scholarly journals Increasing the mechanical strength of fine-grained concrete by introducing finely dispersed mineral additives

2017 ◽  
Author(s):  
Svetlana Khakimullina ◽  
Liliia Il’ina ◽  
Irina Mukhina
Keyword(s):  
Mechanical Strength ◽  
Fine Grained ◽  
Mineral Additives

scholarly journals Effect of freeze-thaw cycles on mechanical strength of lime-treated fine-grained soils

2019 ◽  
Vol 21 ◽  
pp. 100281 ◽  
Author(s):  
Thi Thanh Hang Nguyen ◽  
Yu-Jun Cui ◽  
Valéry Ferber ◽  
Gontran Herrier ◽  
Tamer Ozturk ◽  
...  
Keyword(s):  
Mechanical Strength ◽  
Freeze Thaw ◽  
Fine Grained

Determining the Mechanical Strength of Ultra-Fine-Grained Metals

10.3791/61819 ◽  
2021 ◽  
Author(s):  
Jianing Xu ◽  
Yanju Wang ◽  
Jinyuan Yan ◽  
Bin Chen
Keyword(s):  
Mechanical Strength ◽  
Fine Grained

scholarly journals RESEARCH OF ADHESIVE STRENGTH OF NEW CONCRETE LAYER WITH A SURFACE OF OLD CONCRETE

Vestnik MGSU ◽  
2016 ◽  
pp. 76-83
Author(s):  
Van Lam Tang ◽  
Boris Igorevich Bulgakov
Keyword(s):  
High Performance ◽  
Water Resistance ◽  
High Performance Concrete ◽  
Good Resistance ◽  
Fine Grained ◽  
Fine Grain ◽  
Concrete Layer ◽  
Subway Tunnels ◽  
Mineral Additives ◽  
Shock Impacts

Concrete is a material very commonly used in modern construction, each year over 4 billion m3 of concrete is used around the world. In the recent years high-quality fine grain and other types of concrete allow giving the modern creation city buildings new architectural expressivity, meeting the requirements of the XXI century. The trend of using of these new types of concrete is also applied in the construction of tunnel systems and the subway. The fine-grained high performance concrete obtained by using a mixture of organo-mineral additives and fiber reinforcement, compares fovourably with ordinary fine-grained concrete, namely its bending and tensile strength is higher, it has good resistance to shock impacts and fatigue, as well as crack resistance, water resistance and resistance to erosion. So this type of fine-grained high performance concrete is suitable for the construction of subway tunnels and other special objects. When evaluating the concrete performance in underground rock layers subjected to complex mechanical forces, it is important to take into account the stress of metro upon departure and stopping at the stations. The article presents a new experimental method of determining the adhesion strength of fine-grained high performance concrete layer freshly poured on the surface of old concrete in the process of construction and repair of underground. The result of this method application showed that fine-grained high performance concrete is capable of skid resistance higher than 55 % compared to regular fine-grained concrete without additives.

A study on the formation of hydrothermally prepared BaTiO3 particles

1992 ◽  
Vol 50 (1) ◽  
pp. 304-305
Author(s):  
Fatih Dogan ◽  
Jun Liu ◽  
Mehmet Sarikaya ◽  
Ilhan A. Aksay
Keyword(s):  
Aqueous Solution ◽  
Dielectric Constant ◽  
Low Temperature ◽  
Mechanical Strength ◽  
High Dielectric Constant ◽  
Fine Particles ◽  
Ferroelectric Material ◽  
Fine Grained ◽  
High Dielectric ◽  
Processing Techniques

BaTiO3 is an important ferroelectric material because of its high dielectric constant. To increase the optical transparency and mechanical strength, it is desirable to produce fine grained BaTiO3. Fine particles can be produced by colloidal processing techniques. In this case, however, it is usually necessary to synthesize monodispersed BaTiO3 particles with a predetermined diameter in a suspension. One widely used method to produce colloidal BaTiO3 particles is by reacting TiO2 particles with Ba(OH)2 in an aqueous solution at a moderately low temperature, i.e.,T < 100 °C.

Evolution of Texture in Ultra-Fine Grained Ferrite through Warm-Rolling and Intercritical Annealing

2008 ◽  
Vol 584-586 ◽  
pp. 610-616
Author(s):  
Sandip Ghosh Chowdhury ◽  
B. Mahato ◽  
Hezio Rosa da Silva ◽  
Gustavo Gonçalves Lourenço ◽  
Dagoberto Brandão Santos
Keyword(s):  
Mechanical Strength ◽  
Intercritical Annealing ◽  
Tensile Tests ◽  
Warm Rolling ◽  
Ultrafine Grain ◽  
Low Carbon ◽  
Iron Carbides ◽  
Fine Grained ◽  
Subcritical Annealing ◽  
Good Relation

The ferrite grain size refining is the unique mechanism for increasing both mechanical strength and formability of steels. Steel with an ultra-fine ferrite grained structure must show a good relation between mechanical strength, ductility and toughness, while the low carbon content enhances good welding characteristics. The objective of this work is to investigate the influence of warm rolling on the evolution of texture in a microalloyed low carbon-manganese (0.11%C, 1.41%Mn, 0.028%Nb and 0.012%Ti) steel with ultra-fine grains produced through out quenching, warm rolling, followed by sub and intercritical annealing. The evolution of restoration process - recovery and recrystallization - was followed by optical and scanning microscopy. After subcritical annealing, the microstructure was formed by spheroidal iron carbides and a ferritic recovered matrix. Otherwise, after intercritical annealing, the microstructure was composed mainly by ultrafine grain polygonal ferrite, MA (martensite-austenite) constituent and carbides. The mechanical behaviour of the steel was evaluated using tensile tests. The mechanical properties have been correlated with the evolution of texture in the ultra-fine grained ferrites.

Application of an image management system in microscopy

1992 ◽  
Vol 50 (2) ◽  
pp. 1052-1053
Author(s):  
Richard S. Chemock
Keyword(s):  
Data Storage ◽  
Cost Savings ◽  
Image Data ◽  
Analytical Techniques ◽  
Operational Mode ◽  
Fine Grained ◽  
Image Recording ◽  
Primary Output ◽  
Capacity Data ◽  
Image Management System

One of the most common tasks in a typical analysis lab is the recording of images. Many analytical techniques (TEM, SEM, and metallography for example) produce images as their primary output. Until recently, the most common method of recording images was by using film. Current PS/2R systems offer very large capacity data storage devices and high resolution displays, making it practical to work with analytical images on PS/2s, thereby sidestepping the traditional film and darkroom steps. This change in operational mode offers many benefits: cost savings, throughput, archiving and searching capabilities as well as direct incorporation of the image data into reports.The conventional way to record images involves film, either sheet film (with its associated wet chemistry) for TEM or PolaroidR film for SEM and light microscopy. Although film is inconvenient, it does have the highest quality of all available image recording techniques. The fine grained film used for TEM has a resolution that would exceed a 4096x4096x16 bit digital image.

Use of fractals to describe microstructures of porous thick-film platinum electrodes

1992 ◽  
Vol 50 (1) ◽  
pp. 314-315
Author(s):  
Steven D. Toteda
Keyword(s):  
Fractal Dimension ◽  
Power Plants ◽  
Electrical Response ◽  
Cubic Phase ◽  
Platinum Electrodes ◽  
Fine Grained ◽  
Impedance Response ◽  
Platinum Particles ◽  
Energy Surfaces ◽  
Highly Porous

Zirconia oxygen sensors, in such applications as power plants and automobiles, generally utilize platinum electrodes for the catalytic reaction of dissociating O2 at the surface. The microstructure of the platinum electrode defines the resulting electrical response. The electrode must be porous enough to allow the oxygen to reach the zirconia surface while still remaining electrically continuous. At low sintering temperatures, the platinum is highly porous and fine grained. The platinum particles sinter together as the firing temperatures are increased. As the sintering temperatures are raised even further, the surface of the platinum begins to facet with lower energy surfaces. These microstructural changes can be seen in Figures 1 and 2, but the goal of the work is to characterize the microstructure by its fractal dimension and then relate the fractal dimension to the electrical response. The sensors were fabricated from zirconia powder stabilized in the cubic phase with 8 mol% percent yttria. Each substrate was sintered for 14 hours at 1200°C. The resulting zirconia pellets, 13mm in diameter and 2mm in thickness, were roughly 97 to 98 percent of theoretical density. The Engelhard #6082 platinum paste was applied to the zirconia disks after they were mechanically polished ( diamond). The electrodes were then sintered at temperatures ranging from 600°C to 1000°C. Each sensor was tested to determine the impedance response from 1Hz to 5,000Hz. These frequencies correspond to the electrode at the test temperature of 600°C.

Amorphous silica coating on α-alumina particles

1995 ◽  
Vol 53 ◽  
pp. 210-211
Author(s):  
J. W. Mellowes ◽  
C. M. Chun ◽  
I. A. Aksay
Keyword(s):  
Amorphous Silica ◽  
Heterogeneous Nucleation ◽  
Homogeneous Nucleation ◽  
Silica Coating ◽  
Full Density ◽  
Optimal Conditions ◽  
Fine Grained ◽  
Alumina Particles ◽  
Complete Mullitization ◽  
Powder Compacts

Mullite (3Al2O32SiO2) can be fabricated by transient viscous sintering using composite particles which consist of inner cores of a-alumina and outer coatings of amorphous silica. Powder compacts prepared with these particles are sintered to almost full density at relatively low temperatures (~1300°C) and converted to dense, fine-grained mullite at higher temperatures (>1500°C) by reaction between the alumina core and the silica coating. In order to achieve complete mullitization, optimal conditions for coating alumina particles with amorphous silica must be achieved. Formation of amorphous silica can occur in solution (homogeneous nucleation) or on the surface of alumina (heterogeneous nucleation) depending on the degree of supersaturation of the solvent in which the particles are immersed. Successful coating of silica on alumina occurs when heterogeneous nucleation is promoted and homogeneous nucleation is suppressed. Therefore, one key to successful coating is an understanding of the factors such as pH and concentration that control silica nucleation in aqueous solutions. In the current work, we use TEM to determine the optimal conditions of this processing.

Interfacial structures of dissimilar materials joined by capacitor-discharge welding

1994 ◽  
Vol 52 ◽  
pp. 534-535
Author(s):  
C. P. Doğan ◽  
R. D. Wilson ◽  
J. A. Hawk
Keyword(s):  
Rapid Solidification ◽  
Fusion Zone ◽  
Dissimilar Materials ◽  
Solidification Process ◽  
Weld Interface ◽  
Capacitor Discharge ◽  
Fine Grained ◽  
Iron Aluminum ◽  
Conductive Ceramics ◽  
Capacitor Discharge Welding

Capacitor Discharge Welding is a rapid solidification technique for joining conductive materials that results in a narrow fusion zone and almost no heat affected zone. As a result, the microstructures and properties of the bulk materials are essentially continuous across the weld interface. During the joining process, one of the materials to be joined acts as the anode and the other acts as the cathode. The anode and cathode are brought together with a concomitant discharge of a capacitor bank, creating an arc which melts the materials at the joining surfaces and welds them together (Fig. 1). As the electrodes impact, the arc is extinguished, and the molten interface cools at rates that can exceed 106 K/s. This process results in reduced porosity in the fusion zone, a fine-grained weldment, and a reduced tendency for hot cracking.At the U.S. Bureau of Mines, we are currently examining the possibilities of using capacitor discharge welding to join dissimilar metals, metals to intermetallics, and metals to conductive ceramics. In this particular study, we will examine the microstructural characteristics of iron-aluminum welds in detail, focussing our attention primarily on interfaces produced during the rapid solidification process.

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