical activation and preheating temperature of the formation temperature of the target MAX phase. Subsequently, the microstructural, phase analysis, chemical composition, and determination of surface chemical states studies were carried out through scanning electron microscopy (SEM), X-ray energy distribution spectroscopy (EDS) transmission electron microscopy (TEM), X-ray diffraction analysis (XRD), and X-ray photoelectric spectroscopy (XPS), respectively. DTA results illustrated that applying mechanical activation alters the formation temperature, which leads to an increase in the purity of the MAX phase. The quantitative measurements were carried out using the Rietveld method to determine the purity of the achieved MAX phase. The results indicated that samples subjected to 2 h of mechanical activation at a preheat temperature of 1000 °C exhibited to contain 96.1 % of Ti2AlC MAX phase, which is the highest value among other specimens and the lowest amount of secondary and oxide phases (3.9 % of TiC) during the combustion synthesis process compared to other samples.

INFLUENCE OF MECHANICAL ACTIVATION ON THE PROPERTIES OF CEMENT-WATER COMPOSITIONS WITH THE ADDITION OF GROUND LIMESTONE

The paper considers the issue related to determining the effect of mechanical activation of a mineral binder on the properties of both hardening and hardened cement-water compositions. The mechanical activation of cement in combination with the consumption of ground limestone, the amount of which was adjusted in the range from 0 to 40 % of the cement mass, is relevant for this study. The effect of mechanical chemical activation of Portland cement only and Portland cement with the addition of 20 and 40 % ground limestone on changing the water-solid ratio of equiviscous compositions was studied. It was shown that mechanical and chemical activation of a cement-water composition has a positive effect on reducing the W/S ratio of equiviscous compositions from 0.42 (no activation) to 0.38 (activation period 180 sec). The obtained experimental results indicate the presence of an induction period of heating of the cement paste both on Portland cement not subject to mechanical activation (this period is approximately 6 hours from the moment of interaction of cement with water) and on Portland cement subject to mechanical activation. In this case, the induction period was no more than 2 hours. Joint mechanical activation of an aqueous mixture of Portland cement and ground limestone ensures acceleration of the hydration processes of the binder, which is confirmed by the intensification of the exothermic heating of the filled cement-mixing compositions. The positive role of mechanical activation is also reflected in the acceleration of the thickening rate of the compositions, which was recorded by the kinetics of the decrease in the diameter of their spread over time. The positive role of mechanical activation in reducing the effective viscosity of cement-containing compositions is confirmed, which ensures a decrease in their water-solid ratio by an average of ‒ 8 ... 10 %. A positive effect of mechanochemical activation of Portland cement with the addition of ground limestone on the strength of cement stone at the age of 3 days has been revealed. Experimental studies indicate that only due to mechanical activation the strength of samples made of cement stone with the addition of ground limestone can be increased by almost 25...30 %.

МЕХАНОАКТИВАЦІЯ ПОРТЛАНДЦЕМЕНТУ ТА ЇЇ ВПЛИВ НА ВЛАСТИВОСТІ БУДІВЕЛЬНИХ КОМПОЗИЦІЙ РІЗНОГО ПРИЗНАЧЕННЯ

The issues considered in the article are related to determining the effect of mechanical activation on the properties of cement-water compositions and building mortars based on them. The activation of cement in combination with the use of ground quartz sand and the superplasticizer Relaxol-Super PC is relevant for this study. The amount of quartz sand was adjusted in the range from 0 to 40% of the cement mass, and the superplasticizer (0,15 – 1,5%) of the binder mass. The use of this technology ensures acceleration of cement hydration processes, maintaining the required level of composition mobility with a lower consumption of mixing water, and intensification of exothermic heating. The presented experimental data made it possible to evaluate the effect of the binder activation period and the superplasticizer consumption on the flow of the aqueous cement-containing composition. It was found that the main contribution to the decrease in the water-solid ratio (provided that equiviscous compositions are obtained) is achieved by activating the cement-containing composition for 180 sec. with the addition of 1,5% superplasticizing additive. The water-solid ratio decreases by more than 50%. A further increase in the amount of plasticizer has low efficiency and has little effect on decreasing the water-solid ratio. Activation in combination with reduced water hardening of the cement-water composition contributes to both an increase in the heating intensity and an increase in its maximum temperature. After activation, the maximum temperature increased by 5-11% compared to the non-activated cement-water composition. The peak of the exothermic reaction for the mechanically activated cement-water composition occurs 3 hours earlier compared to the non-activated mixture. The increase in the strength of the mortar on mechanically activated cement with the addition of a superplasticizing additive reached 71% compared to the control.

Role of Mechanical Activation in Enhancing Li and Co Recovery from Spent Li-ion Batteries through Citric Acid Leaching

This study investigates the effect of mechanical activation parameters such as mechanical activation rotation speed (0-550 rpm), mechanical activation time (15-75 min), and solid/ball ratio (1/20-1/50) on the leaching efficiencies in the recycling of lithium-ion batteries. In addition to mechanical activation, the study explores the use of organic acids, specifically citric acid, as leaching agents to enhance metal recovery. A green and innovative recycling process is developed, focusing on optimal conditions of 15 minutes activation time, 450 rpm rotational speed, and a 1/20 solid/ball ratio. The synergistic effect of mechanical activation and organic acid leaching is examined to optimize the process for sustainability and efficiency in recovering valuable metals from lithium-ion batteries. Results indicate that these parameters significantly influence leaching efficiencies, with the highest yields achieved under the identified conditions. This research contributes to advancing sustainable practices in battery recycling by integrating mechanical activation and organic acid leaching as effective and environmentally friendly approaches. The findings highlight the potential of these methods in advancing green technology and materials science, paving the way for more efficient and eco-friendly battery recycling processes.

The Al2O3–ZrB2 Nanocomposite Synthesis using Mechanically Assisted SHS: The Effects of Mechanical Activation and Al2O3 Diluent

The Al2O3–ZrB2 Nanocomposite Synthesis using Mechanically Assisted SHS: The Effects of Mechanical Activation and Al2O3 Diluent

The Effect of Mechanical Activation on Some Soil Properties and Plant Development

The Effect of Mechanical Activation on Some Soil Properties and Plant Development

Pyrometallurgical Approach to Extracting Valuable Metals from a Combination of Diverse Li-Ion Batteries' Black Mass.

Li-ion batteries (LIBs) are widely used nowadays. Because of their limited lifetimes and resource constraints in manufacturing them, it is essential to develop effective recycling routes to recover their valuable elements. This study focuses on the pyrometallurgical recycling of black mass (BM) from a mixture of different LIBs. In this study, the high-temperature behavior of two types of mixed BM is initially examined. Subsequently, the effect of mechanical activation on the BM reduction kinetics is investigated. Finally, hematite is added to the BM to first be reduced by the excess graphite in the BM and second to form an Fe-based alloy containing Co and Ni. This study demonstrates that mechanical activation does not necessarily affect the kinetics of BM high-temperature behavior. Furthermore, it demonstrates that alloy-making by the addition of hematite is a successful method to simultaneously utilize the graphite in the BM and recover Co and Ni, regardless of the LIB type.

Investigation of the effect of mechanical activation on nickel and cobalt extraction from laterite at atmospheric pressure by kinetics and leach residue analysis

ABSTRACT Nickel and cobalt extraction from laterite has been studied for years but has not been investigated enough by leach residue analysis. Also, the kinetic approach and leach residue analysis become important when mechanical activation improves nickel and cobalt extraction. Various kinetic assumptions were applied to understand the dissolution behaviour of Ni, Co, and Fe. The ore was activated mechanically in a planetary ball mill as a pre-treatment. The effects of liquid-to-solid ratio, acid ratio, leaching time, and temperature on the leaching of non-activated ore were studied to fix the parameters for the leaching of pre-treated ore. Leaching efficiencies of activated ore for 15 and 60 min exhibited better results at lower temperatures and shorter times than non-activated ore. Nickel extraction has 70% efficiency for 5 min leaching at 95°C in mechanically activated ore. Besides higher dissolution efficiency, apparent activation energy (Ea) decreased. Dissolution of metals from non-activated and activated ore was found to be mixed-controlled. Two different diffusion-controlled mechanisms that differ in the diffusion coefficient-time relationship were detected. An analysis of leach residue supported this finding.

METHODS OF INFLUENCE ON THE SYSTEM TO CHANGE THE ENERGY STATE OF SUBSTANCE: EXPERIENCE, STATE OF THE ISSUE

Methods of influencing the system, the ultimate goal of which is to destruct the natural structure of the material, can be divided as mechanical, physical, chemical, biological and complex. The changing the energy state of a substance is called activation. The current scientific field of ultradispersed materials and physical and chemical processes caused by dispersion is created by the researches of many scientists. Detailed consideration for the increasing reactivity of a solid substance compared to the change in its specific surface area during its mechanical activation showed that the share attributable to the growth of the specific surface area is only a few percent of the mechanical activation effect. The other part is due to the accumulation of defects in the crystals during the grinding process. According to the law of conservation of energy, when a crystal splits, the potential energy of interaction between lattice nodes is transferred to uncompensated surface energy. In addition, the value of the specific surface energy depends on the type of flat lattice used to split the crystal. Therefore, the activation processes and the application of the substance in the active state are relevant in the development of modern binders and concretes. The purpose of the article is to analyse the advantages and disadvantages of the existing methods of influencing the system with the ultimate goal of destruction of the natural structure of the material to changing the energy state of the substance, i.e. its activation. Conclusions. During the destruction of solids, the formation of new cleavage surfaces is accompanied by the breaking of bonds between the substance structural elements and the transition of the potential bond energy into surface energy. Ceteris paribus, the higher the ionic charges and the smaller the distance between them (between adjacent flat grids in the lattice), the greater the value of σ. In addition, the value of the specific surface energy depends on the type of flat grids used to split the crystal. It is worth mentioning that not all methods of activation for binder and concrete (soluble) mixtures are currently implemented on an i industry level. This is due to various reasons. The main method of activation used on an industry level is mechanochemical activation in various types of mills.

Safe and environmentally friendly use of coal gangue in C30 concrete

Industrial solid waste coal gangue (CG) is used as the research object, and the mechanical activation-water washing pretreatment method was used to explore the feasibility of carbon removal by water washing and the improvement and microscopic mechanism of the treatment process on the cementitious activity of CG. The mechanism and effect of mechanical activation + water washing carbon removal were analyzed by loss on ignition, TG-DSC and heat release of floats. The calorific value of floats was 17.58 MJ/kg (5 min) and 11.18 MJ/kg (20 min), which could be used as coal products. It was found that the compressive and flexural strength of 5 min mechanical activation-water washing cementitious materials reached 30.3 MPa and 4.97 MPa. The concrete was prepared and the mechanical properties test and SEM, XRD, FTIR were carried out to study the microscopic hydration mechanism of the cementitious system. It was found that the replacement rate of CG was inversely proportional to the mechanical properties of concrete, and was proportional to the durability of concrete first and then inversely proportional, mainly because the incorporation of CG reduced the alkalinity of the system and affected the hydration reaction. Using the life cycle method, it is found that the carbon emissions of CG-based cementitious system are significantly lower than those of cement cementitious materials, which proves that the use of CG in the construction industry is a feasible way of low-carbon energy conservation and emission reduction.

Effect of mechanical activation on hydration properties of natural volcanic rock towards partially replacing cement in composite cementitious materials

With the rapid increase in the consumption of various mineral admixtures, using regional distinctive raw materials to prepare cement mineral admixtures is an effective approach to achieve green and sustainable development. In this paper, the natural volcanic rocks (NVR) in Western Sichuan are mechanically activated at different times, subsequently, the ion dissolution characteristics of NVR powder at different activation times and the hydration mechanism of NVR powder composite cementitious material are studied. In a simulated alkaline environment of cementitious liquid phase, based on the dissolution behavior of Si4+, Al3+, and Ca2+ ions in NVR powder and the morphological analysis of NVR powder before and after dissolution, it is indicated that SiO2 and Al2O3 are the primary sources of reactivity in NVR powder and the reduction in particle size promotes the breakage of Si–O and Al–O bonds in NVR powder. Analysis of the hydration process, mineral composition of hydration products, and their microscopic morphology reveals that an appropriate amount (15 %) of NVR powder, after 45 min of mechanical activation, can promote the generation of hydration products and denser mortar structure, enhancing the strength of the composite cementitious material. Mainly attributed to the increased volcanic ash activity of NVR powder through mechanical activation, as well as the nucleation induction and filling effects of NVR powder. This study provides theoretical and technical supports for the efficient use of raw materials with regional characteristics to prepare mineral admixtures.

Investigation of Raman spectra and ionic conductivity of composites based on NaClO4 and KClO4 salts obtained by mechanoactivation

The work is aimed at studying the effect of mechanical activation on the structure and electrical conductivity of the NaClO4 – and KClO4 – basedcomposites. Based on the result of the analysis of the DSC curves of the (1–x) NaClO4 – x Al2O3 and (1–x) KClO4 – x Al2O3 composites measured while heating and cooling the samples, it was established that the enthalpy of phase transitions in them decreased with an increase in the concentration of the nanosized dopant. A complication of all active vibrational contours corresponding to internal vibrations of the molecular anion in the composites with increasing Al2O3 concentration and a shift of the band of the fully symmetric stretching vibration v1 (A) to a low-frequency region was revealed by Raman spectroscopy. Based on electrochemical impedance spectroscopy data, it was determined that for the 0.4NaClO4 – 0.6Al2O3 system subjected to mechanoactivation, the values of specific ionic conductivity increased by two orders of magnitude as compared to that of pure NaClO4, while for the 0.4KClO4 – 0.6Al2O3 system, the values of specific ionic conductivity increased by three orders of magnitude as compared to the initial salt at T = 320 °C.

The effects of mechanical activation on corrosion resistance of cordierite ceramics

The corrosion degrees of produced non-activated and activated cordierite-based ceramics were investigated in hydrochloric and sulfuric acid solutions. The composition of talc, alumina, and kaolinite powders was mechanically activated in a planetary mill. The concentrations of aluminum, magnesium, silicon, calcium, and potassium leached to the acid solutions from non-activated and activated cordierites were measured using ICP-OES. The amorphization of the structures was examined by XRD analysis. As a result, it has been determined that activated cordierite-based ceramics are more durable, and sulfuric acid solution causes more corrosion than hydrochloric acid.

Вплив механохімічної активації композиційного цементу на міцність будівельного розчину

The article discusses issues related to the use of technology for the production of mortar mixtures and mortars based on high-speed mixers, the operation of which causes mechanochemical activation of the binder. The rotary counterflow mill used in the work acts as an activator of the surface zone of both Portland cement grains and quartz sand grains and, thus, contributes to the intensification of the processes of structure formation of cement paste and mortar based on it. Based on the fact that one of the promising ways to reduce the cost of cement activation is to reduce the energy intensity of the dispersion process itself, the use of relatively low-energy rotary mills can be considered as an effective way to increase the activity of the binder. After the joint activation of Portland cement and unground quartz sand (the amount of which was adjusted from 0 to 50 % of the cement mass; activation period - 300 seconds), samples were made from equal-viscosity cement paste. It was experimentally established that the maximum strength of cement stone at 28 days of age was achieved when using composite cement with a 20 % content of activated sand. To determine the influence of the studied factors, such as the consumption of mechanically activated composite binder, the concentration of superplasticizer C-3 (0...1,5 %) and the consumption of microsilica (0...10 %) on the strength of the mortar in 2 and 28-day old, a 3-factor experiment was conducted. It was established that in the studied hardening period, the content of mechanically activated composite cement has the greatest influence on the compressive strength for the studied mortar compositions (from 1:3 to 1:1). The next most important influence on the strength of the mortar is the consumption of superplasticizer C-3. The increase in compressive strength of a mortar from the introduction of microsilica into its composition does not exceed 10-15 %. The combined effect of mechanical activation of the binder and the use of the C-3 additive ensures an increase in the strength of the mortar (mortar composition 1:1) at 28 days of age from 43,5 MPa (non-activated binder; no C-3 additive) to 63 MPa, that is, almost by 45 %. For a mortar of similar age with a lower consumption of composite cement (mortar composition 1:3), mechanical activation of the binder in the presence of 1,5 % C-3 additive ensures an increase in the compressive strength of the mortar from 21 MPa (non-mechanically activated binder; C-3 = 0 %) to 39 MPa.

Mechanism of Potassium Release from Feldspar by Mechanical Activation in Presence of Additives at Ordinary Temperatures.

To improve the potassium availability of feldspar at ordinary temperatures, the mechanical grinding and addition of sodium hydroxide/salts were employed to study the effects of mechanical activation and strong alkali addition on particle characteristics, water-soluble potassium, and the available potassium of feldspar. A laser particle size analyzer was utilized for the direct determination of particle size distribution (PSD) using ground samples. The Brunauer-Emmett-Teller (BET) method was employed for specific surface areas. X-ray diffraction (XRD) was employed for structural characterization, scanning electron microscopy (SEM) for morphology exploration, and energy dispersive spectroscopy (EDS) to determine the chemical composition of potassium feldspar powder. The results revealed that the mechanical activation of potassium feldspar could reduce the particle size and produce agglomerated nanoparticles in the later period. The addition of NaOH and sodium salt did not cause agglomeration, and NaOH dissolved the nanoparticles. The water-soluble potassium content of feldspar in each treatment increased during mechanical grinding, from 21.64 mg kg-1 to 1495.81 mg·kg-1, by adding NaOH 5% weight of potassium feldspar powder and to 3044.08 mg·kg-1 by adding NaOH 10% weight with effects different from those of mechanical shaking. By comparison, only 162.93 mg·kg-1 water-soluble potassium was obtained by adding NaOH 5% weight. The dissolved potassium in the former case was significantly higher than in the latter, and the addition of NaOH and sodium salts significantly enhanced the water-soluble potassium contents due to ion exchange. Furthermore, the addition of sodium hydroxide improved the water-soluble potassium due to its mechanochemical action on potassium feldspar. The mechanical energy changed the crystal structure of potassium feldspar, explaining the increase in available potassium. The addition of sodium salts did not promote change in the feldspar's structure, thereby did not raise the available potassium content. The reason for this was related to the mechanochemical action on sodium hydroxide and feldspar, which could promote the dissolution of fine particles, thereby incrementing the available potassium.

Effect of Mechanical Activation and Combustion Parameters on SHS Compaction of Titanium Carbide

Effect of Mechanical Activation and Combustion Parameters on SHS Compaction of Titanium Carbide

Reuse and Mechanochemical Processing of Ore Dressing Tailings Used for Extracting Pb and Zn

The increasing accumulation of rock waste obtained due to ore processing and its environmental impacts, such as acid mine drainage and elevated concentrations of heavy metals in soils, necessitates the transformation of mining technologies based on the concept of circular waste management. The research is aimed at improving the parameters of the mechanical activation effect produced on technogenic georesources, as well as at expanding the application scope of disintegrators in the field of using the partial backfill of the mined-out space when developing stratified deposits. In this regard, the research purpose was to substantiate the parameters of extracting metals from enrichment tailings using their mechanochemical activation to ensure cyclic waste management. The research involved the application of three-dimensional interpolation methods used for processing the data and the graphical representation. As a result, the following was found to be characteristic of the waste of the Sadonsky mine management. The degree of extracting zinc from pre-activated tailings increases logarithmically when the H2SO4 concentration and the NaCl proportion decrease 3.5 times. The degree of extracting lead from the activated tailings increases according to the Fourier law when decreasing the NaCl mass concentration, and an optimal range of the H2SO4 (0.38–0.51%) proportion decreases six times. One of the key results of the research is the justification of expanding the scope of applying disintegrators in the case of a directed activation influence exerted on the components of the stowing strips. The obtained results expand the understanding of the mechanism of the influence of the mechanochemical activation of dry tailings on the reactivity unevenness when extracting several metals from them.