Powder Technology最新文献

{"title":"Computationally efficient DEM simulation of a basket-type centrifugal filter using a novel switchable contact model","authors":"Damla Serper ,&nbsp;Kevin J. Hanley ,&nbsp;Pekka Oinas","doi":"10.1016/j.powtec.2024.120467","DOIUrl":"10.1016/j.powtec.2024.120467","url":null,"abstract":"<div><div>The discrete element method (DEM) offers enormous potential to gain a better understanding of cake formation in centrifugal filtration. However, the necessity to represent the highly porous filter mesh in these simulations incurs a significant computational cost. We propose replacing the porous mesh boundary that is conventionally used with a ‘switchable contact model’ (SCM) in which the contact model between a particle and a continuous cylindrical shell is selectively enabled or disabled depending on the particle's location at the periphery of the centrifuge basket. SCM is disabled whenever a particle is deemed to be in contact with a pore location, thus allowing its egress from the basket. There was a ∼ 36 % reduction in computation time compared to the conventional mesh-based representation of a bounding filter mesh, with similar particle retention and bulk cake formation behavior. This concept could in principle be applied to model any repetitive porous structure in DEM.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"452 ","pages":"Article 120467"},"PeriodicalIF":4.5,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142746621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of powder size on the moldability and pore characteristics of porous tungsten by injection molding","authors":"Jie Wang ,&nbsp;Hongyue Dong ,&nbsp;Haifeng Xu ,&nbsp;Fengsong Fan ,&nbsp;Hebin Xu ,&nbsp;Haoyang Wu ,&nbsp;Yunpu Qin ,&nbsp;Zihao Li ,&nbsp;Huihuang Song ,&nbsp;Qiang Chen ,&nbsp;Baorui Jia ,&nbsp;Deyin Zhang ,&nbsp;Mingli Qin ,&nbsp;Xuanhui Qu","doi":"10.1016/j.powtec.2024.120472","DOIUrl":"10.1016/j.powtec.2024.120472","url":null,"abstract":"<div><div>Component shape and pore structure are crucial to the application of porous tungsten, and are significantly affected by the powder size. In this work, porous tungsten with complex shape and controllable pore structure were prepared by the combination of jet milling and injection molding, and the effects of powder size (5, 2 and 0.6 μm) on jet milling, injection molding and pore structure were systematically investigated. The results showed that in contrast to the complete dispersion observed with micron-sized powders, ultrafine powder still had residual agglomerations after jet milling, which further led to a relatively low critical solid loading (47 %) and moldability index (<span><math><msub><mi>α</mi><mi>stv</mi></msub></math></span>=1.85) during injection molding. For porous pore structure, finer powder was more conducive to obtain smaller pore size and more complex pore structure. At the same porosity (27 %), with the decrease of powder size, the pore size decreased from 1028 nm to 552 nm and 350 nm, and the corresponding fractal dimension increased from 2.19 to 2.84 and 2.99. In contrast, the compressive strength increased as the powder size decreased, rising from 488 MPa to 640 MPa and 883 MPa. The establishment of the relationship between powder size, moldability, and pore characteristics provides valuable insights for the raw powder selection and pore structure control, which is of great significance for the precise preparation and application promotion of porous tungsten.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"452 ","pages":"Article 120472"},"PeriodicalIF":4.5,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142720942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of active material morphology on PTFE-fibrillation, powder characteristics and electrode properties in dry electrode coating processes","authors":"Marcella Horst ,&nbsp;Franziska Beverborg ,&nbsp;Lukas Bahlmann ,&nbsp;Svenja Schreiber ,&nbsp;Julius Gerk ,&nbsp;Peter Michalowski ,&nbsp;Arno Kwade","doi":"10.1016/j.powtec.2024.120451","DOIUrl":"10.1016/j.powtec.2024.120451","url":null,"abstract":"<div><div>This study investigates the significant impact of different active material particle morphologies – platelet-like graphite, spherical highly porous LFP, and spherical NCM – on PTFE fibrillation during mixing and calendering steps of a dry coating process. Graphite's platelet-like structure slows PTFE fibrillation compared to LFP's structure, which exhibits prolonged PTFE fibrillation due to its fine particle content. NCM, with higher density and compaction speed, promotes faster PTFE fibrillation during mixing. The hierarchical morphology of the fibrils determines the powder blend properties. Consequently, powder behaviour in the calender gap was characterised using uniaxial compression and ring shear cell tests. Uniaxial compression tests revealed that NCM-based powder requires higher compression stress. Under consistent calendering conditions, it forms thicker dry-coated films compared to the graphite-based powder, which requires lower compression stress and forms thinner films. These findings are supported by ring shear cell tests, which showed lower wall friction for graphite-based powder and a higher wall friction angle for NCM-based powder. Additionally, the porosity of the free-standing films can be predicted using uniaxial compression tests. These results highlight the need for tailored mixing and calendering processes for each active material to optimize electrode properties in dry coating processes for lithium-ion batteries.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"451 ","pages":"Article 120451"},"PeriodicalIF":4.5,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700222","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhanced mechanical and electrical properties of Cu matrix composites with ultrafine Cr2O3 particles by spray drying","authors":"Longshan Xu,&nbsp;Xiaoshuai Wang,&nbsp;Yurong Wu,&nbsp;Siqing Song,&nbsp;Yanling Hu,&nbsp;Yuhui Zhang","doi":"10.1016/j.powtec.2024.120466","DOIUrl":"10.1016/j.powtec.2024.120466","url":null,"abstract":"<div><div>This study investigated the effects of different Cr₂O₃ contents on the mechanical and electrical properties of Cu-based composites using spray drying technology. The influence of varying Cr₂O₃ concentrations on the powder morphology was systematically investigated. Cold pressing and sintering were utilized to fabricate composite blocks to examine the microstructures, mechanical properties, and electrical conductivity with different Cr₂O₃ content. Our findings reveal that the inclusion of Cr₂O₃ led to a reduction in conductivity, while significantly improving the hardness. Notably, an optimal Cr₂O₃ concentration of 0.8 wt% gained a remarkable increase in yield strength to 215 MPa and ultimate tensile strength to 255.96 MPa, marking improvements of 104.76 % and 114.91 %, respectively, over composites prepared with pure Cu powders. The balance achieved between mechanical robustness and conductivity suggests a promising potential for these composites in electrical applications.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"451 ","pages":"Article 120466"},"PeriodicalIF":4.5,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimization of surface modification parameters of fly ash with high calcium oxide (CaO) content to use as a filling material","authors":"Metin Uçurum ,&nbsp;Akın Özdemir ,&nbsp;Çağatay Teke","doi":"10.1016/j.powtec.2024.120463","DOIUrl":"10.1016/j.powtec.2024.120463","url":null,"abstract":"<div><div>Fly ash (FA) is the fine-grained waste product obtained by burning coal after being ground to specific sizes in thermal power plants, carried with flue gases, and kept in cyclones or electro-filters. Like every industrial waste, the possibilities of utilizing FA have been investigated, and it can be utilized as an additive in cement and concrete. Despite this, industrial waste, which increases daily in the world, brings many problems, especially environmental problems. For this reason, alternative usage areas of the waste in question are constantly being investigated. In this paper, FA containing approximately 50 % CaO from Afşin-Elbistan, Turkiye was processed with stearic acid in a planetary mill to be used as a filling material in industrial products, and it has a grain size of 68.10 μm on a <em>d</em>₅₀ basis, a specific surface area (SSA) of 176.40 m²/g and a contact angle of 13.89. An optimization and characterization study was conducted to make the hydrophilic surface structure hydrophobic by mechanochemical surface modification. Also, surface modification parameters, such as operational speed (rpm), ball filling ratio (%), FA filling ratio (%), pulp density, stearic acid dosage (% of FA), and modification time (min.) were optimized with the <em>D</em>-optimal experimental design. Based on the optimum surface modification parameters, a coated fly ash (CFA) product was obtained with an active ratio of 99.70 %, a contact angle of 95.06^o, a medium size (<em>d</em>₅₀) size of 10.60 μm, and an SSA of 926.90 m²/g.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"451 ","pages":"Article 120463"},"PeriodicalIF":4.5,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Representation of aggregates from their two-dimensional images for primary particles of different sizes","authors":"Rui Wang,&nbsp;Aisel Ajalova,&nbsp;Subash Reddy Kolan,&nbsp;Torsten Hoffmann,&nbsp;Kaicheng Chen,&nbsp;Evangelos Tsotsas","doi":"10.1016/j.powtec.2024.120465","DOIUrl":"10.1016/j.powtec.2024.120465","url":null,"abstract":"<div><div>This study focused on representing the three-dimensional (3D) structure of individual aggregates based on their two-dimensional (2D) images. This starts with the determination of 2D box-counting fractal dimension (<span><math><msub><mi>D</mi><mrow><mi>f</mi><mo>,</mo><mi>BC</mi><mo>,</mo><mn>2</mn><mi>D</mi></mrow></msub></math></span>), uses a previously derived empirical correlation to obtain 3D power law fractal dimension (<span><math><msub><mi>D</mi><mrow><mi>f</mi><mo>,</mo><mi>PL</mi></mrow></msub></math></span>), and then builds the aggregate on the basis of <span><math><msub><mi>D</mi><mrow><mi>f</mi><mo>,</mo><mi>PL</mi></mrow></msub></math></span> by an existing algorithm. Validation of this procedure can be done in forward or backward manner. Forward validation requires the existence of tomographic measurements of <span><math><msub><mi>D</mi><mrow><mi>f</mi><mo>,</mo><mi>PL</mi></mrow></msub></math></span>. It has been conducted on aggregates of large primary particles produced to this purpose in a spray fluidized bed and analyzed by X-ray micro-computed tomography (μ-CT). For the same agglomerates backward validation has also been exercised, starting the representation from 2D projections of the 3D objects and repeating the same procedure on the represented aggregates to see, how accurately the fractal dimensions of the original objects are reproduced. When the primary particles are too small in size to be resolved by X-ray μ-CT, only 2D imaging data by electron microscopy are usually available. Such images have been taken from literature for aggregates composed of submicron particles or nanoparticles and used for aggregate representation in 3D. Subsequently, backward validation of the procedure has been conducted. Both forward validation and backward validation results indicate a high level of consistency between the fractal characteristics and morphological structures of the represented aggregates and those of the original ones. Additionally, this study shows that the method is effective for aggregates of bidisperse and polydisperse particles.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"451 ","pages":"Article 120465"},"PeriodicalIF":4.5,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142746556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Vapor-mediated impact of droplet on superheated powder bed","authors":"Dongdong Liu,&nbsp;Binjie Tan,&nbsp;Hongdong Yin,&nbsp;Zeyu Wu,&nbsp;Xiang Luo","doi":"10.1016/j.powtec.2024.120434","DOIUrl":"10.1016/j.powtec.2024.120434","url":null,"abstract":"<div><div>Droplet impacting on a sufficiently heated powder bed resembles those on a superheated solid surface, as the surface deformation is mediated by the spontaneously generated vapor flow from the bottom surface of the droplet. This emerged impacting behavior is denoted as vapor-mediated impact to differentiate from the wetting impact, which involves the wetting and absorption of the particles due to capillarity. We systematically vary the impacting velocity and the temperature of the powder bed to characterize the impacting dynamics for these two behaviors. For the vapor-mediated impact, the contact time and the maximum spreading diameter are found to have the same scaling laws derived for impact on the superheated surface. We construct a phase diagram of the impacting behaviors based on experimental observation, and propose a simplified model to predict the transition between these two behaviors. The predicted values match well with the experimental results, suggesting the proposed model captures the physical mechanism of the vapor-mediated impact.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"451 ","pages":"Article 120434"},"PeriodicalIF":4.5,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Three-dimensional numerical simulation of coal and papermaking trash co-combustion in a circulating fluidized bed","authors":"Wanqiang Wu ,&nbsp;Lin Li ,&nbsp;Junhua Mao ,&nbsp;Shuo Zhang ,&nbsp;Quanbin Gu ,&nbsp;Minmin Zhou ,&nbsp;Xiaoyan Lu ,&nbsp;Lunbo Duan","doi":"10.1016/j.powtec.2024.120464","DOIUrl":"10.1016/j.powtec.2024.120464","url":null,"abstract":"<div><div>Circulating fluidized bed (CFB) combustion is a important method of waste treatment with the benefits of harmlessness, recycling, and energy recovery. Using the existing co-firing CFB boiler to dispose of waste can reduce investment in boilers and environmental protection equipment. However, there is currently limited research available on the co-combustion of coal and waste (especially for papermaking trash), and the mechanism of pollutant emissions during unit operation remains unclear. In this work, the co-combustion of coal and papermaking trash in a three-dimensional industrial-scale CFB are investigated by using the Dense Discrete Phase Model (DDPM) method. Both homogeneous reactions (such as fuel particle pyrolysis, combustion, and surface reaction) and non-homogeneous reactions (such as gas combustion and pollutant generation) are considered. The co-combustion characteristics are comprehensively analyzed in terms of gas distribution, chemical reaction rates, and bed temperature under various operating conditions, including fuel mixing ratio, secondary air arrangement, and excess air coefficient. The results are obtained by comparing the distribution profile along the height. By reducing the mixing ratio of papermaking trash, the excess air coefficient, and adjusting the secondary air arrangement in the lower region, an expanding, reducing atmosphere is observed in the vicinity of the fuel feeding point. This, in turn, leads to an increase in CO concentration and a decrease in NO emissions, which is attributable to the interplay of gas distribution, chemical reaction rates, and bed temperature. A reduction in NO gas emissions was achieved by adjusting the secondary air arrangement and the excess air coefficient. Overall, this work provides valuable insights into the co-combustion characteristics of coal and papermaking trash in an industrial-scale circulating fluidized bed boilers.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"451 ","pages":"Article 120464"},"PeriodicalIF":4.5,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Discrete element modeling of irregular-shaped soft pine particle flow in an FT4 powder rheometer","authors":"Zakia Tasnim ,&nbsp;Qiushi Chen ,&nbsp;Yidong Xia ,&nbsp;Ahmed Hamed ,&nbsp;Jordan Klinger ,&nbsp;Ricardo Navar ,&nbsp;Benjamin Davis","doi":"10.1016/j.powtec.2024.120437","DOIUrl":"10.1016/j.powtec.2024.120437","url":null,"abstract":"<div><div>Pine residues are a commonly used biomass feedstock that consists of different anatomical fractions, each with distinct particle characteristics. In this work, an experiment-informed discrete element model is developed to investigate the flowability of pine residues in an FT4 rheometer. Multi-sphere particles with distinct particle attributes are created to model each anatomical fraction type. A systematic analysis of specimens with varying particle characteristics (e.g., anatomical fraction type, particle shape, and size) is conducted to elucidate the relationship between particle attributes and flowability. The results show that stems recorded the highest axial force and torque and, correspondingly, the highest flow energy, which is attributed to their high stiffness and interlocking effect. Increasing their percentage in the mixture increases the flow energy while increasing needles tends to decrease flow energy. Knowledge gained in this study on the flow of anatomical fractions is important for the efficient and robust processing of pine residues.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"450 ","pages":"Article 120437"},"PeriodicalIF":4.5,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142705176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Formulation of blast-furnace slag for use in hydraulically bound construction materials","authors":"Aline Weicht ,&nbsp;Maike Peters ,&nbsp;Lydia Achelis ,&nbsp;Stefan Evers ,&nbsp;Frank Hlawatsch ,&nbsp;Daniel Ufermann-Wallmeier ,&nbsp;Volker Uhlenwinkel ,&nbsp;Udo Fritsching","doi":"10.1016/j.powtec.2024.120455","DOIUrl":"10.1016/j.powtec.2024.120455","url":null,"abstract":"<div><div>Dry powder granulation of slag melts by gas atomization offers a means of reducing the resource expenditure associated with the conventional wet processing of blast furnace slags (BFS). Slags are a by-product of the iron production process and are subsequently processed to create a fine powder, which is then used in the manufacture of building materials.</div><div>The melt atomization process, which is widely used in metal powder production, was adapted to process the slag into fine, amorphous and spherical particles. Therefore, this study investigates the development of an adapted high-temperature atomization process utilizing a new developed atomizer, the resulting properties of the slag particles, and the suitability of atomized blast furnace slag powders (ABFS) for use in building materials.</div><div>It is demonstrated that BFS can be properly atomized to form spherical, amorphous particles that exhibit excellent flowability and a low Carr-Index. The utilization of heated atomization gas and high atomizing gas pressure increases the content of small particles below 200 μm in diameter with up to 60 % of the powder mass. The atomized slag powder exhibits comparable latent hydraulic properties as ground slag powders. The utilization of the atomized slag powder fraction below 90 μm in concrete approaches the results of formulations containing conventionally processed slag. In this way, the requisite water content in concrete formulations can be diminished, and the concrete formulation's CO₂ footprint may be reduced. Consequently, liquid BFS can be directly processed into spherical and amorphous particles through hot gas atomization and the resulting slag powder can be utilized in building materials.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"451 ","pages":"Article 120455"},"PeriodicalIF":4.5,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}