Aggregates Of Flakes Research Articles

An Experimental Study on the Microstructure Evolution of Soil under Lateral Consolidation Compression

Based on the lateral consolidation compression experiment of remolded soil simulating the effects of pile driving and soil squeezing, in this paper, the microstructures of soil with different degrees of lateral consolidation were investigated by a scanning electron microscope. Combined with Image-Pro Plus software to process data, parameters such as the equivalent diameter, porosity, circularity, directional frequency and fractal dimension of the soil microstructure were analyzed. The results demonstrate that the microstructure of the soil sample before consolidation was debris, aggregated particles and irregular flake aggregates. Following consolidation, the microstructure became a closed flake structure, where an obvious agglomeration phenomenon occurred. During the process of lateral consolidation compression, the large pore structure was more likely to be compressed and damaged, resulting in a decrease in the equivalent pore diameter and plane porosity, the approaching of circularity towards unity and an increase in the compaction and homogenization of soil with obvious directionality. Soil particles moved continuously under the action of consolidation compression to adjust the microstructure, and the fractal dimension gradually increased. Then, as consolidation compression continued, it gradually developed to a new equilibrium state, where the fractal dimension began to decrease and approach stability.

Investigation of Electrical Properties of BiFeO3/LDPE Nanocomposite Dielectrics with Magnetization Treatments.

The purpose of this paper is to study the effect of nano-bismuth ferrite (BiFeO3) on the electrical properties of low-density polyethylene (LDPE) under magnetic-field treatment at different temperatures. BiFeO3/LDPE nanocomposites with 2% mass fraction were prepared by the melt-blending method, and their electrical properties were studied. The results showed that compared with LDPE alone, nanocomposites increased the crystal concentration of LDPE and the spherulites of LDPE. Filamentous flake aggregates could be observed. The spherulite change was more obvious under high-temperature magnetization. An agglomerate phenomenon appeared in the composite, and the particle distribution was clear. Under high-temperature magnetization, BiFeO3 particles were increased and showed a certain order, but the change for room-temperature magnetization was not obvious. The addition of BiFeO3 increased the crystallinity of LDPE. Although the crystallinity decreased after magnetization, it was higher than that of LDPE. An AC test showed that the breakdown strength of the composite was higher than that of LDPE. The breakdown strength increased after magnetization. The increase of breakdown strength at high temperature was less, but the breakdown field strength of the composite was higher than that of LDPE. Compared with LDPE, the conductive current of the composite was lower. So, adding BiFeO3 could improve the dielectric properties of LDPE. The current of the composite decayed faster with time. The current decayed slowly after magnetization.

Mathematical regularities of changes in the characteristics of the friction process of a porous composite material based on copper containing oil with graphene particles

The paper presents the results of a study of the sliding friction processes of a porous copper-based material impregnated with lubricating oil with dispersed particles of fluorinated graphene. Mathematical regularities of changes in the characteristics of the friction interaction are established. It is shown that the regularities of changes in the average friction force have a sigmoid-step character. Experimental results have been obtained showing that with an increase in the concentration of aggregates from flakes of fluorinated graphene in the lubricating oil, the average friction force and coefficient of friction decrease, while a good anti-friction effect is observed. It is shown that the average work of the friction force, and consequently the energy losses due to friction, when adding 0.01% of aggregates from fluorinated graphene flakes to the lubricating oil decreases by 3721 j, and when adding 0.1% — by 4098 j. It was found that the average coefficient of friction when adding 0.01% of fluorinated graphene flake aggregates to the lubricating oil decreases by 27%, and when adding 0.1% — by 30%.

The formation of marine red beds and iron cycling on the Mesoproterozoic North China Platform

Abstract Marine red beds (MRBs) are common in sedimentary records, but their genesis and environmental implications remain controversial. Genetic models proposed for MRBs variably invoke diagenetic or primary enrichments of iron, with vastly different implications for the redox state of the contemporaneous water column. The Xiamaling Formation (ca. 1.4 Ga) in the North China Platform hosts MRBs that offer insights into the iron cycling and redox conditions during the Mesoproterozoic Era. In the Xiamaling MRBs, well-preserved, nanometer-sized flaky hematite particles are randomly dispersed in the clay (illite) matrix, within the pressure shadow of rigid detrital grains. The presence of hematite flake aggregates with multiple face-to-edge (“cardhouse”) contacts indicates that the hematite particles were deposited as loosely bound, primary iron oxyhydroxide flocs. No greenalite or other ferrous iron precursor minerals have been identified in the MRBs. Early diagenetic ankerite concretions hosted in the MRBs show non-zero I/(Ca+Mg) values and positive Ce anomalies (>1.3), suggesting active redox cycling of iodine and manganese and therefore the presence of molecular oxygen in the porewater and likely in the water column during their formation. These observations support the hypothesis that iron oxyhydroxide precipitation occurred in moderately oxygenated marine waters above storm wave base (likely <100 m). Continentally sourced iron reactivated through microbial dissimilatory iron reduction, and distal hydrothermal fluids may have supplied Fe(II) for the iron oxyhydroxide precipitation. The accumulation of the Xiamaling MRBs may imply a slight increase of seawater oxygenation and the existence of long-lasting adjacent ferruginous water mass.

Employment the plastic waste to produce the light weight concrete

In recent years, the use of recycled plastic aggregate (RPA) as an alternative aggregate material has been considered to lower the environmental influence of both concrete and waste of plastics. Recycled plastic aggregate concrete (RPAC) is now known as a highly promising technology that can contribute to resource efficiency in the construction industry. In this paper, the first experimental study of the properties of concrete manufactured using recycled Polyethylene terephthalate (PET) Flake aggregates is presented. Five batches of concretes were manufactured with different PET contents (1%, 3%, 5%, 7%, 10%) by the weight of Portland cement. The effect of RPA content on the compressive strength, flexural strength, splitting tensile strength and hardened density of each batch is studied. The results showed that the use of PET at 1% lead to increase the compressive strength in 58% compared to the reference batch (made without waste). Flexural strength results showed that the use of PET at 1%, 3% increases the values flexural strength in 23.11%, 25.59 respectively comparing with reference batch. Also, the ratio 1% of PET gives the optimum value of splitting tensile strength with increment ratio 130%. The density values clearly decreased with increasing the percentage of PET content, the decreasing ratio of density close to14% especially at 10% of PET.

Formation and Characterization of Oil–Mineral Aggregates

Oil associates with fine mineral particles in an aqueous medium not only as molecules adsorbed onto mineral surfaces, but also as a discrete phase to form microscopic oil–mineral aggregates (OMA). As it promotes the dispersion of stranded oil, this process is now believed to be instrumental in the natural recovery of oiled shorelines and in the efficacy of spill countermeasure techniques such as surf-washing (relocation of oiled sediment into the zone of wave action). To predict the fate of residual oil following spills and the effectiveness of such countermeasures, an improved understanding of the nature and properties of OMA and of the factors influencing their formation is required. Laboratory protocols and microscopical methods have been refined for the detection and classification of OMA. Three OMA types have been identified: droplet, solid and flake aggregates. Droplet aggregates are oil droplets (usually a few μm in diameter) surrounded by individual or flocculated mineral particles. Solid aggregates are mixed oil and mineral bodies of various shapes (scale of tens of μm). Flake aggregates are thin sheets that can reach the mm size range in which mineral and oil are arranged in an ordered configuration. The parameters controlling the quantity, type and size of OMA include mineral type and surface properties, quantity, viscosity and composition of the oil, and oil/mineral ratio. It is also evident that water turbulence (i.e. breaking waves, strong flood currents) greatly enhances OMA formation. Once formed, OMA appear to be very stable structures the buoyancy of which depends on the ratio of oil to mineral in each individual aggregate. OMA being on average less dense than mineral-only aggregates and even buoyant, they will be kept in suspension longer and be dispersed further than unoiled sediment. Mineral particles in OMA act as a surfactant preventing the oil from recoalescing. As OMA formation increases the surface to volume ratio of spilled oil, it prolongs and enhances oil weathering processes such as dissolution, evaporation and biodegradation.

CHARACTERIZATION OF OIL-MINERAL AGGREGATES

ABSTRACT Oil associates with fine mineral particles in an aqueous medium not only as molecules adsorbed on mineral surfaces, but also as a discrete phase to form microscopic oil-mineral aggregates (OMA). On the basis of recent studies, OMA formation now is believed to be instrumental in the natural recovery of oil spill impacted shorelines and in the efficacy of cleanup techniques such as surf washing. A better understanding of the nature and properties of OMA will help predict the fate of oil spilled in the aquatic environment. This work describes the various instruments and methods currently available for the detection and identification of OMA. Three types of OMA have been characterized by microscopy techniques: droplet, solid, and flake aggregates. Droplet aggregates are oil droplets (usually a few μm in diameter) surrounded by individual or aggregated mineral particles. Solid aggregates are a mixture of oil and minerals blended into microscopic bodies of various shapes. Flake aggregates are thin sheets reaching several millimeters across in which mineral and oil are arranged in a regular pattern. Energy from breaking waves facilitates OMA formation. Once formed, OMA appear to be very stable structures the buoyancy of which depends on the ratio of oil to mineral in each individual aggregate.

NATURAL DISPERSION OF OIL IN A FRESHWATER ECOSYSTEM: DESAGUADERO PIPELINE SPILL, BOLIVIA

ABSTRACT During a flood event in January 2000, approximately 29,000 barrels of mixed crude oil and condensate was accidentally released from a fracture in the OSSA II pipeline at a crossing point on the Rio Desaguadero, Bolivia. The resultant downstream impact zone included over 400 km of river banks and 500 km2 of flooded lowlands within the Bolivian Altiplano. Analysis of stranded oil samples recovered from the riverbanks suggested that significant oil loss occurred by evaporation (>40%). With additional data on the amount of surface oil remaining (<0.2%) and oil recovered (3–13%) at the end of cleanup operations, it became apparent that a large fraction of the spilled oil remained unaccountable (27–37%). Laboratory tests were undertaken to assess if oil-mineral aggregate (OMA) formation—a natural process believed to promote rapid oil dispersion—may provide part of the explanation for this unaccounted loss. OMA were generated from local oil, sediment and water samples under simulated field conditions. Epi-fluorescence microscopy analysis verified the presence of flake aggregates that would be formed typically by the interaction of oil with smectite minerals (e.g. montmorillonite). On the basis of these microscopy observations and of mineral analysis of suspended material in water from the spill site, which revealed abundant smectite, it is hypothesized that OMA formation occurred, and that this process facilitated significant removal of residual oil from the ecosystem by enhancing biodegradation rates.

DEPENDENCE OF RUPTURE STRENGTH OF MICA-FLAKE AGGREGATES ON FLAKE CONFIGURATIONS

A study was carried out to determine the relationship between the configurations of mica flakes and the tensile strength of flake aggregates at rupture. The configurations of typical ruby muscovite flakes, with size (square root of flake area) of 100-1300 μm and thickness of 1-10 μm were measured by a microscopic method. A hypothesis on tensile rupture strength of flake aggregates was deduced, using the well-known Griffith theory on brittle rupture. It was found statistically that tensile strength at rupture of flake aggregates was inversely proportional to the 1.34 power of flake size, or to 0.49 power of flake volume. The correlation coefficient was − 0.90 or − 0.92, respectively

Seepage‐Induced Mass Wasting in Coarse Soil Slopes

An expression is derived for the critical shear stress of surface flow on a noncohesive soil slope subjected to seepage-induced mass wasting, i.e., erosion caused by a successive mobilization of flake aggregates of surficial grains. The expression is supported with data from experiments with stone fill subjected to throughflow. In current theories for hill-slope erosion of riprap protection on slopes, buoyancy is assumed to be a constant vector directed vertically, or the seepage force is omitted as a variable. However, the present analysis shows that, for many conditions, buoyancy should be described in accordance with the dynamic pressure distribution and the seepage force should be included as a variable in the theory. Furthermore, a parameter denoted “minimum stable volume” per unit width of stone fill is introduced as a measure of global stability of the stone fill, along with seepage height on the downstream face and grain size. Experimental results indicate that the minimum stable volume decreases with increase in grain size and, for the materials investigated, is about 20% lower for crushed rock than for gravel.

Geochemistry of biotite in the Santa Rita porphyry copper deposit, New Mexico

Igneous and hydrothermal biotite in the Santa Rita stock, which hosts the Santa Rita porphyry copper deposit, has been analyzed by electron-microprobe techniques for K, Na, Ca, Ba, Mg, Mn, Ti, Al, Si, Cl, and F; biotite separates were analyzed for ferrous and ferric iron by wet-chemical analysis and atomic absorption. Igneous biotite occurs as phenocrysts and microphenocrysts. Hydrothermal biotite occurs as secondary disseminated flakes, as aggregates of flakes resulting from recrystallization of igneous biotite or replacement of igneous hornblende, and as vein fillings. Included in the analyses are biotite in the least-altered part of the Santa Rita stock and in potassic, argillic, phyllic, and propylitic alteration associated with the stock. Of the 12 elements analytically sought, Ba, Fe, Mg, Ti, Al, Si, Cl, and F show the greatest variations.Systematic variations in the composition of biotite are apparent in the Santa Rita stock and in each type of alteration except phyllic. Mole fraction phlogopite, F, and Si increase progressively from igneous to secondary to vein biotite; the reverse relationship holds for Ti, Cl, and Al. Mole fraction phlogopite correlates positively with F and Si and negatively with Ti, Cl, and Al. These correlations, with the exception of that involving Ti, are well developed in the phyllic alteration. In phyllic alteration, however, the systematic relationship between the different varieties of biotite and their composition is obliterated. In all types of alteration, igneous biotite is distinguished from hydrothermal biotite by its higher Ba content. The Fe (super +2) /Fe (super +3) ratio increases progressively from igneous to secondary to vein biotite in the least-altered and potassically altered parts of the stock. The composition of overgrowths and protruding parts of igneous phenocrysts is intermediate between that of phenocryst and secondary biotite. The Al content of both igneous and hydrothermal biotite associated with phyllic alteration is notably higher than in biotite associated with other types of alteration; also, in general, the higher Al content correlates with a lower phlogopite content.Interpretation of the compositions of the several varieties of biotite in the Santa Rita porphyry copper deposit with various experimental and theoretical investigations and thermodynamic relationships suggests that an aqueous fluid phase exsolved from a partially crystallized melt at a T [asymp] 745 degrees C and a P [asymp] 1 kb. Subsequent hydrofracturing of the solidified part of the stock resulted in a lower T and P environment of potassic alteration which is suggested to range from about 670 degrees to 580 degrees C and 220 to 20 bars.The variable but systematically related content of Fe, Mg, Ti, and Al in relic biotite in the phyllic and argillic alteration of the Santa Rita deposit have resulted mainly from reequilibration with a solution that had variable ratios of Fe, Mg, and Ti to pH; this hydrothermal fluid encroached upon the potassic alteration zone at a temperature estimated to have ranged from 310 degrees to 370 degrees C. A postulated trend of biotite compositions across the phyllic-potassic transition zone of alteration and into the argillic zone indicates a progressive increase in pH and in a Mg (super +2) /a Fe (super +2) of the aqueous phase in that direction.

Defects in eutectic flake graphite

Transmission electron microscopy shows that flake graphite, extracted from directionally frozen eutectic Ni-C specimens, contains various defects including rotational stacking faults and twin/tilt boundaries. The occurrence of these defects is related to the overall morphology of the graphite flake aggregates.

Introduction of Glycerol into Flake Aggregates by Vapour Pressure

Introduction of Glycerol into Flake Aggregates by Vapour Pressure