Quantitative phase analysis of modified hardened cement paste

The relevance of this research is stipulated by the opportunity to control the properties of construction materials through introducing nanomodifying additives. The study of structure parameters of the crystalline phase of hardened cement paste modified by microsilica and Ts38 additives is of great scientific and applied importance

A theoretical and experimental investigation on the SHS synthesis of (HfTiCN)-TiB2 high-entropy composite

In this work, a fundamental possibility of obtaining a high-entropy ceramic (HfTiCN)-TiB2 composite material by the coupled self-propagating high-temperature synthesis is shown. To search for a stable fixed composition of the HfTiCN compound, the USPEX code was used with the CASTEP interface at 0K. According to the XRD analysis, the obtained SHS product is represented by HfTiCN phase (60 wt%) and TiB2 phase (40 wt%). Based on the results of XRD, elemental analysis, and the heat pattern of combustion of the Hf-Ti-C-N-B powder mixture, a probable mechanism for the formation of the (HfTiCN)-TiB2 composite material during the coupled self-propagating high-temperature synthesis was proposed

Fly ash particles spheroidization using low temperature plasma energy

The paper presents the investigations on producing spherical particles 65-110 [mu]m in size using the energy of low temperature plasma (LTP). These particles are based on flow ash produced by the thermal power plant in Seversk, Tomsk region, Russia. The obtained spherical particles have no defects and are characterized by a smooth exterior surface. The test bench is designed to produce these particles. With due regard for plasma temperature field distribution, it is shown that the transition of fly ash particles to a state of viscous flow occurs at 20 mm distance from the plasma jet. The X-ray phase analysis is carried out for the both original state of fly ash powders and the particles obtained. This analysis shows that fly ash contains 56.23 wt.% SiO[2]; 20.61 wt.% Al[2]O[3] and 17.55 wt.% Fe[2]O[3] phases that mostly contribute to the integral (experimental) intensity of the diffraction maximum. The LTP treatment results in a complex redistribution of the amorphous phase amount in the obtained spherical particles, including the reduction of O[2]Si, phase, increase of O[22]Al[20] and Fe[2]O[3] phases and change in Al, O density of O[22]Al[20] chemical unit cell

Nanostructuring of a Surface Layer as a Way to Improve the Mechanical Properties of Hypoeutectic Silumin

The irradiation of hypoeutectic silumin 383.1 with an intense pulsed electron beam in the melting mode and rapid crystallization of the surface layer has been performed. A multiphase submicron nanostructured surface layer with a thickness of up to 70 nm has been formed. Mechanical tests of the irradiated silumin samples in tensile experiments have been carried out. A significant increase in strength and plastic properties of silumin irradiated with an electron beam has been established. Features and patterns in the distribution of displacement fields in the deformation process in surface layers of the samples in realtime have been identified by digital image correlation method using the optical measuring system VIC-3D

Nanostructuring of a Surface Layer as a Way to Improve the Mechanical Properties of Hypoeutectic Silumin

The irradiation of hypoeutectic silumin 383.1 with an intense pulsed electron beam in the melting mode and rapid crystallization of the surface layer has been performed. A multiphase submicron nanostructured surface layer with a thickness of up to 70 nm has been formed. Mechanical tests of the irradiated silumin samples in tensile experiments have been carried out. A significant increase in strength and plastic properties of silumin irradiated with an electron beam has been established. Features and patterns in the distribution of displacement fields in the deformation process in surface layers of the samples in realtime have been identified by digital image correlation method using the optical measuring system VIC-3D

Peculiarities of structure and phase composition of V-Ti-Cr alloy obtained by sintering technique

Abstract Alloy of the V-Ti-Cr system is a promising material exploited under high radiation and in corrosion environment. We sintered V-4.9Ti-4.8Cr alloy from particles with original average size of 30, 280 and 200 μm, respectively for vanadium, titanium and chromium powders, by pressing of the powder mixture and its further sintering. The studies were undertaken using the methods of X-ray structural analysis, scanning electron microscopy with an energy dispersive analyzer and transmission electron microscopy. It was established that the structure of the alloy represented matrix grains (BCC solid solution), along the boundaries and at junctions of which the groups of oxycarbonitride particles of V, Ti, Cr (C,N,O) type of the variable elemental composition were arranged. The particles possessed a plate-like (0.4 x 2.0 μm) and rounded (0.5 μm) shape. The solid solution of the alloy was heterogeneous by concentration. This was evidenced by the complications of the diffraction patterns obtained from the corresponding sections of the structure. These were cords of main reflexes, satellites and emergence of a moire banded contrast in separate sections of the sample. Inside the matrix grains, there were nanoparticles (15 μm) of carbide V55Cr25C20, being a source of elastic internal local stresses

Phase content, structural and thermodynamic properties of AlMgB14, obtained by SHS using the chemical furnace

Based on the Rietveld method, the quantitative phase analysis was performed of AlMgB14-based materials obtained by self-propagating high-temperature synthesis (SHS) of Al12Mg17-B powder mixture using a chemical furnace based on titanium and silicon of various thicknesses (1, 2, and 3 cm). Al0.5Mg0.5B2, AlMgB14, MgAl2O4 phases were identified in the obtained materials: the total contribution to the integrated intensity was no less than 98%. Ab initio calculations of the lattice energy, thermodynamic characteristics, and elastic moduli of the main phases were performed both in the initial (reference) and after the refined state. The phase content in the obtained AlMgB14 materials depends on the chemical furnace thickness. In the materials obtained in the chemical furnace with a thickness of 2 and 3 cm, AlMgB14 phase is dominated, which is modified during the synthesis with an increase in the lattice stability. A sharp decrease in the elastic characteristics and specific heat of the dominant phases was found, which is expected to stimulate a change in the characteristics of the near-surface layers of the synthesized AlMgB14 materials