检索结果-南通市图书馆

Recent advances in the stereolithographic three-dimensional printing of ceramic cores: Challenges and prospects

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第22期117卷 79-98页

作者： Jinguo Li Xiaolong An jingjing liang Yizhou Zhou Xiaofeng Sun Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Space Manufacturing Technology(Chinese Academy of Sciences Key Laboratory) Beijing 100094China

The increasing demand for geometrically complex structures—specifically, higher-inlet-temperature turbine blades for the fifth-generation or other high-generation machines of advanced fighter aircrafts—hasmade the development of more complex double-walled three-layer hollow-cavity structures a necessity.However, this requires the preparation of complex ceramic cores and advanced, integrated technologies.Stereolithographic three-dimensional printing (SLA-3DP) technology, with digital control upon materialmorphology, composition, and structure, is a high integration and versatile technique that is superior tothe traditional manufacturing techniques for ceramic cores, including gel casting, injection molding, andhot pressing. The latent capacity of this technique is contingent on the progress of processing routesthat significantly reduce the distortion and defect formation in response to the elimination of the reactedorganic monomer phase during photo-curing. Despite the tremendous progress in the field, multiple challenges remain, such as the preparation of high-solid-content and low-viscosity suspensions, SLA-3DP oflarge double-walled ceramic cores with complex structures, and process optimization and sinter strengthening for the fabrication of ceramic cores. These challenges have prevented the broader applications andreduced the impact of the SLA-3DP technology. This review discusses cutting-edge research on the crucialfactors governing this production method. Specifically, we outline the existing challenges within the fieldand provide our perspective on the upcoming research work and progress.

关键词： Stereolithographic three-dimensional printing Ceramic cores,Cutting-edge research

Stereolithography 3D printing of ceramic cores for hollow aeroengine turbine blades

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第32期127卷 177-182页

作者： Xiaolong An Yahang Mu jingjing liang Jinguo Li Yizhou Zhou Xiaofeng Sun School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Semiconductor Manufacturing International Corporation Shanghai201203China

Hollow superalloy or single-crystal superalloy turbine blades are the most important component of advanced aeroengines for fifth-and higher-generation fighter aircrafts [1,2,3]. The thrust-toweight ratio is largely influenced by the turbine inlet temperature,which places strict requirements on the performance of the turbine blades at high operating temperatures [4]. To reduce the operating temperature of the blades, complex internal cooling structures are required. However, the fabrication of complex cooling channels inside the blades is an unquestionably challenging task [5].

关键词： superalloy ceramic Stereo

Ceramic composites toughened by vat photopolymerization 3D printing technology

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2023年第15期146卷 42-48页

作者： Qiaolei Li Zhenxue Pan jingjing liang Zongbo Zhang Jinguo Li Yizhou Zhou Xiaofeng Sun School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Research/Education Centre for Excellence in Molecular Sciences Institute of ChemistryChinese Academy of SciencesBeijing 100190China Space Manufacturing Technology(CAS Key Lab) Beijing 100094China

High strength and high toughness are mutually exclusive in structural materials.In ceramic materials,increasing toughness usually depends on the introduction of a ductile phase that reduces the strength and high-temperature stability of the material.In this work,vat photopolymerization 3D printing technology was used to achieve toughening of ceramic composite material.The friction sliding of the 3D-printed ceramic macrolayer structure results in effective energy dissipation and redistribution of strain in the whole structure,and macroscale toughening of the ceramic material is realized.In addition,the bridging and elongation of the crack in situ amorphous ceramic whiskers were significant microscopic toughening results,coupled with the toughening of the crack tip of nano-ZrO_(2).Multiscale collaborative toughening methods based on 3D-printed ceramics should find wide applications for materials in service at extreme high temperatures.

关键词： Ceramic composites 3D printing Flexure strength Fracture toughness Polysilazane

Manufacturing of ceramic cores:From hot injection to 3D printing

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2023年第3期134卷 95-105页

作者： Qiaolei Li Tianci Chen jingjing liang Chaowei Zhang Jinguo Li Yizhou Zhou Xiaofeng Sun School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Shichangxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering Northeastern UniversityShenyang 110819China Space Manufacturing Technology(CAS Key Lab) Beijing 100094China

With the improvement of aero-engine performance,the preparation of hollow blades of single-crystal superalloys with complex inner cavity cooling structures is becoming increasingly urgent.The ceramic core is the key intermediate part of the preparation and has attracted wide attention.To meet this challenge,new technologies that can make up for the defects of long periods and high costs of fabricating complex structural cores by traditional hot injection technology are needed.Vat photopolymerization 3D printing ceramic technology has been applied to the core field to realize the rapid preparation of complex structural cores.However,the industrial application of this technology still needs further research and improvement.Herein,ceramic cores were prepared using traditional hot injection and vat photopolymerization 3D printing techniques using fused silica,nano-ZrO_(2),and Al_(2)O_(3) powders as starting materials.The 3D printed ceramic core has a typical layered structure with a small pore size and low porosity.Because of the layered structure,the pore area is larger than that of the hot injection ceramic core,the leaching performance has little effect(0.0277 g/min for 3D printing cores,0.298 g/min for hot injection cores).In the X and Y directions,the sintering shrinkage is low(2.7%),but in the Z direction,the shrinkage is large(4.7%).The fracture occurs when the inner layer crack expands and connects with the interlayer crack,forming a stepped fracture in the 3D-printed cores.The bending strength of the 3D printed core at high temperature(1500℃)is 17.3 MPa.These analyses show that the performance of vat photopolymerization 3D-printed ceramic cores can meet the casting requirements of single crystal superalloy blades,which is a potential technology for the preparation of complex structure ceramic cores.The research mode of 3D printing core technology based on the traditional hot injection process provides an effective new idea for promoting the industrial application of 3D printing core technology.

关键词： Ceramic cores 3D printing Hot injection Anisotropic Layer structure

Slurry flow characteristics control of 3D printed ceramic core layered structure:Experiment and simulation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2023年第33期164卷 215-228页

作者： Qiaolei Li Yuxiang Qiu Weiqiang Hou jingjing liang Hui Mei Jinguo Li Yizhou Zhou Xiaofeng Sun School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering Shenyang University of TechnologyShenyang 110870China Space Manufacturing Technology (CAS Key Lab) Beijing 100094China Science and Technology on Thermostructural Composite Materials Laboratory School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi'an710072China

Vat photopolymerization 3D printing ceramic technology provides a feasible process for the preparation of complex internal cooling channels for aeroengine single crystal superalloy hollow blades.However,the typical layered structure characteristics of 3D printing ceramic technology led to the anisotropy of ceramic core strength and sintering shrinkage,which greatly affects the performance and accuracy of the complex structure core and requires further research and improvement.Herein,the influence of the thickness of the slurry layer on the flow characteristics of the slurry in the process of the vat photopolymerization 3D printing slurry spreading was systematically studied by the method of simulation and experiment.The simulation results show that the positions of the turbulent zone and maximum velocity zone in the scraper front affect the redistribution of powder particles with different sizes.The layered structure was caused by the redistribution of ceramic particles of different sizes in the slurry layer.By controlling the turbulent flow zone and the maximum velocity zone of the scraper leading edge,the phenomenon of laminar flow can be weakened and the particle redistribution can be improved.With the increase of the thickness of the printing layer,the layered structure appears gradually,and the pores at the interface of the layered structure gradually concentrated into the interfacial pore lines from the uniform distribution,and the crack propagation changes from intergranular micro-crack to interlayer macro-crack.The combination of finite element simulation and experiment,through the slurry flow characteristics to control the layered structure of reductive vat photopolymerization ceramic core 3D printing,the control of crack propagation mode,element distribution and pore evolution of the core was accomplished,which lays a foundation for the performance control of ceramic 3D printing technology.

关键词： 3D printing Ceramic cores Slurry flow Lamellar structure Porosity evolution

Balancing flexural strength and porosity in DLP-3D printing Al_(2)O_(3)cores for hollow turbine blades

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第9期104卷 19-32页

作者： Qiaolei Li Xiaolong An jingjing liang Yongsheng Liu Kehui Hu Zhigang Lu Xinyan Yue Jinguo Li Yizhou Zhou Xiaofeng Sun School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Space Manufacturing Technology(CAS Key Lab) Beijing 100094China NPU-SAS Joint Research Center of Advanced Ceramics Northwestern Polytechnical UniversityXi’an 710072China State Key Laboratory of Tribology Tsinghua UniversityBeijing 100084China School of Materials Science and Engineering Northeastern UniversityShenyang 110819China

High porosity and high strength are usually mutually exclusive in the preparation of ceramic materials.However,high porosity and flexural strength are required for the preparation of complex ceramic cores for hollow turbine blades.In this study,Al_(2)O_(3)cores with high porosity and high flexural strength were successfully prepared using digital light processing(DLP)3 D printing technology.The influence of sintering temperature on the microstructure,pore evolution,and flexural strength of the cores were investigated.With an increase in the sintering temperature,the porosity of the ceramic cores first increased and then decreased,reaching a maximum value of 35%at 1400℃.The flexural strength increased with the increase in sintering temperature,but at 1400℃the incremental enhancement of flexural strength was greatest.Combined with the core service requirements and core performance,this study selected 1400℃(open porosity of 35.1%and flexural strength of 20.3 MPa)as the optimal sintering temperature for the DLP-3 D printed Al_(2)O_(3)core.

关键词： 3D printing Ceramic cores Flexural strength Porosity Sintering temperature

Tree species richness enhances stand productivity while stand structure can have opposite effects, based on forest inventory data from Germany and the United States of America

在线全文

学校读者我要写书评

暂无评论

Forest Ecosystems 2018年第1期5卷 36-52页

作者： Laura Zeller jingjing liang Hans Pretzsch Center of Life and Food Sciences Weihenstephan Technical University of MunichHans-Carl-von-Carlowitz-Platz 285354 FreisingGermany Division of Forestry and Natural Resources Davis College of AgricultureNatural Resources&DesignWest Virginia University340 Percival HallMorgantownWV 26506-6108USA

Background： in recent studies, mixed forests were found to be more productive than monocultures with everything else remaining the same. Methods： To find out if this productivity is caused by tree species richness, by a more heterogeneous stand structure or both, we analyzed the effects of forest structure and tree species richness on stand productivity, based on inventory data of temperate forests in the United States of America and Germany. Results： Having accounted for effects such as tree size and stand density, we found that：（I） tree species richness increased stand productivity in both countries while the effect of tree size heterogeneity on productivity was negative in Germany but positive in the USA; （11） productivity was highest at sites with an intermediate amount of precipitation; and （111） growth limitations due water scarcity or low temperature may enhance structural heterogeneity. Conclusions： In the context of forest ecosystem goods and services, as well as future sustainable forest resource management, the associated implications would be：

关键词： Big data Overyielding Tree size heterogeneity Tree species mixing Climate Biodiversity-productivityrelationship

Systematic Hydrological Evaluation of the Noah-MP Land Surface Model over China

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2019年第11期36卷 1171-1187,I0001,I0002,I0003,I0004,I0005页

作者： jingjing liang Zongliang YANG Peirong LIN Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China Jackson School of Geosciences University of Texas at Austin Austin TX 78712 USA Department of Civil and Environmental Engineering Princeton University Princeton NJ 08540 USA

We evaluate water budget components-namely,soil moisture,runoff,evapotranspiration,and terrestrial water storage (TWS)-simulated by the Noah land surface model with multi-parameterization options (Noah-MP) in China,a large geographic domain challenging for hydrological modeling due to poor observational data and a lack of one single parameterization that can fit for complex hydrological processes.By comparing the model simulations with multi-source reference data,we show that Noah-MP can generally reproduce the overall spatiotemporal patterns of runoff and evapotranspiration over six major river basins,with the annual correlation coefficients generally greater than 0.8 and the Nash-Sutcliffe model efficiency coefficient exceeding 0.5.Among the six basins evaluated,the best model performance is seen over the Huaihe River basin.The temporal trend of the modeled TWS anomalies agrees well with GRACE (Gravity Recovery and Climate Experiment) observations,capturing major flood and drought events in different basins.Experiments with 12 selected physical parameterization options show that the runoff parameterization has a stronger impact on the simulated soil moisture-runoff-evapotranspiration relationships than the soil moisture factor for stomatal resistance schemes,a result consistent with previous studies.Overall,Noah-MP driven by GLDAS forcing simulates the hydrological variables well,except for the Songliao basin in northeastern China,likely because this is a transitional region with extensive freeze-thaw activity,while representations of human activities may also help improve the model performance.

关键词： hydrological evaluation Noah-MP multi-parameterization China

Reduced phosphatidylcholine synthesis suppresses the embryonic lethality of seipin deficiency

在线全文

学校读者我要写书评

暂无评论

Life Metabolism 2022年第2期1卷 175-189页

作者： Jinglin Zhu Sin Man Lam Leilei Yang jingjing liang Mei Ding Guanghou Shui Xun Huang State Key Laboratory of Molecular Developmental Biology Institute of Genetics and Developmental BiologyChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

Seipin plays a vital role in lipid droplet homeostasis,and its deficiency causes congenital generalized lipodystrophy type II in humans.It is not known whether the physiological defects are all caused by cellular lipid droplet defects.Loss-of-function mutation of seip-1,the Caenorhabditis elegans seipin ortholog,causes embryonic lethality and lipid droplet abnormality.We uncover nhr-114 and spin-4 as two suppressors of seip-1 embryonic lethality.Mechanistically,nhr-114 and spin-4 act in the“B12-one-carbon cycle-phosphatidylcholine(PC)”axis,and reducing PC synthesis suppresses the embryonic lethality of seip-1 mutants.Conversely,PC deficiency enhances the lipid droplet abnormality of seip-1 mutants.The suppression of seip-1 embryonic lethality by PC reduction requires polyunsaturated fatty acid.In addition,the suppression is enhanced by the knockdown of phospholipid scramblase epg-3.Therefore,seipin and PC exhibit opposite actions in embryogenesis,while they function similarly in lipid droplet homeostasis.Our results demonstrate that seipin-mediated embryogenesis is independent of lipid droplet homeostasis.

关键词： seipin phosphatidylcholine embryogenesis lipid droplet