Changes In Elemental Composition Research Articles

The Element Composition Variation in Lead Zirconate Titanate upon the Ion-Plasma Deposition: Experiment and Simulation

The element composition modification is experimentally studied in PZT thin films obtained via the RF magnetron sputtering with variable working gas pressure. The experimental data were interpreted through the statistic simulation of thermalization and diffusion of sprayed Pb, Zr, and Ti atoms during the ion-plasma deposition of PZT thin films. The simulation data are shown to adequately describe (within the limits of 5%) the change in element composition at various pressures of the gas environment. The study conducted enables one to produce PZT thin films with a set element composition, which is essential for optimizing the electric and physical properties of solid solutions at the morphotropic phase boundary.

Bioinorganic Markers of a Loss of the Crystalline Lens Capsule Barrier Properties and Consequent Age-Related Cataract Development.

The age-related cataract development consequent upon a loss of the lens capsule barrier properties proved to be associated with accumulation of sodium, calcium, phosphorus and potassium. For the first time the use of spatial cluster and correlation analyses showed that the physical light scattering in the crystalline lens volume depends on changes in the lens matter elemental composition. The fields of elevated concentrations of sodium, calcium, phosphorus, potassium and chlorine conformed to the lens capsule geometry and their clustering was similar to that of opacity fields in the lens body. The accumulation geometry of the elements in the lens body that are commonly seen in the aqueous humor of the anterior chamber, can be considered evidence for excessive transitioning of their compounds through the lens capsule shell, while its spatial connection with transparency changes-proof of participation in cataractogenesis.

ОСОБЕННОСТИ ЭЛЕМЕНТНОГО СОСТАВА FILIPENDULA ULMARIA (L.) MAXIM (ROSACEAE) НА ТЕРРИТОРИИ НОВО-УРСКОГО ХВОСТОХРАНИЛИЩА В КЕМЕРОВСКОЙ ОБЛАСТИ

Актуальность исследования обусловлена необходимостью получения комплексной информации о влиянии радикальных изменений биогеохимического фона в районах распространения хвостохранилищ горнорудного производства с целью прогнозирования путей миграции токсичных компонентов. Цель: выявление изменений в элементном составе корневой и надземной части Лабазника вязолистного (Filipéndula ulmária (L.) Maxim.) и установление индикаторных показателей техногенного влияния хвостохранилища руд Ново-Урского месторождения. Задачами исследования являются: определение коэффициентов концентраций химических элементов относительно фоновых значений, изучение особенностей пространственного распределения элементов в надземной и корневой частях лабазника вязолистного на территории хвостохранилища, установление коэффициентов аккумуляции химических элементов в корневой части лабазника вязолистного по отношению к надземной. Методы. Сбор растительного материала произведен на флангах Ново-Урского хвостохранилища. Элементный состав лабазника вязолистного определен методом масс-спектрометрии с индуктивно связанной плазмой (ИСП-МС) в лаборатории аналитического центра «Плазма» (г. Томск) по аттестованным методикам. Обработка аналитических данных выполнялась с помощью программ Statistica (6.0) и Excel. Картосхемы распределения элементов в надземной и корневой частях лабазника вязолистного построены в программах Surfer (11) и CorelDRAW (16). Результаты. На примере Ново-Урского хвостохранилища в Кемеровской области изучено накопление 67 химических элементов в лабазнике вязолистном. Рассчитаны коэффициенты концентраций элементов относительно фоновой точки и кларка ноосферы. Составлены геохимические ряды, отражающие избыточное накопление таких элементов, как Zn, Ba, Pb, Tl, Se, Ag, W, Hg, Au, P, превышающих фоновые значения в 5 и более раз. Картосхемы пространственного распределения химических элементов в лабазнике вязолистном показали наиболее высокие концентрации элементов в районе расположения отвала переработки окисленных руд и зоны потока рассеяния. Представлены коэффициенты аккумуляции химических элементов в корневой части лабазника вязолистного по отношению к надземным. Выявлено повышенное содержание химических элементов в корнях примерно в 80 % случаев.

Microbial electro-hydrolysis of sewage sludge for acidogenic production of biohydrogen and volatile fatty acids along with struvite

Synergy of multi-biological unit operations was studied to maximize the resource recovery in line with biorefinery using sewage sludge (SS) as primary feedstock. Microbial electro-hydrolysis systems (MES) were used as a pretreatment system to enhance the SS solubilization against the non-electrochemical control operation (AnT) under alkaline conditions. Comparatively, applied potential MES system (polarized) resulted in high SS solubilization (27.5%) than the corresponding MES-closed circuit (21.5%) and MES-open circuit (14.8%). In contrast, low SS solubilization was found in non-electrochemical system (AnT; 8.8%). Morphological changes in the SS refractory structure before and after pretreatment were examined by field emission scanning electron microscopy (FE-SEM). Energy-dispersive X-ray spectroscopy (EDX) spectrums showed significant changes in elemental composition due the course of pretreatment. Consequent utilization of obtained hydrolysate in the acidogenic fermentative reactors (AFR) resulted in good volatile fatty acids (VFA: 4.65 g/L) and Bio-H2 (21%) production. The distribution analysis of VFA revealed acetic acid as a major fraction followed by iso-valeric acid, butyric acid and propionic acid, which accounted the high acidification degree (57%) in AFR-3 system. Rich nutrient content of SS hydrolysate resulted in good struvite precipitation (phosphate fertilizer), which was confirmed with structural morphology and crystalline nature.

Impacts of Land Use and Landscape Patterns on Heavy Metal Accumulation in Soil

Land use cover change (LUCC) is one of the most important human activities that drive the evolution of the environment. It has great effect on the accumulation, distribution, and migration of heavy metals in the environment. Vegetation can absorb heavy metals directly, and it can also change the physical, chemical, and biological properties of soil and then control the mobility and activity of heavy metals in soil, which will eventually cause pollution of heavy metals in soil. In addition, the migration of heavy metals in soil is also affected by changes of landscape element composition and landscape pattern at sample points, plots, watersheds, and regional scales. Based on the soil sampling data and land use data of Ningbo city in 2003 and 2013, the decision tree classification method based on classification and regression tree algorithm was used to classify the land use and cover type. Single-factor pollution index and Nemero composite pollution index were used to evaluate the soil heavy metal pollution status. The landscape pattern indexes were used to explore the change of landscape patterns under different degrees of heavy metal accumulation. Finally, redundancy analysis and partial redundancy analysis were used to identify those landscape pattern factors that had the most significant impacts on the soil heavy metal accumulation in the study area. The results showed that:①The eight soil heavy metal elements including As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn presented different degree of accumulation from 2003 to 2013 in the study area, of which Hg, Ni, and Cr had the highest degree of accumulation. Most of the study area has been polluted by heavy metals, and the pollution degree in the heavily polluted areas is still increasing. ②Higher accumulation degrees of heavy metals was not distributed entirely in areas where land use types have always been construction land, or in areas where other types of land use had been converted to construction land. A considerable proportion of heavy metals accumulated in areas where land use types have always been cultivated land or converted from other types to cultivated land. ③Heavy metal polluted areas have fragmented, complex, and aggregated landscape pattern, and the correlation between this kind of landscape pattern characteristics and soil heavy metal accumulation in arable land, residential land, and industrial land was the highest. ④The higher the aggregation degree of construction land patch, the higher the accumulation degree of most heavy metals. The accumulation degree of Cu, Hg, Pb, and Cd increased significantly with the increase of landscape diversity and shape complexity of agricultural land. The closer the distance to the mining site, the more obvious the effect on the increase of Cd content.

Modelling the alloy element composition change in NiTi achieved through laser induced vaporization

The use of pulse laser processing to join or modify NiTi shape memory alloys has become an area of extreme interest in recent years. Until now, an in-depth investigation into the vaporization mechanisms associated with alloy composition changes during laser processing has not been done. This work systematically examines the effect of laser pulse parameters on the change in alloy composition. It was found that during conduction mode vaporization, the Ti-rich surface oxide limits the vaporization rate of Ni. This allows for less nickel loss and more control over the final composition. Additionally, keyhole formation during laser processing resulted in significantly higher rates of Ni loss, but also a greater amount of variance and reduced control of the final composition. Models are proposed that successfully predict the final bulk composition based on laser pulse parameters.

Tribology of Selected Hard Coatings for Oil and Gas Applications Up to 450 °C

Three different surface treatments, which are of interest to the oil and gas industry, and are commonly used for tribological applications at elevated temperatures, namely chromium carbide (CrC) coating, Ni–P coating, and boronized nickel alloy were investigated. In addition to different structural compositions, these surface treatments possess different surface topographies, which is of practical importance. Pin-on-disk experiments were conducted to measure their friction and wear performance against tungsten carbide. Experiments were carried out at room temperature and 450 °C using a specialized tribometer. Nanomechanical properties of the coatings were obtained at room and elevated temperatures. To investigate the physical and chemical changes that occurred during tribo-testing, scanning electron microscopy of the coatings’ cross section, wear tracks, and wear debris were obtained. Energy-Dispersive X-ray Spectroscopy analysis revealed the changes in elemental composition of the coatings wear track after the experiments, which could affect their tribological performance. It was found that the intensity and composition of the generated oxides, changes in the mechanical properties of the surface materials with temperature, and the surface topographical characteristics affected the tribo-mechanism. Among the tested samples, boronized nickel alloy surface outperformed the coatings with lower friction coefficient and lower wear rate, especially at elevated temperature.

Quantitative Analysis of Trace Metals in Engine Oil Using Indirect Ablation-Laser Induced Breakdown Spectroscopy

In engine oil, the element composition and concentration changes as the engine operates. A rapid and effective detection of these changes, therefore, is needed to prevent accidents. Indirect ablation laser-induced breakdown spectroscopy (IA-LIBS) is a new technology introduced specially for oil samples. In this paper, 5 different oils are used for the analysis. The matrix effect on the calibration curves of analytical elements (Cu, Ti, Fe, and Ni) in these oils is investigated. The results show that the matrix effect is reasonably negligible under the conditions of our experiment. A generalized calibration curve can be established for analytical metals in different types of oils. We use the generalized calibration curves established to determine the concentrations of Cu, Ti, Fe, and Ni in mixed oils. The IA-LIBS results show that good agreement is obtained between the measured and known values.

The effects of structurally different siderophores on the organelles of Pinus sylvestris root cells

Main conclusionSiderophores are a driver ofPinus sylvestrisroot responses to metabolites secreted by pathogenic and mycorrhizal fungi.Structurally different siderophores regulate the uptake of Fe by microorganisms and may play a key role in the colonization of plants by beneficial or pathogenic fungi. Siderophore action, however, may be dependent on the distribution of Fe within cells. Here, the involvement of siderophores in determining the changes of organelle morphology and element composition of some cellular fractions of root cells in Pinus sylvestris to trophically diverse fungi was investigated. Changes in the morphology and concentrations of different elements within organelles of root cells in response to three structurally different siderophores were examined by transmission electron microscopy combined with energy-dispersive X-ray spectroscopy. Weak development of mitochondrial cristae and the deposition of backup materials in plastids occurred in the absence of Fe in the structures of triacetylfusarinine C and ferricrocin. In response to metabolites of both pathogenic and mycorrhizal fungi, Fe accumulated mainly in the cell walls and cytoplasm. Fe counts increased in all of the analyzed organelles in response to applications of ferricrocin and triacetylfusarinine C. Chelation of Fe within the structure of siderophores prevents the binding of exogenous Fe, decreasing the abundance of Fe in the cell wall and cytoplasm. The concentrations of N, P, K, Ca, Mn, Cu, Mg, and Zn also increased in cells after applications of ferricrocin and triacetylfusarinine C, while the levels of these elements decreased in the cell wall and cytoplasm when Fe was present within the structure of the siderophores. These results provide insight into the siderophore-driven response of plants to various symbionts.

Can shell alterations in limpets be used as alternative biomarkers of coastal contamination?

The present study evaluated the association among traditional biochemical biomarkers with biometric, morphometric, and elemental composition of Lottia subrugosa (patelliform gastropod) shells from three multi-impacted coastal areas in Brazil. The study was carried out in Todos os Santos Bay (TSB), Santos/São Vicente Estuarine System (SESS) and Paranaguá Estuarine Complex (CEP), using three sampling sites to seek contamination gradients in each area. Results showed that all biomarkers evaluated responded to environmental contamination, regardless the presence (SESS and CEP) or absence (TSB) of a gradient of contamination. The responses found using biometric and morphometric parameters were consistent with the traditional biomarkers of exposure and effects (lipid peroxidation and DNA damage). Indeed, changes in elemental composition of L. subrugosa shells suggest that exposure to contaminated environments is probably responsible for the alterations detected. Despite the simplicity and lower cost of biometric and morphometric analyzes, these parameters are influenced by natural environmental conditions from which biases may arise. Therefore, these tools should be evaluated through experimental studies before it can be used in future assessments. However, the findings from the present study were observed in three aquatic systems distributed over a wide range of latitudes, which indicates that gastropod shells reflect effects resulting from environmental contamination.

Semi-quantitative analysis of mineral composition in harari coffee with herbal additives by using laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a powerful elemental analysis technique. The Nd:YAG laser of 1064 nm was used in this investigation to perform a semi-quantitative analysis of mineral composition in Harari coffee with and without herbal additives such as clove, ginger, and cardamom. In this work, mineral contents were detected in five samples including pure Harari coffee, coffee with ginger, coffee with cloves, coffee with cardamom and coffee with a mixture of all the previously mentioned additives. The presence of elements such as iron, calcium, potassium, magnesium and sodium was shown in all five samples. Moreover, with the addition of the herbs ginger, cardamom and cloves or its mixture to Harari coffee, an increase in the mineral contents was detected in the coffee samples. The percentage increase of the elements in the samples with added herbs was calculated through the comparison to the pure coffee sample. A semi-quantitative LIBS analysis is shown to be a rapid method to monitor the change in elemental composition of food samples. Furthermore, this work illustrated that adding herbs to coffee might be considered a good option to increase certain deficient elements in the body.

Understanding the performance of gamma‐ray‐irradiated epoxy nanocomposites

Epoxy nanocomposites being used in the high-energy radiation zones as an insulant may undergo changes in their dielectric properties during service. In the present study, the performance of base epoxy resin (S1) is compared with epoxy resin with ion trapping particle (Sample S2) and epoxy resin with nanotitania (Sample S3) particle. The influence of gamma irradiation on nanocomposites was analysed. Corona inception voltage due to water droplet initiated discharge and contact angle reduces post-gamma-ray irradiation. Surface potential decay time constant reduced drastically for gamma-ray-irradiated specimens. Trap distribution characterisation indicated that charge mobility increases after irradiation. The surface roughness of the sample increases with the irradiation dosage. Dielectric relaxation spectroscopy shows that permittivity reduces and loss tangent increases with the gamma-irradiated specimens. Water diffusion rate increases for the gamma-ray-irradiated specimen. No change in elemental composition, measured using laser-induced breakdown spectroscopy, of test specimens was observed. The hardness of the material and plasma temperature formed during laser shine decreases with gamma-ray irradiation intensity for Sample S1, whereas samples S2 and S3 showed only marginal variation. The performance of Sample S2 is found to be better than Samples S1 and S3.

FT-IR measurement on the damage of Japanese paper induced by PIXE analysis

Analysis of cultural heritage samples by PIXE involves the risk of damaging precious samples due to MeV-proton irradiation. To investigate appropriate methods to detect invisible damage due to PIXE analysis, we analyzed the change in chemical bonding of the sample surface subjected to PIXE and RBS measurement by Fourier Transform InfraRed spectroscopy (FT-IR). We used Japanese hemp paper as a simulated cultural property sample. The proton irradiation for the PIXE/RBS measurement was performed in a vacuum with an incident beam energy of 2.5 MeV, a beam current of 1 nA, and an irradiation time up to 10 min. The corresponding beam flux and fluence were 0.06 nA/mm2 and 4 [Formula: see text]Coulomb/cm2, respectively. When the irradiation time was 10 min, the absorbed dose was 480 kGy on the sample surface. We identified neither change of elemental composition nor visible change such as discoloration due to irradiation. However, we found changes in peak heights in the measured FT-IR spectra, which suggest the destruction of chemical bonds such as O–H and C–O due to proton-induced radiation damage.

Изменение элементного состава тонких пленок цирконата-титаната свинца в процессе ионно-плазменного осаждения: эксперимент и моделирование

AbstractThe element composition modification is experimentally studied in PZT thin films obtained via the RF magnetron sputtering with variable working gas pressure. The experimental data were interpreted through the statistic simulation of thermalization and diffusion of sprayed Pb, Zr, and Ti atoms during the ion-plasma deposition of PZT thin films. The simulation data are shown to adequately describe (within the limits of 5%) the change in element composition at various pressures of the gas environment. The study conducted enables one to produce PZT thin films with a set element composition, which is essential for optimizing the electric and physical properties of solid solutions at the morphotropic phase boundary.

Influence of topological constraints on ion damage resistance of amorphous hydrogenated silicon carbide

Radiation damage in materials is an important reliability issue in applications ranging from microelectronic devices to nuclear reactors. However, the influence of atomic structure and specifically topological constraints on the ion damage resistance of amorphous dielectrics has until recently been largely neglected. We have investigated the 120 keV He+ ion damage resistance for a series of amorphous hydrogenated silicon carbide (a-SiC:H) thin films. Changes in elemental composition and atomic structure induced by He+ ion irradiation were monitored using nuclear reaction analysis, Rutherford backscattering spectroscopy, transmission Fourier-transform infrared spectroscopy, and transmission electron microscopy while changes in mechanical properties were investigated using nanoindentation measurements. We show that for 120 keV He+ ion doses producing up to one displacement per atom, significant hydrogen loss, bond rearrangement, film shrinkage, and mechanical stiffening were induced for films with mean atomic coordination (〈r〉) ≤ 2.7, while comparatively minor changes were observed for films with 〈r〉 > 2.7. The observed radiation hardness threshold at 〈r〉rad > 2.7 is above the theoretically predicted rigidity percolation threshold of 〈r〉c = 2.4. Based on the observed elimination of terminal CH bonds and SiCH2Si linkages, the higher radiation hardness threshold is interpreted as evidence that these bonds are too weak to function as constraints in high-energy ion collisions. Eliminating these constraints increased 〈r〉c to 2.7, in agreement with the observed 〈r〉rad = 2.7. These results demonstrate the key role of topological constraints in ion damage resistance and provide additional criteria for the design of ion-damage-resistant amorphous materials.

Degradation mechanisms of high capacity 18650 cells containing Si-graphite anode and nickel-rich NMC cathode

Application of advanced anode and cathode materials in commercial lithium-ion batteries is attracting attention due to their high capacity. Silicon (Si)/graphite anodes and nickel (Ni)-rich lithium nickel manganese cobalt oxide with layered structures have been paired in commercial 18650 high energy density cells (∼270 Wh/kg). It is crucial to investigate the cell performance and the aging behavior of this commercial cell. In this study, we present commercial cell degradation mechanisms by comparing fresh and aged electrodes, including changes of crystal structure, morphology, elemental composition, and electrochemical properties. The quantitative analysis was done based on dV/dQ incremental capacity analysis of 18650 cells. To determine the amount of cyclable lithium ions (Li+) and active material loss, the lithiation and delithiation capacity were compared for fresh and aged electrodes in half coin cells. Results showed that even with 5% (by mass) of Si added in the anode, cracks occurred across the anode leading to contact loss and thickening of the solid electrolyte interphase (SEI) layer. Additionally, the average fluorine (F) ratio of the aged anodes was higher compared to that of the fresh anodes. More severely, the F content on the Si aggregations on aged anodes increased to as high as 5 times that of the fresh anode, indicating SEI growth, especially on Si particles. Solid 7Li nuclear magnetic resonance results showed no detectable Li metal deposition on the aged anode. On the cathode side, cracks on the primary particle interfaces contributed to cathode material loss, contact loss, and impedance rise. Therefore, Li+ loss into the thickened SEI layer, particle cracking, and impedance rise are the main reasons behind cell degradation.

Organismal stoichiometry at the temporal scale: Seasonal variability shapes interspecific differences in fish

Abstract Changes in organismal stoichiometry (OS) may be driven by seasonal changes in lipid reserves (i.e. energy) and gonadal development in fish. However, these relationships are understudied. Hence, we investigated how seasonal changes in body lipid content and gonadal development can drive the seasonal variability of OS traits at the example of three coexisting freshwater fish species. Furthermore, we aimed to assess the importance of seasonal OS alteration in comparison with interspecific differences. Carbon (%C), nitrogen (%N) and phosphorus (%P) contents, and the molar ratios of these elements (C:N, C:P and N:P) were examined in rudd (Scardinius erythrophthalmus), pumpkinseed (Lepomis gibbosus) and Amur sleeper (Perccottus glenii). We consider the sex and seasonal changes in body size as a potential factor in shaping OS. Substantial seasonal intraspecific variability occurred in all OS traits. Its extent exceeded interspecific differences in %C, %N and C:N, while %P and C:P, N:P were determined primarily by species identity. The effect of sex occurred sporadically and was considerable in some cases. Seasonal changes in total length did not contribute to intraspecific variability of OS. Intra‐annual changes in body lipid content affected seasonal variability of OS traits substantially, but the strength of this effect was species‐specific. The regulatory role of lipid reserve alterations worked only for those species that exhibited considerable seasonal variation in body fat content. Gonado‐somatic index proved to be marginal in shaping seasonal changes in OS, presumably because a substantial portion of the essential elemental demand for gonadal growth is supplied by rearrangements within the body, without notable changes in the entire elemental composition. In the light of our findings, we suggest that more attention should be given to the influence of seasonal variability in OS traits, and sex should be considered as a taxon‐dependent effect. Ignoring this substantial degree of variability might lead to inaccuracies in assessing the extent of both intra‐ and interspecific OS differences. We conclude that seasonal OS variability might shape consumer‐driven nutrient dynamics.

Changes in organic acids, polyphenolic and elemental composition of rosé sparkling wines treated with mannoproteins during over-lees aging.

The effect of mannoproteins on the evolution of rosé sparkling wines during over-lees aging was investigated on the basis of the chemical characterization of polyphenols, organic acids, macro- and microelements using a combined analytical approach. Variations on these constituents were assessed using Raman and near-infrared spectroscopy. During the biological aging, caffeic acid, catechin, gallic acid and malvidin-3-O-glucoside were the most abundant polyphenolics in the rosé wines. The phenolic compound tyrosol, a fermentation derivative, was found at concentrations up to 98.07 mg L-1. The addition of mannoproteins significantly affected the concentrations of organic acids and individual polyphenolic compounds, particularly trans-resveratrol, quercetin, catechin, p-coumaric and hydroxybenzoic acids that showed increased concentrations over time. The positive effects of mannoproteins were mainly observed at the end of the biological aging. The mineral composition remained stable, while potassium was the most abundant mineral in all wines. The observed changes involving these constituents may offer new insights on their behavior during wine aging and on the bioactive and nutritional quality of rosé sparkling wines.

Elemental Composition at Silicone Hydrogel Contact Lens Surfaces

The outermost surface composition of 11 silicone hydrogel (SiHy) lenses was measured using X-ray photoelectron spectroscopy (XPS) to understand differences in wettability and potential interactions within an ocular environment. The SiHy lenses tested included balafilcon A, lotrafilcon A, lotrafilcon B, senofilcon A, comfilcon A, and somofilcon A reusable 2-week or monthly replacement lenses and delefilcon A, samfilcon A, narafilcon A, stenfilcon A, and somofilcon A daily disposable lenses. All lenses were soaked for 24 hr in phosphate-buffered saline to remove all packaging solution and dried under vacuum overnight before analysis. X-ray photoelectron spectroscopy measurements were performed at 2 take-off angles, 55° and 75°, to evaluate changes in elemental composition as a function of depth from the surface. Detailed analysis of the XPS data revealed distinct differences in the chemical makeup of the different lens types. For all lenses, carbon, oxygen, and nitrogen were observed in varying quantities. In addition, fluorine was detected at the outermost surface region of comfilcon A (3.4%) and lotrafilcon A and B (<0.5%). The silicon content of the near-surface region analyzed varied among lens types, ranging from a low of 1.6% (lotrafilcon B) to a high of 16.5% (comfilcon A). In most instances, silicon enrichment at the outermost surface was observed, resulting from differences in lens formulation and design. Lenses differed most in their surface silicon concentration, with lotrafilcon B and delefilcon A exhibiting the lowest silicon contents and comfilcon A lens exhibiting the highest. Silicon has hydrophobic properties, which, when found at the surface, may influence the wettability of the contact lenses and their interaction with the tear film and ocular tissues. Higher surface silicon contents have been previously correlated with adverse effects, such as enhanced lipid uptake, thus underscoring the importance of monitoring their presence.

Thermal stresses computation under high–current pulsed radiation of AISI M2 tool steel

Surface modification of metallic materials and alloys with concentrated energy flows (powerful electron beams and ion plasma flow, laser beams) has been widely used in various fields of manufacturing. The aim of physical and mechanical properties modification is to improve the performance of the critical parts fabricated from modified materials. The mentioned energy impacts give rise to radiation, thermal and mechanical effects causing the changes in morphology, microstructure, elemental and phase composition of the surface layers, which in turn may lead to hardness, wear corrosion resistance and red hardness increasing of modified materials. However, as experimental investigations are shown, in some cases irradiation promotes the crystal defects’ occurrence and often non-uniform heating leads to the cracks’ formation in the surface layers. Thus, selection of incident electrons energy, its current density and pulse duration, taking into account the thermal stress state, is an actual problem of modern radiation technologies. This paper provides a numerical solution of differential equations in partial derivatives for the temperature fields’ computation as well as radial and axial thermal stresses distribution in R6M5 (AISI M2) high-speed steel exposed to medium-energy (up to 400 keV) high–current (up to 1 kA/cm2) pulsed (up to 1 μs) electron beam radiation. The obtained results can be useful in the optimal modes selection of tool steels and products at surface radiation treatment and evaluation of their service life.