scholarly journals Bending strength and phase composition of cement stone subjected to loading at an early stage

2018 ◽  
Vol 193 ◽  
pp. 03031 ◽  
Author(s):  
Yuriy Galkin ◽  
Sergey Udodov
Keyword(s):  
Tensile Strength ◽  
Phase Composition ◽  
Amorphous Phase ◽  
Bending Strength ◽  
Early Stage ◽  
Cement Stone ◽  
X Ray ◽  
Early Loading ◽  
Strength In Bending ◽  
Control Samples

The article deals with the results of comparative tests of the phase composition of cement stone distinguished by strength under bending and compression. The comparison has been made between samples subjected to early loading and control samples. An increase in tensile strength in bending of samples subjected to early loading was recorded. The difference in compressive strengths does not exceed 5%. X-ray phase analysis indicates amorphous phase increase with the growth of strength properties, which is manifested in increased intensity of the amorphous phase arc in the X-ray diffraction pattern. The highest peak of the curve corresponds to the maximum flexural strength of the entire row of samples. Among the samples subjected to early loading, the peak intensity of the group of crystal tobermorites with interplanar distances 11.5-11.3Å and 12.5Å appeared to be higher than the intensity of the control samples. It was proposed that the amorphous structure affects the increase in tensile strength in bending of cement stone subjected to early loading.

Preparation of Porous β-TCP Ceramics

2007 ◽  
Vol 280-283 ◽  
pp. 1515-1518 ◽  
Author(s):  
Hu Chen ◽  
Ying Jun Wang ◽  
Jian Wang ◽  
Kai Hui Nan
Keyword(s):  
Phase Composition ◽  
Bending Strength ◽  
Porous Ceramics ◽  
X Ray Diffraction ◽  
Electronic Microscopy ◽  
X Ray ◽  
Pore Sizes ◽  
Increasing Temperature

The processing and properties of porous b-TCP ceramics were investigated. Naphthalene powders used as a pore-making agent. The b-TCP ceramics with a porosity of 75%, a bending strength of 5.3 MPa and pore sizes ranging from 200 ~ 500 µm were obtained. The results showed that the porosity of the ceramics decreased with increasing temperature, while the bending strength increased with increasing temperature. In addition, the phase composition and microstructures of the porous ceramics were examined by x-ray diffraction and scatting electronic microscopy, respectively.

scholarly journals CHANGES IN THE STRUCTURAL AND PHASE COMPOSITION OF CEMENT CONCRETE DURING MICROBIOLOGICAL CORROSION

2021 ◽  
Vol 6 (11) ◽  
pp. 106-113
Author(s):  
K. Strokin ◽  
D. Novikov ◽  
V. Konovalova ◽  
N. Kasiyanenko
Keyword(s):  
Compressive Strength ◽  
Phase Composition ◽  
Portland Cement ◽  
Cement Stone ◽  
Cement Concrete ◽  
Microbiological Corrosion ◽  
Crystalline Phases ◽  
X Ray ◽  
Calcium Hydrosilicates ◽  
Black Mold

The article considers the change in the structural and phase composition of cement stone made of Portland cement of the CEM I 42.5 N brand in the process of bacterial and fungal corrosion during 6 months when humidified. The X-ray images of cement stone show peaks that characterize the non-hydrated components of Portland cement alite, belite, tricalcium aluminate, four-calcium aluminoferrite and gypsum. By the method of X-ray phase analysis, it is found that during microbiological corrosion, the content of all phases of cement stone decreases. The aspergillus niger van Tieghem fungi have a stronger effect on the structural and phase composition of cement stone. Fungal microorganisms destroy the crystalline phases and absorb amorphous phases – calcium hydrosilicates C-S-H (I) and C-S-H (II) and tobermorite. When bacteria Bacillus subtilis affects the cement stone, the content of the calcite phase increases, which is a product of corrosion, while the action of black mold reduces the intensity of CaCO3 peaks. A decrease in the content of low-base calcium hydrosilicates and ettringite, as well as other crystalline phases, leads to a decrease in the compressive strength of the cement stone. During 6 months of microbiological corrosion of cement concrete under conditions of constant wetting, the compressive strength decreases by about 35 %.

Effect of Nano-Al2O3 on Mechanical Properties and Microstructure of Al2O3/Si3N4 Compound Ceramics

2010 ◽  
Vol 168-170 ◽  
pp. 1846-1849 ◽  
Author(s):  
Shi Ming Hao ◽  
Hui Fang Wang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Phase Composition ◽  
Bending Strength ◽  
Nitrogen Atmosphere ◽  
Pressureless Sintering ◽  
X Ray ◽  
Ceramics Matrix

The specimens of Al2O3/Si3N4 compound ceramics which contain 3%, 6%, 9%, 12%, 15%, and 18% nano-Al2O3 additions respectively were obtained by pressureless sintering at 1650 in the nitrogen atmosphere. The bending strength and fracture toughness (KIC) were detected. The microstructure and phase composition of the specimens were analyzed by the means of SEM and X-ray. The results show that Al2O3/Si3N4 compound ceramics can be made only using pressureless sintering. With 9-12% nano-Al2O3addition, the specimens have the top mechanical properties. The bending strength reach 710.86MPa, KIC reach 8.61MPa•M1/2. These excellent properties come from many interwoven nitride distributed uniformly in the Al2O3/Si3N4 compound ceramics matrix, which composed of big and firmly plate-like β- Si3N4, hexagonal Sialon and sheet Si2N2O.

Investigation of Glass Fibre Reinforced Cement (GFRC) Material Exposed to High Temperatures

2014 ◽  
Vol 923 ◽  
pp. 37-41
Author(s):  
Michaela Kostelecká ◽  
Miroslav Vokáč ◽  
Daniel Dobiáš
Keyword(s):  
Tensile Strength ◽  
High Temperatures ◽  
Glass Fibre ◽  
Bending Strength ◽  
Temperature Level ◽  
Dilatometric Analysis ◽  
Reinforced Cement ◽  
Glass Fibre Reinforced ◽  
Fibre Cement ◽  
Strength In Bending

In this paper we present the tests of high temperatures resistances of glass fibre cement plates. The aim of the research was to determine the values of tensile strength in bending for samples subjected to annealing at temperatures 200, 300, 400 and 500 °C in endurance at the highest temperature level for 24 hours. The bending strength was performed according to the norm EN 1170-4. The thermal dilatometric analysis was performed in the temperatures till 540 °C.

Determination of the mineral composition of copper ores by X-Ray methods

2021 ◽  
Vol 87 (10) ◽  
pp. 5-11
Author(s):  
A. S. Kozlov ◽  
P. S. Chizhov ◽  
V. A. Filichkina ◽  
M. N. Filippov
Keyword(s):  
Phase Composition ◽  
Mineral Composition ◽  
Amorphous Phase ◽  
Structural Defects ◽  
Analytical Control ◽  
Universal Method ◽  
X Ray ◽  
Ray Methods ◽  
Copper Ores

One of the most difficult tasks of the analytical control of copper ores is the determination of the mineral forms of copper. Currently, for this purpose, iodometric and atomic absorption methods are used with preliminary leaching of various mineral forms. The disadvantage of those methods is a rather complicated sample preparation procedure and significant time of analysis. The most universal method for determining the mineral composition of solid samples is the X-ray diffraction method. However, significant variations in the phase composition of copper ores, overlapping reflections of different phases, the presence of an amorphous phase and structural defects necessitate the development of special approaches. In this work, the presence of an amorphous phase is taken into account by direct calculation of the mass fractions of crystalline phases by the G-factor method. The total copper content is determined by the X-ray fluorescence method. Methodological approaches based on using only X-ray methods are proposed, which exclude the procedures of leaching and dissolution of samples and provide determination of primary and secondary copper sulfides using calibration characteristics (3 min), and gaining data on the complete phase composition at the stage of routine analysis (10 – 15 min) and for research purposes (15 – 20 min). 

The Proportion of Crystalline and Amorphous Components in Stretched Vulcanized Rubber

1946 ◽  
Vol 19 (4) ◽  
pp. 1124-1136
Author(s):  
A. J. Wildschut
Keyword(s):  
Tensile Strength ◽  
Amorphous Phase ◽  
Distance Function ◽  
Close Agreement ◽  
Crystalline Material ◽  
Temperature Relation ◽  
X Ray ◽  
Vulcanized Rubber ◽  
Equal Importance

Abstract Determinations of the tension-temperature relation of stretched vulcanized rubber can provide us with data about the proportion of crystalline and amorphous components. The amount of crystalline material appears to be 30–32 per cent at 600 per cent elongation and at 20° C. An expression is derived relating percentage of crystalline material and temperature. The results are in close agreement with those of x-ray measurements carried out by Goppel, but diverge largely from those obtained by Field. The cause of this difference is not yet clear. Stretched vulcanized rubber consists of a predominating amorphous phase, with crystallites embedded in it. On stretching orientation occurs, and a systematic addition of secondary valency forces is possible. This is the main cause of the existence of a certain tensile strength. Crystallization, though important as an indication on orientation, is more or less an incidental phenomenon. The distance function of the secondary forces may be of equal importance with the orientation.

Phase Transformations in Ti-7w/oMo-3w/oMe Alloy

1974 ◽  
Vol 32 ◽  
pp. 514-515
Author(s):  
S. Fujishiro
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
Mechanical Processing ◽  
Ray Method ◽  
X Ray ◽  
Transmission Electron ◽  
Water Quench ◽  
Alpha Beta

The mechanical properties of three titanium alloys (Ti-7Mo-3Al, Ti-7Mo- 3Cu and Ti-7Mo-3Ta) were evaluated as function of: 1) Solutionizing in the beta field and aging, 2) Thermal Mechanical Processing in the beta field and aging, 3) Solutionizing in the alpha + beta field and aging. The samples were isothermally aged in the temperature range 300° to 700*C for 4 to 24 hours, followed by a water quench. Transmission electron microscopy and X-ray method were used to identify the phase formed. All three alloys solutionized at 1050°C (beta field) transformed to martensitic alpha (alpha prime) upon being water quenched. Despite this heavily strained alpha prime, which is characterized by microtwins the tensile strength of the as-quenched alloys is relatively low and the elongation is as high as 30%.

Study Of Structure Formation Of Organic-Mineral Compositions With Fibrous Filler By Electron Microscopy Method

2019 ◽  
pp. 41-47
Keyword(s):  
Electron Microscopy ◽  
Structure Formation ◽  
Mineral Composition ◽  
Bending Strength ◽  
Cement Stone ◽  
Hydrated Cement ◽  
Fibrous Filler ◽  
Organic Mineral ◽  
Microscopy Method ◽  
Mineral Compositions

The article presents the study of processes of structure formation of cement stone and products of hardening of organic-mineral compositions with fibrous filler (shavings) by the electronic scanning microscopy method. It is established that the additive-free cement stone at the age of 28 days has a dense and homogeneous structure, consists of calcium hydro-silicates, Portlandite and calcite - newgrowths characteristic for cement systems. Cellulose fibers, which make up the bulk of the substance of shavings, are sufficiently active, which determines the high adhesion of the hydration products of the cement binder to their surface. It is shown that the introduction of shavings into the organo-mineral composition leads to inhibition of cement hydration processes. Organo-mineral compositions with different shavings content (two compositions) were analyzed. The first composition is characterized by a fairly dense structure, the cement stone consists of globular nanoscale nuclei of hydrosilicates, Portlandite and calcite. The second composition has a loose porous structure, cement stone consists of non-hydrated cement grains, newgrowths are represented by calcite and vaterite. The structure of the contact zone "osprey fiber-cement stone" in the organo-mineral composition of the first composition indicates a good adhesion of the filler surface with the phases of hydrated cement. The use of shavings as a fibrous filler (the first composition) increases the tensile and bending strength, as well as the wear resistance of organo-mineral compositions. The data obtained by scanning electron microscopy are confirmed by the results of studying the processes of structure formation of cement stone by quantitative x-ray phase analysis.

Control of the phase composition of advanced calcium phosphates using an x-ray diffractometer with a curved position-sensitive detector

2020 ◽  
Vol 86 (6) ◽  
pp. 29-35
Author(s):  
V. P. Sirotinkin ◽  
O. V. Baranov ◽  
A. Yu. Fedotov ◽  
S. M. Barinov
Keyword(s):  
Phase Composition ◽  
Calcium Phosphates ◽  
Position Sensitive Detector ◽  
Sensitive Detector ◽  
X Ray Diffraction ◽  
X Ray ◽  
Impurity Phases ◽  
Position Sensitive ◽  
Diffraction Peaks ◽  
Diffraction Patterns

The results of studying the phase composition of advanced calcium phosphates Ca10(PO4)6(OH)2, β-Ca3(PO4)2, α-Ca3(PO4)2, CaHPO4 · 2H2O, Ca8(HPO4)2(PO4)4 · 5H2O using an x-ray diffractometer with a curved position-sensitive detector are presented. Optimal experimental conditions (angular positions of the x-ray tube and detector, size of the slits, exposure time) were determined with allowance for possible formation of the impurity phases during synthesis. The construction features of diffractometers with a position-sensitive detector affecting the profile characteristics of x-ray diffraction peaks are considered. The composition for calibration of the diffractometer (a mixture of sodium acetate and yttrium oxide) was determined. Theoretical x-ray diffraction patterns for corresponding calcium phosphates are constructed on the basis of the literature data. These x-ray diffraction patterns were used to determine the phase composition of the advanced calcium phosphates. The features of advanced calcium phosphates, which should be taken into account during the phase analysis, are indicated. The powder of high-temperature form of tricalcium phosphate strongly adsorbs water from the environment. A strong texture is observed on the x-ray diffraction spectra of dicalcium phosphate dihydrate. A rather specific x-ray diffraction pattern of octacalcium phosphate pentahydrate revealed the only one strong peak at small angles. In all cases, significant deviations are observed for the recorded angular positions and relative intensity of the diffraction peaks. The results of the study of experimentally obtained mixtures of calcium phosphate are presented. It is shown that the graphic comparison of experimental x-ray diffraction spectra and pre-recorded spectra of the reference calcium phosphates and possible impurity phases is the most effective method. In this case, there is no need for calibration. When using this method, the total time for analysis of one sample is no more than 10 min.

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