Search

The outermost layer of a fire proximity suit needs to conform to a strict requirement of radiant protection performance (RPP) ≥ 20s, which is indicative of its ability of offering a protection for at least 20s duration from second degree burn upon radiant heat exposure (84 kW/m2). Typically, this layer is fabricated by laminating a single‐side metallized PET (SMPET) layer with glass fabric. However, upon erosion of the deposited metal, this laminate is rendered unsuitable due to loss of reflectivity. Here, we explore the possibility of replacing the SMPET with its dual‐metallized analogue (DMPET) and determine the effect of increasing the optical density (OD) on the adherence and protection level. Metallized films with OD varying from 2.2 to 4.8 were laminated with glass fabrics of twill, satin and plain weave pattern using a silicone adhesive. The peel adhesion strength of laminates prepared using DMPET was found to be higher (1.01 ± 0.03 N/mm), as compared to SMPET (0.63 ± 0.03 N/mm) and the resulting films did not undergo delamination during flexing. Laminates prepared from satin woven glass fabric exhibited lowest flexural rigidity followed by twill and plain woven glass fabric. Protection offered by the laminate from convective heat was quantified in terms of the thermal protective performance (TPP), and the abraded laminate prepared using DMPET (OD‐4.8) was found to meet all the mandatory requirements of proximity clothing, offering an RPP of 27 s and a TPP of 62 cal/cm2 s. In comparison, SMPET laminates exhibited lower level of adhesion and offered an RPP of only 7.5 s. [ABSTRACT FROM AUTHOR]

Erosion and leaching of metal(loid)s from contaminated sites can spread pollution to adjacent ecosystems and be a source of toxicity for living organisms. Phytostabilization consists of selecting plant species accumulating little or no metal(loid)s in aerial parts to establish a vegetation cover and thus to stabilize the contaminants in the soil. Seeds of white lupin, common vetch, and buckwheat were sown in greenhouse on soils from former French mines (Pontgibaud and Vaulry) contaminated with metal(loid)s including high concentrations of As and Pb (772 to 1064 and 121 to 12,340 mg kg−1, respectively). After 3 weeks of exposure, the growth of white lupin was less affected than that of the 2 other species probably because metal(loid) concentrations in roots and aerial parts of lupins were lower (5–20 times less Pb in lupin leaves on Pontgibaud soil and 5–10 times less As in lupin leaves on Vaulry soil than in vetch and buckwheat). To limit oxidation and/or scavenge metal(loid)s, white lupin increased the content of proline and total phenolic compounds (TPC) in leaves and roots by a factor 2 whereas buckwheat stimulated the production of TPC by a factor 1.5–2, and non-protein thiols (NPT) by factors around 1.75 in leaves and 6–12 in roots. Vetch accumulated more proline than white lupin but less NPT than buckwheat and less TPC than the 2 other plant species. The level of oxidation was however higher than in control plants for the 3 species indicating that defense mechanisms were not completely effective. Overall, our results showed that white lupin was the best species for phytostabilization but amendments should be tested to improve its tolerance to metal(loid)s. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Using hydrocarbon oils as a flushing medium causes lots of issues to machinists such as cancer. In this study, the behavior of green flushing medium (SF biodiesel and deionized water) during µED milling of hybrid metal matrix composites (HMMC) under various parametric settings of reinforcement wt%, capacitance and feed rate is analyzed. Metal erosion rate (MER) decreases with rise in capacitance due to longer interval between sparks. Higher MER is attained with lower order wt % reinforcement whereas the surface roughness increases increment in wt % reinforcement. Svk and Sk rise exponentially with increase in capacitance for considered green flushing medium. Kerosene offered higher MER compared to deionized water and Sunflower BD at considered machining condition. RLT appears to be more with DI water compared Sunflower BD due to deposition of debris on the surface. Svk and Sk is found be minimum with SF biodiesel at considered parametric settings. [ABSTRACT FROM AUTHOR]

Few studies have quantified the complex flux of trace metals from mine tailings to rivers through water erosion, especially in the semi-arid region of North Morocco (Zaida mine) where soil erosion is a severe issue. This study applies (i) methods to understand and estimate the complex flux of trace metals from mine tailings to rivers, using the RUSLE model combined with the concentration of trace metals in the soil and additionally (ii) pollution indices and statistical analyses to assess the sediment contamination by Cd, Cu, Pb, and Zn. Our study revealed that the basin has a low erosion rate, with an average of 9.1 t/ha/yr. Moreover, the soil contamination is particularly high at the north of the mine tailings, as prevailing winds disperse particles across the basin. The assessment of the sediments indicated that Pb is the main contaminant, with concentrations exceeding 200 mg/kg specifically downstream of the tailings. This study also identified high a concentration of trace elements 14 km away from the tailings alongside the Moulouya river, due to the specific hydrological transport patterns in the area. This research contributes to a better understanding of the transport and fate of the trace metals in mining areas. It proposes a replicable method that can be applied in other regions to assess the contamination flows and thereby assist water resource management. [ABSTRACT FROM AUTHOR]

Loess is widely distributed in Northwestern China and serves as the preferred engineering construction material for anti-fouling barriers. Heavy metal contamination in soil presents significant challenges to the engineering safety of vulnerable loess structures. Hence, there is an urgent need to investigate the impact of heavy metal ions on their percolation performance. In order to investigate the effectiveness of microbially induced carbonate precipitation (MICP) using Sporosarcina pasturii (CGMCC1.3687) bacteria in reducing internal seepage erosion, a saturated permeability test was conducted on reshaped loess under constant water head saturation conditions. The response of loess to deionized water (DW) and ZnCl2 solution seepages was analyzed by monitoring changes in cation concentration over time, measuring Zeta potential, and using scanning electron microscopy (SEM). The results indicate that the hydrolysis of Zn2+ creates an acidic environment, leading to the dissolution of carbonate minerals in the loess, which enhances its permeability. The adsorption of Zn2+ ions and the resulting diffusion double-layer (DDL) effect reduce the thickness of the diffusion layer and increase the number of free water channels. Additionally, the permeability of loess exposed to ZnCl2 solution seepage significantly increased by 554.5% compared to loess exposed to deionized water (DW) seepage. Following the seepage of ZnCl2 solutions, changes in micropore area ratio were observed, decreasing by 48.80%, while mesopore areas increased by 23.9%. MICP treatment helps reduce erosion and volume shrinkage in contaminated loess. Carbonate precipitation enhances the erosion resistance of contaminated loess by absorbing or coating fine particles and creating bridging connections with coarse particles. These research results offer new perspectives on enhancing the seepage properties of saturated loess in the presence of heavy metal erosion and the geochemical mechanisms involved. [ABSTRACT FROM AUTHOR]

The surface treatment technology is one of the methods to protect the metal materials from erosion which is one of the most common surface damage of mineral processing equipment. In this paper, ultrasonic surface rolling extrusion (USRE) was used to investigate the effect of the USRE process on the erosion behavior of 304SS. Different USRE passes were conducted on the 304SS samples to characterize the microstructure, micromorphology, phase transition, surface hardness and residual stress, respectively. On this basis, the passivation film of the samples before and after USRE were studied and the erosion mechanism of the USRE samples was explored. The results show that better erosion resistance of the USRE samples can be attributed to phase transformation, grain refinement, strengthened surface hardness. The results of this paper provide a theoretical basis for the design of erosion resistant metal materials. [ABSTRACT FROM AUTHOR]

The paper reveals the problem of measuring reactive oxygen (ROS) and nitrogen (RNS) species' concentrations in plasma treated water Milli-Q. We investigate the features of the FOX method for hydrogen peroxide concentration measurement and the Griess method for nitrite ions concentration spectrophotometric measurement using two different ways of an aqueous solution treatment. In the first case, the electrode (non-conducting high-temperature ceramics) was above the aqueous solution and the discharge was in the gas phase. In the second case, the electrodes were fixed around the perimeter inside the cylindrical chamber filled with water, and working gas (air, argon) was injected into interelectrode space. Varying the duration of exposure (2–10 min) leads to changes in the chemical composition and biological activity of the liquid medium, and this approach is effective for proving of the methods in complex liquids. We found the erosion of the electrodes (stainless steel, duralumin) with the injection of argon and air. The erosion can affect reactions of the methods used, as a result, it makes a contribution to measured concentration. For further applications, it is necessary to consider these features to obtain the correct and reproducible results. When plasma exposure occurs with an electrode that is above the surface of the liquid and does not erode, both methods work in the proper way. But when erosion is present ions of eroded materials (iron, aluminum) contribute to the measurement of hydrogen peroxide concentration using the FOX method. A method with xylenol orange is proposed for taking this feature into account by measuring the concentration of metal ions. In the Griess assay it is possible to obtain strongly erroneous results due to visually similar color and close values of absorbance at the chosen wavelength (525 nm) for both low concentration of nitrites (within linear part of the calibration curve) of nitrites and high concentration (far beyond linear part of the calibration curve). In our research concentration of nitrites does drastically change in the experiment after changing material of the electrodes from stainless steel to duralumin. The Griess assay leads to the formation of a stable fluorescent complex when erosion of the metal electrodes is present. [ABSTRACT FROM AUTHOR]

Discharges in liquids are very efficient to synthesize nanoparticles by electrode erosion. This simple process is only simple in appearance. Mechanisms responsible for the production of nanoparticles are several depending on the choice of process parameters. They determine size distributions, shapes, composition, and defects of produced particles. They also control their possible assembly into more complex structures. This article describes the basic physics of nanoparticles' synthesis by discharges in liquids using electrodes and gives a summary of the research efforts that have been devoted to the understanding of this process. A special attention is paid to thermodynamics of these systems driven by discharges that are at or close to local equilibrium. Although a complete picture is not available yet, huge progress has been made and offers new capabilities for a better control of these kinds of processes. Finally, among important challenges that are still to tackle, the possibility of forming nanoalloys from immiscible elements or achieving unimodal monodisperse size distributions is questioned from the current mastery reached in this field. [ABSTRACT FROM AUTHOR]

This article reports a new approach toward fabrication and directed assembly of nanoparticulate reactive system (Nanofoils) on patterned substrates. Different from current state‐of‐the‐art, gas phase electrodeposition uses nanoparticles instead of atoms to form densely packed multilayered thin films at room temperature‐pressure. On ignition, the multilayer system undergoes an exothermic self‐propagating reaction. The numerous contact points between two metallic nanoparticulate layers aid in high heat release. Sub‐10‐nm Platinum (Pt) and Aluminum (Al) particles are synthesized through cathode erosion of metal electrodes in a flow of pure nitrogen gas (spark ablation). Pt/Al bilayer stacks with total thickness of 3–8 µm undergo self‐propagating reaction with a 10.3 mm s−1 wavefront velocity on local ignition. The reaction wavefront is captured using high speed videography. Calorimetry studies reveal two exothermic peaks suggesting Pt/Al alloy formation. The peak at 135 °C has a higher calorific value of 150 mW g−1 while the peak at 400 °C has a 12 mW g−1 exothermic peak. X‐ray diffraction study shows reaction‐products are cubic Al2Pt with small quantities of orthorhombic Al6Pt and orthorhombic AlPt2. Electron microscopy studies help draw a correlation between film morphology, bimetallic interface, nanoparticle oxidation, and self‐propagating reaction kinetics that is significant in broadening our understanding towards nanoparticulate reactive systems. [ABSTRACT FROM AUTHOR]

With the increasing construction activities in dry or degraded lands affected by wind-driven particle action, the deterioration of metal structures in such environments becomes a pressing concern. In the design and maintenance of outdoor metal structures, the emphasis has mainly been on preventing corrosion, while giving less consideration to abrasion. However, the importance of abrasion, which is closely linked to the terrain, should not be underestimated. It holds significance in two key aspects: supporting the attainment of sustainable development goals and assisting in soil planning. This study aims to address this issue by developing a predictive model that assesses potential material loss in these terrains, utilizing a combination of the literature case studies and experimental data. The methodology involves a comprehensive literature analysis, data collection from direct impact tests, and the implementation of a machine learning algorithm using multivariate adaptive regression splines (MARS) as the predictive model. The experimental data are then validated and cross-verified, resulting in an accuracy rate of 98% with a relative error below 15%. This achievement serves two primary objectives: providing valuable insights for anticipating material loss in new structure designs based on prospective soil conditions and enabling effective maintenance of existing structures, ultimately promoting resilience and sustainability. [ABSTRACT FROM AUTHOR]

Simulation of surface erosion by impact of abrasive water-jet (AWJ) is challenging for traditional mesh-based numerical methods, because it involves complex phenomena related to fluid–solid interaction, material removal and free surface flows. In this study, the surface erosion mechanism of ductile target materials by AWJ is investigated based on the smoothed particle hydrodynamics method (SPH, a mesh-free method). The water-jet, abrasives and solid target are all discretized with a series of SPH particles. The water-jet is modeled as a continuous fluid flow, the target material is modeled as a elastic–plastic material, and the abrasives are modeled as rigid bodies. The SPH model is improved by combining several correction algorithms and techniques, which help us to increase the stability and the accuracy of the simulation. The density diffusion correction term is introduced for water-jet, which reduces the pressure noise and makes the pressure field more stable. The dynamic boundary algorithm is used for the abrasives, and the pressure distribution around the abrasive is improved. The interactions among the water-jet, abrasives and solid target are realized by different contact algorithms. The dynamic process of plastic deformation, material removal and crater generation of the target material under AWJ impact can be simulated by the improved SPH model. The proposed model could be useful in the applications of AWJ machining and metal surface erosion. [ABSTRACT FROM AUTHOR]

In order to explore the erosion reason of the hearth sidewall built with high thermal conductivity and small hot-pressed graphite carbon bricks, the carbon brick samples were obtained by boring in different parts of the hearth sidewall. By the research on microcosmic structure, thermal conductivity, chemical composition of the carbon bricks, it was concluded that the high portion of large size pore leaded to poor properties of resistance to Zn permeation. And due to the formation of the weakened layer, the transfer system of lining was destroyed, which result in poor effect of titanium protecting and resistance to hot metal erosion. For the purpose of prolonging the campaign of BF hearth, the properties of resistance to hot metal erosion and the thermal conductivity of carbon brick should be matched well. [ABSTRACT FROM AUTHOR]

The article presents a method for calculating the erosion furrow depth and the metal loss of piles and other structures of marine hydraulic facilities under wave action containing a water-pebble mixture (pebble bombardment of piles). [ABSTRACT FROM AUTHOR]

Liquid impingement erosion has been known as mechanical degradation, where the original material is removed progressively from a solid surface due to continued exposure to impacts by high-speed liquid droplets. This is a major issue in many industries, including aerospace and aviation and power generation, particularly gas and steam turbines, nuclear power plants, and wind energy. Tremendous numerical and experimental studies have been performed so far to understand the physical phenomena involved in this process and to improve the erosion resistance of different surfaces. In this review paper, first, the liquid–solid impact in a wide range of relative velocities is reviewed fundamentally. Then, the liquid impingement erosion of metals, including damage regimes and damage accumulation mechanisms, as well as the role of solid properties on erosion performance are explained. Finally, promising water droplet erosion-resistant materials and surface treatments are discussed. This review paper is intended to summarize the present knowledge of the different mechanisms involved in the liquid impingement erosion process. [ABSTRACT FROM AUTHOR]

The surface preparation of shiny stainless steels is a must for applying esthetic paints, effective functional plasma spray coating, laser cladding, welding, etc., applications. The current work aims for effective surface roughening and erosion MRR of SS 304 work surface using SiC abrasive jet erosion and optimization of the process parameters. The response surface approach is used to design and conduct the studies using the Box–Behnken design method. The surface topography of the eroded surfaces is examined by a 2D profilometer, 3D profilometer, and scanning electron microscope (SEM). The abrasive grit size and working gas pressure greatly affect the surface roughness of SS 304 samples. The influence of the process parameters on the variation of these topographical features is analyzed and confirmed. The working jet pressure is seen to significantly impact erosion MRR. The lower working gas pressure shows a typical influence on Ra (surface preparation) and as pressure increases, erosion MRR rises, and the surface preparation mode shifts to the erosion metal removal/cutting zone. The quality of SS 304 surface prepared from SiC abrasive jet impact is characterized by 3D profilometry. [ABSTRACT FROM AUTHOR]

Spinel LiNi 0.5 Mn 1.5 O 4 (LNMO) has gained significant attention as a promising cathode material for lithium-ion batteries due to its high working voltage (>4.7 V) and energy density. However, challenges such as electrolyte decomposition-induced material interface erosion and transition metal dissolution under high operating voltage hinder its commercial use. In this study, a thin and uniform Sm 2 O 3 layer has been successfully deposited on the surface of LNMO using a wet chemical method. A comprehensive investigation of surface morphology, crystal structure, and electrochemical performance of the modified LNMO is conducted. The results demonstrate that the Sm 2 O 3 surface modification acts as a robust multifunctional protective layer, effectively shielding against hydrofluoric acid-induced chemical attack and enhancing the migration efficiency of lithium ions. Notably, the capacity retention rate of LNMO@Sm 2 O 3 (3 wt%) remains up to 88 % after 280 cycles, significantly surpassing the uncoated counterpart. The coated material exhibits a capacity of 114 mAh g−1 even under 10 C rate conditions. Moreover, the AC impedance values and manganese dissolution of the modified material in the organic electrolyte are considerably lower than those of the uncoated counterpart. Theoretical calculations strongly support the experimental findings, revealing higher Mn vacancy formation energy and density of states at the Fermi energy level for the Sm 2 O 3 -modified electrodes. This research contributes to the field of surface modification and paves the way for further enhancements in the electrochemical performance of other high-voltage manganese-based lithium-ion batteries (LIBs). • 1. A robust Sm 2 O 3 surface layer is introduced to the LNMO electrode via wet-chemical process. • 2. The surface coating method confirmed to stabilize LNMO through theoretical calculations. • 3. This strategy reveals fascinating electrochemical and the surface structural properties. [ABSTRACT FROM AUTHOR]

Accelerated soil erosion and trace metal pollution in aquatic environments have become a pervasive aspect of global environmental changes during the Anthropocene, threatening food security and ecosystem viability. Long-term records of these processes can promote an improved understanding of their timing, amplitude, and environmental impacts. Here we present a sedimentary record from Lake Jian in Yunnan Province, southwestern China, which shows that land-use changes affected the lake watershed by at least 1200 CE, and that the intensity of soil erosion increased from 1450 CE onwards, as evidenced by increases in magnetic susceptibility and high concentrations of trace metals. The timing of the increase in atmospheric lead (Pb) transport, which was possibly related to the growth of metallurgical activity in the region, occurred ~250 years earlier than the anthropogenic soil erosion. Pb emissions resulting from the mining and smelting industry, coal burning, and the use of leaded gasoline led to enhanced Pb pollution in the area since the 1950s CE. Comparison of the results with geochemical records from lakes in northwestern Yunnan reveals that environmental disturbances were relatively limited during the intervals of the Nanzhao and Dali Kingdoms. However, enhanced human disturbances of lake watersheds in Yunnan occurred from the Yuan dynasty onwards, as a result of population increases caused by immigration to the area, which was followed by the changes in the type and intensity of human activity, with an enhanced anthropogenic impact after the middle twentieth century. Overall, our study provides a case study for understanding the historical background of the Anthropocene. [ABSTRACT FROM AUTHOR]

[Display omitted] • A spatially confined cavitation with sonoluminescence (SL) was taken to study the erosion resistance of metals. • The erosion effect is intensified with deeper pit depth and appearance of melting effect under high hydrostatic pressure. • A method for evaluating materials' erosion resistance with measurable SL intensity was established. • This work is benefit to predict and avoid the cavitation erosion in deep-sea applications. Cavitation erosion is a general phenomenon in the fields of aviation, navigation, hydraulic machinery, and so on, causing great damage to fluid machinery. With the vast requirements in deep ocean applications, it is urgent to study the mechanism of cavitation erosion and the cavitation erosion resistance of different materials under high hydrostatic pressure to predict and avoid the effect of cavitation erosion. In this work, the spatially confined cavitation bubble cloud associated with Gaussian-like intensity distribution sonoluminescence (SL) was produced by a spherically focused ultrasound transducer with two opening ends near metallic plates under different hydrostatic pressures (0.1, 3, 6, and 10 MPa). The cavitation erosion effects on copper, 17-4PH stainless steel and tungsten plates were studied. Through coupling analysis towards the SL intensity distribution, the macro/micro morphology of cavitation erosion, and the physical parameters of different metallic materials (hardness, yield strength, and melting point), it is found that with increasing hydrostatic pressure, the erosion effect is intensified, the depth of cavitation pits increases, the phenomenon of melting can be observed on materials with relatively low melting points, and the cavitation erosion experienced an evolution process from high-temperature creep to fracture. This work has also established a method for the evaluation of materials' cavitation erosion resistance with measurable SL intensity distribution, which is promising to promote the designing and selection of anti-cavitation materials in deep-sea applications. [ABSTRACT FROM AUTHOR]

Sediment cores were used to establish past environmental impacts associated with eutrophication, erosion and metal contamination in the subtropical Atibainha reservoir (São Paulo State, Brazil). We hypothesize that: (1) the levels of nutrients, determined by a spectrophotometric method, reflect the contributions of these elements over time and (2) changes in sedimentation rates, determined by 210Pb geochronology, and metal flows, determined by ICP-AEOS, are related to anthropic activities. Stratigraphic changes in the analysed variables were used to divide the sediment cores into three intervals, according to PCA and cluster analysis (Euclidian distances, Ward's method). Interval I, composed by the period prior to operation of the reservoir, was influenced by organic matter levels. Interval II, between 1967 and 1993 (PC2: 14.94% of the total variability), a period of minor impacts, was mainly influenced by Mn (eigenvalue of 0.71) and Zn (0.74). Interval III, which included sediment deposited between 1993 and 2015 (PC1: 60.28% of the total variability), was influenced by the highest levels of the pigments lutein (0.86), zeaxanthin (0.90) and fucoxanthin (0.65), together with total nitrogen (0.78) and sedimentation rate (0.91), suggesting changes in the phytoplankton community composition probably associated to the intensification of eutrophication and erosion processes. Despite the limitations of applying paleolimnological techniques in reservoirs and the use of pigments as proxies in regions with higher temperatures, it was observed that the anoxic conditions and the aphotic environment in the hypolimnion acted to preserve pigments associated with the groups Chlorophyta (lutein), Cyanobacteria (zeaxanthin) and Bacillariophyta (fucoxanthin). The isolated analysis of nutrients was not sufficient to make conclusive inferences regarding the eutrophication history, since the levels of TP tended to decrease over time, in contrast to an increase in the levels of TN. Despite intensification of eutrophication and erosion, associated to anthropic activities, no signs of metal contamination were recorded. [ABSTRACT FROM AUTHOR]

Carbon erosion of bulk metals and alloys in a carbon-containing atmosphere can be used as an effective tool for the targeted synthesis of carbon nanomaterials. In this study, a set of bulk Ni0.89Cu0.11 (11 at % Cu) alloys has been synthesized by the mechanochemical alloying of metal powders in an Activator 2S planetary mill. The synthesized samples have been studied as precursors of catalyst for the synthesis of carbon nanofibers (CNFs) from ethylene at 550°C. The effect of the activation time on the particle morphology and phase composition of the alloys, the kinetics of growth, and the carbon product yield in C2H4 decomposition has been studied. For the most active samples, the CNF yield has exceeded 100 g/gcat within 30 min of reaction. The early stage of carbon erosion of a bulk Ni0.89Cu0.11 alloy has been studied by electron microscopy methods. It has been found that the nucleation of carbon fiber growth active sites occurs during a short-term contact of the sample with the reaction mixture (less than 1 min); the complete disintegration of the alloy is observed in a few minutes. The carbon product is represented by nanofibers having a submicrometer diameter and characterized by a dense "stacked" and coaxial-conical packing of graphene layers. The material has a developed specific surface area (140–170 m2/g) and a low bulk density (less than 30 g/L). [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The metal surface erosion under powerful plasma pulse flows typical of transient processes in tokamaks, ELMs, and plasma disruptions and simulated on a quasistationary plasma accelerator (QSPA) is studied. The hillock relief formation on the molten metal surface over which the plasma flow parallel to the surface moves and also the formation of metal jets moving in the direction of the plasma flow are considered. On the basis of the motion of the jets, the molten metal transport along the surface and the erosion of this surface are explained. [ABSTRACT FROM AUTHOR]

Direct impingement (DI) erosion testing of steel and cobalt-based alloys is conducted with particles entrained in air and water. The tests are performed using 75- and 300-μm silica particles with three particle velocities and five impact angles. The mass loss results are used to develop an empirical equation that contains an explicit exponential term for the particle size effect. The erosion equation obtained from the gas jet experiments is implemented into a CFD solver with Lagrangian particle tracking for the liquid-submerged geometry. The CFD-based erosion predictions agree fairly with the experimental measurement for both particles. Strong effect has been observed for the exponential correction term in the erosion equation for liquid-solid flow cases; particularly with small particles at low impact velocities. [Display omitted] • Dry and wet direct impingement tests have been performed. • Particle size of 75 μm and 300 μm have been used. • Erosion of cobalt-based alloys have been characterized and compared with that of steel. • Experiment based erosion equation has been developed for particle size variation. • Computational Fluid Dynamics (CFD) model predicts erosion compareble to test measurements. [ABSTRACT FROM AUTHOR]

The failure of tube heat exchangers is an acute problem in industry and, in most cases, is due to the solid particle erosion of a few tubes. Identifying the critical erosion surfaces and thereafter changing the particle impingement pattern on the surfaces is one of the solutions to increase the lifetime of heat exchangers. In this work the fluid flow, solid particle motion and metal erosion of different two-pass copper-tube heat exchangers were simulated with a refined model and the sophisticated RANS-SST approach. The results showed the importance of the model in capturing the asymmetrical flow, uneven fluid distribution through tube bundle and other flow features for better erosion prediction. The erosion characteristics of three heat exchangers were compared to evaluate their structure with respect to producing low erosion. The simulations provided basic data for identifying the critical areas and damage locations of each heat exchanger. It was found that the particle separation in the inlet header altered the critical erosion locations but did not significantly affect the erosion rate. Theerosion rates at critical areas were also predicted. The results can be applied for predicting the service life and improving the structure of tube heat exchangers.

Microparticles are an inevitable component of vacuum arcs. This paper focused on the dynamics of microparticle and erosion behavior in high-current vacuum arcs. The arc was sustained with AC 110 Hz between two butt CuCr alloy contacts with a diameter of 10 mm. An in situ microparticle diagnostic system suitable for vacuum arcs was developed. Three sources of microparticles were observed and the corresponding motion characteristics were obtained by our method. The influence of current and Cr content on erosion characteristics was investigated. The results indicate that the increase of Cr content contributes to inhibiting production of microparticles when the current is small. CuCr30 has the best effect of suppressing microparticle production among the three tested alloy materials under large current. The work of this paper helps with the understanding of microparticle behavior in high-current vacuum arcs and may provide a path for the design of a vacuum electrode. [ABSTRACT FROM AUTHOR]

Al-Si alloys exhibit promising wear resistance, thus being mainly employed to weld Al alloy parts and processed into components of equipment. During the new continuous casting direct rolling (CCDR) process, the raw material gradually cools and solidifies, simultaneously plastically deformed. Hence, the materials manufactured through the CCDR process presented an unparalleled microstructure. The experimental results indicated that the strength of the CCDR Al-Si alloy can be increased through cold rolling. A two-stage heat treatment (solid solution and aging treatment) was introduced to improve the ductility and satisfy the industrial application. Furthermore, the erosion wear characteristics and fracture mechanism of the CCDR Al-Si alloy dominated by the ductility were confirmed. Both cold rolling specimens (FR) and those with heat treatment (FRH) showed greater wear resistance than as-manufactured (F). The FR specimens exhibited greater wear resistance owing to a higher Al matrix strength at a lower impact angle; on the other hand, at a higher impact angle, the FRH specimens with a softer Al matrix presented better wear resistance due to the formation of a lip structure to reduce material removal. The TEM results confirmed that the nanoscale grains formation was induced in the erosion-affected region and affected the Si concentration. Conclusively, the heat-treated CCDR Al-Si alloy possessed excellent erosion resistance and workability, which can serve as a reference processed as wear-resistant mechanical parts. [ABSTRACT FROM AUTHOR]

Soil is an essential element for life in natural environment. Agricultural and industrial human activities alter the properties of soil, which increase soil erosion and deteriorate the soil fertility. Indiscriminative use of synthetic inputs, improper management, industrialization and urbanization activities increase heavy metal pollution that degrade the natural environment. Excess amount of heavy metal affects plant metabolic activities and enter into food chain process that ultimately affects the health of animals and humans. The issues of soil erosion and heavy metal pollution are very much concerned because of their degradability in natural system. Therefore several management practices are followed to minimize the soil erosion and heavy metal toxicity. Some of the traditional cultural methods are either extremely costly or they are simply applied for short term management. The biological technologies require long period for reclamation. Recently, the application of nanoparticle is used for rehabilitation of natural environment. The effectiveness in controlling soil erosion and heavy metal pollution is more by integrating any of the cultural, biological and nano technological approach than using individually. [ABSTRACT FROM AUTHOR]

The process of conjoined stress cycling and abrasive or erosive wear is encountered in industry. However, very scant attention has been paid till now to this issue. The paper presents two test rigs designed and built to cope with this experimental problem. Tests were carried out on the range of pure iron (Armco), carbon steels namely S235JR, C45, C70U, C80U, C110U and unalloyed cast steels (L40III, L45III and L50III). Tested iron-based alloys differ in chemical composition, microstructure and Brinell hardness ranging from 80 HB to 350 HB. Stress cycling caused strain hardening of ferrite in hypoeutectoid steels and thus reduced their abrasive wear loss. In the hypereutectoid steel stress cycling impaired integrity of the microstructure thus increasing abrasive wear loss. Alternating stresses enhanced ploughing and cutting micromechanisms of erosion. Tensile stress in the tested cast steel had stronger effect on wear loss than the prior stress history. [ABSTRACT FROM AUTHOR]

Aluminum based alloy type 5083 have a large applicability in the area of automobile and naval constructions (such as: Shipbuilding, Rail cars, Vehicle corps, Type truck body, Mine skips and cages, Pressure vessel). The components of these parts are sometimes required for high aggressiveness factors. Thus, during operation, both the pump rotors and the propellers are subjected to hydrodynamic stresses of the cavity, which, by erosion, leads to their removing, completely or until repair. At the same time, to increase the service life, chemical corrosion of the liquid environment, these others contain various alloying elements, which change the structure and improve the chemical, physical and mechanical properties. In order to increase the resistance to erosion and mechanical stresses of the cavitational current, heat treatments are applied which also modify the microstructure and the values of the mechanical properties. The study presents the results of research on its vibrating cavity of another 5083 cast, subjected to the heat treatment of the solution at 350°C followed by artificial aging at 180°C with different maintenance times (one hour, 12 hours, 24 hours). The analysis of the results, based on the specific curves used in the Cavitation Erosion Research Laboratory in Timișoara, recommended by ASTM G32-2016, as well as macro images of eroded surfaces for 165 minutes, shows the dependence of cavitation erosion resistance of the microstructure type results from heat treatment and not of durable value, respectively of resilience, properties with great influence on the resistance to cavitation stresses, as happens, most often, in the case of steels. [ABSTRACT FROM AUTHOR]

[Display omitted] • Detonation sprayed Iron aluminide coatings exhibit excellent microstructural integrity. • Coating structure is significantly influenced by spray deposition frequency. • Iron aluminide coating improves the corrosion resistance of mild steel by 4 times. • Coatings illustrate their potential use at 400 °C for erosion resistance applications. The electrochemical corrosion and erosion behavior of FeAlCr coating was reported in this article. The FeAlCr coatings were deposited by detonation spray coating system (DSC) by utilizing the gas atomized powder with a nominal composition of Fe-12Al-5Cr at two different pulse frequencies on mild steel (MS) substrate. Feedstock and coatings were characterized using XRD, SEM and elemental mapping. Nanoindentation tests using a Berkovich indenter indicate a hardness of 5.5 GPa and 4.9 GPa for the coatings deposited at 3 Hz and 6 Hz respectively as compared to 1.5 GPa of the substrate. Electrochemical corrosion tests were performed on coated samples in 3.5 wt% NaCl and 2 N H 2 SO 4 media and are compared with the bulk MS substrate. Detonation pulse frequency significantly influenced the coating microstructure and corrosion performance. The coating deposited at a frequency of 6 Hz exhibited higher resistance against electrochemical corrosion in 3.5 wt% NaCl medium than the coating that was deposited at 3 Hz frequency. Solid particle erosion tests performed at room temperature (25 °C) and an impingement angle of 90° (normal incidence) using Al 2 O 3 as the erodent medium demonstrate a higher erosion loss of the coatings than the bulk MS. On the contrary, at a temperature of 400 °C, the coatings exhibited notably better erosion resistance than the MS substrate, illustrating the potential of FeAlCr coatings for high temperature wear-corrosion resistant applications. [ABSTRACT FROM AUTHOR]

The effect of solid boronizing at 950°C for 2 and 4 h on the phase composition, microstructure, hardness and abrasive wear of steel AISI 304L is studied under the impact of a flow of hard particles. The boronized steel is shown to consist of three layers (metal boride, porous layer and matrix) from the external surface to the center. The hardness of the boride is much higher than that of the matrix phase. The wear resistance of the steel is the highest after the 2-h boronizing, and the wear depends on the angle of impact of the hard particles on its surface. With growth of the duration of the boronizing the wear behavior of the steel changes from ductile one to brittle one. [ABSTRACT FROM AUTHOR]

The work is devoted to the production of powder by electrical discharge erosion (EDE) in oil from WC-10Co cemented carbide scrap, post processing of the obtained powder and sintering of a submicron alloy from it. As a result of EDE of WC-10Co alloy in oil, a powder with an average particle diameter of 12.7 μm, was obtained. Pyrolysis of the oil prevented the loss of carbon by tungsten carbide and led to an increase in the carbon content of the powder from 5.5% to 8.6%. A technique of heat treatment of the obtained powder in CO 2 , for the removal of excess carbon (3.1%) was developed. On sintering the powder at 1370 °C, a WC-10Co alloy with a stoichiometric carbon content (5.5%) was obtained, in which plate-like and prismatic WC grains an average diameter of 0.58 μm were formed. The alloy combines high hardness (1520 HV) and fracture toughness (14.6 MPa√m). [Display omitted] • A technique of WC-Co recycling by electric discharge erosion in oil was developed. • The pyrolysis of oil leads to an increase in the carbon content in resulting powder. • Heat treatment in CO 2 reduces the carbon content to the required value. • Plate-like grains of WC-Co were formed in the particles during heat treatment. • Recycled alloy have the high hardness (1520 HV) and fracture toughness (14.6 MPa √m). [ABSTRACT FROM AUTHOR]

The gas spark switch is the most used key device in pulsed power systems. As a difficult problem affecting the performance of the gas spark switch, electrode erosion has always been of wide concern and has been studied by scholars. In order to reduce electrode erosion, the erosion resistance of the electrode materials is particularly critical. At present, researchers at home and abroad mainly perform a large number of experiments to compare the erosion resistance of different electrode materials, which require a lot of time and are expensive. Based on the theoretical derivation of the erosion heat conduction process and the analysis of the molten pool movement process, a theoretical prediction model of erosion resistance of electrode materials is established in this paper. The prediction results of this model are consistent with the experimental results of most researchers in the past. In order to further verify the accuracy of this model, this paper selected six electrode materials [stainless steel, brass, RHEAs (Refractory High Entropy Alloys), 90WCu alloy, 70WCu alloy, and 50WCu alloy] tested for 10 000 times under the experimental conditions of a peak current of 30 kA, a single discharge charge transfer of 78 mC, and 2 bars dry air. The final experimental results show that the six electrode materials ranked from weak to strong in erosion resistance: brass, stainless steel, 50WCu, 70WCu, RHEAs, and 90WCu, which is consistent with the prediction results of the model. [ABSTRACT FROM AUTHOR]

Copyright of China Sciencepaper is the property of China Sciencepaper and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The hot chamber die casting process is capable of producing castings of superior mechanical properties and internal integrity. However, this process cannot be used for die casting of aluminum alloys because the molten aluminum erodes ferrous alloy tooling such as the gooseneck. Ceramic gooseneck was tested, but was not accepted commercially. This work evaluates the feasibility of using refractory metals for the tooling of the hot chamber die casting process. Experiments were performed to measure the weight loss of selected materials in molten aluminum at die casting temperatures. Refractory metals with excellent aluminum erosion resistance were selected and used for making gooseneck and nozzle. These components were installed in a hot chamber die casting machine. The world's first hot chamber die casting machine equipped with refractory metal tooling is now running at Purdue University for making aluminum alloy castings. [ABSTRACT FROM AUTHOR]

An in-depth study on the characteristics of coke in the hearths of blast furnaces is of great significance for explaining the mechanism of coke deterioration in blast furnaces. In the present work, the changes in macromorphology, degree of graphitization, and microstructure of the coke taken from different hearth locations of a 5,800 m3 superlarge blast furnace during its intermediate repair period were systematically studied. Significant differences were found between cokes obtained from the edge ("edge coke") and from the center ("center coke") of the hearth in terms of properties and degradation mechanisms. Edge coke was severely eroded by liquid metal, and only a small amount of slag was detected in the coke porosity, whereas center coke was basically free from erosion by liquid metal, and a large amount of slag was detected in the coke porosity. The degree of graphitization of edge coke was higher than that of center coke. The carburizing effect of liquid metal was the main cause of the degradation of edge coke and made it smaller or even disappear. Center coke was degraded due to the combination of two factors: slag inserted into micropores on the surface of center coke loosened the surface structure; and graphite-like flakes that appeared on the center coke surface lowered the strength and caused cracks in the surface. [ABSTRACT FROM AUTHOR]

This work aims to develop a mathematical model and predict the machining performance characteristics of electric discharge machining (EDM) process using response surface methodology (RSM) coupled with desirability function approach (DFA). The effect of various factors, such as electrode material, pulse current, pulse ON time and pulse OFF time were selected as input process parameters with an objective to maximize the material removal rate (MRR), minimize the surface roughness (SR) and electrode wear ratio (EWR). The machining was conducted on Al-Zn-Mg-Cu (AA7075) alloy composite reinforced with 10 wt.% TiO2 particulates produced by stir casting route. The experimental work was planned as per L27 orthogonal array using design of experiments through RSM. Experimental results show that, pulse current and pulse ON time are the most significant factors for MRR and SR while electrode materials and pulse current have notable effect on EWR. Finally, multi-response optimization was performed to predict the EDM parameters by using DFA. The optimum combination of parameters were identified as electrode material (Br), pulse current (15 amps), pulse ON time (900 μ s) and pulse OFF time (30 μ s). [ABSTRACT FROM AUTHOR]

Copyright of Technical Electrodynamics / Tekhnichna Elektrodynamika is the property of National Academy of Sciences of Ukraine, Institute of Electrodynamics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Sciencepaper is the property of China Sciencepaper and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Regular nanoscopic ripple and dot patterns are fabricated on poly‐crystalline titanium samples by irradiation with 1.5 keV argon ions at normal incidence. The morphology of the nanostructures is investigated by scanning electron microscopy and scanning force microscopy. The ripple structures exhibit a saw‐tooth cross‐section profile. Electron backscatter diffraction experiments are performed to analyze the local grain structure. The study suggests a distinct correlation of the nanostructure morphology to the crystallographic orientation of the titanium surface. [ABSTRACT FROM AUTHOR]

The extensive application of titanium alloys is delimited as their erosion wear properties deteriorate when exposed to erosive and harsh environments. The present research investigates the effects of TiN additions (2, 4, and 6 vol.%) on the Ti-6Al-4V alloy prepared by spark plasma sintering technique. Erosion wear behaviour of the composites was investigated by high-velocity solid particle erosion test and tribometer pin-on-disc friction module method. The duration of the test was 10 min, while the mass loss of the sample was recorded after 2-min interval. The surface analysis and phase identifications of the sintered composites were examined by optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction (XRD), respectively. Microstructural analysis revealed a transformation from lamellar with β grain boundaries in Ti-6Al-4V alloy to bimodal structures upon addition of TiN nanoparticles. XRD patterns of the alloy indicated an increase in diffraction peaks from lower intensity to high intensity with an increase in TiN nanoparticle content. Erosion is visible in Ti-6Al-4V alloy, 4 and 6 vol.% TiN, but less severe with 2 vol.% TiN addition for all the test times. However, this is due to grain detachment of the hard phase regions between the matrix and the reinforcing phase of the composites. The results showed the presence of micro-voids on the eroded surfaces. It was found that Ti-6Al-4V alloy with TiN nanoparticle addition was resistant to erosion wear, while the recorded steady-state friction coefficients for all the samples range from 0.2 to 0.4. However, an increase in microhardness values ranges from 342 to 513 HV0.1. [ABSTRACT FROM AUTHOR]

The research on laser drilling of amorphous foils can promote the application of amorphous alloy in micro-machining. In this article, the effects of current, pulse width and defocusing amount on the quality of machined hole on Fe78Si9B13 amorphous alloy foils were analyzed by controlling the laser parameters. The experimental results showed that the hole diameter, remelting area (RMA) thickness and heat affected zone (HAZ) thickness increased obviously with the increase of current and pulse width. But high current caused serious erosion near the entrance of the hole and the taper of the machined holes increased with increasing pulse width. When the defocusing amount was 0, the hole diameter was the smallest and the forming quality of the machined hole was the best. Every parameter needs to be adjusted and coordinated to improve the quality of laser drilling. [ABSTRACT FROM AUTHOR]