Papers by Keyword: X-Ray Microanalysis

Abstract: The objective of this research is to study and analyse the properties of a cement-based composite modified with nickel/carbon nanocomposite (Ni/C NC). According to previous studies carried out by scientists in the field of nanostructures, it was assumed that metal/carbon nanostructures can increase the strength and impart electrically conductive properties to composite materials [9,12]. To confirm this hypothesis, in this research, mechanical strength tests and measurements of the electrical resistance of the modified samples were carried out. It was found that the addition of nickel/carbon nanocomposite in the amount of 0.05% increases the compressive strength of silicate composites by 35%. Moreover, by measuring the electrical conductivity of the samples, it was established that with the introduction of additives in the amount of 0.01-0.05% in relation to Portland cement, the resistance decreases by 80-84%. Further, the structural effect of Ni/C NC on the cement matrix was studied by the methods of IR spectral, differential thermal analyses, X-ray microanalysis. As a result of the analysis, it was revealed that the dispersions are crystallization centers during cement hydration and create chemical bonds with silicon oxide in the composition of the silicate composite. Ni/C NC has a structuring effect on the silicate binder matrix through the formation of a denser packing, which affects the mechanical properties and electrical conductivity of the material. The results of the study can be used to obtain electrically conductive materials with desired properties that can perform the functions of heating, monitoring the state of structures during operation, and protecting against an electromagnetic pulse.

Abstract: The article describes the influence of chrysotile nanofibers dispersion introduction on the properties of the cement matrix. Comparison of the dispersion level of suspensions obtained using cavitation and ultrasonic processing methods is presented. The positive effect of chrysotile fibers application on the strength characteristics of the material has been confirmed. A 34% increase in the compressive strength of the samples was achieved on the 7th day of hardening, while on the 28th day it increased by 36% and with the steam treatment - by 38% compared to the reference sample. Laser particle size analysis confirmed the predominance of the nanosized component of chrysotile fibers in the suspension, which affected the structuring of the cement matrix. The results of the differential thermography, IR spectrometry, X-ray microanalysis and scanning electron microscopy of the samples are also presented. The analysis methods confirmed that introduction of chrysotile nanofibers suspension into the composition of a cement binder makes it possible to significantly vary the structure and morphology of new formations in fine-grained concrete. It also changes the quantitative and qualitative phase composition of the material with the formation of calcium silicate hydrates of lower basicity, leading to an increase in the strength of cement concrete.

Abstract: Currently, the technology of arc metallization according to technical and economic indicators is a promising way to restore worn parts of equipment. In the coating process the cored wire is melted by an electric arc, and molten particles are accelerated towards the surface parts with high temperature gas flow. On the subsequent formation of strengthening coatings are significantly influenced the technological modes of electric arc metallization. As practice shows, the coatings obtained by electric arc metallization are characterized by a heterogeneous layered structure. The structure of powder coatings, the distribution, composition and properties of the phases affect on the wear resistance, hardness and strength of the machined surface of machine parts and mechanisms. It is therefore necessary a detailed study of the structure of wear-resistant coatings taking into account technological properties of cored wire, and process heating of the particles by arc spraying. In this work the X-ray microanalysis of the elements of the structure of wear-resistant coatings obtained from cored wire with a refractory additives were conducted. The results of the study will be useful for the improvement technology of electric-arc metallization cored wires.

Abstract: This article presents the results of the study of the joint effect of the processing conditions of the new composition of the Al-Zr system alloy by combined casting and rolling-extruding and two-stage annealing on the structure and properties of round bars used in the manufacture of heat-resistant wires. The research show patterns of changes in the properties, the specific electrical resistance of the bars, depending on different conditions of deformation and heat treatment of aluminum alloy with a content of 0.3% zirconium and 0.2% iron. The results of micro-X-ray spectral analysis and the granular structure of the samples before and after two-stage annealing confirming the stability of the structure after heating and preserving the strength of semi-finished products. Presented parameters of combined casting and rolling-extruding and two-stage annealing for the manufacture of rods from the studied alloy make it possible obtaining good combination of mechanical properties and electrical conductivity.

Abstract: The paper dwells upon the specifics of worn spots being formed on a silicon-carbide crystal in microscratching of iron, cobalt, and nickel. Analysis was done using a Versa 3D dual-beam electron microscope. The chemical composition of worn spots was studied by local X-ray microanalysis. It was found out that the amount of metal transferred to the silicon-carbide worn spot was associated with the electron structure of metal atoms.

Abstract: Alkali-activated slag is studied using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and x-ray microanalysis. Attention is focused on delineating the phases induced by the alkali activation, as these phases are important in determining the mechanical properties of the material. The starting material, slag, is found to be a heterogeneous material with at least two phases. Upon alkali activation the material becomes more heterogeneous, now exhibiting at least four phases with significant different chemical composition. Furthermore, the alkali activation is found to modify the phase rich in Ca in the unactivated slag more than the other. Alkali activation of the slag produced mostly an amorphous material with some crystalline phases such as hydrotalcite and calcite, also some nanocrystalline structures were detected by TEM.

Abstract: The results of X-ray microanalysis of powder obtained by the electroerosion dispersing of solid alloy waste VK8 in kerosene are presented. It is established that the basic elements in the powder, obtained by the electroerosion dispersing of waste, are tungsten, cobalt, carbon and oxygen.

Abstract: Quality of metal-matrix composite castings, similarly as quality of conventional metal castings is defined by the collection of data concerning chemical constitution, properties (e.g. strength) and structure of final products. During study aimed at determining these parameters, the priority is to maintain the highest possible repeatability and automation of measurement. In case of chemical constitution or mechanical properties analysis it is considerably easy to achieve thanks to application of appropriate research procedure. Analysis of structure of studied materials is however a much bigger problem. To improve it, different tools of digital image analysis are being used, but because of only slight differences (e.g. in color) between different elements of structure, conducting such analysis without performing additional study may result in obtaining false results. In such case, identification of an object is very important: unequivocal conclusion whether a given object is a reinforcement or maybe an impurity or an inclusion foreign matter, or is it a structure of improper, unintentional chemical constitution. It is particularly important concerning composites for which on the images obtained using both optical and scanning microscopy individual phases (reinforcement, matrix and impurities) are difficult to distinguish. In such case identification of particular phases is aimed at avoiding mistakes, for example while analyzing the quantity or uniformity of spacing of reinforcement phase in given space. X-ray diffraction may be a solution for this problem. An example of identification (quantitative and qualitative description) of reinforcement phase in suspension composites is presented further in the paper. The authors present also a chemical constitution of selected elements of structure of metal-matrix composites from ex-situ group.

Abstract: This paper present the determination of concentration profiles of an Mg Al diffusion couple that was obtained with a high resolution field emission scanning electron microscope, the Hitachi SU-8000 equipped with a SDD EDS detector. From these concentration profiles, the inter-diffusion coefficient is determined with the Boltzmann-Matano technique. The advantages and disadvantages of working at high and low beam energy for quantitative x-ray microanalysis are highlighted. The f ratio method is used in this work to convert the x-ray intensities into composition.

Abstract: The aim of the present work was to solve the technology for welding Mg alloy type AZ 63 with aluminium and to assess the quality of the fabricated joints (bimetals-composites). In solving the welding technology, the high affinity of Mg to oxygen has to be considered and therefore as suitable technology either metallurgical joining in vacuum (electron beam etc.) or high-speed solid state welding seem to be feasible. Explosion welding with Semtex S 30 explosive was approved experimentally. Parallel arrangement of welded materials was applied. The more plastic Al material was accelerated. Quality of bonds (bimetals) was assessed by defectoscopy (ultrasound), optical microscopy, microhardness measurement and X-ray microanalysis. It can be generally stated that the basic requirement on joint quality (namely the undulated boundary) was met. The structural composition and absence of inhomogeneities in fabricated bimetals suggest that the desired quality was achieved.