Papers by Keyword: X-Ray

Abstract: The mathematical model of the broadband transmission X-ray thickness gauge is developed. The mathematical model consists of sectors: generation and transformation of radiometric signals; equation of transmission X-ray thickness gauge; error estimation of thickness measurement; performance rating. The example of the use of the proposed model to calculate of the transmission X-ray thickness gauge for aluminum items is provided. In the example the dependences of integral mass X-ray attenuation coefficients and the thickness of monitored objects made from aluminum are calculated. The range of optimum measured thickness depending on the maximum X-ray energy was selected, the measurement time to provide the desired thickness measurement error was estimated. The possibility of measuring the thickness of a cooper test object for a wide beam conditions has been experimentally confirmed.

Abstract: EVA (poly (ethylene-co-vinyl acetate)) is a copolymer widely used in the Brazilian footwear industry, where approximately 18% of the EVA remains as waste, principally after the cutting out of insoles. EVA wastes cannot be recycled or reused for the original purpose, but it may be possible to add them to Portland cement to produce concrete for non-structural applications in constructions. This work presents an analytical technique based on the interpretation of X-ray images to assess the spatial distributions of these wastes within concrete test specimens. Evaluation was made of the feasibility of using this technique to study the incorporation of the wastes. Test specimens of concrete were produced according to Brazilian technical standard ABNT-NBR 5738, using a sand/gravel/cement ratio of 3:2:1, where EVA replaced part of the gravel content (10, 20, 50, and 70% of the total gravel volume). Analysis of front projection X-ray images of the specimens showed that the waste was homogeneously incorporated throughout the entire material, as required for concrete. The results of compressive strength tests showed that for samples containing up to 20% of EVA waste, the compression resistance remained almost unchanged, while incorporation of 50 or 70% of waste led to decreases of up to 64% in the resistance.

Abstract: Time-resolved and in-situ observations using synchrotron radiation X-rays were performed to observe solidification of cast iron (CE=4.5, 0.02mass%Mg). Morphology of graphite particles was influenced by specimen holder material. In the Al₂O₃ holder, graphite particles were spheroidal at the beginning and then deviated from the spheroidal shape. In addition, the coupled eutectic solidification of austenite and graphite occurred at the final stage. In contrast, the divorced eutectic solidification, in which graphite particles and austenite dendrites independently grew, was selected until the end of solidification in MgO holder. Spheroidal graphite particles were engulfed by austenite. Consequently, typical microstructure observed in ductile cast iron was reproduced in the in-situ observation. The results suggested that oxygen potential, which was determined by Al₂O₃ or MgO (specimen holder) in the observations, could be an important factor for the selection of eutectic growth mode and graphite morphology.

Abstract: In this paper, we aim at characterizing three different cast iron alloys and their microstructural features, namely lamellar, compacted and nodular graphite iron. The characterization of microscopic features is essential for the development of methods to optimize the behavior of cast iron alloys; e.g. maximize thermal dissipation and/or maximize ductility while maintaining strength. The variation of these properties is commonly analyzed by metallography on two-dimensional representations of the alloy. However, more precise estimates of the morphologies and material characteristics is obtained by three-dimensional reconstruction of microstructures. The use of X-ray microtomography provides an excellent tool to generate high resolution three-dimensional microstructure images. The characteristics of the graphite constituent in the microstructure, including the size, shape and connectivity, were analyzed for the different cast iron alloys. It was observed that the lamellar and compacted graphite iron alloys have relatively large connected graphite morphologies, as opposed to ductile iron where the graphite is present as nodules. The results of the characterization for the different alloys were ultimately used to generate finite element models.

Abstract: Ferrite with mixed complex oxides BiNaFe₂O₅, BiKFe₂O₅ was synthesized by high temperature solid state reaction. The structure of the ferrites, type of syngony, parameters of the unit cells, radiographic and pycnometric densities were determined by X-ray phase analysis for a first time: BiNaFe₂O₅ – а=5,577, с=13,86 Å, γ=120º, Vun.cell. = 373,9 Å3, Z=4, ρrad.= 7,5262 г/см³, ρpicn.=7,5271 г/см3, BiKFe₂O₅ –а=5,545, с=13,65 Å, γ=120º, Vun.cell.= 363,45Å3, Z=6, ρrad.= 8,0367, ρpicn.=8,0375 г/см³. A comparative analysis of the relationship between crystal lattice parameters with parameters of the crystal lattice of initial oxides and complex ferrites has been performed. Research dependence of the magnetic moment of the complex ferrite BiNaFe₂O₅ of the applied magnetic field at a constant temperature T = 6.1405 K showed a paramagnetic shift in the structure.

Abstract: Nowadays, X-ray tomography is one of the most pertinent directions of the development of non-destructive testing methods. Besides the experimental setup to conduct the X-ray tomographic measurements, it is necessary to have stable and flexible software. In most cases, existing software packages for the reconstruction of tomographic data are not freeware. This makes tomographic experiments not flexible because of the restriction of the source code correction. This papers explains how to implement one of important parts of tomographic research, namely, experimental data simulation, which allows to test reconstruction algorithms further.

Abstract: In this research work, we consider the problem of sensor selection for the system controlling full penetration mode in electron beam welding. For this, we have investigated four signals from the backside of the workpiece: electron current in root plasma, ion current in root plasma, through-thickness electron current and penetrating bremsstrahlung X-ray. After having done the research we have estimated the advisability of two signals: one for cases if requirements for control precision are high and the other for other cases.

Abstract: Silver nanoparticles were synthesized at 293÷353 K temperature range by NaBH₄ and HCOOH solutions with low concentration at polyethyleneglycol having average molecular weight of 40000 and 200 kDa gum arabic medium. Obtained silver nanoparticles were studied using methods of X-ray diffraction, UV-Vis, FTIR spectroscopy, scanning electron microscope. It was determined that sizes of silver nanoparticles which stabilize at polymer medium vary from 12 to 26 nm range depending on mole ratio, temperature and reduction medium of initial substances. It was shown by FTIR-spectroscopy that -OH and -COOH groups in polymer take an active part in stabilization of silver nanoparticles. It was determinated by UV-Vis study of silver nanoparticles containing polymer composition in aqueous condition that 412 nm which is specific to silver atoms do not change sharply for 4-5 days.

Abstract: Gleeble study of the quenching and partitioning (Q&P) process has been performed on Domex 960 steel (Fe, 0.08 %C, 1.79 %Mn, 0.23 %Si, 0.184 %Ti, and 0.038 %Al). The effect of different Q&P conditions on microstructure and mechanical properties were investigated. The aim of the process is to produce a fine grained microstructure for better ductility and controlled amounts of different micro-constituents to increase the strength and toughness simultaneously. Three different quenching temperatures, three partitioning temperatures and three partitioning times have been selected to process the 27 specimens by Gleeble® 1500. The specimens were characterized by means of OM, SEM, XRD, hardness and impact tests. It was found that, fine lath martensite with retained austenite is achievable without high amount of Si or Al in the composition although lack of these elements may cause the formation of carbides and decrease the available amount of carbon for partitioning into the austenite. The hardness increases as the quenching temperature is decreased, however, at highest partitioning temperature (640^◦C) the hardness increases sharply due to extensive precipitate formation.

Abstract: This paper describes a fundamental experiment on X-ray stress measurement of austenitic stainless steel (JIS SUS316L) with a new equipment which was developed in this study. An image plate (IP) as a two-dimensional X-ray detector and the cosα method as a principle of the measurement of stress were used in it. An experiment was conducted with CrKβ characteristic X-ray and γFe-311 diffraction line, and the results were compared to those that were obtained with the conventional sin²ψ method under the similar X-ray conditions. It was found that the accuracy of stresses obtained with the equipment developed are almost as same as those of the sin²ψ method. However, the measuring time can be shorten by several times by using it.