The effect of copper concentration on the performance of the catalytic reaction between silicon and methyl chloride was investigated using online gas chromatogram. The catalyst concentration greatly influences various...The effect of copper concentration on the performance of the catalytic reaction between silicon and methyl chloride was investigated using online gas chromatogram. The catalyst concentration greatly influences various aspects of the direct organosilane synthesis process, including the reaction rate, the selec- tivity, and the silicon conversion. The reaction activity and the silicon conversion increase as the catalyst concentration increases. However, the reaction selectivity decreases for the catalyst concentrations more .than 9 wt.%. The cross-sections of deactivated contact mass particles were observed by optical microscopy and analyzed by scanning electron microscope combined with energy dispersive X-ray detector （SEM-EDX） The observations showed that a textured substance formed on the original flat surface of the silicon particles after deactivation with copper only in a shallow surface layer of the contact mass. This indicates that the copper diffusion is the rate limiting step which causes the reaction deactivation.展开更多
Developing high-performance energy storage and conversion(ESC)device relies on both the utilization of good constituent materials and rational design of assembly structure.Graphene-based materials,due to their superio...Developing high-performance energy storage and conversion(ESC)device relies on both the utilization of good constituent materials and rational design of assembly structure.Graphene-based materials,due to their superior properties like high electrical/thermal conductivity,large surface area,and unique optical properties,have been extensively reported for ESC applications.The emerging three-dimensional(3D)printing techniques,especially extrusion-based direct ink writing technique,have brought a revolutionary improvement in structure control accuracy and designing capability to graphene-based macro-assemblies,triggering a boost in functionalities and performances of graphene-based ESC devices.In these circumstances,understanding the very recent progress of 3Dprinted graphene materials and their design philosophy to bring new concepts for material designs and address the requirements for high-performance ESC devices are urgently important.In this review,we aim to outline recent developments in 3D printing of graphene-based materials and their applications in ESC applications.Basic requirements and theoretical analysis for preparation printable inks are discussed,as well as feasible GO ink preparation strategies in existing literatures.The representative explorations of 3D-printed graphenematerials in ESC applications like batteries,supercapacitors,solar steam generators,and electro-thermal conversion are also reviewed.This study attempts to provide a comprehensive overview of the progresses and limitations of present 3D printed graphenematerials,and seeks to enlighten the opportunities and orientations of future research in this field.展开更多
Many wave energy conversion devices have not been well received. The main reasons are that they are too complicated and not economical. However, in the last two decades direct conversion systems have drawn the attenti...Many wave energy conversion devices have not been well received. The main reasons are that they are too complicated and not economical. However, in the last two decades direct conversion systems have drawn the attention of researchers to their widely distributed energy source due to their simple structure and low cost. The most well-known direct conversion systems presently in use include the Archimedes Wave Swing (AWS) and Power Buoy (PB). In this paper, these two systems were simulated in the same conditions and their behaviors were studied in different wave conditions. In order to verify the simulations, results of the generator of the finite element computations were followed. An attempt was made to determine the merits and drawbacks of each method under different wave conditions by comparing the performance of the two systems. The wave conditions suitable for each system were specified.展开更多
Excavation and earth surface processes(e.g.,river incision)always induce the unloading of stress,which can cause the failure of rocks.To study the shear mechanical behavior of a rock sample under unloading normal stre...Excavation and earth surface processes(e.g.,river incision)always induce the unloading of stress,which can cause the failure of rocks.To study the shear mechanical behavior of a rock sample under unloading normal stress conditions,a new stress path for direct shear tests was proposed to model the unloading of stress caused by excavation and other processes.The effects of the initial stresses(i.e.,the normal stress and shear stress before unloading)on the shear behavior and energy conversion were investigated using laboratory tests and numerical simulations.The shear strength of a rock under constant stress or under unloading normal stress conforms to the Mohr Coulomb criterion.As the initial normal stress increases,the cohesion decreases linearly and the tangent of the internal friction angle increases linearly.Compared with the results of the tests under constant normal stress,the cohesions of the rock samples under unloading normal stress are smaller and their internal friction angles are larger.A strength envelope surface can be used to describe the relationship between the initial stresses and the failure normal stress.Shear dilatancy can decrease the total energy of the direct shear test under constant normal stress or unloading normal stress,particularly when the stress levels(the initial stresses in the test under unloading normal stress or the normal stress in the test under constant normal stress)are high.The ratio of the dissipated energy to the total energy at the moment failure occurs decreases exponentially with increasing initial stresses.The direct shear test under constant normal stress can be considered to be a special case of a direct shear test under unloading normal stress with an unloading amount of zero.展开更多
文摘The effect of copper concentration on the performance of the catalytic reaction between silicon and methyl chloride was investigated using online gas chromatogram. The catalyst concentration greatly influences various aspects of the direct organosilane synthesis process, including the reaction rate, the selec- tivity, and the silicon conversion. The reaction activity and the silicon conversion increase as the catalyst concentration increases. However, the reaction selectivity decreases for the catalyst concentrations more .than 9 wt.%. The cross-sections of deactivated contact mass particles were observed by optical microscopy and analyzed by scanning electron microscope combined with energy dispersive X-ray detector （SEM-EDX） The observations showed that a textured substance formed on the original flat surface of the silicon particles after deactivation with copper only in a shallow surface layer of the contact mass. This indicates that the copper diffusion is the rate limiting step which causes the reaction deactivation.
基金NationalNatural Science Foundation of China,Grant/Award Numbers:52090030,51533008,51973191,51703194,51803177China Postdoctoral Science Foundation,Grant/Award Number:2021M692772+4 种基金National Key R&D Program of China,Grant/Award Number:2016YFA0200200FundamentalResearch Funds for the CentralUniversities,Grant/Award Numbers:30920041106,K20200060,30919011271Hundred Talents Programof Zhejiang University,Grant/Award Number:188020*194231701/113Key Research and Development Plan of Zhejiang Province,Grant/Award Number:2018C01049KeyLaboratory of Novel Adsorption and Separation Materialsand Application Technology of Zhejiang Province,Grant/AwardNumber:512301-I21502。
文摘Developing high-performance energy storage and conversion(ESC)device relies on both the utilization of good constituent materials and rational design of assembly structure.Graphene-based materials,due to their superior properties like high electrical/thermal conductivity,large surface area,and unique optical properties,have been extensively reported for ESC applications.The emerging three-dimensional(3D)printing techniques,especially extrusion-based direct ink writing technique,have brought a revolutionary improvement in structure control accuracy and designing capability to graphene-based macro-assemblies,triggering a boost in functionalities and performances of graphene-based ESC devices.In these circumstances,understanding the very recent progress of 3Dprinted graphene materials and their design philosophy to bring new concepts for material designs and address the requirements for high-performance ESC devices are urgently important.In this review,we aim to outline recent developments in 3D printing of graphene-based materials and their applications in ESC applications.Basic requirements and theoretical analysis for preparation printable inks are discussed,as well as feasible GO ink preparation strategies in existing literatures.The representative explorations of 3D-printed graphenematerials in ESC applications like batteries,supercapacitors,solar steam generators,and electro-thermal conversion are also reviewed.This study attempts to provide a comprehensive overview of the progresses and limitations of present 3D printed graphenematerials,and seeks to enlighten the opportunities and orientations of future research in this field.
基金supported by the National Natural Science Foundation of China(21833004)Taishan Scholar Program of Shandong Provincethe Natural Science Foundation of Shandong Province(ZR2020QA055)。
文摘Many wave energy conversion devices have not been well received. The main reasons are that they are too complicated and not economical. However, in the last two decades direct conversion systems have drawn the attention of researchers to their widely distributed energy source due to their simple structure and low cost. The most well-known direct conversion systems presently in use include the Archimedes Wave Swing (AWS) and Power Buoy (PB). In this paper, these two systems were simulated in the same conditions and their behaviors were studied in different wave conditions. In order to verify the simulations, results of the generator of the finite element computations were followed. An attempt was made to determine the merits and drawbacks of each method under different wave conditions by comparing the performance of the two systems. The wave conditions suitable for each system were specified.
基金This research was funded by the Fundamental Research Funds for the Central Universities,CHD(Grant Nos.300102210307 and 300102210308)the National Natural Science Foundation of China(Grant Nos.41831286 and 41972297)the Natural Science Foundation of Shaanxi Province(Grant No.2020JQ-369).
文摘Excavation and earth surface processes(e.g.,river incision)always induce the unloading of stress,which can cause the failure of rocks.To study the shear mechanical behavior of a rock sample under unloading normal stress conditions,a new stress path for direct shear tests was proposed to model the unloading of stress caused by excavation and other processes.The effects of the initial stresses(i.e.,the normal stress and shear stress before unloading)on the shear behavior and energy conversion were investigated using laboratory tests and numerical simulations.The shear strength of a rock under constant stress or under unloading normal stress conforms to the Mohr Coulomb criterion.As the initial normal stress increases,the cohesion decreases linearly and the tangent of the internal friction angle increases linearly.Compared with the results of the tests under constant normal stress,the cohesions of the rock samples under unloading normal stress are smaller and their internal friction angles are larger.A strength envelope surface can be used to describe the relationship between the initial stresses and the failure normal stress.Shear dilatancy can decrease the total energy of the direct shear test under constant normal stress or unloading normal stress,particularly when the stress levels(the initial stresses in the test under unloading normal stress or the normal stress in the test under constant normal stress)are high.The ratio of the dissipated energy to the total energy at the moment failure occurs decreases exponentially with increasing initial stresses.The direct shear test under constant normal stress can be considered to be a special case of a direct shear test under unloading normal stress with an unloading amount of zero.
