Physical Microstructure Research Articles

Preparation of Highly Porous Materials based on Refractory Clays

A porous ceramic based on clay and nonplastic aluminosilicate raw material of Uzbekistan was prepared by slip casting. Molding was conducted using a foaming agent — technical foam and sawdust, which stabilized the structure, followed by firing at 1300 – 1350°C. The effect of different fillers on the physical and technical properties and microstructure of the samples was studied after sintering. It was determined that ceramic with density 700 – 900 kg/m3 and strength 1.6 – 11.0 MPa can be obtained by foam technology with foam content ranging from 15 to 25 wt.%. Porous samples with the finest grain and pore structure were obtained on the basis of Samarkand chamotte.

Temperature-Dependent Chemical and Physical Microstructure of Li Metal Anodes Revealed through Synchrotron-Based Imaging Techniques.

The Li metal anode has been long sought-after for application in Li metal batteries due to its high specific capacity (3860 mAh g-1 ) and low electrochemical potential (-3.04 V vs the standard hydrogen electrode). Nevertheless, the behavior of Li metal in different environments has been scarcely reported. Herein, the temperature-dependent behavior of Li metal anodes in carbonate electrolyte from the micro- to macroscales are explored with advanced synchrotron-based characterization techniques such as X-ray computed tomography and energy-dependent X-ray fluorescence mapping. The importance of testing methodology is exemplified, and the electrochemical behavior and failure modes of Li anodes cycled at different temperatures are discussed. Moreover, the origin of cycling performance at different temperatures is identified through analysis of Coulombic efficiencies, surface morphology, and the chemical composition of the solid electrolyte interphase in quasi-3D space with energy-dependent X-ray fluorescence mappings coupled with micro-X-ray absorption near edge structure. This work provides new characterization methods for Li metal anodes and serves as an important basis toward the understanding of their electrochemical behavior in carbonate electrolytes at different temperatures.

Understanding the relationship between physical properties and crystallization behavior of interesterified blend-based fast-frozen special fat with varied triacylglycerol composition

To understand the relationship between physical properties and crystallization behavior of fast-frozen special fat with varied triacylglycerol (TAG) composition, interesterified blend-based fast-frozen special fats (IBSFs) with 41–45 °C slip melting point were prepared. Compared with corresponding physical blend-based fast-frozen special fats, the IBSFs had wider plastic range indicated by solid fat content (45%–6% at 0–45 °C), less hardness (20–50 g) and elasticity (104–105 Pa at 25 °C), more β′ crystals (β′/β = 6/4–7/3). In addition, the IBSFs possessed small-sized spherical or short needle-shaped crystals which were uniformly and densely distributed in the crystalline network. The trained 6-27-3 artificial neural network (ANN) model was successfully to describe the complicated relation between physical properties and microstructure of IBSFs with diverse TAG composition. The physical properties of IBSFs would be predicted according to their crystallization behavior with distinct TAG composition, which is helpful in constructing specific fast-frozen special fat.

Effects of coagulant promoter on the physical properties and microstructure of the mixed system of ultrafine fishbone and surimi

The object of this paper is a new type of canned lunch fish which is made of ultrafine freshwater fish (fishbone and surimi). The gel-promoting effects of four different coagulant accelerators were studied according to production formula and process conditions. The different accelerators played different roles in promoting gelation in the mixed system of ultrafine fishbone and surimi. The four coagulants showed synergistic promotion effects. Starch and complex phosphates play a major role in the production of high-calcium lunch fish meat. The limited addition of soy protein isolate in lunch meat is the main reason for its limited gel-promoting effect. The weak activity of transglutaminase (TGase) was caused by enzyme activity, temperature, and the degradation of surimi itself. A difference in gel temperature, resulted in the limited the gel-promoting effect of TGase.

Physical Properties and Microstructure of Ice Cream Supplemented With Minor Components of Wheat Germ Oil

Physical Properties and Microstructure of Ice Cream Supplemented With Minor Components of Wheat Germ Oil

The effect of mastication time on the physical properties and structure of natural rubber

The effect of mastication time in an internal mixer on the physical properties and microstructure of natural rubber (NR) was studied. The Mooney viscosity, plasticity, and complex viscosity reduced with increases in the mastication time due to the molecular breakdown of the rubber. The microstructural changes in the NR were studied using small-angle X-ray scattering. The results revealed that a reduction in the physical properties correlated with the structural changes, which occurred due to mastication. Increases in mastication time affected the distribution and size of the nonrubber component aggregations and the uniformity of the molecular structure of the NR.

In Vitro Gastrointestinal Digestion of Palm Olein and Palm Stearin-in-Water Emulsions with Different Physical States and Fat Contents.

The impacts of lipid physical state and content on lipid digestion behavior were investigated using 4 and 20% palm olein-in-water emulsions (4% PO and 20% PO) and 4 and 20% palm stearin-in-water emulsions (4% PS and 20% PS). The changes of lipid physical state, particle size, and microstructure during gastrointestinal digestion; the free fatty acid (FFA) released in the intestinal phase; and the fatty acid composition of micellar phases were investigated. After gastric digestion, all emulsions underwent flocculation and coalescence, with 20% PS showing the most extensive aggregation. During intestinal digestion, the FFA release rate and level decreased as the lipid content increased from 4 to 20%, with 4% PO presenting the highest digestion rate and extent. Besides, the solid fat in 4% PS and 20% PS decreased and increased the maximum lipid digestibility, respectively. These results highlighted the combined roles of lipid physical state and content in modulating dietary lipid digestion.

Mechanical and Microstructural Properties of Alkali Wastes as Filling Materials for Abandoned Salt Caverns

Alkali solid waste from soda industries has previously been stacked on surface and contaminated soil and groundwater. In China, an engineering method of filling alkali wastes into abandoned salt caverns is adopted. This method can solve the problem of waste disposal and the potential geological disasters associated with salt caverns. In such filling projects, the engineering properties of alkali wastes are important for the safety and stability of salt caverns. In this study, the microstructural and mechanical properties of alkali wastes were investigated. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to analyze the microstructure and mineralogy of such wastes. Direct shear tests were conducted to evaluate the mechanical performance and to obtain the strength parameters of alkali wastes. The basic physical characteristics, microstructure, mineral compositions, and mechanical properties of alkali wastes vary significantly at different burial depths. Moreover, the strength properties of alkali wastes are close to those of the two other common filling materials, sandstone–mudstone mixtures and tailings. The research results can be used as a reference for similar filling projects and can also be beneficial for the cyclic utilization of alkali wastes. An engineering method that utilizes alkali solid wastes to fill abandoned salt caverns is introduced, and the engineering properties of alkali wastes are studied.

Soy Protein Isolate Films Incorporated with Pinhão (Araucaria angustifolia (Bertol.) Kuntze) Extract for Potential Use as Edible Oil Active Packaging

One of the traditional residues obtained from pinhao seeds (Araucaria angustifolia (Bertol.) Kuntze) consists of an aqueous extract produced from the cooking process, which presents a significant concentration of phenolic compounds with antioxidant properties. In this work, soy protein isolate (SPI) films with different concentrations of pinhao cooking water extract (EP, 0.5, 1, and 2% wt/wt) were produced and physical properties, microstructure, and antioxidant capacity were investigated. The films were applied as packaging (as sachet-type) for linseed oil, and the oil oxidative stability was evaluated during 10 days under accelerated storage condition (60 °C) by conventional procedures (peroxide index, specific extinction coefficient, and UV-Vis spectrophotometry) and by multivariate curve resolution with alternating least squares (MCR-ALS) chemometric method. The film with EP contributed to the oxidative stability of linseed oil being an interesting alternative of active biodegradable packaging for edible oils.

Physical properties and microstructure of nickel slag/metakaolin-based geopolymer with different contents of nickel slag

Geopolymer pastes based on nickel slag/metakaolin (NS/MK) were prepared and their physical properties and microstructure as a function of NS content were studied. The results showed that the addition of NS in an appropriate proportion not only enhanced the compressive strength but also led to volume-expansive behaviour of the hardened pastes. Analysis of the pore size distribution indicated that increasing the NS content reduced the total pore volume and increased the average pore size. The silicate species dissolved from the NS participated in the geopolymerisation and influenced the mineralogical composition and microstructure of the gel phase. The addition of NS had no detrimental effect on the concentrations of alkali metals and pH of the leaching solution obtained from the geopolymer samples. In addition, the addition of NS had no detrimental effect on the dissolution behaviour of MK. This work presents a further step in the development of alternative ‘low-carbon’ binders for the construction industry.

Identification of the causes of non-uniformity of the condensate collector metal of the main gas pipeline

The complex of negative effects of hydrogen on metal, leading to destruction of metal structures, is commonly called hydrogen corrosion. The object of the study was a sample of steel A 516-55 condensate collector of the main gas pipeline, which was subjected to hydrogen stratification. The aim of the work was to establish a link between the non-uniformity of the metal and its tendency to hydrogen stratification. The work solved problems that were aimed at studying the physical and mechanical properties and microstructure of the analysed metal. X-ray fluorescence analysis was carried out to identify the causes of discontinuities within the metal. A light microscopy method was carried out to study the microstructure of the test sample taken from the focus zone of the condensate collector destruction. The microstructure was examined using the “METAM RV - 22 type EU LOMO metallographic microscope. An X-ray fluorescence analysis was carried out to determine the causes of the discontinuity within the metal. Tests were performed on a EDX-800HS spectrometer at various X-ray tube operations. It has been found that the inhomogeneities are due to the uneven distribution of manganese in the metal body. A post-publication change was made to this article on 11 Jun 2020 to correct the pdf so that it matched the webpage.

Baseline White Matter Is Associated With Physical Fitness Change in Preclinical Alzheimer's Disease.

White matter (WM) microstructure is a sensitive marker to distinguish individuals at risk of Alzheimer’s disease. The association of objective physical fitness (PF) measures and WM microstructure has not been explored and mixed results reported with physical activity (PA). Longitudinal studies of WM with PA and PF measures have had limited investigation. This study explored the relationship between objective PF measures over 24-months with “normal-appearing” WM microstructure. Data acquired on magnetic resonance imaging was used to measure “normal-appearing” WM microstructure at baseline and 24-months. Clinical variables such as cognitive and blood-based measures were collected longitudinally. Also, as part of the randomized controlled trial of a PA, extensive measures of PA and fitness were obtained over the 24 months. Bilateral corticospinal tracts (CST) and the corpus callosum showed a significant association between PF performance over 24-months and baseline WM microstructural measures. There was no significant longitudinal effect of the intervention or PF performance over 24-months. Baseline WM microstructural measures were significantly associated with PF performance over 24-months in this cohort of participants with vascular risk factors and at risk of Alzheimer’s disease with distinctive patterns for each PF test.

Effect of particle size and CO2 treatment of waste cement powder on properties of cement paste

This paper studies the role of CO2 treatment and the impact of particle size (<75 μm and 75–150 μm) of waste cement powder (WCP) with different cement replacement content (0%, 5%, 10%, 15%, 20%, and 30%) on the physical properties and microstructure of blended cement paste. The results show that carbonation of WCP can effectively increase the flowability of paste due to the formation of calcite and decrease the porosity of WCP microstructure, while the water demand to achieve the same workability decreases with increasing size of WCP particles. Cement paste containing decreased particles of carbonated waste cement powder possesses a higher 28 day compressive strength due to formation of a higher amount of calcite and hydration products, based on the thermogravimetric analysis.

Effect of build orientation on the manufacturing process and the properties of stereolithographic dental ceramics for crown frameworks

Statement of problemStereolithography (SLA) ceramic crown frameworks are suitable for clinical use, but the impact of SLA build orientation has not been identified. PurposeThe purpose of this in vitro study was to investigate the effect of 3 build orientations on the physical and mechanical properties and the microstructure of SLA alumina dental ceramics. Material and methodsThe physical and mechanical properties and microstructures of 3 different oriented SLA alumina ceramics (ZX, ZY, and XY) were evaluated by visual observation, hydrostatic weighing (n=10/group), Weibull analyses (n=30/group), scanning electron microscopy, 3-point flexural strength (n=30/group), fracture toughness (indentation, single-edge-V-notched-beam) (n=4/group), and Vickers hardness (n=15/group) testing. The hydrostatic weighing, 3-point flexural strength, fracture toughness, and Vickers hardness testing data were statistically analyzed (α=.05). ResultsThe minimum resting period of slurries between the polymerization of 2 layers was shorter for the ZY- and ZX-oriented specimens and increased with the layer surface. The density and Vickers hardness of the SLA-manufactured specimens were similar for all groups (P>.05). The 95% confidence intervals of the Weibull moduli of the ZX- and ZY-oriented specimens were higher than that of the XY-oriented specimens, with no overlap fraction. The ZY-oriented specimens displayed significantly higher 3-point flexural strength (P<.05) and fracture toughness as evaluated by the single-edge-V-notched-beam method than the ZX-oriented specimens (P<.05). They also displayed significantly higher 3-point flexural strength than the XY-oriented specimens (P<.05). The microstructural analysis showed that the texturing was heterogeneous and that the major axis of the large grains of alumina ran parallel to the orientation of the layers. ConclusionsThe ZY orientation produced a reliable dental ceramic by SLA, with the shortest general manufacturing time and the highest mechanical strength when the layers were perpendicular to the test load surface.

Role of Saturation on Elastic Dispersion and Attenuation of Tight Rocks: An Experimental Study

AbstractUsing the forced‐oscillation method, we measure the dispersion of Young's modulus, extensional attenuation, and Poisson's ratio of tight sandstone and carbonate samples at seismic frequencies (1–1000 Hz) under a constant confining pressure of 20 MPa and for a water saturation varying between 0% and 100%. The experimental data suggest that the dispersion of Young's modulus and attenuation of tight rocks is significant in a broad frequency band spanning over 1–1000 Hz. A comparison with the high‐porosity and high‐permeability sample data shows a contrasting dispersion and attenuation characteristics. For the tight sandstone, Young's modulus reaches a maximum dispersion of 16% at 60% water saturation and a 13% dispersion at 100% saturation. Attenuation is insignificant in dry condition and for water saturation ≤30%. In contrast with the peak attenuation occurring at very high water saturation (e.g., 80–100%) in partially saturated high‐porosity rocks, peak attenuation of tight sandstone takes place at a water saturation of 60%. For the tight carbonate, the magnitude of dispersion (~3%) and attenuation are markedly lower for all saturation levels. In the explored frequency range (1–1000 Hz), Young's modulus increases monotonously, and no obvious attenuation peak is observed when saturation levels are greater than 10%. Using well‐established theoretical models based on physical properties and microstructure of the tested rocks, we suggest that the observed attenuation characteristics are possibly attributed to the combined physical mechanism of microscopic (squirt) flow, mesoscopic flow in partially saturated rock, and shear dispersion due to viscous flow in grain contacts.

Microstructures and properties of a novel γ′-strengthened multi-component CoNi-based wrought superalloy designed by CALPHAD method

The γ′-strengthened Co-based superalloys have a lower γ′ solvus temperature and a higher γ′ volume fraction compared with Ni-based wrought superalloys, making this type of alloy more appropriate as a wrought superalloy for hot components of aero engines and industrial gas turbines, such as turbine disk. In order to accelerate the development and application of novel γ′-strengthened Co-based superalloys, CALPHAD method was employed to design a γ′-strengthened multi-component CoNi-based wrought superalloy with improved comprehensive performances on the basis of the Co–7Al–8W–4Ti–1Ta (at.%) quinary alloy. The preliminary evaluation of physical properties, microstructure, oxidation resistance, and mechanical properties of the designed alloy in as cast and as heat treated state shows that, in comparison with Ni-based wrought superalloys, the designed alloy which has a comparable density and a larger processing window, demonstrates better oxidation resistance and comparable mechanical properties. These results suggest that the CALPHAD method is helpful for the design and development of the γ′-strengthened multi-component CoNi-based superalloys, and the designed alloy has a potential for engineering application.

Physical properties and microstructure of plastic aggregate mortars made with acrylonitrile-butadiene-styrene (ABS), polycarbonate (PC), polyoxymethylene (POM) and ABS/PC blend waste

This paper investigates cement mortars made with waste plastic aggregates (polycarbonate-PC-, polyoxymethylene -POM-, acrylonitrile-butadiene-styrene -ABS-, an ABS/PC blend -ABSC- and polyethylene terephthalate -PET-) as partial sand replacements at 5–20% by volume.Even at 20% plastic content, the strength surpasses the standard strength requirements for masonry, rendering and plastering mortars, with compressive strengths ranging from c.37–71 MPa and flexural strengths reaching 4–9 MPa. Most plastics, in contents up to 15%, enhance the flexural strength of the standard cement mortar which can improve the resistance to tensile stress caused by loading and expansion by frost, salt or swelling clays.The plastic aggregates increase the cement mortar's ability to deform on stress application, delaying failure and turning the typical brittle failure of cement mortars into a ductile failure, a notable asset for those specifying repair mortars for masonry which typically deforms over time.The fall in the mechanical/hygric properties and density caused by the plastic (>15% content), is mainly due to the proliferation of disrupted interfaces rather than to the physical properties of the plastics themselves. There is not significant direct correlation between the properties of the mortars and those of their plastic aggregates – except for the compressive strength. The relationship can sometimes appear inverse, suggesting that larger differences between plastic and cement matrix properties can enhance incompatibility and lower durability. However, the grading, shape and surface characteristics of the plastic particles impact the properties of the resultant mortars. The results highlight the performance of the ABS (best graded plastic) barely rising the hygric properties, even at 15% replacement, and showing high strengths and sealed interfaces.

Physical–microstructural evaluation and sulfate resistance of no‐cement mortar developed from a ternary binder of industrial by‐products

AbstractThe present research evaluates the physical properties and microstructure of no‐cement mrtar specimens, which were developed using three waste materials, rice husk ash (RHA), ground granulated blast furnace slag (GGBFS), and circulating fluidized bed combustion fly ash (CFA), as binders. Various weight ratios of GGBFS/RHA were used (100/0, 15/85, 30/70, and 45/55), and CFA was added at ratios of 10, 15, and 20% of total binder weight. Slump flow and unit weight were used to evaluate the fresh properties of the no‐cement mortar samples, while hardened properties of the mortar samples were evaluated through compressive strength (CS) and drying shrinkage tests. In addition, scanning electron microscopy/energy dispersive spectrometer and X‐ray diffraction patterns were used to analyze the microstructure of the samples, while visual examination and loss CS tests were used to estimate sulfate resistance. As a result, the inclusion of RHA required a higher amount of superplasticizer in order to achieve a similar flowability with RHA‐free mortar and remarkably reduced the fresh unit weight of the mortar mixture. In addition, the partial replacement of GGBFS with RHA up to 30% improved the 120‐day CS of mortar specimens with 10, 15, and 20% CFA content by 8.8, 10.4, and 10.1%, respectively. Moreover, the developed no‐cement mortars exhibited excellent performance against sulfate attack. Higher CFA content in the mixtures also generated higher volumes of hydration products and ettringite gel, which further increased mortar strength.

Effect of nano sand on the properties of metakaolin-based geopolymer: Study on its low rate sintering

The main goal of the present work is to optimize the effective percentage of nano sand which leads to improving the properties of kaolin-based geopolymer. An attempt to study the low rate sintering of the prepared geopolymer at 800, 1000 and 1200 °C was also investigated. Various percentages of nano sand i.e. 2.5, 5, 7.5 wt-%, were added to alkali-activated kaolin-based geopolymers. The phase composition and microstructure of none sintered and sintered geopolymers were examined by X-ray diffraction and scanning electron microscope. Fourier-transform infrared spectroscopy was also utilized to confirm the composition of prepared geopolymers. Furthermore, the bulk density, apparent porosity and compressive strength of prepared geopolymers were also determined. The results showed that the physical properties, microstructure and compressive strength of none sintered and sintered geopolymers were improved after adding 2.5% nano sand. 2.5% nano sand was suitable to increase the polymerization, fill the open pores and consequently enhanced the properties. The compressive strength of none sintered geopolymer that contains 2.5% nano sand was 60 MPa while that of geopolymer sintered at 1000 °C was 95 MPa. The higher percentages of nano sand (5 and 7.5%) deteriorated the properties of prepared geopolymers.

Grain size-dependent energy partition in phase transition of NiTi shape memory alloys studied by molecular dynamics simulation

Nanocrystalline NiTi shape memory alloys show fundamental changes in phase transition behavior when the grain size is reduced down to nano-scale (grain size <30 nm). However, due to the extreme difficulties of in-situ experimental observation, universally acknowledged physical mechanisms and detailed microstructures at atomic level are still not clear. In this paper, detailed microstructure images and quantified energy partition at atomic level during stress-induced phase transition are obtained by molecular dynamics simulation. Phase transition is gradually suppressed and incomplete phase transition occurs as grain size decreases. The potential energy landscape of the nanocrystalline system changes significantly from nonconvex to convex, which leads to corresponding changes in stress–strain response and microstructural evolution. With decreasing grain size, the interface (grain boundary and phase boundary) energy makes much more contributions in variation of the system potential energy than the crystallite (austenite and martensite) energy. The mechanism of energy dissipation changes from atomic interface friction in phase transition to plastic deformation caused by grain boundary sliding. It is the gradual dominance of interfacial energy terms in total potential energy that leads to the observed fundamental changes of phase transition behavior in nanocrystalline NiTi.