scholarly journals Radiation Resistance of a Structural Material Based on Modified Titanium Hydride

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
R. N. Yastrebinsky ◽  
V. I. Pavlenko ◽  
A. A. Karnauhov ◽  
N. I. Cherkashina ◽  
A. V. Yastrebinskaya ◽  
...  
Keyword(s):  
Structural Material ◽  
Portland Cement ◽  
Radiation Resistance ◽  
Titanium Hydride ◽  
Structural Phase ◽  
Absorbed Dose ◽  
Phase Changes ◽  
Cement Matrix ◽  
Γ Irradiation ◽  
Γ Radiation

This work investigates the radiation resistance of a structural material based on modified titanium hydride and a Portland cement in a flux of neutron and γ-radiation. An assessment of the geometric and physicomechanical properties is given, along with the surface structure of irradiated cement composites, and the phase composition of the main hydrosilicates of the hydrated cement matrix during its γ-irradiation. It is shown that the use of a shot of titanium hydride increases the radiation resistance of radiation shielding based on a cement matrix, in comparison with the unmodified shot. A composite based on a modified shot of titanium hydride retains its basic properties after γ-irradiation, at an absorbed dose of up to 10 MGy. At an absorbed dose of 2 MGy in the Portland cement matrix of a composite based on a modified shot of titanium hydride, the formation of suolunite hydrosilicates occurs. It was established using X-ray fluorescence that, in the titanium hydride, a redistribution of the electron density occurs at an absorbed dose of γ radiation of 5 MGy, caused by structural phase changes due to the ongoing dehydrogenation processes.

Effect of W/B ratios on pozzolanic reaction of biomass ashes in Portland cement matrix

2012 ◽  
Vol 34 (1) ◽  
pp. 94-100 ◽  
Author(s):  
V. Sata ◽  
J. Tangpagasit ◽  
C. Jaturapitakkul ◽  
P. Chindaprasirt
Keyword(s):  
Portland Cement ◽  
Pozzolanic Reaction ◽  
Cement Matrix ◽  
Biomass Ashes

Effects of initial concentration and irradiation dose to degradation of di butyl phthalate from phosphoric acid (30 % P2O5)

2018 ◽  
Vol 106 (11) ◽  
pp. 909-916
Author(s):  
Louisa Bounemia ◽  
Abdelhamid Mellah
Keyword(s):  
Organic Matter ◽  
Phosphoric Acid ◽  
Optimal Recovery ◽  
Γ Irradiation ◽  
Γ Radiation ◽  
Initial Concentration ◽  
First Order ◽  
First Order Kinetics ◽  
Butyl Phthalate

Abstract The pretreatment of the phosphoric acid is a stage of utmost importance leading to an optimal recovery of the uranium present in this acid. To this end, the degradation of the organic matter which obstructs considerably this recovery was tested by γ irradiation. This study lies within the scope of the radiation/matter interaction; concerning the use of the γ irradiator as proceed of phosphoric acid purification by the degradation of di butyl phthalate (DBP). Studies of the interaction of γ radiation with phosphoric acid solutions polluted by an organic matter concern the study of the influence of some parameters such as: dose rate (0.5–35 kGy), initial concentration (50–500 mg/L) of the pollutant, pH and % in P2O5 on the degradation of organic matter by γ irradiation. The reactions followed pseudo first order kinetics for different initial concentrations. The results made it possible to say that the degradation of di butyl phthalate by γ irradiation is dependent on the amount of the concentration of DBP and pH. The G-values decreased with absorbed doses, and increased with higher initial concentrations.Purification of phosphoric acid by γ radiation does not degrade the quality of this acid.

scholarly journals Protective and strengthening coatings on reinforcing steels

2020 ◽  
Vol 96 (4) ◽  
pp. 39-46
Author(s):  
S.A. Vodennikov ◽  
◽  
V.O. Skachkov ◽  
O.S. Vodennikova ◽  
◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Corrosion Resistance ◽  
Electrochemical Oxidation ◽  
Mechanical Characteristics ◽  
Aluminide Coating ◽  
Structural Phase ◽  
Phase Changes ◽  
Electrolytic Deposition ◽  
Reinforcing Steel ◽  
Aluminum Coatings

A conceptually new technology for the application of aluminum coatings on 18G2C steel by the electrolytically deposited NaF-NaCl - AlF3 ionic melt method has been developed. To solve the tasks set in the work, a set of experimental and computational research methods was used: metallographic analysis, energy dispersion microanalysis, mechanical tests, and calculation of the oxidation rate of samples. The mechanical characteristics of the samples of reinforcing steel were determined on a rupture machine FP-100 at an active capture rate of 2.5 mm / min. The relationship between the rates of electrochemical oxidation of the aluminide coating, its mechanical properties, with the distribution of aluminum in the depth of the samples and its phase composition have been determined. The increase of mechanical characteristics of samples from 18G2S steel with an aluminum covering in comparison with usual reinforcing steel is shown. The sequence of structural-phase changes of metal in the process of aluminide coating is determined and its influence on mechanical and corrosion resistance is determined. Experimental evaluation of the rate of oxidation of 18G2C steel samples with aluminum coating under the conditions of sulfuric acid electrolyte at an electric current of 11 to 18 A has been conducted. The developed technology of electrolytic deposition of aluminum has scientific and practical interest for the construction industry. The developed coating makes it possible to increase the mechanical properties of steel by almost 12% and to increase the corrosion resistance. Keywords: aluminum coatings, 18G2C steel, electrochemical oxidation, electrolytic deposition.

scholarly journals STRUCTURAL AND PHASE CHANGES OF THE SURFACE LAYERS OF HEATRESISTANT MULTICOMPONENT COATING OF ION-PLASMA COATING Ni-Cr-Al-Y AFTER MODIFICATION BY HIGH-CURRENT ELECTRON BEAMS MICROSECOND DURATION

2020 ◽  
Vol 17 (34) ◽  
pp. 459-468
Author(s):  
Oksana A BYTSENKO ◽  
Igor G STESHENKO ◽  
Vladimir A PANOV ◽  
Victor V TISHKOV ◽  
Alexey B MARKOV
Keyword(s):  
Electron Beams ◽  
Structural Phase ◽  
Plasma Coating ◽  
Phase Changes ◽  
High Current ◽  
Surface Layers ◽  
Heat Resistant ◽  
Ion Plasma ◽  
Current Electron ◽  
High Current Electron

The development of aerospace engineering and mechanical engineering directly depends on the development of new metal materials and advanced technologies. The problem of creating materials and their types of processing to increase the level of operational properties is relevant in connection with the complication and tightening of working conditions of modern technologies. One of the most important tasks of contemporary aircraft construction is to increase the operational properties of the surface layer. The purpose of the article is to elucidate the effect of high-current electron beams of microsecond duration on changes in the surface layers of the heat-resistant multicomponent ion-plasma coating Ni-Cr-Al-Y under various conditions. Using a complex of metallophysical research methods, the physicochemical and structural-phase states of the surface layer were studied before and after modification of the samples. These samples were coated with heat-resistant condensed ion-plasma coatings of three different compositions using nine high-current electron beams in 9 modes with different values of electron energy and number of pulses in the selected interval of electron energy. An analysis of the structural phase changes occurring during modification was carried out. Cylindrical samples of targets made of heat-resistant nickel alloy ZhS36 coated with ion-plasma condensed multicomponent coating SDP-2 + VSDP-16. These samples were used according to serial technology, both with subsequent modification using highcurrent electron beams and without modification. It was found that chromium in the initial state is unevenly distributed: chromium is present in the particles; the matrix is depleted in chromium. The research results can be useful for scientists to study the properties of heat-resistant multicomponent ion-plasma coatings Ni-Cr-Al-Y and the effect of high-current electron beams on it, as well as for the manufacture of more heat-resistant materials in aerospace engineering and mechanical engineering.

scholarly journals Properties of cement composites based on limestone depending on their granulometric composition

Vestnik MGSU ◽  
2020 ◽  
pp. 999-1006
Author(s):  
Svetlana V. Samchenko ◽  
Olga V. Alexandrova ◽  
Anton Yu. Gurkin
Keyword(s):  
Composite Materials ◽  
Portland Cement ◽  
Granulometric Composition ◽  
Coarse Grained ◽  
Cement Matrix ◽  
Cement Composites ◽  
Construction Costs ◽  
Initial Strength ◽  
Fine Grained ◽  
Additional Formation

Introduction. The use of limestone in cement compositions as an additional cementing agent solves both environmental and economic problems, namely, reduction of construction costs. In this regard, the study of the properties of the granulometric composition and volumetric content of cement composites, containing limestone, becomes increasingly important. The mission of this research is to optimize the properties of composite materials containing Portland cement and limestone by changing the granulometric composition of flour limestone. Materials and methods. Limestone, having three different Blaine milling fineness values of 250, 300 and 450 m2/kg, was used; its content reached 10, 15, 25 and 35 %. Cement and sand mortars were applied for testing purposes. The influence of the granulometric composition of limestone on the workability and compressive strength of composite cement was determined. Results. The effect of limestone on the limit shear stress becomes more pronounced when the amount of limestone increases to 25 and 35 %. This is most noticeable for limestone with a high content of fine fractions of 5–20 µm. The use of finely milled limestone increases the initial strength of the composite material. By adding 10 and 15 % of such limestone we can increase the strength by 16–20 %, and supplementary 25–35 % of limestone increases strength by 5–8 %. Strength enhancement is due to the reactivity of limestone and formation of calcium hydrocarbon aluminate 3CaO∙Al2O3∙СаСО3∙12H2O, which promotes formation of the crystal framework of the cement matrix. Additional formation of crystalline hydrates in the initial coagulation structure deteriorates the mortar workability, but increases its strength. Conclusions. The use of coarse-grained limestone significantly improves mortar workability, while the use of fine-grained limestone increases its content without reducing its strength. The granulometric composition of ground limestone shall be as close as possible to the granulometric composition of cement for the properties of composite materials containing Portland cement and limestone to be optimized.

scholarly journals AN EFFECTIVE WAY TO RECYCLE 3D PRINTING CONCRETE SCRAP

2021 ◽  
Vol 4 (2) ◽  
pp. 12-18
Author(s):  
D.A. Tolypin ◽  
N. Tolypina
Keyword(s):  
Compressive Strength ◽  
3D Printing ◽  
Portland Cement ◽  
Quartz Sand ◽  
Raw Materials ◽  
Electricity Consumption ◽  
Cement Matrix ◽  
Fine Aggregate ◽  
Fine Grained ◽  
Control Samples

the article proposes a rational method for processing 3D printing concrete scrap using vibration equipment, which allows obtaining a multicomponent building material with minimal electricity consumption. As a crite-rion for the degree of grinding of concrete scrap, it is proposed to use the specific surface area of the finely dispersed part of concrete scrap, which should correspond to 400-500 m2/kg. The possibility of reusing the resulting product instead of the traditional fine aggregate of quartz sand is shown. It was found that the con-crete scrap without the addition of Portland cement hardens, reaching up to 48% of the compressive strength of the control samples by 28 days. When 10% of the binder CEM I 42.5 N was added to the concrete scrap processing product, the compressive strength of fine-grained concrete increased by 106.6%, and 20% of Portland cement - by 112.2 %, compared to the strength of control samples of a similar composition on tra-ditional quartz sand after 28 days of hardening. It is noted that this is primarily due to the weak contact zone of quartz sand and the cement matrix of concrete. The use of the product of processing concrete scrap al-lows obtaining building composites based on it with the complete exclusion of natural raw materials

Structure and Crack Resistance of N-A-XTRA-70 Steel Joints Manufactured by Hybrid Laser-Arc Welding

2018 ◽  
Vol 927 ◽  
pp. 29-34 ◽  
Author(s):  
V. Pozniakov ◽  
L. Markashova ◽  
O. Berdnikova ◽  
T. Alekseienko ◽  
S. Zhdanov
Keyword(s):  
Crack Resistance ◽  
Welded Joints ◽  
Arc Welding ◽  
Structural Phase ◽  
Consumable Electrode ◽  
Phase Changes ◽  
External Loading ◽  
Hybrid Laser Arc Welding ◽  
Source Power ◽  
Scanning Electron

Crack resistance of welded joints is one of the most important indices of service reliability of critical designation structures. The purpose of the research is the establishment of the influence of technological modes, hybrid laser-arc welding of high strength steel NA-XTRA-70 on the formation of structure in the metal welded joints, as well as analysis of the influence of this structure on their crack resistances. For the experiments the laboratory setup has been developed on which the experiments were carried out in the technological scheme that provides the location of the consumable electrode arc at a certain distance in front of the laser beam in the welding direction. Nd: YAG-laser DY 044 of company ROFIN (Germany) was a laser radiation source. Power for consumable electrode arc was carried out by welding generator PSG-500. Investigations of structural-phase changes in weld metal and HAZ were carried out by means of optical microscopy (optical microscope Versamet-2 and Neophot-32), microhardness was measured using M-400 gage of Leco company at 0.98N loading. Fractographic investigations were carried out by scanning electron microscopy (scanning electron microscope SEM-515 of PHILIPS company, Netherlands) on fractured specimens of welded joints, made as a result of impact bend tests. An analysis of crack resistance of the welded joints was carried out under different conditions of test temperatures. It was based on experimental data, received by a quantitative fractography method. It is shown that metal of a welded joint produced by hybrid laser-arc welding at Vw = 72m/h rate has mainly failure of ductile nature after external loading. This indicates sufficient level of crack resistance and further working capacity under operation conditions.

scholarly journals Topological phonons in oxide perovskites controlled by light

2020 ◽  
Vol 6 (46) ◽  
pp. eabd1618
Author(s):  
Bo Peng ◽  
Yuchen Hu ◽  
Shuichi Murakami ◽  
Tiantian Zhang ◽  
Bartomeu Monserrat
Keyword(s):  
Tetragonal Phase ◽  
Structural Phase ◽  
Thermal Fluctuations ◽  
Perovskite Oxides ◽  
Phase Changes ◽  
Nodal Lines ◽  
Rich Variety ◽  
External Conditions ◽  
Photoexcited Carrier ◽  
Physical Phenomena

Perovskite oxides exhibit a rich variety of structural phases hosting different physical phenomena that generate multiple technological applications. We find that topological phonons—nodal rings, nodal lines, and Weyl points—are ubiquitous in oxide perovskites in terms of structures (tetragonal, orthorhombic, and rhombohedral), compounds (BaTiO3, PbTiO3, and SrTiO3), and external conditions (photoexcitation, strain, and temperature). In particular, in the tetragonal phase of these compounds, all types of topological phonons can simultaneously emerge when stabilized by photoexcitation, whereas the tetragonal phase stabilized by thermal fluctuations only hosts a more limited set of topological phonon states. In addition, we find that the photoexcited carrier concentration can be used to tune the topological phonon states and induce topological transitions even without associated structural phase changes. Overall, we propose oxide perovskites as a versatile platform in which to study topological phonons and their manipulation with light.

Sign in / Sign up

Export Citation Format

Share Document