Mica Layers Research Articles

Determination of critical condition for initiation of dynamic recrystallisation in Zr-1%Nb alloy

The critical stress and strain for initiation of dynamic recrystallisation (DRX) in Zr-1%Nb alloy have been determined by employing two different approaches. The work hardening rate versus stress curve and the natural logarithm of work hardening rate versus strain were used for this analysis. To evaluate the onset of DRX in Zr-1%Nb alloy, the hot deformation behaviour of this alloy has been studied in the temperature range of 770–850 °C and strain rates range 10−2 to 1 s−1. To reduce friction during the tests, the ends of samples were coated with graphite powder and a thin layer of mica placed between the surface of samples and the anvils. Nevertheless, the flow stress values were corrected to eliminate the effects of friction and adiabatic heating during the tests. The outcomes of work hardening rate analysis showed that the first method (work hardening rate versus stress) is the best method to determine the critical conditions of initiation of DRX. All in all, for Zr-1%Nb alloy, the dynamic recrystallisation was found to start when the normalised stress and strain reach the values of 0.91 and 0.87, respectively. Furthermore, the transmission electron microscopy (TEM) analysis showed that the DRX took place through a continuous mechanism, and optical microstructures confirmed that at low temperature and high strain rate the flow curves could be explained by localised deformation and shear band formation.

Study on Brazilian 18th century imperial carriage using x-ray nondestructive techniques

In this study was verified the presence of gold in the coatings of the emperor D. Pedro's II Berlin device, part of the Imperial Museum of Petropolis collection, Brazil. The perform was evaluation of the thickness of the gold leaf, using the technique of X-Ray Fluorescence, measuring peak intensities (Kα / Kβ or Lα / Lβ) of the elements of interest in the layer. It was possible to verify in the XRF spectra the presence of four elements: Ti, Fe, Au and Pb. The Pb was present in all sampling points, which indicates the presence of lead carbonate (lead-white) as preparation layer. The presence of Au in some sampling points indicates that several parts of the Berlin devices were covered with gold leaf. The presence of Ti and Fe is due to the application of golden mica over the entire length of the berlin device during the process of last restoration. The presence of the mica layer on the gold covering was relevant for gold thickness determination. The average value of the gold thickness obtained was 0.6 ± 0.5 µm, with a coefficient of variation of 83% and a confidence interval of 0.5–0.8 µm (α = 0.05). The values are compatible with the thickness of gold foil normally found in the coating of pieces of wood from the same period that the Berlin device was built.

Degradation of methylene blue using pillared TiO2 on de-oiled spent bleaching clay

Degradation of methylene blue (MB) using pillared TiO2 onto spent bleaching clay has been conducted. Activation of deoiled spent bleaching clay (DSBC) has been done using acid, followed by pillarization with TiO2 using rarasaponin from Klerak fruit as surfactant. From the X-ray diffraction results show the mineral on DSBC is rectorite with dioctahedral mica layer and dioctahedral smectite with ratio 2:1. This molecule have formula Na.Al4(Si, Al)8.O20.(OH)4. H2O and after calcinations the pattern TiO2 was appearance at 2θ: 27.4460°, 36.0850°, 54.3216° and 56.6403°. In order to test the catalytic performance of Ti-DSBC for photodegradation of MB under UV light was conducted under several reaction conditions. The highest degradation of MB was 90 % within 50 minutes and Ti-DSBC can be reused until 5 cycles with percent degradation MB was 84 %.

Determination of Minor Contents of Smectite Layers in the Dispersed Dioctahedral K-bearing Micaceous Minerals of the Illite, Aluminoceladonite, and Glauconite Composition

A theoretically substantiated technique has been elaborated for the precise determination of minor contents of smectite layers in the dioctahedral mixed-layer structures with a disordered alternation of K-bearing micaceous and ethylene glycol-saturated smectite layers. It is shown that observed positions of the possible mixed-layer mica–smectite structures in the d(003)obs–d(007)obs or 2θ(003)obs–2θ(007)obs diagrams are distributed along a set of parallel straight lines. Data points of each straight line correspond to the mixed-layer structures with one and the same content of smectite layers. A complete matching of theoretical model was recorded in the positions of d(003)obs–d(007)obs and 2θ(003)obs–2θ(007)obs pairs of the basal reflections determined in diffractograms simulated for 160 two-component mixed-layer mica–smectite structures differing in the thickness of alternating layers and their relative content. We studied samples of the dioctahedral K-bearing micas of the glauconite, illite, and aluminoceladonite composition with different thickness of micaceous layers. Positions of the mixed-layer structures of the studied samples on the 2θ(003)obs–2θ(007)obs and d(003)obs–d(007)obs plots make it possible to visually determine the content of smectite layers in each structure accurate to 0.5%. The content of smectite layers in the studied samples varied from 2 to 15%. We obtained equations relating the thickness of smectite and micaceous layers for a specified content of smectite layers. They make it possible to determine the thickness correlation between specified mica and smectite layers. Analogous equations can be used to calculate the Wsm value in each sample for specified experimental values of d(001)mc and d(001)sm and d(003)obs or d(007)obs. The Wsm values coincide within an error limit of 0.2% with those based on the visual estimates in plots.

Pilarization TiO2 onto De-oiled spent bleaching clay using Rarasaponin as surfactant

Synthesis and characterization TiO2 pillared deoiled spent bleaching clay (DSBC) with rarasaponin as surfactant had been done. Activation DSBC have been done with H2SO4 1N, followed by pillarization with TiO2 using rarasaponin as surfactant. Characterization has done with Fourier transform infrared spectroscopy showed the rarasaponin as surfactant was successfully carried out in DSBC with the presence of absorption peak C=O stretching group in a sharp 1720.50 cm-1 wavelength range. As well as the C-CH2 stretching uptake peak is represented on wave number 1462.04 cm−1 and 1033,85 cm−1 for aromatic functional group C=C stretching. After pillared by TiO2, the XRD pattern on DSBC showed new peak appears on 2θ = 27,4460° 36,0850° and 55,3216° and the mineral contain on DSBC is rectorite with dioctahedral mica layer and dioctahedral smectite with ratio 2:1. This molecule have formula Na.Al4(Si, Al)8.O20.(OH)4. H2O. Crystallinty of pillared clay showed 72,5014 % after calcination and there is some Ti suspected on the layer based on SEM.

Synthesis, structure, and thermal properties of new polypropylene nanocomposites prepared by using MgCl2‐mica/TiCl4 based catalyst

ABSTRACTPreparation of polypropylene/mica nanocomposites via in situ polymerization is investigated. The nanocomposites were successfully synthesized using a Ziegler‐Natta catalyst based on MgCl2/modified mica/TiCl4. Muscovite mica was organically modified with quaternary ammonium salt, and with triethylaluminum. The treatment with triethylaluminum increased the disorder in the stacking of clay layers, producing a more active catalyst for propylene polymerization, although the mica containing catalysts had lower activity than the standard one prepared without clay. The nanostructure of the composites was characterized by X‐ray diffraction. The results showed that part of the mica layers were exfoliated in the polymer matrix, although tactoids were still present. Small‐angle X‐ray scattering analysis was used to determine how mica and its concentration influence the size of the polymer nanocrystals. Differential scanning calorimetry was used to investigate both melting and crystallization temperatures, as well as the crystallinity of the nanocomposite samples. Thermogravimetric analysis showed that polypropylene/mica nanocomposites presented much higher thermal stability than the polypropylene without mica, which means that mica had a barrier effect against heat. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45587.

Hot deformation behavior of Zr-1%Nb alloy: Flow curve analysis and microstructure observations

The hot deformation behavior of Zr-1%Nb alloy has been studied at temperatures of 770–850°C and strain rates of 10−2 to 1s−1. To minimize friction during the tests at high temperature, the ends of the specimens were coated with graphite powder and a thin layer of mica was placed between the face of the specimen and the anvils. In order to investigate the warm working behavior of Zr-1%Nb alloy, all data were analysed stepwise and the step-by-step procedure was provided. The occurrence of the dynamic recrystallization (DRX) phenomena at different working conditions was analysed by the work hardening rate analysis. The stress-strain curve of many samples was identical to the typical DRX stress-strain curve which consists of a single peak stress followed by a gradual decrement toward the steady-state stress. Microstructural observations showed that at low temperatures and high strain rates the flow curves can be explained by localized deformation as a consequence of shear band formation. The transmission electron microscopy (TEM) analysis showed that the DRX has taken places through a continuous mechanism. At high Zener-Hollomon (Z) parameter a drop in flow stress was detected as a consequence of adiabatic deformation heating. The warm working constants of this alloy were determined through the general constitutive equations. Furthermore, after analyzing the work hardening behavior of this alloy, the activation energy for deformation of Zr-1%Nb alloy was calculated as 514kJ/mol.

Fabrication of highly hydrophilic filter using natural and hydrothermally treated mica nanoparticles for efficient waste oil-water separation

For the effective oil/water separation, a novel superhydrophilic (underwater superoleophobic) filter is fabricated with the naturally and hydrothermally treated mica particles. To fabricate a double layered filter, hydrothermally treated mica particles were initially electrodeposited on a stainless steel mesh and a natural mica particles were sprayed on the first hydrothermally deposited mica layer. The double layered mica coated membrane showed superamphiphilic and superhydrophilic/superoleophobic (contact angle >159°) characteristics in air and underwater respectively. The membrane can separate range of oil-water mixtures with oil/water separation efficiency over ∼99%. Properties of double layered mica membrane were investigated and noted that the surface adhesion properties of mica is enhanced by the hydrothermal treatment of mica and the higher roughness of the mica layer is maintained by the natural mica.

Characterization of rectorite from the Beatrix Gold Mine in South Africa

Three rectorite samples from the Beatrix Gold Mine, South Africa were characterized. Scanning electron microscopy revealed a layered morphology. High resolution transmission microscopy showed well distinguished light and dark layers of about 2.20nm consistent with the 1:1 interstratified mica-smectite nature. X-ray diffraction measurements confirmed the basal spacing d001 of 2.20nm consistent with a one-water-layer structure. Unit cell parameters, for a monoclinic unit cell with primitive lattice, refined to a=5.177Å; b=8.980Å; c=22.489Å and β=97.335° with mean crystallite size around 14nm and calculated cell volume of 1045Å3. The Greene-Kelly test suggested that the expandable smectite layers have montmorillonite-beidellite composition. Nuclear magnetic resonance spectroscopy indicated a high degree of Al substitution and the presence of two different Al sites corresponding to six- and four-fold octahedral and tetrahedral aluminum respectively. The chemical composition and diffraction data suggest that the mica is Na-Ca-rich, i.e. of paragonite-margarite series. The fixed interlayer regions (mica interlayers) contains proportionally dominant Na+ and Ca2+ and minor amounts of K+. The exchangeable smectitic interlayers contain almost equal amounts of Na+ and Ca2+ ions. The distribution of the interlayer Na+ ions was quantified by 23Na solid-state NMR spectroscopy. It points to a three component mixed-layer structure with considerable variation in the composition of the mica layer of the different samples.

Novel 18650 lithium-ion battery surrogate cell design with anisotropic thermophysical properties for studying failure events

Cylindrical 18650-type surrogate cells were designed and fabricated to mimic the thermophysical properties and behavior of active lithium-ion batteries. An internal jelly roll geometry consisting of alternating stainless steel and mica layers was created, and numerous techniques were used to estimate thermophysical properties. Surrogate cell density was measured to be 1593 ± 30 kg/m3, and heat capacity was found to be 727 ± 18 J/kg-K. Axial thermal conductivity was determined to be 5.1 ± 0.6 W/m-K, which was over an order of magnitude higher than radial thermal conductivity due to jelly roll anisotropy. Radial heating experiments were combined with numerical and analytical solutions to the time-dependent, radial heat conduction equation, and from the numerical method an additional estimate for heat capacity of 805 ± 23 J/kg-K was found. Using both heat capacities and analysis techniques, values for radial thermal conductivity were between 0.120 and 0.197 W/m-K. Under normal operating conditions, relatively low radial temperature distributions were observed; however, during extreme battery failure with a hexagonal cell package, instantaneous radial temperature distributions as high as 43–71 °C were seen. For a vertical cell package, even during adjacent cell failure, similar homogeneity in internal temperatures were observed, demonstrating thermal anisotropy.

Intensifying the Casimir force between two silicon substrates within three different layers of materials

We investigate the Casimir force for a system composed of two thick slabs as substrates within three different homogeneous layers. We use the scattering approach along with the Matsubara formalism in order to calculate the Casimir force at finite temperature. First, we focus on constructing the reflection matrices and then we calculate the Casimir force for a water–lipid system. According to the conventional use of silicon as a substrate, we apply the formalism to calculate the Casimir force for layers of Au, VO2, mica, KCl and foam rubber on the thick slabs of silicon. Afterwards, introducing an increasing factor, we compare our results with Lifshitz force in the vacuum between two semispaces of silicon in order to illustrate the influence of the layers on intensifying the Casimir force. We also calculate the Casimir force between two slabs of the forementioned materials with finite thicknesses to indicate the substrate's role in increasing the obtained Casimir force. Our simple calculation is interesting since one can extend it along with the Rigorous Coupled Wave Analysis to systems containing inhomogeneous layers as good candidates for designing nanomechanical devices.

How the unique properties of soil kaolin affect the fertility of tropical soils

The kaolin (s.l.) in many tropical soils is distinctly different from most specimen and industrial kaolins. Crystal structure is highly disordered and crystal sizes are much smaller than for specimen and industrial kaolins. The crystal habit of soil kaolins is diverse ranging through euhedral hexagonal and anhedral platy, spheroidal and tubular. The specific surface of soil kaolins is higher than for most industrial kaolins. Consequently, cation and anion retention capacities are higher although there is no compelling evidence that the high structural disorder of soil kaolin is associated with a greater specific reactivity of the kaolin surface. A small amount of ferric iron substitutes for octahedral Al but there is generally little or no substitution of other cations. Soil kaolin commonly contains minor amounts of potassium but this is present in mica layers within, attached or associated with kaolin crystals so that potassium is not within the kaolin structure. Due to its considerable chemical reactivity soil kaolin helps provide an effective substrate to support agriculture and other land uses in the tropics.

Globular layer silicates of the glauconite–illite composition in Upper Proterozoic and Lower Cambrian rocks

The paper presents the generalized results of structural and crystal-chemical study of globular dioctahedral 2 : 1 layer silicates of the glauconite–illite composition (45 samples) taken from the Lower Cambrian sequences of North Siberia (Olenek Uplift); Riphean, Vendian, and Lower Cambrian sequences of East Siberia; Upper Riphean sequences of the South Urals and Srednii Peninsula; and Vendian–Cambrian boundary rocks of the Podolian Dniester region (Ukraine). Monomineral fractions of grains were studied using modern chemical and physical methods: X-ray analysis, oblique-texture electron diffraction (OTED), scanning electron microscopy (SEM), classical chemical and microprobe analyses, IR and Mossbauer spectroscopy, and others. Simulation of the experimental diffraction patterns of glycolated specimens (Sakharov et al., 1999) allowed us to determine the degree of expandability (4–13%), type of expandable layers (16.85 A, smectite and 13.2 A, vermiculite), their proportions in twoand three-component mixed-layers, unit cell parameters b (9.02–9.11 A) and csinβ (9.94–10 A) of mica layers, as well as the degree of short-range order in the alternation of layers of different types (R = 0, 2, 3). The classification of low-charge (layer charge ≈ 0.6–0.85 per f.u.) dioctahedral 2: 1 layer silicates is given with account taken of the recommendations of the International Nomenclature Committee on Micas and Clay Minerals (IMA NC, AIPEA NC) (Reider et al., 1998; Guggenheim et al., 2006). Based on the crystal-chemical data on 79 samples obtained in (Ivanovskaya et al., 2012) and in the present paper, it is shown that the globular micaceous varieties are represented by a continuous isomorphic series ranging from illites through Fe-illite and Al-glauconite to glauconites (VIAl/(VIFe3+ + VIAl) = 0.81–0.91, 0.60–0.78, 0.51–0.59, and 0.11–0.50, respectively). Following (Kossovskaya and Drits, 1971; Drits et al., 2013), we distinguish Fe-illites (VIAl/(VIFe3+ + VIAl) = 0.6–0.8) and retain the term Alglauconite for mineral varieties with the Al index KAl = VIAl/(VIFe3+ + VIAl) between 0.51 and 0.59. The structural characteristics (unit cell parameters b, csinβ, and others) and IR spectroscopic data on illite, Fe-illite, Al-glauconite, and glauconite are compared. Special attention is given to samples with elevated Mg contents found in these groups of mineral varieties. Since compositional variations of the studied glauconite–illite minerals fall beyond the fields accepted for these minerals by IMA NC and AIPEA NC, the existing classifications for low-charge dioctahedral micaceous micas may need to be revised.

Characterization of two low charge vermiculites after hydrochloric acid treatment

Two natural vermiculites (Ver) with very similar chemical composition but slightly different low charge on the layers were investigated to find an answer the question, how to change their structural and chemical properties after exposure to different concentrations of HCl solutions. Vermiculite from Bulgaria (Ver-B) with the layer charge 0.47 eq/O10(OH)2 and from Brazil (VerSL) with the layer charge 0.36 eq/O10(OH)2 were studied on their particle size fraction less than 40 μm after treatment at different HCl concentrations (0.5 M HCl and 1 M HCl). Both samples represent a mixed-layer structure after incomplete transformation of mica (biotite) to vermiculite. Based on the XRD patterns, Ver-B may be considered as the mixed-layer vermiculite interstratified with small proportion of mica layers and Ver-SL as the mixed-layer micavermiculite. The leaching with 0.5 M HCl increased SA of Ver-B from 29.5 m 2 .g -1 to 261 m 2 .g -1

Evolution of Robust Manufacturing Process in Machining of DC Motor Commutator Using Complementing Problem Solving Tools

Machining the mica insulation in commutator to provide under cut in the surface of contact with the carbon brush is a vital process related to the life of the product. Complete removal of mica in the contact surface is essential and this requires complex sensing and positioning of the thin mica layer during machining. This study revealed improving the sensing and positioning technologies is not adequate and evolved a robust product-process design to overcome the real root cause of variations in the manufacturing process. Combined use of orthogonal array, Shainin technique, physical-mechanism analysis, relations-diagram and evaporating-cloud method complemented the problem solving approach in gaining knowledge and evolving robustness.

Design, Assembly, and Test of the CERN 2-m Long 11 T Dipole in Single Coil Configuration

The upgrade of the LHC collimation system includes additional collimators in the LHC lattice. The longitudinal space for the collimators can be obtained by replacing some LHC main dipoles with shorter but stronger dipoles compatible with the LHC lattice and the existing powering circuits, cryogenics, and beam vacuum. A joint development programme aiming at building a 5.5 m long two-in-one aperture Nb 3 Sn dipole prototype suitable for installation in the LHC is being conducted by FNAL and CERN. As part of the first phase of the programme, 1 m and 2 m long single aperture models are being built and tested. Later on, the collared coils from these models will be assembled and tested in a two-in-one aperture configuration in both laboratories. A 2 m long practice model made of a single coil wound with Nb 3 Sn cable, MBHSM101, was developed and constructed at CERN. It has been completed, and tested at both 4.3 K and 1.9 K. This practice model features collared coils based on removable pole concept, S2-glass cable insulation braided over a mica layer, and coil end spacers made of sintered stainless steel with springy legs. The paper describes the main features of this practice model, the main manufacturing steps and the results of the cold tests.

Self-Assembling of Tetradecylammonium Chain on Swelling High Charge Micas (Na-Mica-3 and Na-Mica-2): Effect of Alkylammonium Concentration and Mica Layer Charge.

A family of tetradecylammonium micas is synthesized using synthetic swelling micas with high layer charge (Na(n)Si(8-n)Al(n)Mg6F4O20·XH2O, where n = 2 and 3) exchanged with tetradecylammonium cations. The molecular arrangement of the surfactant is elucidated on the basis of XRD patterns and DTA. The ordering conformation of the surfactant molecules into the interlayer space of micas is investigated by IR/FT, (13)C, (27)Al, and (29)Si MAS NMR. The structural arrangement of the tetradecylammonium cation in the interlayer space of high-charge micas is more sensitive to the effect of the mica layer charge at high concentration. The surfactant arrangement is found to follow the bilayer-paraffin model for all values of layer charge and surfactant concentration. However, at initial concentration below the mica CEC, a lateral monolayer is also observed. The amount of ordered conformation all-trans is directly proportional to the layer charge and surfactant concentration.

Effects of swift heavy ion irradiation parameters on optical properties of muscovite mica

Muscovite mica sheets with a thickness of 25μm were irradiated by various kinds of swift heavy ions (Sn, Xe and Bi) in HIRFL (Heavy Ion Research Facility in Lanzhou). The fluences ranged from 1×1010 to 8×1011ions/cm2 were applied. The electronic energy loss (dE/dx)e in mica was changed from 14.7 to 31.2keV/nm. The band gaps and Urbach energy of pristine and irradiated mica were analyzed by ultraviolet–visible spectroscopy (UV–Vis). A red shift of the absorption edge was found in the absorption spectra of muscovite mica irradiated by ions with increasing (dE/dx)e. The results show that the chemical bonds between Tetrahedral–Octahedral–Tetrahedral (TOT) layers of mica were destroyed by ion irradiation. With increasing (dE/dx)e and fluences, the band gaps became narrow and the Urbach energy increased. It suggests that the amount of defects and the proportion of amorphous structure were increased in mica irradiated with increasing (dE/dx)e and fluences.

Specular neutron reflection at the mica/water interface – irreversible adsorption of a cationic dichain surfactant

Neutron reflection from the important mineral mica at the solid/liquid interface is presented here using a new approach – a very thin mica crystal supported on a silicon substrate. This approach avoids the problems of crystal defects and surface undulations that have hindered previous work. The use of mica as a reflectivity substrate is important as it is a model surface, which is atomically smooth with a high structural charge. In this work the mica/water interface is fully characterized. In particular, a characteristic double critical edge is observed, arising from the higher scattering length densities of the mica and D2O subphase relative to the silicon support. The experimental data are modelled using a combined approach: conventional amplitude summation (matrix method) for the thin layers and reflected intensity summation with attenuation terms for the thick layers of mica and hydrocarbon adhesive. Reflection data from the adsorption of the dichain cationic surfactant didodecyldimethylammonium bromide (DDAB) to the surface of muscovite mica from aqueous solution are also presented. It is found that, at twice the critical micelle concentration, a bilayer of DDAB with a thickness of 24 Å is observed, containing essentially no water. Its partial removal by washing and ion exchange is also presented.

The 3D quantitative lattice and shape preferred orientation of a mylonitised metagranite from Monte Rosa (Western Alps): Combining neutron diffraction texture analysis and synchrotron X-ray microtomography

Two complementary 3D techniques, neutron diffraction and synchrotron X-ray microtomography (SXR-μCT), were used to compare the Shape and Lattice Preferred Orientations of a mylonitised metagranite from the Monte Rosa unit (Western Alps, Italy). The goal of using these techniques was to obtain two different orientation distribution functions. Although the two functions describe relatively independent characteristics of the rock fabric, nonetheless they also exhibit close relationships to macroscopic fabrics and may be complementarily used to quantify rock fabrics and microstructures, thereby highlighting 3D features that cannot be obtained with either technique, if used independently. We describe an approach that can be potentially useful in various disciplines, e.g., structural geology, rock mechanics, tectonics and geophysics, when a complete data set of preferred orientations and size distribution is needed.Micas display a strong orthorhombic symmetry between mesoscopic lineation and microscopic SPO and LPO, whereas quartz and feldspars are characterised by a monoclinic symmetry between mesoscopic lineation and LPO. These observations suggest a rheological decoupling between the weak phase mica layers and the stronger quartz + feldspar layers. This mechanical decoupling occurred during the Alpine subduction-collision, when the Monte Rosa unit was part of the Insubric Line system and accommodated large vertical strain.