Papers by Keyword: X-Ray Diffraction Analysis

Abstract: In the course of the study, several different methods of surface structural engineering are reviewed. The methods described in this paper are characterized by different process physics on the way to obtaining the result, but they are aimed at modifying the structure and properties of the surfaces to which they are applied. Among them, two different technological directions are considered. The first area involves technologies that include a friction component, namely thermofriction treatment (TFT) for thermofriction strengthening (TFS), additional thermofriction strengthening (ATFS) or thermofriction welding (TFW). The second direction is a technology that involves the use of an anode-cathode electrolysis mode in an alkaline-silicate electrolyte – micro-arc oxidation (MAO). The paper describes the features and results of the application of such technologies and the feasibility of using this or that method for materials of different classes, and presents schemes of the corresponding installations. The result of additional hardening of the surface of U8A steel from a microhardness level of 7.2 GPa to 14.7 GPa using the ATFS method after its thermal hardening to almost the maximum possible level is shown. The microstructure of the cross-section of a prehardened specimen of U8A steel after ATFS is presented, where the degree and nature of surface hardening are reliably visible. It is emphasized that in previous studies, consistently effective hardening of steels of various classes has been achieved, even up to the level of 22 GPa in 65G steel. Regarding the method of microarc oxidation, the structure and properties of coatings on low-alloy aluminum alloys AB and AD1 formed in an alkaline-silicate electrolyte in the anode-cathode MAO mode were investigated. It is shown that the method of MAO in alkaline-silicate electrolyte allows to obtain a coating thickness of up to 300 μm, a coating growth rate of ~ 2 μm/min, and a coating hardness of 10-20 GPa. The coatings have high adhesion to the substrate; they have a layered structure. The properties of the coatings are determined by the properties of the base layer. The coatings have a crystalline structure and consist of the following phases: γ-Al₂O₃, α-Al₂O₃, mullite (3Al₂O₃·2SіO₂), the ratio between the phases depends on the electrolysis conditions. It has been established that phase formation begins with the γ-Al₂O₃ phase, which in the process of further coating growth turns into the α-Al₂O₃ phase or interacts with silicon oxide to form the mullite phase.

Abstract: In this article are presented the results of X-ray and IR spectroscopic studies of the structure of the atmosphere - and chemically resistant composite materials based on medium density polyethylene. The presence of specific interactions with polyethylene ingredients in composite materials. It has revealed the appearance on the surface of the active radicals that promote increased interaction fillers with polyolefins, as well as the increase of the elastic-strength characteristics of composite materials are revealed.

Abstract: Thermochromic properties were found in bimetallic hybrid inorganic-organic complex compounds of hexa (thiocyanate-N) chromates (III) of IIIb-group rare-earth metals and lanthanides complexes with dimethylsulfoxide [M(C₂H₆SO)₈]L, dimethylformamide [M (C₃H₇NO)₈]L, ε-caprolactam [M(εC₆H₁₁NO)₈]L and nicotinic acid [M(C₅H₅NCOO)₃(H₂O)₂]L·nH₂O, n=1,2, L=[Cr (NCS)₆]^3-, M=Sc³⁺, Y³⁺, Ln³⁺, obtained by means of direct synthesis from the aqueous solutions, the composition of substances was studied by methods of chemical and electron microscopic analyzes, solubility and chemical resistance were determined. Radiographic and thermogravimetric characteristics, IR spectra, magnetic properties are studied. The experimental data obtained indicate the antiferromagnetic nature of the interaction between paramagnetic centers in the studied ionic compounds, the crystallographic parameters of which were determined by the method of X-ray diffraction analysis of single crystals at low temperatures. In the temperature range of 383-493 K, substances, without changing the physicochemical characteristics, reversibly change color, withstanding many heating-cooling cycles.

Abstract: This study is dedicated to investigating contact melting, including cases of electrotransport is a Sn-Bi system after introduction of a small admixture of indium. It has been shown that the dopant ambiguously influences the rate of the contact melting. The structure of obtained alloys is strongly non-uniform and abounds with dendritic forms. An attempt is made to explain the results.

Abstract: This study is dedicated to application of x-ray methods to investigate phase formation in contact melting in a Cd-In system after introduction of a small admixture of sodium to cadmium, including cases of electrotransport. Formation of both two-and three-component intermetallic compounds has been established. An attempt is made to explain the results.

Abstract: The authors have studied the impact of mechanomagnetic activation (MMA) of the solutions NA-CMC, widely used for mixing water-cement paste, on the structure and properties of cement composites. By the method of dynamic light scattering, the appearance of nanosize particles of grouting fluid’s dispersion phase has been proved. On the base of the results of X-ray diffraction analysis, there have been found alterations of cement stone structure; the influence of MMA on the processes of structure formation has been proved; the principal components of cement stone structure have been identified.

Abstract: Synthesis of YSAG:Yb ceramic powders with different stoichiometry by chemical precipitation method was carried out. It has been established that scandium can replace both dodecahedral and octahedral positions of garnet. It is shown that scandium is embedded in those positions that become available to it when the YAG:Yb composition deviates from stoichiometric. Thus, scandium can compensate for the lack of one of the components of the oxide composition Y₂O₃, Yb₂O₃, and Al₂O₃ during the formation of the garnet phase.

Abstract: Bovine bone is a considerable source for the production of hydroxyapatite. The recent study reported a novel method to extract hydroxyapatite from bovine bone without producing hazardous residue. The bovine bones were cut and boiled in the opened chamber followed by boiling in pressurized tank. The bones were then soaked into 95% ethanol. Calcination was then conducted in 800°C, 900°C and 1,000°C, for 2 hours. The result was then grinded and sieved. The powder then was characterized using Fourier transform infrared (FT-IR), Scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) to measure the purity of hydroxyapatite. It is concluded that the hydroxyapatite derived from this process showed 100% purity, resulting 35.34 ± 0.39% w/w from the wet bone weight and 72.3% w/w from the dried weight. The present extraction method has been proven to yield high amount of pure hydroxyapatite as well as reducing the use of hazardous reagent.

Abstract: The paper describes a methodological system of testing and diagnosing technogenic waste to create new construction composites. The converter slag structure is shown both in the form of lump materials and on the nanoscale. The results of determining the mineralogical composition of converter slags are also presented. Petrographic research of slags and their X-ray diffraction analysis are conducted with the results shown. Special attention is paid to the atomic force microscopy method. It shows that the composing minerals have unique features of the surface topography with the indication of averaged statistical data of characteristics. In further research, this experience can significantly ease the task of determining the bi-calcium silicate in the structure of other types of metallurgical slags. The information about the morphological features of the structure of various minerals will help to use this method as independent in determining the mineralogical composition of the observed materials.

Abstract: The possibility of obtaining the vermiculite fire treatment at low temperature (burnt vermiculite) is considered in the article. The vermiculite structure features are investigated to reduce the subsequent burn temperature. By X-ray diffraction analysis it is established that the pre-treatment by a salt solution causes a change in the elementary cell of the vermiculite crystalline grid. It allows to receive the extended vermiculite under the lower burn temperature than in case of the ordinary non-treated vermiculite. To show the creation possibility of the building materials with burnt vermiculite the concrete unit weight and strength with gypsum and cement binder are studied. It is determined that the mentioned concrete strength is higher compared to concrete with ordinary vermiculite at the same density of these concretes. The thermal insulation properties are also significantly higher. The light concrete with vermiculite aggregate is used as the thermal-shield enclosing structures in building and structure constructions. The decrease of the vermiculite burn temperature will contribute to reducing the energy intensity of construction as a whole.