Powder Technology最新文献

Influence of graphene coating structure on the hydrodynamic properties of porous media

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2025-04-07 DOI: 10.1016/j.powtec.2025.121016

Asif Khan , Daniyar Balapanov , Andrey Glushchuk , Mehdi Feizpour , Carlo S. Iorio

In light of the growing interest in carbon-based coatings, this paper investigates the influence of graphene coatings on the main hydrodynamic characteristics of sintered porous media. We developed a consistent methodology for coated porous medium characterization, which involves measurement techniques for the three most important parameters: porosity, capillary pressure, and permeability. The latter required special attention because of the coating fragility, which prevented the application of the conventional forced flow method. Thus, a mass rate-of-rise principle has been used, where the absorbed liquid mass is monitored in time and then fitted to the Lucas-Washburn model. The model's validity is strictly proven for the particular experimental conditions and the samples, as well as the rigorous theory for uncertainty estimation in the case of the least squares method. Using a pressing technique, the authors created porous samples of stainless-steel 316 L polydisperse and nickel spherical particles. The graphene coating is applied by the chemical vapour deposition technique. We found that the coating reduces the porosity and permeability of the nickel samples and increases their capillary pressure, with this influence proportional to the synthesis time. Conversely, the stainless-steel 316 L samples evidenced unintuitive results with 3D disordered carbon addition. The variation in porosity and permeability is within the measurement uncertainty, and capillary pressure exhibits an inverse dependence on the deposition process time. The measurement results are correlated with the analysis of the porous space structure and the coating structure obtained by SEM imaging and Raman spectroscopy.

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引用次数: 0

Investigating the dynamic combustion characteristics of Al-Mg-Li powders in equal cross-section combustion chamber: An experimental study 研究铝镁锂粉末在等截面燃烧室中的动态燃烧特性：实验研究

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2025-04-04 DOI: 10.1016/j.powtec.2025.120997

Yingying Lu , Hongyan Li , Changchao Guo , Wenxiong Xi , Sicong Xi , Shipeng Li , Shaoqing Hu

Given the promising applications of powder ramjet engine technology in hypersonic vehicles, metal powder fuels have garnered significant research interest due to their high energy density. Among these, Al-based metal powder is particularly notable as a potential fuel option with important application prospects. Consequently, investigating the combustion properties of Al-based powder is crucial. In this study, we conducted experimental combustion studies on Al-Mg-Li powders with four different particle size distributions using a cyclone combustion system in an equal cross-section combustion chamber. The results demonstrated a significant effect of particle size distribution on the combustion efficiency of Al-Mg-Li powders. Powders with particle sizes below 75 μm achieve full combustion more rapidly. Additionally, the flame profile at the chamber exit is smoother and more continuous for particles below 45 μm, indicating higher combustion efficiency. The varying sizes of the spoiler cone influence combustion flame intensity by affecting the velocity, heating time, and concentration distribution of the Al-Mg-Li powders. Furthermore, when the cone is positioned closer to the bottom of the combustion chamber (80 mm), both the combustion intensity and efficiency of the Al-Mg-Li powders were improved. Finally, under cold air inflow conditions, self-sustained combustion of Al-Mg-Li powders was observed, with a re-ignition pulse period of 0.7–0.8 s.

{"title":"Investigating the dynamic combustion characteristics of Al-Mg-Li powders in equal cross-section combustion chamber: An experimental study","authors":"Yingying Lu , Hongyan Li , Changchao Guo , Wenxiong Xi , Sicong Xi , Shipeng Li , Shaoqing Hu","doi":"10.1016/j.powtec.2025.120997","DOIUrl":"10.1016/j.powtec.2025.120997","url":null,"abstract":"<div><div>Given the promising applications of powder ramjet engine technology in hypersonic vehicles, metal powder fuels have garnered significant research interest due to their high energy density. Among these, Al-based metal powder is particularly notable as a potential fuel option with important application prospects. Consequently, investigating the combustion properties of Al-based powder is crucial. In this study, we conducted experimental combustion studies on Al-Mg-Li powders with four different particle size distributions using a cyclone combustion system in an equal cross-section combustion chamber. The results demonstrated a significant effect of particle size distribution on the combustion efficiency of Al-Mg-Li powders. Powders with particle sizes below 75 μm achieve full combustion more rapidly. Additionally, the flame profile at the chamber exit is smoother and more continuous for particles below 45 μm, indicating higher combustion efficiency. The varying sizes of the spoiler cone influence combustion flame intensity by affecting the velocity, heating time, and concentration distribution of the Al-Mg-Li powders. Furthermore, when the cone is positioned closer to the bottom of the combustion chamber (80 mm), both the combustion intensity and efficiency of the Al-Mg-Li powders were improved. Finally, under cold air inflow conditions, self-sustained combustion of Al-Mg-Li powders was observed, with a re-ignition pulse period of 0.7–0.8 s.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"458 ","pages":"Article 120997"},"PeriodicalIF":4.5,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143800470","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}

引用次数: 0

Coupled thermo-electric discrete element model for spark plasma sintering

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2025-04-04 DOI: 10.1016/j.powtec.2025.120957

F. Nisar , J. Rojek , S. Nosewicz , K. Kaszyca , M. Chmielewski

Spark Plasma Sintering (SPS) is an emerging powder consolidation technique that employs electric current to generate heat through the Joule effect while applying pressure to achieve densification efficiently. A common concern in this process is the localization of Joule heat at the contacts between particles where electrical resistance is highest. This study investigates the coupled thermo-electric phenomena in sintered material using an original discrete element model (DEM). The model employs a two-particle sintering geometry, with particles interconnected by the neck. Neck size is evaluated using volume preservation criteria, and a correction factor compensating for non-physical overlaps as well as additional grain boundary resistance is introduced. The DEM model is verified by comparing with FEM simulations. A simple three-particle geometry is used to demonstrate that the simple DEM model gives the same potential evolution, resultant currents and temperature evolution as the more complex finite element model. Thereafter, the DEM model is validated on geometry generated using real particle size distribution to ensure heterogeneous microstructure. The effect of density on the electrical potential evolution, Joule heating and resulting increase in temperature is analysed. It is shown that the Joule heat is concentrated in the smaller particles and is conducted throughout the sample, resulting in a homogeneous increase in temperature. Ultimately, the effect of densification on heating rate is analysed. This study improves the overall understanding of thermo-electric behaviour in the SPS process, providing significant insights into the microscopic phenomena.

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引用次数: 0

From cloudy suspensions to clear data: Particle imaging enabled by automated dilution 从混浊的悬浮液到清晰的数据：通过自动稀释实现粒子成像

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2025-04-04 DOI: 10.1016/j.powtec.2025.120965

Daniel Biri , Ashwin Kumar Rajagopalan , Marco Mazzotti

We present a novel dilution device designed for accurately and robustly diluting dense suspensions to enable real-time particle characterization using optical imaging systems. The device employs tangential flow filtration, allowing for continuous operation at high solid weight fractions typical in industrial crystallization processes. It demonstrates the ability to monitor suspensions continuously over 24 h and to quickly adapt to changing particle densities, whilst continuously enabling accurate measurements. This paper presents also a study of the impact of particle density on measurement accuracy; extensive testing confirms the reliability of the dilution device for distributions of various particle sizes and shapes. The dilution device successfully tracks the evolution of the particle size and shape distribution (PSSD) during cooling crystallization. The innovation presented here, overcomes the limitations of existing methods hindered by high particle densities, providing a significant advancement in real-time monitoring and characterization capabilities under realistic conditions. This technology holds potential for broad applications, including the validation of new crystallization theories and, thus enhanced development of efficient crystallization processes.

{"title":"From cloudy suspensions to clear data: Particle imaging enabled by automated dilution","authors":"Daniel Biri , Ashwin Kumar Rajagopalan , Marco Mazzotti","doi":"10.1016/j.powtec.2025.120965","DOIUrl":"10.1016/j.powtec.2025.120965","url":null,"abstract":"<div><div>We present a novel dilution device designed for accurately and robustly diluting dense suspensions to enable real-time particle characterization using optical imaging systems. The device employs tangential flow filtration, allowing for continuous operation at high solid weight fractions typical in industrial crystallization processes. It demonstrates the ability to monitor suspensions continuously over 24 h and to quickly adapt to changing particle densities, whilst continuously enabling accurate measurements. This paper presents also a study of the impact of particle density on measurement accuracy; extensive testing confirms the reliability of the dilution device for distributions of various particle sizes and shapes. The dilution device successfully tracks the evolution of the particle size and shape distribution (PSSD) during cooling crystallization. The innovation presented here, overcomes the limitations of existing methods hindered by high particle densities, providing a significant advancement in real-time monitoring and characterization capabilities under realistic conditions. This technology holds potential for broad applications, including the validation of new crystallization theories and, thus enhanced development of efficient crystallization processes.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"458 ","pages":"Article 120965"},"PeriodicalIF":4.5,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143800469","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}

引用次数: 0

Effect of friction on the angle of repose of elongated particles

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2025-04-03 DOI: 10.1016/j.powtec.2025.120974

Manuel Cárdenas-Barrantes, Carlos Ovalle

The angle of repose (

A O R

) is a key parameter in powder engineering, primarily influenced by the pouring process, the inter-particle constitutive laws and particle shape. Therefore, the

A O R

of a bulk material is intuitively linked to its macromechanical internal friction angle. Previous studies indicate that more irregular particle shapes, such as angular or elongated particles, increase both shear strength and

A O R

. However, in granular materials with highly irregular shapes and low interparticle friction (or frictionless conditions), this trend reverses for the shear resistance. Despite these results, studies on the

A O R

of such materials are rare and the physical mechanisms of this behavior are unclear. This study investigates the

A O R

of dry, cohesionless granular piles composed of elongated particles using 3D DEM simulations. To represent a wide range of conditions specific to various industrial processes — including pharmaceuticals, food engineering, geotechnics, and mining — we extensively vary particle characteristics, focusing on particle elongation and interparticle friction. The particles, modeled as rounded-cap cylinders, have aspect ratios (length/diameter) ranging from 1 (spheres) to 4. For high interparticle friction (

μ > 0.2

), the

A O R

increases systematically with elongation. However, at low friction, a critical aspect ratio of 1.5 emerges, beyond which the tendency changes and the

A O R

decreases. We show that this counterintuitive behavior is related to the solid fraction, which depends on particle shape, and can be traced to purely geometrical characteristics such as coordination number and statistical particle orientation. Non-intuitively, the elongation of the particles does not influence the force distributions within the piles.

{"title":"Effect of friction on the angle of repose of elongated particles","authors":"Manuel Cárdenas-Barrantes, Carlos Ovalle","doi":"10.1016/j.powtec.2025.120974","DOIUrl":"10.1016/j.powtec.2025.120974","url":null,"abstract":"<div><div>The angle of repose (<span><math><mrow><mi>A</mi><mi>O</mi><mi>R</mi></mrow></math></span>) is a key parameter in powder engineering, primarily influenced by the pouring process, the inter-particle constitutive laws and particle shape. Therefore, the <span><math><mrow><mi>A</mi><mi>O</mi><mi>R</mi></mrow></math></span> of a bulk material is intuitively linked to its macromechanical internal friction angle. Previous studies indicate that more irregular particle shapes, such as angular or elongated particles, increase both shear strength and <span><math><mrow><mi>A</mi><mi>O</mi><mi>R</mi></mrow></math></span>. However, in granular materials with highly irregular shapes and low interparticle friction (or frictionless conditions), this trend reverses for the shear resistance. Despite these results, studies on the <span><math><mrow><mi>A</mi><mi>O</mi><mi>R</mi></mrow></math></span> of such materials are rare and the physical mechanisms of this behavior are unclear. This study investigates the <span><math><mrow><mi>A</mi><mi>O</mi><mi>R</mi></mrow></math></span> of dry, cohesionless granular piles composed of elongated particles using 3D DEM simulations. To represent a wide range of conditions specific to various industrial processes — including pharmaceuticals, food engineering, geotechnics, and mining — we extensively vary particle characteristics, focusing on particle elongation and interparticle friction. The particles, modeled as rounded-cap cylinders, have aspect ratios (length/diameter) ranging from 1 (spheres) to 4. For high interparticle friction (<span><math><mrow><mi>μ</mi><mo>></mo><mn>0</mn><mo>.</mo><mn>2</mn></mrow></math></span>), the <span><math><mrow><mi>A</mi><mi>O</mi><mi>R</mi></mrow></math></span> increases systematically with elongation. However, at low friction, a critical aspect ratio of 1.5 emerges, beyond which the tendency changes and the <span><math><mrow><mi>A</mi><mi>O</mi><mi>R</mi></mrow></math></span> decreases. We show that this counterintuitive behavior is related to the solid fraction, which depends on particle shape, and can be traced to purely geometrical characteristics such as coordination number and statistical particle orientation. Non-intuitively, the elongation of the particles does not influence the force distributions within the piles.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"458 ","pages":"Article 120974"},"PeriodicalIF":4.5,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143777577","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}

引用次数: 0

“Nanoencapsulation of astaxanthin using gum arabic and whey protein isolate as wall materials: Characterization and invitro release kinetics” "用阿拉伯树胶和分离乳清蛋白作为壁材对虾青素进行纳米封装：表征和体外释放动力学"

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2025-04-02 DOI: 10.1016/j.powtec.2025.120982

Samira Habib , Sajad Mohd Wani , Khansa Rasool , Barjees Ashaq , Nadira Anjum , Shahid Ahmad Padder , Syed Zameer Hussain , Nageena Nazir , Shabeena Majid , Sehrish Mustafa

Astaxanthin (AST) has various biological activities, such as antioxidant, antitumor, and anti-inflammatory, but poor water solubility, instability, and low bioaccessibility greatly limit the development of its industrial application. Nanoencapsulation offers an effective method to enhance AST's stability and bioavailability. This study investigated the nanoencapsulation of AST from Xanthophyllomyces dendrorhous using gum arabic (GA), whey protein isolate (WPI), and GA/WPI complex as wall materials. The nanoemulsions were characterized for viscosity, droplet size and zeta potential. Analyses also included nanoencapsulated powder properties, encapsulation efficiency, encapsulation yield, FTIR, thermal stability, morphology and invitro release kinetics. Parameters such as viscosity, droplet size and zeta potential showed significant differences (p ≤ 0.05) among various nanoemulsions. The moisture content and water activity were in the range of 3.95–6.23 % and 0.32–0.35, respectively, which is suitable for long-term storage. The best results were achieved in GA/WPI-AST, where it had the highest encapsulation efficiency (90.31 %). FTIR revealed that the AST was well encapsulated in the nanocapsules. The results of DSC showed that the encapsulated AST changed from a crystalline state to an amorphous state. Nanocapsules displayed controlled release under simulated gastrointestinal conditions, and all the data showed good correlation with Korsmeyer-Peppas model kinetics.

{"title":"“Nanoencapsulation of astaxanthin using gum arabic and whey protein isolate as wall materials: Characterization and invitro release kinetics”","authors":"Samira Habib , Sajad Mohd Wani , Khansa Rasool , Barjees Ashaq , Nadira Anjum , Shahid Ahmad Padder , Syed Zameer Hussain , Nageena Nazir , Shabeena Majid , Sehrish Mustafa","doi":"10.1016/j.powtec.2025.120982","DOIUrl":"10.1016/j.powtec.2025.120982","url":null,"abstract":"<div><div>Astaxanthin (AST) has various biological activities, such as antioxidant, antitumor, and anti-inflammatory, but poor water solubility, instability, and low bioaccessibility greatly limit the development of its industrial application. Nanoencapsulation offers an effective method to enhance AST's stability and bioavailability. This study investigated the nanoencapsulation of AST from <em>Xanthophyllomyces dendrorhous</em> using gum arabic (GA), whey protein isolate (WPI), and GA/WPI complex as wall materials. The nanoemulsions were characterized for viscosity, droplet size and zeta potential. Analyses also included nanoencapsulated powder properties, encapsulation efficiency, encapsulation yield, FTIR, thermal stability, morphology and invitro release kinetics. Parameters such as viscosity, droplet size and zeta potential showed significant differences (<em>p</em> ≤ 0.05) among various nanoemulsions. The moisture content and water activity were in the range of 3.95–6.23 % and 0.32–0.35, respectively, which is suitable for long-term storage. The best results were achieved in GA/WPI-AST, where it had the highest encapsulation efficiency (90.31 %). FTIR revealed that the AST was well encapsulated in the nanocapsules. The results of DSC showed that the encapsulated AST changed from a crystalline state to an amorphous state. Nanocapsules displayed controlled release under simulated gastrointestinal conditions, and all the data showed good correlation with Korsmeyer-Peppas model kinetics.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"458 ","pages":"Article 120982"},"PeriodicalIF":4.5,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143800472","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}

引用次数: 0

A micromechanical framework for understanding the role of fines in the monotonic and cyclic response of granular mixtures 了解细粒在颗粒混合物单调和循环反应中的作用的微观力学框架

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2025-04-02 DOI: 10.1016/j.powtec.2025.121002

Kangle Zuo , Xiaoqiang Gu , Jing Hu , Jun Yang

The discrete-element method was employed to simulate a series of monotonic and cyclic triaxial tests on host sands (i.e. clean sands) with varying particle gradations, mixed with a range of non-plastic fines. The cyclic liquefaction resistance, critical state, and micromechanical responses of both clean sands and sand-fines mixtures were investigated. The findings reveal that both fines content (FC) and the uniformity coefficient of host sand (C_us) significantly influence liquefaction resistance, the critical state line in e-logp’ space, and force transmission within contact network. However, the critical stress ratio is unaffected by FC and C_us. Microscopic analysis indicates that, under both monotonic and cyclic loadings, sand-sand contacts primarily contribute to the deviatoric stress, while fines-fines contacts, despite their high proportion, contribute negligibly. A new contact state variable, termed the soil skeleton coordination number (MCN_sk), is proposed to capture active contacts within soil skeleton and effectively characterize the critical state behavior and liquefaction resistance of granular mixtures, independent of particle size distribution. Furthermore, liquefaction resistance is well interpreted within both macroscopic and microscopic frameworks of critical state soil mechanics. The integration of macro- and micro-level results enhances understanding of the force transmission network and associated mechanical behavior in sand-fines mixtures with varying particle size distributions.

{"title":"A micromechanical framework for understanding the role of fines in the monotonic and cyclic response of granular mixtures","authors":"Kangle Zuo , Xiaoqiang Gu , Jing Hu , Jun Yang","doi":"10.1016/j.powtec.2025.121002","DOIUrl":"10.1016/j.powtec.2025.121002","url":null,"abstract":"<div><div>The discrete-element method was employed to simulate a series of monotonic and cyclic triaxial tests on host sands (i.e. clean sands) with varying particle gradations, mixed with a range of non-plastic fines. The cyclic liquefaction resistance, critical state, and micromechanical responses of both clean sands and sand-fines mixtures were investigated. The findings reveal that both fines content (FC) and the uniformity coefficient of host sand (<em>C</em><sub>us</sub>) significantly influence liquefaction resistance, the critical state line in <em>e</em>-log<em>p</em>’ space, and force transmission within contact network. However, the critical stress ratio is unaffected by FC and <em>C</em><sub>us</sub>. Microscopic analysis indicates that, under both monotonic and cyclic loadings, sand-sand contacts primarily contribute to the deviatoric stress, while fines-fines contacts, despite their high proportion, contribute negligibly. A new contact state variable, termed the soil skeleton coordination number (MCN<sub>sk</sub>), is proposed to capture active contacts within soil skeleton and effectively characterize the critical state behavior and liquefaction resistance of granular mixtures, independent of particle size distribution. Furthermore, liquefaction resistance is well interpreted within both macroscopic and microscopic frameworks of critical state soil mechanics. The integration of macro- and micro-level results enhances understanding of the force transmission network and associated mechanical behavior in sand-fines mixtures with varying particle size distributions.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"458 ","pages":"Article 121002"},"PeriodicalIF":4.5,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143777574","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}

引用次数: 0

Synthesis of low-cost kaolinite-based cobalt blue composite pigments by eco-friendly mechanochemical method

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2025-04-02 DOI: 10.1016/j.powtec.2025.121007

Kai Chen, Sikai Zhao, Jingyu Zhang, Mingtao Tang, Qiang Zhao, Shuling Gao, Yanbai Shen

Cobalt blue (CoAl₂O₄) pigment is widely used in various fields such as coatings, glass, ceramics, and plastics due to its brilliant blue color and excellent stability. However, the high energy consumption and the pollution of conventional preparation methods of cobalt blue pigments, as well as the gradual depletion of cobalt resources, lead to high production costs and hinder its further adoption. In this study, we prepared novel kaolinite-based CoAl₂O₄ composite pigments through a mechanochemical method followed by a calcination process, significantly reducing cobalt consumption. The experimental results showed that, with the addition of sodium carbonate at 450 %, addition of kaolinite at 40 wt%, molar ratio of added Co to Al at 0.14, and calcination temperature at 1100 °C, the prepared composite pigment exhibited optimal blue color (L^⁎ = 56.62, a^⁎ = 4.50, b^⁎ = −49.92, and C^⁎ = 50.12) coupled with good chemical stability (∆E^⁎ ≤ 1.15). Further characterization analysis revealed that the enhanced color performance was mainly attributed to the uniformly dispersed CoAl₂O₄ particles with high crystallinity on the surface of kaolinite, which led to a strong reflectance of blue visible light. Therefore, this study is expected to serve as a reference for the cost-effective and eco-friendly preparation of cobalt blue composite pigments.

{"title":"Synthesis of low-cost kaolinite-based cobalt blue composite pigments by eco-friendly mechanochemical method","authors":"Kai Chen, Sikai Zhao, Jingyu Zhang, Mingtao Tang, Qiang Zhao, Shuling Gao, Yanbai Shen","doi":"10.1016/j.powtec.2025.121007","DOIUrl":"10.1016/j.powtec.2025.121007","url":null,"abstract":"<div><div>Cobalt blue (CoAl<sub>2</sub>O<sub>4</sub>) pigment is widely used in various fields such as coatings, glass, ceramics, and plastics due to its brilliant blue color and excellent stability. However, the high energy consumption and the pollution of conventional preparation methods of cobalt blue pigments, as well as the gradual depletion of cobalt resources, lead to high production costs and hinder its further adoption. In this study, we prepared novel kaolinite-based CoAl<sub>2</sub>O<sub>4</sub> composite pigments through a mechanochemical method followed by a calcination process, significantly reducing cobalt consumption. The experimental results showed that, with the addition of sodium carbonate at 450 %, addition of kaolinite at 40 wt%, molar ratio of added Co to Al at 0.14, and calcination temperature at 1100 °C, the prepared composite pigment exhibited optimal blue color (L<sup>⁎</sup> = 56.62, a<sup>⁎</sup> = 4.50, b<sup>⁎</sup> = −49.92, and C<sup>⁎</sup> = 50.12) coupled with good chemical stability (∆E<sup>⁎</sup> ≤ 1.15). Further characterization analysis revealed that the enhanced color performance was mainly attributed to the uniformly dispersed CoAl<sub>2</sub>O<sub>4</sub> particles with high crystallinity on the surface of kaolinite, which led to a strong reflectance of blue visible light. Therefore, this study is expected to serve as a reference for the cost-effective and eco-friendly preparation of cobalt blue composite pigments.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"458 ","pages":"Article 121007"},"PeriodicalIF":4.5,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143800542","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}

引用次数: 0

Study on spatial flow field instability in a disturbing rotary centrifugal air classifier based on simulation and experimental methods

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2025-04-01 DOI: 10.1016/j.powtec.2025.120990

Xinhao Li , Runyu Liu , Yuhan Liu , Jiale Yuan , Chenlong Duan , Jida Wu , Hong Wang , Haishen Jiang , Long Huang

Efficient particle classification in air classifiers is essential for optimizing industrial processes. However, the instability of the flow field under loading conditions remains a challenge. The gas-solid phase is subject to complex drag forces in the flow field. An imbalance in these forces can result in phenomena such as vortex eccentricity, which adversely affects the separation of target particles. In this paper, a new disturbing rotary centrifugal classifier is designed. Furthermore, numerical simulations and experimental analyses are utilized to investigate how the operating parameters influence regional flow field instability in air classifiers under loading conditions. Following the experiments, the motion of the gas-solid phase cyclone under the influence of a double-vortex structure is explored. The results indicate that the flow field in the toothed blades area exhibits a double-vortex structure with inner quasi-forced vortices and outer quasi-free vortices. The curved impeller area flow field presents a double-vortex structure with outer axial circulation and inner secondary flow. The flow field stability depends on the stability of the double-vortex structure. The impact of double-vortex structure instability on the flow field is mitigated at a critical rotational speed of 950 rpm. Comprehensive signal and experimental analyses reveal that the flow field stabilizes and classification efficiency increases to 94.9 % at a disturbing frequency of 45 Hz (950 rpm), a feed rate of 0.3 kg/s, and an inclination of - 2°. The causes of flow field instability in classifiers are clarified, and alleviation strategies are proposed in this paper, offering valuable insights for large-scale equipment applications.

{"title":"Study on spatial flow field instability in a disturbing rotary centrifugal air classifier based on simulation and experimental methods","authors":"Xinhao Li , Runyu Liu , Yuhan Liu , Jiale Yuan , Chenlong Duan , Jida Wu , Hong Wang , Haishen Jiang , Long Huang","doi":"10.1016/j.powtec.2025.120990","DOIUrl":"10.1016/j.powtec.2025.120990","url":null,"abstract":"<div><div>Efficient particle classification in air classifiers is essential for optimizing industrial processes. However, the instability of the flow field under loading conditions remains a challenge. The gas-solid phase is subject to complex drag forces in the flow field. An imbalance in these forces can result in phenomena such as vortex eccentricity, which adversely affects the separation of target particles. In this paper, a new disturbing rotary centrifugal classifier is designed. Furthermore, numerical simulations and experimental analyses are utilized to investigate how the operating parameters influence regional flow field instability in air classifiers under loading conditions. Following the experiments, the motion of the gas-solid phase cyclone under the influence of a double-vortex structure is explored. The results indicate that the flow field in the toothed blades area exhibits a double-vortex structure with inner quasi-forced vortices and outer quasi-free vortices. The curved impeller area flow field presents a double-vortex structure with outer axial circulation and inner secondary flow. The flow field stability depends on the stability of the double-vortex structure. The impact of double-vortex structure instability on the flow field is mitigated at a critical rotational speed of 950 rpm. Comprehensive signal and experimental analyses reveal that the flow field stabilizes and classification efficiency increases to 94.9 % at a disturbing frequency of 45 Hz (950 rpm), a feed rate of 0.3 kg/s, and an inclination of - 2°. The causes of flow field instability in classifiers are clarified, and alleviation strategies are proposed in this paper, offering valuable insights for large-scale equipment applications.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"458 ","pages":"Article 120990"},"PeriodicalIF":4.5,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143777573","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}

引用次数: 0

CFD-DEM study on effect of particle property on solid-liquid two-phase flow structure in a centrifugal pump under stall conditions

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2025-04-01 DOI: 10.1016/j.powtec.2025.121003

Yong Wang , Ming Li , Jie Chen , Jianing Lei , Zhenyu Tao , Qiang Xu , Houlin Liu

This study investigates the solid-liquid two-phase flow characteristics in a centrifugal pump under stall conditions, with a particular focus on the influence of particle property. A CFD-DEM coupled approach is used to simulate the interaction between liquid and particles. The blockage intensity and pressure pulsation under varying particle concentrations and sizes are analyzed in detail. Entropy theory is used to evaluate the energy loss due to the combined effects of liquid and particles. The results indicate that the severity of stall significantly influences the flow structure. While the primary frequency of pressure pulsation in the impeller is the shaft frequency (f_n), stall vortices induce strong secondary frequency pulsation with a characteristic frequency of 0.11f_n. Compared to the critical stall condition, the blockage intensity is 10 % higher than that under the deep stall condition. Furthermore, the pressure pulsation amplitude and entropy generation are also significantly higher under the deep stall condition. However, the influence of particle concentration and size on flow structure is less pronounced than that of the stall severity. Increased particle concentration and size leads to slight increases in blockage intensity, pressure pulsation amplitude, and entropy generation, with concentration exhibiting a greater impact than size.

{"title":"CFD-DEM study on effect of particle property on solid-liquid two-phase flow structure in a centrifugal pump under stall conditions","authors":"Yong Wang , Ming Li , Jie Chen , Jianing Lei , Zhenyu Tao , Qiang Xu , Houlin Liu","doi":"10.1016/j.powtec.2025.121003","DOIUrl":"10.1016/j.powtec.2025.121003","url":null,"abstract":"<div><div>This study investigates the solid-liquid two-phase flow characteristics in a centrifugal pump under stall conditions, with a particular focus on the influence of particle property. A CFD-DEM coupled approach is used to simulate the interaction between liquid and particles. The blockage intensity and pressure pulsation under varying particle concentrations and sizes are analyzed in detail. Entropy theory is used to evaluate the energy loss due to the combined effects of liquid and particles. The results indicate that the severity of stall significantly influences the flow structure. While the primary frequency of pressure pulsation in the impeller is the shaft frequency (<em>f</em><sub>n</sub>), stall vortices induce strong secondary frequency pulsation with a characteristic frequency of 0.11<em>f</em><sub>n</sub>. Compared to the critical stall condition, the blockage intensity is 10 % higher than that under the deep stall condition. Furthermore, the pressure pulsation amplitude and entropy generation are also significantly higher under the deep stall condition. However, the influence of particle concentration and size on flow structure is less pronounced than that of the stall severity. Increased particle concentration and size leads to slight increases in blockage intensity, pressure pulsation amplitude, and entropy generation, with concentration exhibiting a greater impact than size.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":"458 ","pages":"Article 121003"},"PeriodicalIF":4.5,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143760620","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}

引用次数: 0