Where grains and fluids meet: the complex physics of wet granular matter

2017 ◽  
Author(s):  
S. Herminghaus
Keyword(s):  
Mechanical Properties ◽  
Energy Consumption ◽  
Raw Materials ◽  
Granular Matter ◽  
Deep Understanding ◽  
Dynamical Behaviour ◽  
Practical Significance ◽  
Granular Systems ◽  
Snow Avalanches ◽  
Granular Form

In this chapter, the physics of wet granular matter is discussed. The practical significance of wet granular matter goes of course well beyond the construction of sand sculptures. Most industrial raw materials are solids and come in granular form, and the processes into which they feed involve their being mixed with liquids and agglomerated, conveyed, kneaded, or cast in moulds. For appropriately engineering these processes, including the minimization of energy consumption, a deep understanding of the mechanical properties of this class of materials is indispensable. Furthermore, if we want to mitigate, or even reliably predict, such devastating events as land slides or mud flows, we need to study the dynamical behaviour of wet granular matter in detail. This applies as well to other, similar systems of relevance, such as ice and snow avalanches, which can be modelled as wet granular systems as well.

scholarly journals NEW DIRECTIONS OF MODERNIZATION OF SILICON TECHNOLOGY OF SEMICONDUCTOR PURITY

2020 ◽  
Author(s):  
Tatiana Kritskaya ◽  
Leonid Schwartzman ◽  
Vladimir Dodonov ◽  
Anatoly Kravtsov
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Energy Consumption ◽  
Raw Materials ◽  
Environmental Safety ◽  
Economic Conditions ◽  
Production Cycle ◽  
New Approach ◽  
New Directions ◽  
The Cost

In the current economic conditions, a new approach to industrial methods of obtaining polycrystalline and monocrystalline silicon of semiconductor purity is required. This is a reduction in the cost and increase in the productivity of processes while ensuring their environmental safety (optimization of the used raw materials, a closed production cycle, a decrease in energy consumption, special methods of processing and alloying single crystals to control their mechanical properties, thermal stability and radiation resistance).

The Sintering Behaviour and Mechanical Properties of Hydroxyapatite - Based Composites for Bone Tissue Regeneration

2018 ◽  
Vol 69 (5) ◽  
pp. 1272-1275 ◽  
Author(s):  
Camelia Tecu ◽  
Aurora Antoniac ◽  
Gultekin Goller ◽  
Mustafa Guven Gok ◽  
Marius Manole ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tricalcium Phosphate ◽  
Cosmetic Surgery ◽  
Mechanical Stability ◽  
Raw Materials ◽  
Oyster Shell ◽  
Bone Tissue Regeneration ◽  
Sintering Behavior ◽  
Bovine Bone ◽  
Human Teeth

Bone reconstruction is a complex process which involves an osteoconductive matrix, osteoinductive signaling, osteogenic cells, vascularization and mechanical stability. Lately, to improve the healing of the bone defects and to accelerate the bone fusion and bone augmentation, bioceramic composite materials have been used as bone substitutes in the field of orthopedics and dentistry, as well as in cosmetic surgery. Of all types of bioceramics, the most used is hydroxyapatite, because of its similar properties to those of the human bone and better mechanical properties compared to b-tricalcium phosphate [1]. Currently, the most used raw materials sources for obtaining the hydroxyapatite are: bovine bone, seashells, corals, oyster shell, eggshells and human teeth. There are two common ways to obtain hydroxyapatite: synthetically and naturally. Generally, for the improvement of the mechanical properties and the structural one, hydroxyapatite is subjected to the sintering process. Considering the disadvantages of hydroxyapatite such as poor biodegradation rate, b-TCP has been developed, which has some disadvantages too, such as brittleness. For this reason, the aim of this study is to look into the effect of adding magnesium oxide on the sintering behavior, the structure and the mechanical properties of the hydroxyapatite-tricalcium phosphate composites.

Study of Rheological Properties of Modified Concrete Mixtures at Vibration

2019 ◽  
Vol 968 ◽  
pp. 96-106
Author(s):  
Oleksandr Pshinko ◽  
Olena Hromova ◽  
Dmytro Rudenko
Keyword(s):  
Mechanical Properties ◽  
Rheological Properties ◽  
Physical Nature ◽  
Concrete Mixture ◽  
Practical Significance ◽  
Vibration Displacement ◽  
Concrete Mixtures ◽  
Variable Quantity ◽  
Vibration Compaction ◽  
Mechanism Of Interaction

Study of rheological properties of concrete mixtures based on modified cement systems in order to determine process parameters. Methodology. To study structural-mechanical properties of modified concrete mixtures of different consistency at their horizontal vibrating displacement an oscillatory viscometer was designed. Results. The optimization of the process of vibration displacement of concrete mixtures with the specification of parameters of vibration impacts taking into account structural-mechanical properties of the mixture is performed. It has been established that the viscosity of the modified cement system of the concrete mixture is a variable quantity, which depends on the parameters of the vibration impacts. Scientific novelty. The mechanism of interaction of the modified concrete mixture with the form and the table vibrator during its vibration compaction is determined. On the basis of this, a model of concrete laying process control is proposed, that allows to predict the ability to form a dense concrete structure. Practical significance. Disclosed physical nature of the process of vibrating displacement of modified concrete mixtures using the principles of physical-chemical mechanics of concrete allows reasonably choose the best options for vibration impacts.

scholarly journals DFT Study of Electronic Structure and Optical Properties of Kaolinite, Muscovite, and Montmorillonite

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 618
Author(s):  
Layla Shafei ◽  
Puja Adhikari ◽  
Wai-Yim Ching
Keyword(s):  
Mechanical Properties ◽  
Optical Properties ◽  
Electronic Structure ◽  
Hydrogen Bonds ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Bond Order ◽  
Deep Understanding ◽  
Pharmaceutical Applications ◽  
Structure Properties

Clay mineral materials have attracted attention due to their many properties and applications. The applications of clay minerals are closely linked to their structure and composition. In this paper, we studied the electronic structure properties of kaolinite, muscovite, and montmorillonite crystals, which are classified as clay minerals, by using DFT-based ab initio packages VASP and the OLCAO. The aim of this work is to have a deep understanding of clay mineral materials, including electronic structure, bond strength, mechanical properties, and optical properties. It is worth mentioning that understanding these properties may help continually result in new and innovative clay products in several applications, such as in pharmaceutical applications using kaolinite for their potential in cancer treatment, muscovite used as insulators in electrical appliances, and engineering applications that use montmorillonite as a sealant. In addition, our results show that the role played by hydrogen bonds in O-H bonds has an impact on the hydration in these crystals. Based on calculated total bond order density, it is concluded that kaolinite is slightly more cohesive than montmorillonite, which is consistent with the calculated mechanical properties.

scholarly journals Crushed Bricks: Demolition Waste as a Sustainable Raw Material for Geopolymers

2021 ◽  
Vol 13 (14) ◽  
pp. 7572
Author(s):  
Gigliola D’Angelo ◽  
Marina Fumo ◽  
Mercedes del Rio Merino ◽  
Ilaria Capasso ◽  
Assunta Campanile ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Building Materials ◽  
Mechanical Performance ◽  
Raw Materials ◽  
Construction Material ◽  
Raw Material ◽  
The European Union ◽  
Total Energy Consumption ◽  
Demolition Waste ◽  
Crushed Brick

Demolition activity plays an important role in the total energy consumption of the construction industry in the European Union. The indiscriminate use of non-renewable raw materials, energy consumption, and unsustainable design has led to a redefinition of the criteria to ensure environmental protection. This article introduces an experimental plan that determines the viability of a new type of construction material, obtained from crushed brick waste, to be introduced into the construction market. The potential of crushed brick waste as a raw material in the production of building precast products, obtained by curing a geopolymeric blend at 60 °C for 3 days, has been exploited. Geopolymers represent an important alternative in reducing emissions and energy consumption, whilst, at the same time, achieving a considerable mechanical performance. The results obtained from this study show that the geopolymers produced from crushed brick were characterized by good properties in terms of open porosity, water absorption, mechanical strength, and surface resistance values when compared to building materials produced using traditional technologies.

scholarly journals Effect of Sintering Temperature on Microstructure and Mechanical Properties of Hot-Pressed Fe/FeAl2O4 Composite

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 422
Author(s):  
Kuai Zhang ◽  
Yungang Li ◽  
Hongyan Yan ◽  
Chuang Wang ◽  
Hui Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Hot Press ◽  
Microstructure And Mechanical Properties ◽  
Powder Particles ◽  
Hot Press Sintering ◽  
Sintering Method

An Fe/FeAl2O4 composite was prepared with Fe-Fe2O3-Al2O3 powder by a hot press sintering method. The mass ratio was 6:1:2, sintering pressure was 30 MPa, and holding time was 120 min. The raw materials for the powder particles were respectively 1 µm (Fe), 0.5 µm (Fe2O3), and 1 µm (Al2O3) in diameter. The effect of sintering temperature on the microstructure and mechanical properties of Fe/FeAl2O4 composite was studied. The results showed that Fe/FeAl2O4 composite was formed by in situ reaction at 1300 °C–1500 °C. With the increased sintering temperature, the microstructure and mechanical properties of the Fe/FeAl2O4 composite showed a change law that initially became better and then became worse. The best microstructure and optimal mechanical properties were obtained at 1400 °C. At this temperature, the grain size of Fe and FeAl2O4 phases in Fe/FeAl2O4 composite was uniform, the relative density was 96.7%, and the Vickers hardness and bending strength were 1.88 GPa and 280.0 MPa, respectively. The wettability between Fe and FeAl2O4 was enhanced with increased sintering temperature. And then the densification process was accelerated. Finally, the microstructure and mechanical properties of the Fe/FeAl2O4 composite were improved.

scholarly journals Comparative Study of High-Performance Concrete Characteristics and Loading Test of Pretensioned Experimental Beams

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 427
Author(s):  
Pavlina Mateckova ◽  
Vlastimil Bilek ◽  
Oldrich Sucharda
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
High Performance Concrete ◽  
Raw Materials ◽  
Load Capacity ◽  
Materials Testing ◽  
Loading Test ◽  
Conventional Concrete ◽  
Concrete Mechanical Properties ◽  
Normal Strength

High-performance concrete (HPC) is subjected to wide attention in current research. Many research tasks are focused on laboratory testing of concrete mechanical properties with specific raw materials, where a mixture is prepared in a relatively small amount in ideal conditions. The wider utilization of HPC is connected, among other things, with its utilization in the construction industry. The paper presents two variants of HPC which were developed by modification of ordinary concrete used by a precast company for pretensioned bridge beams. The presented variants were produced in industrial conditions using common raw materials. Testing and comparison of basic mechanical properties are complemented with specialized tests of the resistance to chloride penetration. Tentative expenses for normal strength concrete (NSC) and HPC are compared. The research program was accomplished with a loading test of model experimental pretensioned beams with a length of 7 m made of ordinarily used concrete and one variant of HPC. The aim of the loading test was to determine the load–deformation diagrams and verify the design code load capacity calculation method. Overall, the article summarizes the possible benefits of using HPC compared to conventional concrete.

Microstructure and Mechanical Properties of ZrB2/h-BN Multiphase Ceramics by Low-Temperature Reactive Sintering

2016 ◽  
Vol 697 ◽  
pp. 510-514 ◽  
Author(s):  
Feng Rui Zhai ◽  
Ke Shan ◽  
Ruo Meng Xu ◽  
Min Lu ◽  
Zhong Zhou Yi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Relative Density ◽  
Fracture Strength ◽  
Solid Phase ◽  
Raw Materials ◽  
Solid Phase Reaction ◽  
Phase Reaction ◽  
Microstructure And Mechanical Properties ◽  
Multiphase Ceramics ◽  
Strength And Toughness

In the present paper, the ZrB2/h-BN multiphase ceramics were fabricated by SPS (spark plasma sintering) technology at lower sintering temperature using h-BN, ZrO2, AlN and Si as raw materials and B2O3 as a sintering aid. The phase constitution and microstructure of specimens were analyzed by XRD and SEM. Moreover, the effects of different sintering pressures on the densification, microstructure and mechanical properties of ZrB2/h-BN multiphase ceramics were also systematically investigated. The results show that the ZrB2 was obtained through solid phase reaction at different sintering pressures, and increasing sintering pressure could accelerate the formation of ZrB2 phase. As the sintering pressure increasing, the fracture strength and toughness of the sintered samples had a similar increasing tendency as the relative density. The better comprehensive properties were obtained at given sintering pressure of 50MPa, and the relative density, fracture strength and toughness reached about 93.4%, 321MPa and 3.3MPa·m1/2, respectively. The SEM analysis shows that the h-BN grains were fine and uniform, and the effect of sintering pressure on grain size was inconspicuous. The distribution of grain is random cross array, and the fracture texture was more obvious with the increase of sintering pressure. The fracture mode of sintered samples remained intergranular fracture mechanism as sintering pressure changed, and the grain refinement, grain pullout and crack deflection helped to increase the mechanical properties.

In Situ Preparation and Mechanical Properties of (ZrB2+ZrC)/Zr3[Al(Si)]4C6 Composites

2014 ◽  
Vol 602-603 ◽  
pp. 438-442
Author(s):  
Lei Yu ◽  
Jian Yang ◽  
Tai Qiu
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Bending Strength ◽  
Coefficient Of Thermal Expansion ◽  
Raw Materials ◽  
Linear Increase ◽  
Fine Grain ◽  
Fine Grain Strengthening ◽  
Uniform Microstructure

Fully dense (ZrB2+ZrC)/Zr3[Al (Si)]4C6 composites with ZrB2 content varying from 0 to 15 vol.% and fixed ZrC content of 10 vol.% were successfully prepared by in situ hot-pressing in Ar atmosphere using ZrH2, Al, Si, C and B4C as raw materials. With the increase of ZrB2 content, both the bending strength and fracture toughness of the composites increase and then decrease. The synergistic action of ZrB2 and ZrC as reinforcements shows significant strengthening and toughing effect to the Zr3[Al (Si)]4C6 matrix. The composite with 10 vol.% ZrB2 shows the optimal mechanical properties: 516 MPa for bending strength and 6.52 MPa·m1/2 for fracture toughness. With the increase of ZrB2 content, the Vickers hardness of the composites shows a near-linear increase from 15.3 GPa to 16.7 GPa. The strengthening and toughening effect can be ascribed to the unique mechanical properties of ZrB2 and ZrC reinforcements, the differences in coefficient of thermal expansion and modulus between them and Zr3[Al (Si)]4C6 matrix, fine grain strengthening and uniform microstructure derived by the in situ synthesis reaction.

Effect of the Short Fiber on the NR Composite and the NR-SBR Composite

2012 ◽  
Vol 581-582 ◽  
pp. 552-555
Author(s):  
Cai Jun Liu
Keyword(s):  
Mechanical Properties ◽  
Energy Consumption ◽  
Short Fiber ◽  
Maximum Power ◽  
Mechanical Process ◽  
Contrast Method ◽  
Unit Energy ◽  
Unit Energy Consumption

The influence of the pretreatment polyester short fiber on the mechanical process and the properties of the NR/ SBR compound was studied by using contrast method. The results showed that the maximum power and the unit energy consumption increased because of short fiber, and the temperature also enhanced. So the low rotate speed is better. When the composite were cured, it had much characteristic such as rapid vulcanization speed, short scorch time and vulcanization smooth period. But the mechanical properties were increased. In the end, the microscopic photo of composite with the scanning electronic micrograph was taken.

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