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A study of metallurgy and erosion in laser surface alloying of AlxCu0.5FeNiTi high entropy alloy
摘要： AlxCu0.5FeNiTi high entropy alloy coating is synthesized by premixed high purity Cu, Fe, Ni and Ti powders on AA1050 aluminium substrate by laser surface alloying, with the aim to improve microhardness and erosion rate. Phase constituents, microstructure and microhardness were investigated using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Vickers Microhardness tester, respectively. The erosion behavior of AlxCu0.5FeNiTi coating is checked using an air jet erosion setup. SEM images show presence of three regions. Percentage compositions of these regions are evaluated using Energy Dispersive Spectroscopy. XRD analysis of AlxCu0.5FeNiTi coating confirmed that these regions are a mixture of disordered BCC and two FCC solid solution phases. The microhardness of the AlxCu0.5FeNiTi HEA is 18 times that of the AA1050 aluminium substrate. Results show that AlxCu0.5FeNiTi HEA coating has improved erosion resistance.
关键词： Laser Surface Alloying,Microhardness,Microstructure,High Entropy Alloy,Erosion rate
更新于2025-11-21 11:18:25
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Fabrication and photocatalytic performance evaluation of hydrodynamic erosion–resistant nano-TiO2–silicone resin composite films
摘要： Herein, we present the preparation of nano-TiO2–silicone resin composite films by double liquid phase spray deposition. The films exhibit better adhesion stability and photocatalytic activity under a hydrodynamic erosion condition than conventional nano-TiO2 composite films. The TiO2 layer morphology and effective TiO2 coverage ratio (CR) were affected by the initial curing time (ICT) of the silicone resin, e.g., the increase in an ICT from 10 to 40 min resulted in a CR change from 79.1 to 98.7%. The surface morphology evolution of composite films was studied under a hydrodynamic erosion period of 4 weeks. Obtained results allowed the 4-week evolution to be divided into four stages (pitting, crack pregnant, banded stripping, and surface stripping periods), additionally revealed that the CR of all samples was remained above 65%. The photocatalytic activity of composite films before and after 4-week hydrodynamic erosion was evaluated by rhodamine B degradation experiments. The 4-week erosion only led to the decrease of the photodegradation efficiencies by less than 40% in all cases. Thus, the fabricated TiO2–silicone composite films demonstrated excellent durability and photocatalytic activity under the conditions of long-term hydrodynamic erosion, allowing one to conclude that this work paves the way to the fabrication of next-generation photocatalytic materials for industrial applications.
关键词： Photocatalysis,Film formation mechanism,Silicone resin,Photodegradation,Hydrodynamic erosion resistance,Nano-TiO2
更新于2025-09-23 15:23:52
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Impact of surface micromorphology and demineralization severity on enamel loss measurements by cross-polarization optical coherence tomography
摘要： Objectives: Optical Coherence tomography (OCT) is a promising clinical imaging technology for quantitative and objective assessment of dental erosion. We aimed to determine the influence of enamel surface roughness and demineralization severity (by erosive challenge) on dental surface loss measurements by cross-polarization OCT (CP-OCT). Materials and methods: Human enamel specimens were prepared with three surface roughness levels (very rough, rough and polished; n = 10 each). They were evaluated using CP-OCT and optical profilometry (gold standard) at baseline, and after 1, 2, 4, 6, 8, 16 and 24 h of erosion demineralization. The effects of roughness and demineralization on enamel loss were analyzed using ANOVA (alpha = 0.05). Intraclass correlation coefficients (ICCs) and Bland-Altman plots were used to evaluate inter-method agreement and intra-examiner repeatability. Results: CP-OCT surface loss measurements did not significantly differ with the changes in enamel surface roughness (p = 0.27). Among demineralization severities, CP-OCT surface loss measurements at 1, 2, 4 and 8 h did not differ among each other, but they showed significantly lower enamel loss than 16 and 24 h; 6 and 16 h were significantly lower than 24 h (p < 0.05). Overall, CP-OCT and optical profilometry measurements did not differ (p = 0.73); however, ICC was relatively low (ICC = 0.34). Enamel loss estimation by CP-OCT presented an error of approximately ± 150 μm compared to profilometry. Intra-examiner repeatability with CP-OCT was excellent (ICC = 0.98). Conclusions: Enamel roughness did not affect CP-OCT measurements. The estimated error of CP-OCT measurements limited the appropriate assessment of enamel erosion surface loss, in the magnitude simulated in this study. Clinical relevance: Enamel thickness measurement by CP-OCT presents potential as an objective method for monitoring dental erosion lesions; however, its use may be limited for the assessment of the initial stages of enamel surface loss by erosion.
关键词： Tooth wear,Optical coherence tomography,Surface roughness,Enamel,Dental erosion,Demineralization
更新于2025-09-23 15:23:52
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Elucidating Spray Dried Dispersion Dissolution Mechanisms with Focused Beam Reflectance Measurement: Contribution of Polymer Chemistry and Particle Properties to Performance
摘要： Amorphous spray dried dispersions (SDDs) are a key enabling technology for oral solid dosage formulations, used to improve dissolution behaviour and clinical exposure of poorly-soluble active pharmaceutical ingredients (APIs). Appropriate assessment of amorphous dissolution mechanisms is an ongoing challenge. Here we outline the novel application using Focused Beam Reflectance Measurement (FBRM) to analyse particle populations orthogonal to USP 2 dissolution. The relative impact of polymer substitution and particle attributes on 25% BMS-708163/HPMC-AS SDD dissolution was assessed. Dissolution mechanisms for SDDs were categorized into erosion versus disintegration. Beyond an initial mixing period, FBRM particle counts diminish slowly and particles are detectable until the point where API dissolution is complete. There is correlation between FBRM particle count decay rate, representing loss of SDD particles in the dissolution media, and UV dissolution rate, measuring dissolved API. For the SDD formulation examined, the degree of succinoyl substitution for HPMC-AS, SDD particle size and surface area all had an impact on dissolution. These data indicate the SDD displayed an erosion mechanism and that FBRM is capturing a rate-limiting step. From this screening tool, the mechanistic understanding and measured impact of polymer chemistry and particle properties can inform a risk-assessment and control strategy for this compound.
关键词： HPMC-AS,FBRM,SDD,substitution,dissolution-mechanism,amorphous,surface area,erosion,dispersion,particle-size
更新于2025-09-23 15:22:29
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Deciphering controls for debris-flow erosion derived from a LiDAR-recorded extreme event and a calibrated numerical model (Ro?bichelbach, Germany)
摘要： Debris flows are among the most destructive and hazardous mass movements on steep mountains. An understanding of debris-flow erosion, entrainment and resulting volumes is a key requirement for modelling debris-flow propagation and impact, as well as analysing the associated risks. As quantitative controls of erosion and entrainment are not well understood, total volume, runout and impact energies of debris flows are often significantly underestimated. Here, we present an analysis of geomorphic change induced by an erosive debris-flow event in the German Alps in June 2015. More than 50 terrestrial laser scans (TLS) of a 1.2 km long mountain torrent recorded geomorphic change in comparison to an airborne laser scan (ALS) performed in 2007. Errors were calculated using a spatial variable threshold based on the point density of ALS and TLS and the slope of the digital elevation models. Highest erosion rates approach 5.0 m3/m2 (mean 0.6 m3/m2). During the event 9,550 ± 1,550 m3 was eroded whereas only 650 ± 150 m3 was deposited in the channel. Velocity, flow pressure, momentum and shear stress were calculated using a carefully calibrated RAMMS Debris Flow model including material entrainment. Here we present a linear regression model relating debris-flow erosion rates to momentum and shear stress with an R2 up to 68 %. Channel transitions from bedrock to loose debris sections cause excessive erosion up to 1 m3/m2 due to previously unreleased random kinetic energy now available for erosion.
关键词： erosion,numerical modeling,debris flow,geomorphic change,RAMMS,LiDAR
更新于2025-09-23 15:22:29
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Quantification and analysis of geomorphic processes on a recultivated iron ore mine on the Italian island of Elba using long-term ground-based lidar and photogrammetric SfM data by a UAV
摘要： This study focuses on the quanti?cation and analysis of geomorphic processes on the barely vegetated slopes of a recultivated iron ore mine on the Italian island of Elba using photographs from terrestrial laser scanning (TLS) and digital photogrammetry by an unmanned aerial vehicle (UAV) over a period of 5 1/2 years. Beside this, the study tried to work out the potential and the limitations of both methods to detect surface changes by geomorphic process dynamics within a natural environment. Both UAV and TLS show the pattern of the erosion and accumulation processes on the investigated slope quite well, but the calculated amounts differ clearly between the methods. The reasons for these differences could be found in the different accuracies (variable level of detections) of the methods and the different viewing geometries. Both effects have an impact on the detectable process dynamics over different timescales on the slope and their calculated amounts, which in both cases can lead to an underestimation of erosion and accumulation by ?uvial processes.
关键词： terrestrial laser scanning,erosion,geomorphic processes,UAV,recultivated iron ore mine,accumulation,digital photogrammetry
更新于2025-09-23 15:21:21
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - A Fiber Bragg Grating-based Wind Erosion Monitoring System
摘要： This paper proposes a wind erosion monitoring system includes a shunt-hedging and cyclone-separation sand sampler built by Fluent and a weighting sensor based on FBG. According to the simulation and experiment, this system had anti strong wind interference performance and time, passively, in real continuously, and in a long distance. it could measure
关键词： wind erosion,weighting sensor,sand sampler,fiber Bragg grating
更新于2025-09-23 15:21:01
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[Laser Institute of America ICALEO?? 2017: 36th International Congress on Applications of Lasers & Electro-Optics - Atlanta, Georgia, USA (October 22a??26, 2017)] International Congress on Applications of Lasers & Electro-Optics - A composite stellite alloy hardfacing with improved laser cladding behavior and wear resistance
摘要： To solve the existing wear and corrosion problems in power generation industry, this research investigates the wear and corrosion behavior of Stellite alloys in NaOH solution, which simulates the amine media in the feedwater service of power generation plants. The Stellite alloys under this study include Stellite 6 and a composite Stellite alloy. The composite Stellite alloy hardfacing, which consists of 70% Stellite 3 and 30% Stellite 21, is created via laser cladding for control valve seat sealing surfaces, aiming at enhancing hardness and wear resistance, compared with Stellite 6 hardfacing, and improving cracking in laser cladding process, compared with Stellite 3. The composite Stellite alloy hardfacing is made on 316 stainless steel substrate and it does not show any cracking. The microstructure of the hardfacing is analyzed using SEM, EDS and XRD. The hardness, dry sliding wear resistance and cavitation-erosion resistance in NaOH solution are evaluated. Stellite 6 hardfacing is prepared with the same laser process parameters and is also analyzed and tested under the same conditions with the composite Stellite alloy hardfacing for comparison. The experimental results and real industrial test demonstrate superior performance of the composite Stellite alloy hardfacing to Stellite 6 hardfacing for control valve seat sealing application.
关键词： Cavitation-erosion,Hardfacing via laser cladding,Stellite alloy,Dry-sliding wear
更新于2025-09-23 15:19:57
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[Developments in Earth Surface Processes] Remote Sensing of Geomorphology Volume 23 || Terrestrial laser scanner applied to fluvial geomorphology
摘要： Measuring river geometry and its evolution through time has always been a cornerstone of fluvial geomorphology. While experimental and numerical modeling of fluvial dynamics has been central in understanding long-term dynamics and testing ideas, they remain simplified versions of complex natural systems and cannot necessarily include all relevant processes. Field measurements are thus central to our understanding of elementary processes such as sediment entrainment and deposition, bank erosion, bedrock incision as well as the macroscopic dynamics of river reaches such as channel bed accretion/erosion, bedforms mobility, and river meandering. It is therefore not surprising that fluvial geomorphologists have quickly embraced the use of terrestrial laser scanner (TLS) to study rivers (e.g., Heritage and Hetherington, 2007; Hodge et al., 2009a). TLS allows 3D digitization of fluvial environment in a dense (sub-cm), accurate (mm precision), and nearly exhaustive way (Fig. 1). The very large range of spatial scales covered is particularly impressive, from individual pebbles to km long river reaches (e.g., Brasington et al., 2012). Sub-cm accuracy also offers the possibility of detecting very subtle changes (Lague et al., 2013), a key attribute to measure slow processes such as bedrock abrasion (Beer et al., 2017). Given the recent emphasis on the role of riparian processes on fluvial processes, the ability to digitize vegetation in 3D in relation to channel morphology offers a unique perspective in biogeomorphology. However, many of the promises of TLS have not really been fulfilled, and the scientific potential of the TLS dataset remains often untapped. This is largely due to the challenging aspects surrounding the processing of TLS data which, to a large extent, also apply to structure from motion (SfM) surveys (Passalacqua et al., 2015). Three challenges, akin to typical Big Data issues can be identified as follows: 1. Data Complexity: TLS data are 3D data and nearly exhaustive. This makes for very rich data but also extremely complex to process as the relevant information (e.g., ground, grains, riverbanks, vegetation) must be detected prior to scientific analysis (Fig. 1). TLS data is also natively non-regularly sampled, with strong spatial variations in point density and requires processing methods that are more complex than for 2D raster-based data such as satellite imagery. 2. Data Volume: the latest generation of TLS instruments generates billions of points in a day. Manual processing cannot realistically be applied, and automatic processing methods are paramount. This requires good programing skills as well as a culture of machine learning and computer vision approaches that are not necessarily part of the training of geomorphologists and requires bridging the gap with computer sciences. 3. Data Incompleteness: despite the very large field of view of TLS sensors, the resulting 3D data do not sample the entire surface (Fig. 1). The ground-based viewpoint imparts missing data behind obstacles (grains of any size and vegetation) and the laser is generally fully absorbed by water resulting in the lack of bathymetric data, a strong limitation in river environments. Processing methods must account for this lack of information.
关键词： Terrestrial laser scanner,sediment transport,vegetation classification,bank erosion,3D digitization,point cloud processing,bedrock incision,fluvial geomorphology
更新于2025-09-23 15:19:57
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Measuring Streambank Erosion: A Comparison of Erosion Pins, Total Station, and Terrestrial Laser Scanner
摘要： Streambank erosion is difficult to quantify; models and field methods are needed to assess this important sediment source to streams. Our objectives were to (1) evaluate and compare three techniques for quantifying streambank erosion: erosion pins, total station, and laser scanning, (2) spatially assess streambank erosion rates in the Indian Mill Creek watershed of Michigan, USA, and (3) relate results with modeling of nonpoint source pollution. We found large absolute and relative errors between the different measurement techniques. However, we were unable to determine any statistically significant differences between techniques and only observed a correlation between total station and laser scanner. This suggests that the three methods have limited comparability and differences between measurements were largely not systemic. Further, the application of each technique should be dependent on site conditions, project goals, desired resolution, and resources. The laser scanner collected high-resolution data on clear, barren streambanks, but the erosion pin and total station were more representative of complex vegetated banks. Streambank erosion rates varied throughout the watershed and were influenced by fluvial processes. We estimate that streambank erosion contributed 28.5% of the creek’s total sediment load. These findings are important to address sources of watershed impairments related to sedimentation, as choosing an applicable technique for individual purposes can help reduce the challenges and costs of a streambank erosion study.
关键词： erosion,sediment,stream,streambank,lidar,watershed
更新于2025-09-23 15:19:57