Granular Compositions Research Articles

Obtaining mechanically fused modifying ligatures with a high content of alloying component for the production of chrome bronzes

The paper presents the results of a study of the regularities of the formation of granulometric composition, structure and properties of modifying ligatures with a high content of alloying component for the production of chrome bronzes. The kinetics of changes in the physico‑mechanical properties of granular compositions depending on the temperature in the grinding chamber and the ratio of the volume of working bodies to the volume of the charge has been studied. The results of the topography of granules and their structure are presented, showing that the granules obtained according to the optimal mode of mechanical fusion are dense bodies with microinclusions of chromium, the maximum size of which does not exceed 15–20 microns.Based on the results of thermodynamic modeling, thermodynamically justified refractory compounds synthesized in the process of obtaining a ligature have been established, which should effectively perform the role of modifiers of the first kind, ensuring the production of bronzes with a sub‑/microcrystalline type of base structure.The processes of compacting mechanically fused compositions were optimized and the influence of the main technological factors – the heating temperature of cold‑pressed briquettes and the extraction coefficient during hot pressing on the physical and mechanical properties of compact materials was investigated. The results of studying the structure and properties of the most promising Cu – 20 %Cr composition are presented, which make it possible to identify its microcrystalline type, which persists after prolonged high‑temperature exposure during the processing of the granular composition into a semi‑finished product, and to conclude about the dispersed nature of its hardening, which additionally confi ms the data of thermodynamic modeling on the possibility of mechanical synthesis of nanocrystals of refractory compounds to perform the role of modifiers.According to the results of the research, a comparative analysis of the properties of the developed ligature and beryllium bronze was performed, establishing the possibility of its use as an independent material for electrical purposes.

Analysis of nickel-clad ceramic powder materials

The task of developing new powder materials for use in gas-thermal technologies is solved by cladding metal oxide particles with a refractory metal component. The results of studies of powders of domestic production based on aluminum oxide (corundum) and zirconium dioxide subjected to chemical nickel cladding (8 and 30 %) are presented. The morphology, granular and phase compositions, as well as the distribution of the elemental composition were studied using electron microscopy and X-ray diffraction analysis. It is shown that the formation of a dense and homogeneous metal shell around the particles of the matrix material occurs when 30 % of the metal is clad. According to X-ray diffraction analysis, powder materials have a multiphase composition: (Ni + α-Al2O3 + γ-Al2O3 + γ*-Al2O3) − for aluminum oxide powder clad with 8 % Ni; (Ni + α-Al2O3 + γ-Al2O3) - for aluminum oxide powder clad with 30 % Ni, (Ni + T-ZrO2) - for dioxide powder zirconium clad with 30 % nickel. New powder materials of domestic production are competitive in relation to foreign analogues and due to cladding with a metal component will contribute to improving the plasticity of plasma coatings formed from them.

Three-dimensional imaging of high-velocity-impact induced crack growth in carbonaceous meteorites

The material strength of meteorites provides useful information on the make-up and history of asteroids. However, the unique determination of the material strength of a meteorite is difficult because of the wide range of strengths many meteorites exhibit. Even within a single sample, complicated textures and mineral granular compositions make measurements difficult. Michikami et al. (2019) investigated the impact-induced crack growth in ordinary (L5) chondrites and indicated that crack growth is largely affected by the strength of individual mineral grains (and/or chondrules). In this study, we examine the strengths of mineral grains in carbonaceous meteorites qualitatively. To this end, we use X-ray microtomography to investigate how chondrules are affected by impact-induced crack growth in carbonaceous meteorites. Spherical alumina projectiles with a diameter of 1.0 mm were fired into the surfaces of seven Allende (CV) meteorite target samples with sizes of ∼1 to 2 cm at a nominal impact velocity of 2.0 km/s. In addition, spherical glass projectiles with a diameter 0.8 mm were fired into the target surfaces of two Murchison (CM) and two Aguas Zarcas (CM) meteorite target samples with sizes of ∼2 cm at a nominal impact velocity of 4.0 km/s. The results show that most cracks in CV chondrites tend to grow along the boundary surfaces of the chondrules, while most chondrule-related cracks in CM samples grow regardless of the boundary surfaces of the chondrules. This suggests that crack growth is largely affected by the chondrules' strength as indicated by Michikami et al. (2019). The weaker the strength of chondrules, the more likely crack growth tends to occur regardless of chondrule boundaries. We found that the mesostasis of chondrules in CM meteorite Murchison (and likely Aguas Zarcas) has experienced aqueous alteration and the chondrules have become structurally weak as a whole. This indicates that impact-induced crack propagation in CM chondrites differs from thermal-fatigue induced crack propagation inferred from previous studies. As the sample material to be returned from asteroid Bennu is considered to be related to CM chondrites, we propose that observation of the cracks in chondrules in Bennu samples might tell us whether those cracks are impact- or thermal-fatigue-induced.

Influence of Fillers on Silicate Compositions Porization

The article is devoted to the problem of raw material base expanding and improving construction and technical properties of porous granular materials. The results of experimental studies of silicate compositions based on liquid glass and technogenic fillers containing burnable or gas-forming components are presented. Influence of molding mixtures’ composition on thermal expansion nature of granular compositions was established. Preference of a filler combined, containing glass cullet, silica clay and mineral additives was revealed. Multicomponent composition of a filler helps to intensify composition’s expansion. Electron microscopy studies of porous silicate granules have confirmed the advantages of combined fillers using. Effectiveness of sodium additive introduction to regulate technological properties of the raw material and the process of pores formation has been proven. Expediency of mechanical activation of a raw mixture to reduce the temperature of expansion and obtain granules with a bulk density of not more than 300 kg/m3 has been determined.

Lithology and geochemistry of the Guadalupe Group base around Tunja, Boyacá, Colombia

The base of the Guadalupe Group, in the Tunja area of Colombia, contains cherts, porcellanites, mudstones, and siltstones with subordinate quartz arenites. The lithostratigraphic description of two stratigraphic sections showed that the dominant facies have fine granular textures and siliceous compositions, which considerably differ from those of the prevailing sandy terrigenous facies described in the type locality in the Eastern Hills of Bogotá, in the Arenisca Dura Formation, the basal unit of the Guadalupe Group in this sector.
 The units that form the Guadalupe Group (base of the Guadalupe Group, Plaeners, and Arenisca Tierna) markedly differ from each other morphologically, which facilitates their mapping because the base and top units generate a steep morphology, and the intermediate units form surface depressions or valleys, similar to the morphology of the Guadalupe Group in its type locality in the Eastern Hills of Bogotá. The base of the Guadalupe Group consists of cherts and porcellanites toward the NW of the study area (Alto del Gavilán section), with mudstones, siltstones, quartz arenites, and to a lesser extent porcellanites and cherts prevailing toward the SE (Vereda Salitre section).
 Geochemical analysis of total rock samples by XRD and XRF confirmed the primarily siliceous nature of the base of the Guadalupe Group, with SiO2 ranging from 62 to 98%, CaO less than 3.0%, and P2O5 peaking at 15.0%. Etayo-Serna (2015) conducted paleontological determinations of ammonites found in the stratigraphic section of Alto del Gavilán and assigned the base of the Guadalupe Group mainly to the Lower Campanian.

Mechanical and durability properties of concrete based on recycled coarse and fine aggregates produced from demolished concrete

Faced with aggressive environments, the durability of recycled aggregate concretes constitutes one of the most unknown aspects. The employment opportunities of recycled concrete aggregates will inevitably remain cautious due to the absence of well-established performance criteria. This paper is to investigate the influence of different granular compositions (recycled coarse and fine aggregate) on the mechanical characteristics and durability of concrete. Five series of concrete mixes, manufactured with various granular combinations (natural/recycled), were studied The formulation of the reference concrete was based on a constant quantity of 400 kg/m3of cement and a constant workability of fresh concrete securing S2 class of flowability and C25/30 concrete class, according to European standards.The experimental program consisted of comparing the long-term mechanical strength of concrete conserved in different types of water baths: fresh tap water sourced directly from the supply network, deionized water, and salt water. Also, the durability indicators were observed, such as capillary water absorption, porosity accessible to water, helium gas permeability, and an ammonium nitrate leaching test.The obtained results have highlighted the superiority of concrete composed of natural aggregate over concrete incorporating recycled aggregate for mechanical behaviour, case-observed with three types of water used as a conservation bath. The replacement of natural aggregate by recycled aggregate does not provide any substantial improvement in terms of durability. The use of recycled sand in concrete increases its porosity and vulnerability to an aggressive environment.

Hydraulic performance of anionic polymer-treated bentonite-granular soil mixtures

Abstract In this study, hydraulic conductivity and viscosity determination tests were performed on two different bentonite-granular soil mixtures having various amounts of bentonite in order to obtain the optimum mixture to be used as a liner for waste containment facilities. To enhance the hydraulic capability of these mixtures, an anionic polymer was added to the bentonite. In bentonite-granular soil mixtures, two different aggregate compositions were used: A typical aggregate composition used in the production of C20 type concrete with a void ratio of 0.33 and an aggregate composition with a void ratio of 0.21 that was the minimum void ratio determined by testing various granular soil compositions. In these two mixtures, the bentonite content varied from 8 to 15% whereas the polymer content was within the range of 0.5–10% by mass. Test results indicated that intrinsic permeability decreased drastically due to an increase in the bentonite content. 15% bentonite addition caused a decrease of almost 5.5 orders of magnitude when compared with the granular soils without any bentonite content. 2% anionic polymer addition resulted in a decrease of approximately 2.5 orders of magnitude in hydraulic conductivity. However, further increase in polymer content had almost no effect on lowering hydraulic conductivity. 2% polymer addition in bentonite-granular soil mixtures provided hydraulic conductivity values as low as 10−11 m/s. The decrease in hydraulic conductivity was attributed to the increase in the viscosity of the fluid. Due to polymer addition, an inverse relationship existed between hydraulic conductivity and intrinsic permeability. As a result, polymer-treated bentonite-granular soil mixtures can effectively be used as barrier layers in waste containment facilities.

Prospects of Production of Granular Composite Materials by Method of the Plasma-Centrifugal Atomization

We discuss the prospects of development of the complex approach to the design of high-density, structurally homogeneous hard materials produced from granules obtained on plasma-centrifugal atomization installations with formation of molten baths from the melts in rotating crucibles with skull. The analyzed technology and equipment prove to be promising and commercially attractive for the production of granules intended for manufacturing monolithic composite materials. Granular compositions obtained from spherical particles by using known methods of compaction or layer-by-layer synthesis can be in demand in the domestic industry.

A study of the characteristics of the combustion of Ti + xC (x > 0.5) powder and granular compositions in a gas coflow

The characteristics of the combustion of Ti + 0.5C, Ti + 0.75C, and Ti + C powder and granular mixtures in a flow of inert (argon) and reactive (nitrogen) gases at various pressure differences are studied. It is shown that the influence of the pressure difference on the burning velocity of the powder mixture decreases with increasing fraction of carbon in it, but a pressure difference of 1 atm producing practically no effect on the burning rate of the Ti + C mixture. The data obtained are indicative of a nonequilibrium mechanism of the combustion of Ti + xC granular mixtures in a nitrogen coflow, in which case the sequence of chemical reactions in the combustion wave is determined by the kinetic characteristics of the interaction of titanium with nitrogen and carbon. It is concluded that the reactive gas flow ignites the surface of the granules and thereby leads the propagation of the combustion wave. It is established that, for all the mixtures studied, the mechanism of the combustion of a granular charge in a nitrogen flow is fundamentally different from the combustion of a powder charge under the same condition.

An in vivo study on bone formation behavior of microporous granular calcium phosphate.

This study was developed based on in vivo investigation of microporous granular biomaterials based on calcium phosphates, involving matrices of β-tricalcium phosphate (β-TCP), hydroxyapatite (HA), biphasic compositions of both phases and a control group. The physicochemical characterization of materials was carried out by X-Ray diffraction (DRX) and mercury porosimetry. Biodegradability, bioactivity and neoformation processes were investigated by Raman spectroscopy, scanning electron microscopy (SEM) and polarized light conducted on biopsies obtained from in vivo tests for periods of 90 and 180 days. These were performed to evaluate the behavior of granular microporous compositions in relation to bone neoformation. Through the performance obtained from in vivo assays, excellent osseointegration and bone tissue neoformation were observed. The results are encouraging and show that the microporous granular biomaterials of HA, β-TCP and biphasic compositions show similar results with perfect osseointegration. Architectures simulating a bone structure can make the difference between biomaterials for bone tissue replacement and repair.

Prediction Modeling of Maximum Dry Density of Coarse Grained Soil Using Improved Artificial Neural Networks

To characterize the coarse-grained soil of the fillers in Zhijiang North station of Shanghai-Kunming Passenger Dedicated Line, the vibration compaction test was conducted to study maximum dry densities under different granular compositions. Considering the non-linear relations between granular compositions and maximum dry densities, a BP neural network prediction model of which the input layer was consisted of granular compositions, grading index and fractal index was established based on the backwards error propagation algorithm and the results of the maximum dry density tests. As was improved by the adaptive learning rate method and additional momentum method, the final model established in this paper performed well in predicting the maximum dry density of the coarse-grained soil of various granular compositions.

Analysis of production parameters for operations involving automated manufacture of combined multicomponent articles

The production molding of multicomponent articles consisting of several granular compositions in a multiocular molding tool, which makes it possible to execute all required production operations on the basis of an automated robotized system, is examined. An example is given for implementation of the production molding of multicomponent combined articles on the basis of the automated robotized system. Procedures are cited for calculation of the pressure and selection of the optimal rate of pressing as a function of the physico-mechanical properties of the compositions that enter into the multicomponent article, and the properties of the material of the molding tool.

Observation of enhanced positive magnetoresistance at low temperatures in Ni 0.8Fe 0.2/C granular composites

(Ni 0.8Fe 0.2) x C 100− x ( x = 0–50%) granular compositions were prepared using mechanically alloyed nanocrystalline NiFe powders and graphite. Magnetic measurements and structural data on mechanically alloyed samples show the presence of dominant NiFe phase along with fcc-Ni phase. All the samples exhibit positive magnetoresistance (MR) in the whole temperature range and applied field range of present study. The analysis of the magnetization and MR data suggests that large positive MR could be due to the graphite matrix rather than magnetic particle contribution.

Measurements of mid-winter spatial distribution of meltwater saturation

AbstractUnder melt–freeze conditions crusts may evolve within a snowpack, which may favour avalanche initiation by forming a hard bed surface for weakly bonded faceted grains. We used a parallel-probe saturation profiler (PPSP) to record the distribution of water contents within the snowpack. Diurnal effects of melt–freeze action on the growth of crusts were monitored with the help of the PPSP device. Saturation profiles were collected from a partially wet snow cover. Snow stratigraphy was conducted manually in the morning, after overnight freezing, to identify the location and the granular compositions of the crusts that had evolved. A one-to-one correspondence between the saturation spikes collected using the PPSP and the actual positions of the crusts was established. The PPSP was also used to monitor three-dimensional variations in the maximum percolation depths within a south-facing snowpack. The operation of the PPSP is faster than existing dielectric measurement techniques, so it was applied to study the spatial variability of maximum percolation depths on the slopes of different aspects.

Assessment of sediment toxicity by metal speciation in different particle-size fractions of river sediment

Mobility and toxicity of metals associated with sediments are generally affected by metal speciation and granular compositions. Due to the various speciation patterns of heavy metals in sediments, it is not reliable to assess the potential toxicity of heavy metals on the aquatic environment with the total concentrations of heavy metals in sediments. The purposes of this study were to investigate the distribution of metal speciation in different particle-size fractions of sediments collected from two rivers (the Ke-Ya River and Ell-Ren River) in Taiwan, and to assess their potential toxicity to the aquatic ecosystem. Metals in the exchangeable, carbonate-bound and Fe/Mn oxide-bound forms obtained by sequential extraction were considered to be mobile and related with anthropogenic pollution. The degree of metal pollution and potential toxicity of sediments were higher in the lower reaches of both rivers. The metal speciation in sediments had a bimodal distribution over particle-size fractions. Heavy metals were subject to accumulation in the silt/clay fraction (< 25 microm) and coarse sand (420-2,000 microm). By normalizing the sum of the exchangeable, carbonate-bound, and Fe/Mn oxide-bound metals, it suggested that the potential toxicity to the aquatic ecosystem was caused by the fine sediments as well as coarse sediments.

Ceramic Tiles Made of Granular Technogenic Raw Materials

Sintering and properties of granular compositions containing quartz-feldspar sand (ore processing waste) are studied. Low-melting binders having mineralogical compatibility with the sand grains, reaction activity toward their surface, and a favorable phase composition (regarding sintering and ceramic properties) are developed. The effect of the mixture composition, binder content, grain composition of the sand, and firing temperature on the sintering of mixtures intended for production of tiles for various purposes is established. The tiles thus obtained successfully imitate the surface of granite-like natural stones.

Improved scaling technique for two-phase pressure—saturation relationships

Current methods of scaling imbibition and drainage pressure-saturation data scale the capillary pressure head using ratios of surface tension, constant intrinsic contact angle, fluid density difference and bubbling pressure. These methods are applicable to scaling either the main drainage or imbibition curve for different fluid pairs. However, for a given fluid pair, scaling of the drainage to the imbibition curve is generally unsatisfactory. For the drainage to imbibition case, the maximum error in computed saturations typically occurs at saturations representative of the funicular zone. It is proposed that an empirical functional relationship between advancing and receding apparent contact angles for a specific porous medium can be used to improve the scaling of imbibition to drainage pressure-saturation data for organic liquid-water systems. The Leverett J scaling function is modified by including the ratio of the apparent contact angles as a new scaling term. In the term cos (φ R ) cos(φ A ) p , the advancing apparent contact angle is first corrected for the combined effects of hysteresis and surface roughness by a constant exponent p. The exponent p is equal to the power of the fit of the advancing apparent contact angle, φ A, to the receding apparent contact angle, φ R. The magnitude of the correction appears to be a characteristic of the medium; however, more laboratory tests are needed for verification. The scaling procedure is tested for a limited series of fluid pairs in several porous media that are characterized by differing pore size distributions and granular compositions. The scaling technique is inadequate, however, for systems subjected to forced imbibition.

5591703 Liquid or granular automatic diswashing detergent compositions containing builder, enzyme and low molecular weight, modified polyacrylate copolymers : Sadlowski Eugene S Cincinnati, OH, United States Assigned to The Procter & Gamble Company

5591703 Liquid or granular automatic diswashing detergent compositions containing builder, enzyme and low molecular weight, modified polyacrylate copolymers : Sadlowski Eugene S Cincinnati, OH, United States Assigned to The Procter & Gamble Company

Granular laundry detergent compositions containing selected builders

Granular laundry detergent compositions containing selected builders

Granular detergent compositions with high bulk density and improved rinsing properties

Granular detergent compositions with high bulk density and improved rinsing properties