Mica Particles Research Articles

Mica/nylon composite nanofiber film based wearable triboelectric sensor for object recognition

The wearable sensors have essential impacts on the progress of intelligent technology, while the traditional sensors cannot meet the sensitivity requirements. Here, we propose a high performance intelligent triboelectric wearable sensor (HITWS) by Mica/Nylon composite nanofiber film (MCNF), which is fabricated by the electrospinning and dielectric particle doping process. The addition of Mica particles effectively improves the dielectric constant, surface charge density and functional group properties of MCNF and further optimizes its positive triboelectric properties. Therefore, the HITWS demonstrates significantly higher signal-to-noise ratio, sensitivity and power density (11.82 W/m2) compared to previous similar studies. Furthermore, based on HITWS, 4-channel STM32 signal acquisition and deep learning algorithm, an intelligent tactile sensing system is achieved. Combined with the structurally optimized VGG16 network model, the recognition of 7 kinds of objects can reach an average accuracy of 96.57 %. This work provides new idea and method for the development of applications based on object recognition, such as remote interaction, medical prosthetics and smart robots.

Surface functionalization of naturally occurring silicate minerals infused hydrocarbon polymer matrix for ultra‐low dielectric performance at high frequency domain

AbstractThe expanding realm of high‐frequency electronics necessitates materials with exceptional attributes: notably, a low dielectric constant (Dk) to minimize signal propagation delays, high thermal conductivity for effective heat dissipation, higher breakdown strength, and robust mechanical properties to withstand demanding operational environments. While cycloolefin copolymers (COC) excel in electrical insulation, chemical resistance, and mechanical durability, their intrinsic slightly higher dielectric constant compared to other polymers, along with challenges such as poor dispersibility and low compatibility with nanoparticles, hinder their full potential in this domain. Considering these drawbacks, this study fabricated a series of COC/mica composites by integrating natural mica particles into the COC matrix via a CTAB‐assisted surface modification of mica to enhance dispersibility and mitigating particle aggregation through in‐situ mixing and hot‐press methods. The resultant composites demonstrate an outstanding ultra‐low Dk of 1.44, marking a significant decrease of over 36% compared to pristine COC with a Dk of 2.26, along with exceptionally low dielectric loss (δ) of 0.00013 at the frequency of 10 GHz, high dielectric breakdown strength ~49.40 kV/mm and enhanced thermal conductivity up to 0.88 W/(m K) at 40% mica loading. Additionally, the composites heightened mechanical performances like tensile strength 69 MPa at 6.5% elongation at break, impact strength up to ~17.9 kJ × m−2, and exceptional water resistance with absorption below 0.097%. These exceptional ultra‐low dielectric performance with above mentioned properties can meet the stringent requirements of modern high‐frequency electronics packaging for next generation electronics development.Highlights Surface modification by CTAB enhanced homogeneous dispersibility of composites. Achieved ultra‐low dielectric constant and loss compared to pure COC. Thermal conductivity improved significantly with incorporation of mica. Unlocking high‐frequency applications potential with ultralow Dk performance.

Corrosion resistance of powder metallurgy fabricated Cu–10Sn/SiC/mica hybrid composite

Abstract For the first time, bronze/SiC/mica hybrid composite has been manufactured using powder metallurgy method. Mixture – process variable design has been applied to design of experiments and optimization of the composite composition, as well as the production process variables (compaction pressure and sintering temperature) to attain superior corrosion resistance. This involved mixing different compositions of bronze, SiC, and mica powders, which were subsequently subjected to varied pressures and temperatures during the pressing and sintering stages, all in accordance with the experimental design plan. The microstructure, chemical composition, and elemental distribution of the samples were examined using scanning electron microscope equipped by energy dispersive X-ray analyzer, and an optical microscope. In order to study the corrosion resistance, potentiodynamic polarization test and electrochemical impedance spectroscopy were performed in 3.5 wt.% NaCl solution. The results revealed that co-incorporation of SiC and mica particles in Cu–10Sn bronze matrix increases the corrosion resistance, with a synergistic effect between these particles. The result of optimization process showed that the highest corrosion resistance could be achieved for the composite with the composition of Cu–10Sn/9.85SiC/0.67mica. This outcome was subsequently validated through experimental procedures.

Potassium Ions Release from Mica by Organic Acids Present in Potassium Solubilizing Bacteria

Plants require a variety of life-building ingredients to grow properly and optimally. Plants that lack essential nutrients are unable to reach their full potential, have lesser yields, and are more susceptible to diseases. The primary macronutrients are nitrogen (N), phosphorus (P), and potassium (K), which are the three most critical nutrients without which plants wouldn‘t survive. Fertilizers must be added to K-depleted soil to produce a feasible soil environment for plant growth. Chemical K fertilizers are costly and cause soil pollution. Bio-fertilizers gaining popularity because of their low harmful effects. In Sri Lanka, new ways of producing Bio K-fertilizer are convenient in the field of agriculture. Phlogopite mica is a natural mineral that contains K as a major component (7.22% of mass as K2O) that can be used as the source of Bio-K fertilizer production. In this research, the solubilization of phlogopite mica (sample was obtained from Matale district, Sri Lanka) by major types of organic acids which are mainly released from bacteria was determined. In this study special attention was paid to the following main factors: Type of organic acids (Citric, Oxalic, Succinic and Tartaric acid), Acid concentrations (0.01 M, 0.02 M, 0.03 M, 0.04 M, and 0.05 M), Effect of ground mica particle sizes (0.300 mm-0.150 mm and <0.150 mm), the effect of time on solubilization in three shaking time intervals (1 hour, 2.5 hours, 4 hours) the indicated solubilization patterns and pH changes were observed. The current findings show that Citric acid is the most efficient K solubilizer because at 0.04 M, citric releases the 17.00 mg/L of K whereas the lowest value of released K 2.33 mg/L was observed for oxalic acid which is determined by Flame Photometer using 50.00 mg/L of standard K+ solution. Therefore, Citric acid has a significant potential for the solubilization of K in mica. When particle size increases, the rate of solubilization appears to decrease with each acid. Also, when shaking time was increased the amount of soluble K released has been increased. Future studies of this research will be extended to find and isolation of citric acid-releasing bacteria for solubilizing mica to produce K Biofertilizer to improve soil fertility thereby increasing the crop yield in Sri Lanka. 
 Keywords: Phlogopite mica, Bioconversion, Bio-fertilizers, Chemical K-fertilizers

Effects of natural mica particle fillers on the mechanical properties of glass fiber/epoxy composite plates

Effects of natural mica particle fillers on the mechanical properties of glass fiber/epoxy composite plates

Engineering geological characterization of micaceous residual soils considering effects of mica content and particle breakage

The engineering geological characteristics of micaceous residual soil (MRS), which is prevalent in subtropical regions, are markedly influenced by the presence and breakage of mica particles. Nevertheless, a comprehensive understanding of the underlying mechanisms responsible for these effects remains elusive. In this study, a series of experimental tests were conducted on two groups of reconstituted MRS samples. These samples were prepared by mixing natural MRS, from which the original mica had been removed, with intact and crushed mica powder, respectively. The aim was to investigate the effect of the mica content and particle breakage on the physical and mechanical properties of MRS. Scanning electron microscopy was employed to scrutinize the microstructural alternations of mica particles at different states of breakage, and a conceptual model was proposed based on the observations. The findings revealed that the presence of mica considerably altered the physical properties of MRS, resulting in higher Atterberg limits but lower plasticity, along with unfavorable mechanical properties, including high compressibility and swelling potential, low compactability, stiffness, strength, and ductility. The microstructural analysis elucidates that these effects stem from the resilient nature of layered mica flakes with high water-retention capacity. On the other hand, the breakage of mica particles changed these effects. The disappearance of interlayered voids following mica particle breakage leads to reduced Atterberg limits and enhanced compaction efficiency of the mixture. Moreover, MRS with a higher proportion of crushed mica exhibited more significant deformation and compression during shearing. This behavior can be attributed to the diminished stiffness of crushed mica and weaker interparticle contacts within the soil matrix. This study provided a multi-scale insight into how mica affected the engineering geological properties of MRS and proposes references for more effectively incorporating of MRS into engineering construction projects.

Design, Fabrication, and Performance Analysis of Fire‐resistant Damping Polyurethane

AbstractTo improve the noise reduction and fire resistance of marine coating materials, some fire‐resistant polyurethane damping materials were prepared by varying the ratio of esterified branched polyols (EBP) and the 1,4 butanediol (1,4 BD), the content, and the particle size of the mica filler. The effects of branch chain, mica filler content, and particle size in polyurethane structure on the mechanical, dynamic mechanical properties, and fire resistance of polyurethane and its polymerization process were studied. The experimental results showed that the effective damping temperature range of polyurethane material widened from 42.1 °C to 76.6 °C, and then narrowed to 31.2 °C with the increase in EBP ratio. And the maximum loss factor (tanδmax) of these samples is 0.989. The increase of mica content and the decrease of mica particle size in polyurethane damping materials make the dynamic mechanical properties of polyurethane damping materials present a trend of first improving and then impairing. Moreover, the mechanical properties of polyurethane enhanced with the increase of EBP and weakened with the increase of mica mass fraction. This research is expected to advance the development of marine coatings and address noise reduction and fire protection challenges for marine materials.

Breaking new ground in mica exfoliation: Harnessing biaxial straining principles through H2 and N2 intercalation for enhanced layer separation

This study introduces a novel method for mica exfoliation using biaxial straining principles through H2 and N2 intercalation. Our two-stage approach combines microwave irradiation with biaxial straining triggered by H2 and N2. Our first principles simulations showed that N2 leads to a larger drop in bulk modulus per tensile strain than H2, resulting in decreased mica strain entropy (or less disordering) and ineffective exfoliation due to the resulting positive (H2) and negative (N2) Poisson ratio. Therefore, we applied H2 and performed SEM, FT-IR, and XRD analyses. The results indicate that our pre-treatment methods did not alter the mica's crystalline structure, and our two-step treatment method increased the interlayer distances of bulk mica particles. TEM analysis revealed the presence of mica nanosheets in single layers. This study represents a significant breakthrough in 2D exfoliation research not only for mica but also for non-van der Waals bonded crystals. By utilizing innovative biaxial straining principles through H2 and N2 interclation, our approach offers a promising avenue for achieving enhanced layer separation in layered materials.

Effect of platy gangue minerals in sulfide flotation: Part 2: Mechanisms

The presence of the usually unwanted, hydrophilic ore particles (gangue) in a mineral flotation froth plays a critical role. While they reduce the grade of the concentrate, they are also an important influence on the dynamical structure of the froth and its ability to transport value particles into the launder for ultimate recovery. This paper discusses how the shape and size of these gangue particles affect their transport through the froth zone under conditions typical of commercial sulfide flotation, but without hydrophobic ore particles present.Advective transport of gangue particles via entrainment depends on slurry drag due to the upward motion of air bubbles and the drainage effects of gravity on the liquid and solid phases confined in the network of fluid channels in the froth. In a companion paper (Bhambhani et al., 2023a) a significant increase in gangue transport rates through the froth zone was observed when a copper sulfide ore was mixed with platy mica (higher aspect ratio) compared to when the same ore was mixed with globular (lower aspect ratio) silica. It was hypothesized that this increased upwards transport rate was related to the greater upward drag experienced by the platy mica particles as compared to the lower aspect-ratio silica particles of comparable size. This hypothesis was tested by conducting froth sampling experiments, reported here, under increased upward drag conditions for the suspension and thus increased upward advective forces on the particles. It was observed that the entrainment vs particle size curves shifted upwards for the coarser sizes for both mica and silica. This was unexpected. It was additionally hypothesized that as the particle size approached the size of the channels (Plateau borders), through which settling particles must pass if they are to move downward, the particles become more confined and on average experience less downward motion. Platy mica particles of a certain sieve size are more susceptible to confinement in the channels than their lower aspect-ratio counterparts due to their reduced mass per particle. This was suggested from froth sampling experiments where drag and drainage were balanced in one case, and more drag dominated in the other.

Effect of platy gangue minerals in sulfide flotation: Part I-transport rates

Observations from operating flotation plants suggest that the presence of the platy gangue mineral mica leads to significantly reduced concentrate grades. The combined effects of gangue particle shape (platy vs globular) and particle size on flotation has not been systematically investigated. Flotation tests were conducted on ground ore mixed with different amounts of sized mica (platy) or silica (globular) minerals. This essentially allowed us to alter the already present non-sulfide gangue (NSG) composition in a controlled manner and to investigate gangue size and shape effects on flotation recovery. The use of purposefully added mineral particles with narrow size distributions improved our ability to determine the different pathways by which hydrophilic particles of various sizes and shapes are transported through the froth. Cumulative mineral and water recovery data for each composition was used to calculate the degree of NSG entrainment for each ore plus adulterant (mica or silica). Analysis of the degree of entrainment vs adulterant particle size and shape showed that the addition of mica typically results in higher gangue recovery compared to when silica is added at comparable concentrations. The data for recovery when mica was added followed a trend associated with typical entrainment behavior, i.e., there was a decrease in the degree of entrainment with increasing mica particle size up to about 100μ. However, for greater mica size fractions, an increase in the degree of entrainment was observed. The reason for this behavior is discussed in the part II companion to this paper (Bhambhani, T., Farinato, R., Somasundaran, P., Nagaraj, D., 2022. Effect of play gangue minerals in sulfide flotation: Part 2: Mechanisms, Submitted to Minerals Engineering). The entrainment effects of mica were also evidenced to be concentration dependent. For coarser fractions of mica added to the ore pulp, where the degree of entrainment now increases with mica size, an increase in concentration of mica in that pulp resulted in a steeper increase in the degree of entrainment with mica particle size. This suggested second-order effects arising from particle-particle interactions. Similar results were seen with silica; however, deviations in the degree of entrainment vs particle size plots were less pronounced or required greater concentrations to be seen.

Impact of different additives on low-temperature recrosslinkable preformed particle gel to mitigate fluid losses in fractured formations

During drilling through highly permeable or fractured formations, the entire drilling fluid or most of it might be lost into formations; this phenomenon is called lost circulation. Lost circulation can cause serious issues during drilling, such as challenging well control operations, and in some cases, complete loss of the well. In this paper, a Low-Temperature Recrosslinkable Preformed Particle Gel (LT-RPPG) was evaluated in the presence of various conventional additives to control drilling fluid loss in fractured formations. The additives tested in the study included mica, walnut shell and bentonite. Different factors were investigated, including mica concentrations, mica particle size, walnut shell concentrations and bentonite. Core flooding experiments were conducted to evaluate the LT-RPPG with the various additives plugging performance utilizing open fractured cores. The results showed that by mixing the LT-RPPG with the drilling fluid, a stronger material, reflected in a higher elastic modulus and sealing pressure, was obtained as compared by solely hydrating the LT-RPPG with brine. Also, the addition of mica and walnut shell further improved the LT-RPPG strength. While the mica particle size selection influenced the LT-RPPG rheological properties, the results from the core flooding experiments indicated the mica particle size had insignificant impact on the sealing pressure as compared with the mica concentration. Among the different tested addtivies, the optimum improvement on the LT-RPPG plugging performance was obtained by introducing 1.00% walnut shell. The mixture achieved a sealing pressure up to 5685.41 psi/ft for 3.0 mm fracture width. Furthermore, the core flooding results exhibited that the LT-RPPG combined with the additives effectivility reduced the fracture permeability to more than 108 times even after the gel rupture by subsequent drilling fluid circulation.

Reducing the adhesion of mica on arsenopyrite surface using sodium phytate and the application in flotation separation

ABSTRACT The adhesion of clay minerals into sulfides concentrate is one of the key problems of mineral processing industry. In this study, sodium phytate (SP) was used as a dispersant in mixed mica and arsenopyrite system. The addition of mica affected the rheological property of arsenopyrite pulp, and this effect could be mostly reduced after the addition of SP. The reflection polarizing microscope results confirmed the adhesion behavior of mica with arsenopyrite to form the aggregate structure; and the addition of SP could disperse them from each other, which is regarded as advantageous to the flotation separation. Adsorption test results revealed that the SP molecules selectively adsorbed onto mica surface. XPS results showed that the P-O groups in SP anions mainly adsorbed with the Al active sites on mica surface, resulting in the greater electrostatic repulsion between mica particles, mica and arsenopyrite particles. This is the mechanism for mica/arsenopyrite dispersion. In flotation tests, SP exhibited well performance in increasing the flotation indexes. A 6 × 10−5mol/L of SP enlarged the recovery difference between arsenopyrite and mica from 19% to 60.0%. In real ore flotation, it also showed better performance regardless compared with the system without dispersant or with traditional dispersant SHMP.

The effect of different fillers, loads, and sliding distance on adhesive wear in woven e-glass fabric composites

In this study, adhesive wear of woven E-Glass fabric reinforced composites filled with aramid, B4C and mica particles at 0.5% wt. and 1.5% wt. ratios were carried out under dry sliding conditions. The effects of filler type, applied loads (5, 10 and 15 N) and sliding distances (250, 500 and 750 m) on the tribological behavior of the composites were investigated on the pin-on-disc device. As a result of the studies, it was determined that the friction coefficient in aramid reinforced composites was lower than the other reinforced composites. In wear volume due to wear, it was observed that the aramid wear volume was less. In addition, Wear volume increased with increasing load for all particle reinforcements. But, the highest wear volume occurred in the neat wear sample at 15 N load conditions. For the wear rate and wear volume, the fillers have shown improvement up to 1.5% wt. in the composite. 1.5% wt. aramid-filled glass fiber woven composites showed the lowest wear rate: 2.82 × 10−4 mm3/N-m (at 15 N normal load). In addition, in the scanning electron microscope images taken, it was observed that there were breaks in the size of 15.07 µm in the epoxy and 61.11 µm in the fibers. The use of aramid with particle reinforcement rather than fiber is important for wear. In addition, the lowest wear volume was 65% more resistant at 1.5% wt aramid reinforcement and at 15 N load compared to the unreinforced composite in the abrasion tests.

Process mineralogical characterization and vanadium extraction from vanadium-bearing shale by oxidation roasting-acid leaching

• Modern technology was used to study mineralogical characteristics of V-bearing shale. • The key to vanadium extraction is to destroy the lattice of mica and oxidize V(III). • Oxidation roasting is an optimal process for V-bearing shale with complex structure. • After roasting, the holes and cracks will enlarge and improve vanadium leaching rate. Vanadium, as an important rare metal, was listed as national strategic metal in the 14th Five-Year Plan of China. Vanadium-bearing shale is a unique resource in China and the reserve of vanadium in its accounts for 87% of the total. However, the production processes for vanadium-bearing shale ores from various origins are different due to the difference in mineral composition, the occurrence of vanadium, and the embedded relationship of main minerals. Analyzing their process mineralogical characterization is key to selecting an efficient vanadium extraction process. Therefore, in this work, we systematically studied the mineralogical characteristics of vanadium-bearing shale from Shaanxi province. Analysis results of process mineralogical showed that vanadium was the most valuable element for recovery, with a grade of 1.67%. Mica was the main vanadium-bearing mineral and coexisted closely with limonite, kaolinite, quartz, and feldspar. In the mica, vanadium generally presented the trivalent state of form. According to the analysis of mineralogical characterization, the process of “oxidation roasting-acid leaching” was used to extract vanadium from the shale ore. Under the condition of roasting temperature 900 °C, roasting time 3 h, air flow 600 mL·min-1, leaching temperature 25 °C, leaching time 4 h, leaching acid dosage 10 wt% and the liquid–solid ratio of 2:1, vanadium leaching rate was 75.24%. After oxidation roasting, the lattice of mica was destroyed, and the distribution of V(Ⅴ) increased from 0 to 89.68%. Meanwhile, holes and cracks appeared on the surface of mica particles, which promoted the contact between vanadium and acid, and improved the leaching efficiency of vanadium. Therefore, a link between process mineralogical characterization and selection of vanadium extraction process could be developed, which would be helpful in the efficient utilization of vanadium-bearing shale resources.

Preparation of high near-infrared reflectance mica/(Ni, Sb)-co-doped rutile yellow composite pigment via mechanochemical pretreatment and sintering

Mica/(Ni, Sb)-co-doped rutile yellow composite pigment with a high near-infrared reflectance was prepared via mechanochemical pretreatment and subsequent sintering. (Ni, Sb)-co-doped rutile yellow pigment was synthesized by a solid-phase method in the presence of sodium fluoride (NaF) as a mineralizer, and mica was peeled by ultrafine grinding. The pigment, mica and mica/pigment composite were characterized by X-ray diffraction, laser diffraction particle size analysis, nitrogen gas adsorption method, scanning electron microscopy, energy dispersive spectroscopy, ultraviolet–visible–near-infrared spectroscopy, CIEL*a*b* color scales, and infrared irradiation image, respectively. The results show that the temperature of synthesizing a pure rutile pigment in solid-phase reaction is reduced by 100°C due to the addition of mineralizer NaF. (Ni, Sb)-co-doped rutile pigment has better color rendering performance and near-infrared (NIR) reflectance. Ultrafine grinding produces the finer flatty mica particles with fresh reflective surfaces, thus improving NIR reflectance of peeled mica. In mica/pigment composite prepared via mechanochemical pretreatment and subsequent sintering, peeled mica has a synergistic effect on (Ni, Sb)-co-doped rutile pigment particles to further scatter near-infrared radiation through the multiple layer reflections, leading to a better heat insulation. The high near-infrared reflectance of composite pigment increases to 97.72%, and the b* value of the pigment synthesized with 1 wt% NaF is 37.77. For the irradiation infrared lamp, the surface temperature of aluminum plate coated with mica/(Ni, Sb)-co-doped rutile yellow composite pigment is 40.1 ± 0.2°C, which is lower than that of aluminum plate uncoated determined by thermal camera and thermocouple. When aluminum plate coated with mica/(Ni, Sb)-co-doped rutile yellow composite pigment is under sunshine, its surface temperature is 38.6 ± 0.2°C. In addition, the mechanism of preparing the composite pigment via mechanochemical pretreatment and subsequent sintering and the multiple structure reflection effect on peeled mica surface coated with (Ni, Sb)-co-doped rutile yellow pigment particles were also discussed.

Human Vimentin Layers on Solid Substrates: Adsorption Kinetics and Corona Formation Investigations.

Adsorption kinetics of human vimentin on negatively charged substrates (mica, silica, and polymer particles) was analyzed using atomic force microscopy (AFM), quartz microbalance (QCM), and the laser doppler velocimetry (LDV) method. AFM studies realized under diffusion conditions proved that the adsorbed protein layer mainly consisted of aggregates in the form of compact tetramers and hexamers of a size equal to 11–12 nm. These results were consistent with vimentin adsorption kinetics under flow conditions investigated by QCM. It was established that vimentin aggregates efficiently adsorbed on the negatively charged silica sensor at pH 3.5 and 7.4, forming compact layers with the coverage reaching 3.5 mg m–2. Additionally, the formation of the vimentin corona at polymer particles was examined using the LDV method and interpreted in terms of the electrokinetic model. This allowed us to determine the zeta potential of the corona as a function of pH and the electrokinetic charge of aggregates, which was equal to −0.7 e nm–2 at pH 7.4 in a 10 mM NaCl solution. The anomalous adsorption of aggregates exhibiting an average negative charge on the negatively charged substrates was interpreted as a result of a heterogeneous charge distribution. These investigations confirmed that it is feasible to deposit stable vimentin layers both at planar substrates and at carrier particles with well-controlled coverage and zeta potential. They can be used for investigations of vimentin interactions with various ligands including receptors of the innate immune system, immunoglobulins, bacterial virulence factors, and spike proteins of viruses.

Effect of particles on tensile and bending properties of jute epoxy composites

Abstract In this investigation, mechanical properties of composite materials produced from woven jute type were investigated. These composites were produced in the form of epoxy adhesive layers by using hand lay-up method in which aluminum, mica and ceramic particles were added into epoxy as a structural adhesive by 2, 4 and 6 wt%. Samples produced according to ASTM D procedures were subjected to tensile and three point bending loads to examine the effect of the particles. Experimental results were presented in tables and graphs. As a result, it was observed that the tensile and bending failure loads of the composite materials obtained by using the particle reinforced adhesive increased. Also, the biggest rise in tensile strength was achieved with 4 wt% aluminum and the biggest increase in bending strength was observed for 2 wt% aluminum particles.

Studying the Influence of Mica Particle Size on the Properties of Epoxy Acrylate/Mica Composite Coatings through Reducing Mica Particle Size by the Ball-Milled Method

In this work, a series of epoxy acrylate (EA)/mica composite coatings were synthesized through introducing mica powders of different particle size into epoxy acrylate coatings and using an ultraviolet (UV) curing technique to investigate the influence of mica particle size on the coatings. Mica powders of different particle sizes were obtained by ball-milling for 4, 8, 12, 16, and 20 h with a planetary high-energy ball mill. The particle size and morphologies of ball-milled mica powders were characterized by laser particle size analyzer and scanning electron microscopy (SEM). The results indicated that planetary ball-milling reduced the particle size of mica powders effectively. Mica powders that were un-ball-milled and ball-milled were added into the epoxy acrylate matrix by a blending method to synthesize the organic-inorganic UV curable coatings. The optical photographs of the coatings showed greater stability of liquid mixtures with smaller particle size fillers. The chemical structures of EA/mica composite coatings were investigated by Fourier transform infrared spectroscopy (FTIR), and the conversion rate of C=C bonds was calculated. The results indicated that the C=C conversion of coatings with mica powders of smaller particle sizes was higher. Tests of mechanical properties and tests using electrochemical impedance spectroscopy (EIS) showed that pencil hardness, impact resistance, and coating resistance were improved due to the reduction of mica powders particle size.

Mechanical and tribological behavior of flyash, red mud and mica particles reinforced Al7075 alloy hybrid metal composites

In the present research Al7075 alloy with 1, 3 and 5 varying weight percentages of flyash, 1, 2 and 3 varying wt.% of red mud along with constant 4 wt.% of mica particles composites were synthesized by stir casting technique. Thus prepared Al7075 alloy composites were subjected to the microstructural characterization using SEM and EDS. Mechanical properties were evaluated to know the impact of multi micro particles addition on the hardness, ultimate strength, yield strength, and ductility behavior of Al7075 alloy composites. Further, wear behavior of the prepared Al7075 alloy with mica, flyash and redmud composites were experimented using pin-on-disc apparatus by varying normal load and sliding velocity at constant 3000 m sliding distance. The improved mechanical properties were observed with the addition of micro scaled flyash, redmud and mica particles, further improvement was attained with the increasing weight percentage of flyash and red mud in the Al7075 matrix alloy. However, there was decrease in the ductility of the composites with an incorporation of hard micro particles in the soft Al matrix. Fractography and worn surface analysis were carried out to know the influence of micro particles on the tensile failure and wear surfaces of the composites.

Nanoencapsulation of isotropic and anisotropic particles through a green chemistry aerosol method: a scalable approach for ad-hoc surface tuning

The interest in core–shell materials with chemically tunable mesoporous surfaces has significantly grown in recent years. The main limitation to obtain these systems through sequential precipitation is the tuning of the core and shell sol-gel chemistry, which usually implies low concentrations and leads to high-quality colloids although in small quantities after a lengthy and costly process. Aerosol approaches can lead to faster production and easier separation of functional materials with well-defined architectures. We present a “green chemistry” general method to coat sub-micron colloidal particles with a variety of mesoporous metal oxide nanofilms via an aerosol synthesis technique. Different types of particulate supports with isotropic and anisotropic shapes were dispersed into the precursor solutions in order to synthesize a mesoporous shell keeping the shape of the support. We chose the synthesis of TiO2 and TiSiO4 nanofilms on conventional Stöber SiO2 spherical particles, and on anisotropic micronized mica particles as a case study. We used the commercial surfactant Pluronic® F127 as a porogen. The structure and composition of the obtained nanofilms were characterized by electron microscopy, X-ray diffraction, focused ion beam coupled to SEM, and nitrogen adsorption/desorption isotherms. The TiO2 shells obtained (with an anatase-like structure) have pore diameters between 3.9–4.8 nm depending on the support with film thicknesses of ~100 nm, while amorphous TiSiO4 shells have larger diameters (9.5–16 nm) with film thicknesses of between 50 and 200 nm depending on the support used. The method presented shows high reproducibility and, unlike batch methods, allows the continuous production and straightforward recovery of the materials.