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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]

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]

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]

[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]

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.

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]

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]

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]

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]

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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]

This work carried out liquid–solid two-phase jet experiments and simulations to study the erosion behavior of 304 stainless steel at 30° impingement. The single-phase impinging jet was simulated using dense grid by one-way coupling of solid phase due to its dilute distribution. The simulation results agreed well with experiments. It was found that after impinging particle attrition occurred and particles became round with decreasing length-ratio and particle breakage occurred along the "long" direction. Both experiment and simulations found that the erosion generated on the sample could be divided into three regions that were nominated as stagnant region, cutting transition region and wall jet region. Most particle–wall impacts were found to occur in the cutting transition region and the wall jet region. In the cutting transition region, holes and lip-shaped hogbacks were generated in the same direction as the flow imping. In the wall jet region, furrows and grooves were generated. The averaged grooves depth tended to become constant with the progress of impinging and reach the steady state of erosion in the end. In addition, it was found that impinging effect increased erosion and anti-wear rate. [ABSTRACT FROM AUTHOR]

This work investigates and elucidates the influence of B 4 C and BN reinforcements on the solid particle erosion behavior of Al6061/B 4 C/BN metal matrix hybrid composites fabricated through the powder metallurgy technique. The metal matrix hybrid composites with reinforcement content of (2, 4, 6, and 8 wt %) B 4 C, and 2 wt% BN was fabricated by compacting the mechanically alloyed powders within closed circular cavity compaction die at 800 MPa pressure and subsequently sintering them at 600 °C for 3 h. The morphology of milled powders and surface profiles of samples before and after erosion were examined by X-ray diffraction, scanning electron microscope, energy-dispersive X-ray spectroscopy, elemental mapping, and surface roughness tester. The composites showed a maximum compressive strength of 249 MPa and maximum hardness of 184HV. To determine the erosion rate, various control parameters like reinforcement content, erodent velocity, erodent discharge rate and angle of impingement were considered. Taguchi's L 16 (44) orthogonal array-based design of experiments was used to govern the optimum parameter settings, which led to the minimization of the erosion rate. Further, for obtaining the best response from solid particle erosion trails, the whole process was analyzed by multiple linear regression model to establish a relationship between the input and output parameters. Finally, nature-inspired, robust evolutionary strategy antlion optimization (ALO) was used for finding out the optimal parameters for the minimum erosion rate, which were found out to be 8 wt % B 4 C reinforcement, 80 ms−1 erodent velocity, 8 gmin-1 erodent discharge rate and 45° angle of impingement. Among all the parameters used for the erosion test, impact velocity is the most significant factor in determining the erosion rate. [ABSTRACT FROM AUTHOR]

This paper presented a new electrical discharge machining (EDM) method using powder mixed effects formed by the graphene–water dielectric to improve the machining performance in processing titanium alloy. Theoretical and simulation models were developed to analyze the effects of graphene bubbles on discharge breakdown characteristics and the plasma channel. To validate the theoretical model, single-pulse experiments were conducted by analyzing the shape and dimension of single-discharge craters. Comparative and exploratory experiments were carried out to investigate the erosion characteristics of the new machining approach. Experimental results show that graphene bubbles could affect the erosion characteristics and improve the machinability of titanium alloy. The material removal rate was increased by 28% and surface roughness was reduced by 55%, whereas relative electrode wear was reduced by 43% compared to traditional EDM processes. [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. [ABSTRACT FROM AUTHOR]

Aluminum alloy spool valve body material is prone to severe wear on the wall under the condition of oil contamination. Aiming at this problem, combined with the theory of liquid-solid two-phase flow and erosion wear, the wear prediction model of aluminum alloy sliding valve wall is established based on computational fluid dynamics, and the effects of turbulence and wall materials, particle size distribution, and particle shape on particle motion are discussed. The calculation of the wear prediction model is done with Fluent software. This study predicts the wear of the wall under actual working conditions and calculates the influence of particle size, particle shape, and pressure difference on the wall wear of the aluminum alloy sliding valve. The research results have certain significance for the maintenance and upkeep of aluminum alloy sliding valve wall, improved design, and life prediction. [ABSTRACT FROM AUTHOR]

The common approach for sand control in sandstone reservoir is the application of metal mesh screen (MMS). Production process and physical properties of production formation play a vital role on the service life of screen. A model was proposed to evaluate the erosion rate of commonly used screen. The simulation experiment was conducted to investigate the effect of formation properties, such as particle size and concentration of sand grains and production pressure differential, on the erosion of screen with monolayer metal wire mesh (MWM). The results show that: 1) The erosion rate of screen with monolayer MWM was increased exponentially with the flow velocity of crude oil containing sand; 2) With the increase of sand median grain size and sand content, the erosion rate increased first and then decreased. For a screen with certain accuracy, the erosion rate of monolayer MWM of screens may reach the maximum value with the change of median grain size and sand content; 3) A formula was proposed to predict the erosion rate under the effect of fluid velocity, particle size and concentration of sand. The mathematical model was verified by experimental results. • The erosion rate of monolayer metal mesh screen increases exponentially of fluid velocity. • Choosing an appropriate production rate or pressure can prolong the service life of screens. • With the increase of the sand size, the erosion rate of the screen first increases and then decreases. • A mathematical model of sand erosion is established based on the experimental data. [ABSTRACT FROM AUTHOR]

In the present effort, aluminium matrix composites (AMCs) were produced by the addition of submicron‐sized WC particles of low (up to 2.5 vol%) content into a melt of Al1050. Casting was assisted by the use of K2TiF6 as a wetting agent and mechanical stirring in order to limit particle clustering. Particle distribution was reasonably uniform comprising both clusters and isolated particles. Various different reinforcing particles' phases were identified, both in situ (Al‐W, Al‐Ti, and Al‐W‐Ti intermetallic phases) and ex situ (WC particles) of various morphologies shapes and sizes. Increase of the reinforcing particle content led to an increase of the tendency for clustering. The wear properties of the composite were examined by dry sliding wear. The worn surfaces and the produced debris were examined by SEM‐EDX, and an effort to correlate the wear response of the produced materials with the matrix and the reinforcing phase characteristics was attempted. In general, the increase of the reinforcing phase content led to an improvement of the sliding wear response. Solid particle erosion experiments were carried out for impact angles of 30°, 60°, and 90°. Τhe eroded surfaces were examined with SEM‐EDX, and possible erosion mechanisms were proposed based on morphological and other material characteristics. Intensive particle clustering seemed to deteriorate the erosion resistance of the systems. Medium concentrations of the reinforcing particles (1.0‐1.5 vol% WC) are proposed as a recipe for optimum sliding wear and solid particle erosion resistance behavior. [ABSTRACT FROM AUTHOR]

Abstract Three-dimensional (3D) continuous Ni-network-reinforced Ag-matrix composite materials were prepared by hot-pressing Ag–Ni composite powders with Ni powders coated on the surface of Ag granules. The formation of a 3D continuous Ni network enhances the load transferred from the Ag matrix to the second-phase Ni, inducing the co-deformation of Ag and Ni during the drawing deformation. The co-deformation begins as orientation rotation and refinement; e.g. the Ag matrix slips on {111}〈1 1 - 0〉, twins on {111}〈11 2 - 〉, and 〈100〉 drawing texture are formed in second-phase Ni along the drawing direction. Finally, the 3D continuous Ni networks were torn and drawn into belts that are parallel to the axial direction of the composite wire. Increasing the real strain could increase the length of the Ni belts in the axial direction, thus increasing the hardness and electrical conductivity of Ag–Ni electrical contact materials. Additionally, the two-dimensional characteristics of the belts with high profile drag increase the flow resistance of molten Ag. Therefore, the belt-reinforced Ag–Ni electrical contact materials show a low mass loss after 100000 times of contact (1.8 mg, only 22.8% of that of the round fibres reinforced sample). Highlights • A Ni-belt-reinforced Ag-based electrical contact material was developed. • Higher hardness than Doduco products (50–70 HV) was obtained in cross section (94.5 HV). • Elimination of segregation of Ni particles under arc erosion by the pinning mechanisms and their high profile drag. • Anti-arc erosion performance with a mass loss about 30.5% of that of a particulate-reinforced sample. [ABSTRACT FROM AUTHOR]

Interruptions in the operation of the installations and machines in the energy industry are caused in most cases by the inevitable effects of erosion / corrosion processes in pipes, basins, reservoirs or heat exchangers. The materials (metals or alloys) used in the construction of energy equipment and not only are in contact with the different chemical media with which they interact (atmospheric air, water, steam, chemicals), the result of this interaction being erosion and corrosion of the metal product. The simultaneous action of the mechanical stresses and the corrosive environment manifests differently on the metallic materials, depending on the nature of the metal-environment couple, leading to substantial changes in their behavior towards the situation where the influence of the working environment was neglected or it was considered inert. In order to ameliorate these defects, several design solutions have been analyzed and proposed so as to avoid such phenomena by extending the service life of the component parts of the energy machines. [ABSTRACT FROM AUTHOR]

Various factors of thermo-chemical erosion process in gun steel were analysed. The factors are mainly related to the thermal load of gun barrel inside surface, characteristics of barrel surface and chemical interactions between propellant combustion products and barrel surface. The experimental simulation of conditions in gun barrel was carried out by vented vessel firings in the device based on modification of 37 mm M39 gun. The nozzle mass loss during firing was the measure of gun steel erosion. The main thermal factor of erosion is maximum nozzle inner surface temperature. This temperature was determined experimentally by micro thermocouples measurements at specified distance away from the inner surface and by numerical analysis of the inverse heat conduction problem. Modelling of two-phase flow of propellant combustion products and unburned propellant grains in the vented vessel and heat transfer to the nozzle were conducted using developed 1-D interior ballistic code and CFD simulation in FLUENT. Influence of different propellants, TiO²/wax wear reducing liner and tungsten-disulfide nanoparticles layer on nozzle erosion was analysed. Good agreement between experimental and computational results was achieved. [ABSTRACT FROM AUTHOR]

Abstract This study investigated the integrity of the outlet nozzle and elbow of the piping system downstream the finfan cooler in sour water stripping unit. The piping system in these locations experienced severe thinning and occasional leaks. The unit was modelled using process simulation software with the use of the appropriate thermodynamic methods for electrolyte models to accurately estimate the flow rates, properties in vapour and liquid phases in the piping system. The results from the process simulation were subsequently used in the Computational Fluid Dynamics (CFD) simulation. The CFD simulation results matched the erosion pattern that caused the loss of wall thickness. The eroded nozzles were also visually and optically examined using scanning electron microscopy (SEM) and Energy Dispersion X-ray (EDX). The results have indicated that the erosion is inevitable regardless of the fluctuation in the throughputs to the unit. Iron sulfide, indicative of the synergy between erosion and corrosion, was observed in the pipes elbows. For mitigation, an option has been recommended to change the operating mode of the finfan cooler so as to alleviate alloy change. Highlights • The simulation carried out has predicted the patterns of metal thinning by erosion • Erosion is inevitable regardless of the feed throughput changes to the unit • Synergy between erosion and corrosion as indicated by iron sulfide was observed • Mitigation measures of erosion-corrosion were addressed • Alloy change has been alleviated by change mode of operation of the finfan cooler [ABSTRACT FROM AUTHOR]

Low-temperature salt bath nitriding of heat treated and tempered 13/4 Martensitic stainless steel (13/4HTT) was carried at 450 °C (N450) and 500 °C (N500) for 10 h each. The nitrided samples were characterized by using x-ray diffractometer, field emission scanning electron microscope and optical microscope. The nanohardness and elastic modulus of the cross section of nitrided specimen were measured by nanoindentation test using Hysitron TI950 triboindenter. The nitrided 13/4HTT (N450 and N500) and 13/4HTT specimens were subjected to slurry erosion test in a slurry pot tester. The test was conducted for 48 h, and weight loss was measured after every 6 h. The relative speed of slurry with respect to specimen was 4.55 m/s. It was found that the weight loss due to erosion of the N450 is 83% less than that of 13/4HTT and that of N500 was 92% more than that of 13/4HTT. The erosion mechanism is correlated to the phases present in the specimens. The improvement in the slurry erosion resistance of N450 is due to presence of expanded martensite (αN-Fe). Increasing the temperature of nitriding to 500 °C led to the decrease in the slurry erosion resistance of N500 due to the formation of brittle CrN phase. [ABSTRACT FROM AUTHOR]

In this work, the results on solid particle erosion of an ultrafine-grained Grade 5 titanium alloy, which was produced using high-pressure torsion (HPT) technique, are presented. In order to assess influence of the HPT treatment on material’s behavior in erosive conditions, special experimental procedures were developed. The ultrafine-grained (UFG) alloy was tested alongside with a conventional coarse-grained (CG) Grade 5 titanium alloy in equal conditions. The experiments were conducted in a small-scale wind tunnel with corundum particles as an abrasive material. Both particle dimensions and particle velocities were varied in course of the experiments. Erosion resistance of the samples was evaluated in two ways—mass reduction measurements with subsequent gravimetric erosion rate calculations and investigation of samples’ surface roughness after erosion tests. The UFG titanium alloy demonstrated considerable improvement of static mechanical properties (ultimate tensile strength, microhardness), whereas its CG counterpart appeared to be slightly more resistant to solid particle erosion, which might indicate the drop of dynamic strength properties for the HPT-processed material. [ABSTRACT FROM AUTHOR]

Cu-based composites are considered as one of the high performance and cost-effective materials to replace the noble metal-based electrical contact materials used in low-voltage electrical apparatus. However, the oxidation resistance of Cu-based electrical contact materials at high temperatures is still the major challenge that limits their applications. In this study, CuZr/Zn 2 SnO 4 composites were prepared through powder metallurgy method. The air arc erosion resistance of the composites under AC 380 V and 20 A was evaluated through the mass loss and the electrical contact resistance after experienced over 10,000 arc discharge cycles. The microstructure evolution, which reflected the deterioration process of the composites, was demonstrated through SEM analysis. The results indicated that the oxidation of Zr occurred along with the oxidation of Cu at high temperature, which considerably consumed the oxygen and thus significantly enhanced the oxidation resistance of Cu-based composites. In addition, TEM result showed a smooth and clear interface between Cu and Zn 2 SnO 4 phases, suggesting that the addition of Zn 2 SnO 4 phases was beneficial to enhance the durability of the composite. This work will not only merit the design and development of Cu-based electrical contact materials but also expand the applications of Cu-based composites in the air at high temperature. [ABSTRACT FROM AUTHOR]

Ti 3 AlC 2 (TAC) has the potential to replace CdO as the reinforcement in Ag matrix for applications in electrical contacts. The arc erosion behavior of Ag/10 wt%Ti 3 AlC 2 (Ag/10TAC), Ag/20 wt%Ti 3 AlC 2 (Ag/20TAC) and commercial Ag/CdO contact materials were investigated under 100 A/400 V/AC. The morphology, the microstructure, the thickness loss, and the mass loss of the materials were investigated. The Ag/10TAC contact demonstrated comparable arc resistance to the Ag/CdO. The Ag/20TAC demonstrated severe arc erosion. The arc erosion mechanism for the Ag/TAC composites was proposed. The good wettability between the Ag and the TAC restricted the flow and splash of Ag in the molten pool, which strengthened the resistance to arc erosion. [ABSTRACT FROM AUTHOR]

In the present investigation, erosive wear property of high chromium white cast irons (HCWI) is reported. HCWI were destabilized at two different temperatures of 955oC and 1100°C, air cooling followed by tempering heat treatment at 400°C and 700°C at each destabilized temperature. Erosion damage was evaluated by the removed material mass at impact angle 45° and time of 10 Hours. The surface metal flow was observed. Surface morphology of each specimen was characterized with scanning electron microscopy (SEM). The effect of heat treatment on differences in wear features of specimens is discussed. Experiment showed that the erosion rate of specimen destabilized at 1100°C, air cooled followed by tempering at 400°C air cooling is the best than other treatments. The hardness of test surface by this treatment increased from the initial 57 to 58 HRC after 10 hour. It showed that austenite in the surface structure has been transformed to martensite , which hardened the surface. Similarly, workhardening effect also occurred on specimen destabilized at 955°C, air cooled followed by tempering at 400oC, air cooling to make its surface hardness increased to 59 HRC. It was shown that HCWI series heat treated at 955°C and 1100°C and tempered at 400°C have a very good erosive wear resistance and they are expected to find wide application as wear-resistant materials. [ABSTRACT FROM AUTHOR]

This article presents the results of an examination of the properties of arc-sprayed aluminum on alloyed armor-grade steel. Thermal arc spraying was conducted with a EuTronic Arc Spray 4 wire arc sprayer. Aluminum wire 1.6 mm in diameter was used to produce dense, abrasion- and erosion-resistant coatings approx. 1.0 mm thick with and without nickel/5% aluminum-buffered subcoating. Aluminum coatings were characterized in accordance with ASTM G 65-00 abrasion resistance test, ASTM G 76-95 erosion resistance tests, ASTM C 633-01 adhesion strength, HV0.1 hardness tests and metallographic analyses. Results demonstrate properties of arc-sprayed aluminum and aluminum-nickel material coatings that are especially promising in industrial applications where erosion-, abrasion- and corrosion-resistant coating properties are required. [ABSTRACT FROM AUTHOR]

We report herein on the arc erosion behavior of Ti 3 AlC 2 cathode under atmosphere at 7 kV d.c. voltage. The arc life and the breakdown strength for Ti 3 AlC 2 are 28.468 ms and 1.239 × 10 6 V/m, respectively. The process of arc discharging can be divided into three stages: arc formation, steady burning and attenuation, which was observed by a high-speed camera. During steady burning, the arc column is the brightest and the largest. The eroded material was detected by X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscope and energy dispersive X-ray spectroscopy. Under the action of arc discharging, the arc erosion morphology characterized with cracks, pores, protrusions with holes displays on the surface of Ti 3 AlC 2 . Meanwhile, the material is dissociated and oxidized to TiO, TiO 2 , Al 2 O 3 , arising from the high temperature and energy intensity of electric arc. The different composition and Marangoni effect are responsible for the multiple morphologies. [ABSTRACT FROM AUTHOR]

Complex electrical and electrochemical erosion is the overlapping, in time and space, within the working gap, of the processing through electrochemical erosion and electrical erosion. Complex erosion processing is defined as the process of simultaneous development of anodic dissipation and impulse discharge in the space bounded by OT connected to the negative pole of the direct current supply source and OP connected to the positive pole of the power source in the presence of the working environment (ML). The process of complex erosion processing is influenced by a large number of parameters and factors, acting in close interdependence and influencing each other in order to achieve the stability of the processing process and the achievement of the final technological characteristics. [ABSTRACT FROM AUTHOR]

Erosion of drill pipe caused by the rock particles in annular space is very serious in gas drilling. The aim of this paper is to study the erosion wear law of drill pipe by theoretical derivation and laboratory experiment. Based on the micro-cutting model of single rock particle, the erosion model of drill pipe is established to calculate the erosion wear loss. This model establishes the relationship between the erosion wear loss of drill pipe and drilling parameters, such as gas injection volume and rate of penetration (ROP). The laboratory experiment is carried out to verify and revise the erosion model, and the results show that when ROP is less than 20 m/h, the erosion wear loss of drill pipe is approximatively proportional to the square of gas injection volume and has positive correlation with ROP. However, it has negative correlation with ROP when ROP is faster than 20 m/h. In addition, it is also obtained that gas injection volume has more impact on drill pipe erosion compared to ROP based on the analysis of an engineering example, and high ROP will suppress the erosion wear of drill pipe. Therefore, under the premise of satisfying the drilling requirements, employing lower gas injection volume and higher ROP can reduce drill pipe erosion in gas drilling, which will save the drilling cost greatly. [ABSTRACT FROM AUTHOR]

A new method is proposed for preparing metal pulse end seals improving their reliability and durability due to increasing the wear resistance of ring working end surfaces and contact surfaces of the secondary seals. [ABSTRACT FROM AUTHOR]

The erosion mechanisms during abrasive waterjet (AWJ) machining have been examined for a variety of materials. However, no systematic study has considered the effect of the microstructure–property relationship on the erosion mechanisms in metals. In this work, the influence of microstructure and mechanical properties on the erosion mechanisms is investigated using AWJ controlled-depth milling and single particle impact experiments performed on nanocrystalline, microcrystalline and single crystal nickel samples. The resulting footprints and subsurface microstructure evolution were analysed using advanced characterization techniques. The erosion rate of the target metal is found to correlate positively with grain size and negatively with hardness but this correlation is nonlinear. The subsurface microstructure of the single crystal and microcrystalline are altered, while only the texture of the nanocrystalline nickel is modified. The grain refinement mechanism observed in microcrystalline and single crystal microstructure is elucidated by electron backscatter diffraction. It proceeds by the generation of dislocations under severe plastic deformation, which transforms into subgrains before forming new grains under further strain. Therefore, severe plastic deformation induced by AWJ machining leads to surface nanocrystallization and induces substantial subsurface work-hardening, as revealed by nanoindentation tests and confirmed by single particle impacts, with the consequence that the erosion rate decreases with decreasing grain size. This work clarifies the erosion mechanisms in pure metals and highlights the dynamic nature of AWJ machining as a result of the complex interplay between microstructure, mechanical properties and material removal mechanisms, providing new insights into AWJ controlled-depth milling technique. [ABSTRACT FROM AUTHOR]

In this paper, a continuous and uniform Mg-alloy coating was deposited by magnetron sputtering to protect flexible polyimide substrate from atomic oxygen (AO) erosion in the low earth orbit. AO exposure experiments indicated that the erosion yield of the as-deposited Mg-alloy coating was 8.897 × 10 −26 cm 3 atom −1 , about two orders of magnitude lower than that of blank polyimide. During AO exposure, a relatively compact and continuous thin MgO scale formed on the surface of the Mg-alloy coating, resulting in the enhanced AO erosion resistance of the polyimide with Mg-alloy coating. [ABSTRACT FROM AUTHOR]

In this paper, the erosion mechanism of infiltrated W-10wt%Cu composites against liquid alumina particles as well as the effect of sintering activators was studied. The fabrication of samples consists of infiltration of copper into sintered porous tungsten skeleton in presence of activators such as Ni and Co. Ni and Co was used as solid state sintering activators. The erosion of prepared specimens observed after the static firing and explained in terms of microstructure, transpiration cooling and erosion mechanism. Chemical analysis of the material after erosion test was obtained using energy dispersive X-ray analysis (EDS). SEM images were employed to identify the microstructure evolution due to erosion. The obtained results show that Composite prepared by Ni additive show about 33% better erosion resistance compare to specimen without additive. Also, presence of sintering activator could enhance transpiration cooling mechanism during erosion. These results discussed based on hardness, contiguity and connectivity. [ABSTRACT FROM AUTHOR]

Different nano- and micro-fillers are added to modify the mechanical properties, wear resistance, thermal properties and the curing process of polymers. A very important application for epoxy resins is to be used as coating for anti-cavitation painting. Pyrogenic silica is already used in adhesives and paints, being its application related to rheology. The objective of this work is to study the effect of pyrogenic silica on epoxy resins, usually not present in their formulation. SiO 2 /epoxy nanocomposites with two different loads of nano-silica, 3 and 5 wt% were manufactured. In particular, the study focuses on the influence that the addition of nano-silica has on the mechanical, wear and cavitation erosion properties as well as on the thermal properties and the curing reaction. To accomplish these goals, nanocomposite samples in bulk and as coating were prepared. Mechanical properties (hardness, bending and tensile strength), wear resistance (in bulk and coating) and cavitation erosion were evaluated. The epoxy curing process and the influence of nano-SiO 2 additions on the glass transition temperature ( T g ) were studied by Differential Scanning Calorimetry (DSC). In general, a plasticising effect was observed with nano-silica addition. Moreover, the resistance to erosion by cavitation, in terms of cumulative erosion and erosion rate, was higher for the nanocomposites than for clear resin. [ABSTRACT FROM AUTHOR]

The process of processing through complex erosion is influenced by a large number of parameters and factors, acting in close interdependence and influencing each other in order to achieve the stability of the process of processing and the achievement of the final technological characteristics. The dimensions characterizing the process of processing, imposed on it and having constant values, are process parameters. The dimensions that contribute to the development of the fundamental phenomena of the mechanism of processing through complex erosion and contribute to the definition of the technological characteristics are factors. [ABSTRACT FROM AUTHOR]

With the diversification of the types of materials, due to the requirements of high strength and hardness and, at the same time, with the necessity of increasing their processing speed, it was necessary to conceive and realize new processing technologies, which ensure obtaining of parts with mechanical properties with a complex form, multi-faceted surfaces and the use of appropriate tools for them. [ABSTRACT FROM AUTHOR]

In this paper, the effect of rare earth oxide nano-additives on micro-mechanical properties and erosion behavior of Fe-Cr-C-B hardfacing alloys was studied. Optical microscope was used to observe microstructure of hardfacing alloys. X-ray diffractometer was used to analyze phases of hardfacing alloys. Vickers micro-hardness tester was used to measure micro-hardness of constitutional phases. Fracture toughness (K IC ) of primary carbide was calculated by indentation method. Erosion tests were carried out using JZB sand blaster. The experimental results showed that hardfacing alloys were hypereutectic, which were composed of M 7 C 3 , martensite and retained austenite. Nano-additives increased the hardness and the K IC of primary carbide. The hardness of the primary carbide in the hardfacing alloy with 0.288 wt% nano-additives reached a maximum of 1716.54HV 0.2 . The K IC of the primary carbide in the hardfacing alloy with 0.432 wt% nano-additives was 9.27 MPa√m, which increased by 51.7% than that of the primary carbide in the hardfacing alloy without nano-additives. Erosion test results showed that nano-additives improved the erosion resistance of hardfacing alloys. The erosion rate of the hardfacing alloy with 0.432 wt% nano-additives decreased by 31.8% than that of the hardfacing alloy without nano-additives. [ABSTRACT FROM AUTHOR]

SiC coating with a thickness of 50–70 µm was prepared on the surface of C/C composites by in-situ reaction method. The SiC coated C/C composites were then tested in a wind tunnel where a temperature gradient from 200 to 1600 °C could be obtained to investigate their erosion behavior. The results of wind tunnel test indicated that the service life of C/C composites was prolonged from 0.5 to 44 h after applying the SiC coating. After the wind tunnel test, three typical oxidation morphologies, including glassy SiO 2 layer, porous SiO 2 layer and clusters of honeycomb-like SiO 2 grains, were found on the SiC coated C/C composites. With the decrease of oxidation temperature, the amount of glassy SiO 2 declined and the thermal stress increased, which induced the cracking followed by the degradation of the SiC coating. [ABSTRACT FROM AUTHOR]

The effects of destabilization treatment and destabilization followed by cryogenic treatment have been evaluated on the microstructural evolution and sand-water slurry erosion behavior of Cr-Mn-Cu white cast irons. The phase transformations after the destabilization and cryotreatment have been characterized by bulk hardness measurement, optical and scanning electron microscopy, x-ray diffraction analysis. The static corrosion rate has been measured in tap water (with pH=7) and the erosion-corrosion behavior has been studied by slurry pot tester using sand-water slurry. The test results indicate that the cryogenic treatment has a significant effect in minimizing the as-cast retained austenite content and transforming into martensitic and bainitic matrix embedded with ultra-fine M7C3 alloy carbides. In contrast, by conventional destabilization treatment retained austenite in the matrix are not fully eliminated. The slurry erosive wear resistance has been compared with reference to destabilized and cryotreated high chromium iron samples which are commonly employed for such applications. The cryotreated Cr-Mn-Cu irons have exhibited a comparable erosive wear performance to those of high chromium irons. Higher hardness combined with improved corrosion resistance result in better slurry erosion resistance. [ABSTRACT FROM AUTHOR]

The possibility to apply the Finite Element Method to calculate internal stresses which occur in Ti+TiN, Ti+Ti(CxN1-x) and Ti+TiC coatings obtained in the magnetron PVD process on the sintered high-speed steel of the PM HS6-5-3-8 type. For the purpose of computer simulation of internal stresses in coatings with the use of MES, the correct model of analyzed specimens was worked out and then it was experimentally verified by comparison of calculation results with the results of computer simulation. Accurate analysis of correlations indicated especially strong dependence between internal stresses and microhardness and between microhardness and erosion resistance what created conditions for establishing the dependence between internal stresses obtained in the result of computer simulation and erosion resistance as basic functional quality of coating. It has essential practical meaning because it allows to estimate predictable erosion resistance of coating exclusively on the base of the results of computer simulation for used parameters in the process of coating manufacturing. [ABSTRACT FROM AUTHOR]