This work proposes a novel horizontal high-shear granulator for iron ore granulation before sintering process.The granulation behavior such as growth process and structure of granules were firstly analyzed,followed by...This work proposes a novel horizontal high-shear granulator for iron ore granulation before sintering process.The granulation behavior such as growth process and structure of granules were firstly analyzed,followed by the effects of operation conditions such as water content,initial particle size distribution,and the concentrate ratio.The results show that the granule size increased significantly with increasing the granulation time,and the structure of granule can be divided into three types:non-nuclei,single-nuclei,and multi-nuclei.Water promotes the coalescence and growth of particles,and a better granulation performance was obtained at the water content of 8.8wt%under the current raw material conditions.Increasing the nuclei particle ratio led to an increase in average size of granules and permeability of the granules bed,but a decrease in growth index.Besides,with increasing of concentrate ratio,granulation performance such as granule size,bed permeability,and uniformity became worse.展开更多
The present study seeks the feasibility of using short carbon fibres recycled from polymer matrix composites as alternative to virgin carbon fibres in the reinforcement of magnesium alloys.The microstructures,high tem...The present study seeks the feasibility of using short carbon fibres recycled from polymer matrix composites as alternative to virgin carbon fibres in the reinforcement of magnesium alloys.The microstructures,high temperature mechanical and creep properties of AZ91 alloy and its composites with various recycled carbon fibre contents(2.5 and 5 wt.%)and lengths(100 and 500μm)were investigated in the temperature range of 25-200℃.The microstructural characterization showed that the high shear dispersion technique provided the cast composites with finer grains and relatively homogenous distribution of fibres.The materials tested displayed different behaviour depending on the type of loading.In general,while enhancements in the mechanical properties of composites is attributed to the load bearing and grain refinement effects of fibres,the fluctuations in the properties were discussed on the basis of porosity formation,relatively high reinforcement content leading to fibre clustering and interlayer found between the matrix and reinforcement compared to those of AZ91 alloy.The compressive creep tests revealed similar or higher minimum creep rates in the recycled carbon fibre reinforced AZ91 in comparison to the unreinforced AZ91.展开更多
Small mixer impeller design is not tailored for granulation because impellers are intended for a wide range of processes. The aim of this research was to evaluate the performances of several impellers to provide guida...Small mixer impeller design is not tailored for granulation because impellers are intended for a wide range of processes. The aim of this research was to evaluate the performances of several impellers to provide guidance on the selection and design for the purposes of granulation. Lactose granules were produced using wet granulation with water as a binder. A Kenwood KM070 mixer was used as a standard apparatus and five impeller designs with different shapes and surface areas were used. The efficacy of granulate for- mation was measured by adding an optically sensitive tracer to determine variations in active ingredient content across random samples of granules from the same size classes. It was found that impeller design influenced the homogeneity of the granules and therefore can affect final product performance. The vari- ation in active ingredient content across granules of differing size was also investigated. The results show that small granules were more potent than larger granules,展开更多
There is a need for mesoscale resolution and coupling between flow-field information and the evolution of particle properties in high-shear granulation. We have developed a modelling framework that com- partmentalizes...There is a need for mesoscale resolution and coupling between flow-field information and the evolution of particle properties in high-shear granulation. We have developed a modelling framework that com- partmentalizes the high-shear granulation process based on relevant process parameters in time and space. The model comprises a coupled-flow-field and population-balance solver and is used to resolve and analyze the effects of mesoscales on the evolution of particle properties. A Diosna high-shear mixer was modelled with microcrystalline cellulose powder as the granulation material. An analysis of the flow-field solution and compartmentalization allows for a resolution of the stress and collision peak at the impeller blades. Different compartmentalizations showed the importance of resolving the impeller region, for aggregating systems and systems with breakage. An independent study investigated the time evolution of the flow field by changing the particle properties in three discrete steps that represent pow- der mixing, the initial granulation stage mixing and the late stage granular mixing. The results of the temporal resolution study show clear changes in collision behavior, especially from powder to granular mixing, which indicates the importance of resolving mesoscale phenomena in time and space.展开更多
Nickel-based alloy has been widely used due to its outstanding mechanical properties.However, Nickel-based alloy is a typical difficult-to-machine material, which is a great constrain for its application in the manufa...Nickel-based alloy has been widely used due to its outstanding mechanical properties.However, Nickel-based alloy is a typical difficult-to-machine material, which is a great constrain for its application in the manufacturing field. To improve the surface quality of the ground workpiece, a new high-shear and low-pressure grinding wheel, with high ratio of tangential grinding force to normal grinding force, was fabricated for the grinding of selective laser melting(SLM) manufactured Inconel718 alloy. The principle of high-shear and low-pressure grinding process was introduced in detail, which was quite different from the conventional grinding process. The fabrication process of the new grinding wheel was illustrated. A serial of experiments with different processing parameters were carried out to investigate the grinding performance of the developed grinding wheel via analyzing surface roughness and surface morphology of the ground workpiece.The optimal processing parameters of high-shear and low-pressure grinding were obtained. The surface roughness of ground workpiece was reduced to 0.232 μm from the initial value of 0.490 μm under the optimal grinding conditions. It was found that the initial scratches on the ground workpiece were almost completely removed after the observations with the metalloscopy and the fieldemission scanning electron microscopy(FE-SEM). The capability of the newly developed highshear and low-pressure grinding wheel was validated.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos. 51974048 and 52004046)the China Postdoctoral Science Foundation (Nos. 2021T140783 and 2020M673131)the Postdoctoral Science Foundation of Chongqing (No. cstc2020jcyj-bsh X 0030)
文摘This work proposes a novel horizontal high-shear granulator for iron ore granulation before sintering process.The granulation behavior such as growth process and structure of granules were firstly analyzed,followed by the effects of operation conditions such as water content,initial particle size distribution,and the concentrate ratio.The results show that the granule size increased significantly with increasing the granulation time,and the structure of granule can be divided into three types:non-nuclei,single-nuclei,and multi-nuclei.Water promotes the coalescence and growth of particles,and a better granulation performance was obtained at the water content of 8.8wt%under the current raw material conditions.Increasing the nuclei particle ratio led to an increase in average size of granules and permeability of the granules bed,but a decrease in growth index.Besides,with increasing of concentrate ratio,granulation performance such as granule size,bed permeability,and uniformity became worse.
基金the German Academic Exchange Service(DAAD)for the scholarship。
文摘The present study seeks the feasibility of using short carbon fibres recycled from polymer matrix composites as alternative to virgin carbon fibres in the reinforcement of magnesium alloys.The microstructures,high temperature mechanical and creep properties of AZ91 alloy and its composites with various recycled carbon fibre contents(2.5 and 5 wt.%)and lengths(100 and 500μm)were investigated in the temperature range of 25-200℃.The microstructural characterization showed that the high shear dispersion technique provided the cast composites with finer grains and relatively homogenous distribution of fibres.The materials tested displayed different behaviour depending on the type of loading.In general,while enhancements in the mechanical properties of composites is attributed to the load bearing and grain refinement effects of fibres,the fluctuations in the properties were discussed on the basis of porosity formation,relatively high reinforcement content leading to fibre clustering and interlayer found between the matrix and reinforcement compared to those of AZ91 alloy.The compressive creep tests revealed similar or higher minimum creep rates in the recycled carbon fibre reinforced AZ91 in comparison to the unreinforced AZ91.
文摘Small mixer impeller design is not tailored for granulation because impellers are intended for a wide range of processes. The aim of this research was to evaluate the performances of several impellers to provide guidance on the selection and design for the purposes of granulation. Lactose granules were produced using wet granulation with water as a binder. A Kenwood KM070 mixer was used as a standard apparatus and five impeller designs with different shapes and surface areas were used. The efficacy of granulate for- mation was measured by adding an optically sensitive tracer to determine variations in active ingredient content across random samples of granules from the same size classes. It was found that impeller design influenced the homogeneity of the granules and therefore can affect final product performance. The vari- ation in active ingredient content across granules of differing size was also investigated. The results show that small granules were more potent than larger granules,
文摘There is a need for mesoscale resolution and coupling between flow-field information and the evolution of particle properties in high-shear granulation. We have developed a modelling framework that com- partmentalizes the high-shear granulation process based on relevant process parameters in time and space. The model comprises a coupled-flow-field and population-balance solver and is used to resolve and analyze the effects of mesoscales on the evolution of particle properties. A Diosna high-shear mixer was modelled with microcrystalline cellulose powder as the granulation material. An analysis of the flow-field solution and compartmentalization allows for a resolution of the stress and collision peak at the impeller blades. Different compartmentalizations showed the importance of resolving the impeller region, for aggregating systems and systems with breakage. An independent study investigated the time evolution of the flow field by changing the particle properties in three discrete steps that represent pow- der mixing, the initial granulation stage mixing and the late stage granular mixing. The results of the temporal resolution study show clear changes in collision behavior, especially from powder to granular mixing, which indicates the importance of resolving mesoscale phenomena in time and space.
基金supported by the National Natural Science Foundation of China(Nos.51875329 and 51905322)China postdoctoral Science Foundation(No.2021T140420)+4 种基金Taishan Scholar Special Foundation of Shandong Province(No.tsqn201812064)Shandong Provincial Natural Science Foundation(No.ZR2017MEE050)Shandong Provincial Key Research and Development Project(No.2018GGX103008)Scientific Innovation Project for Young Scientists in Shandong Provincial Universities(No.2019KJB030)Key Research and Development Project of Zibo City(No.2019ZBXC070).
文摘Nickel-based alloy has been widely used due to its outstanding mechanical properties.However, Nickel-based alloy is a typical difficult-to-machine material, which is a great constrain for its application in the manufacturing field. To improve the surface quality of the ground workpiece, a new high-shear and low-pressure grinding wheel, with high ratio of tangential grinding force to normal grinding force, was fabricated for the grinding of selective laser melting(SLM) manufactured Inconel718 alloy. The principle of high-shear and low-pressure grinding process was introduced in detail, which was quite different from the conventional grinding process. The fabrication process of the new grinding wheel was illustrated. A serial of experiments with different processing parameters were carried out to investigate the grinding performance of the developed grinding wheel via analyzing surface roughness and surface morphology of the ground workpiece.The optimal processing parameters of high-shear and low-pressure grinding were obtained. The surface roughness of ground workpiece was reduced to 0.232 μm from the initial value of 0.490 μm under the optimal grinding conditions. It was found that the initial scratches on the ground workpiece were almost completely removed after the observations with the metalloscopy and the fieldemission scanning electron microscopy(FE-SEM). The capability of the newly developed highshear and low-pressure grinding wheel was validated.