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quantitative characterization of defects in stereolithographic additive manufactured ceramic using X-ray computed tomography

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Journal of Materials Science & Technology 2022年第23期118卷 153-166页

作者： Keqiang Zhang Qiaoyu Meng Xueqin Zhang zhaoliang qu Rujie He Institute of Advanced Structure Technology Beijing Institute of TechnologyBeijing 100081China Beijing Key Laboratory of Lightweight Multi-Functional Composite Materials and Structures Beijing Institute of TechnologyBeijing 100081Chin

Ceramics have been widely fabricated by additive manufacturing(AM).Compared to conventional technologies,the strength of additive manufactured ceramic is relatively low owing to the formation of defects during manufacturing *** defects have significant effects on the microstructure and mechanical properties of additive manufactured ***,systematic research on defects,including defect geometrical features,quantitative statistics,and formation mechanism,as well as the intrinsic relationship with mechanical properties,need to be studied in *** this work,Al2 O3 ceramics were prepared from photosensitive slurries with different solid loadings by using stereolithographic(SL)additive *** defects,including their sizes and distributions,in both green and sintered bodies were investigated by using scanning electron microscopy(SEM)and X-ray computed tomography(X-CT).Geometrical features and quantitative statistics of the defects were evaluated and discussed to reveal their formation ***,the intrinsic relationship between defects and mechanical properties of the additive manufactured ceramic was *** study can give some fundamental understanding of the defects in additive manufactured ceramics.

关键词： Ceramic Stereolithographic additive manufacturing Defects X-CT Strength

A modified single edge V-notched beam method for evaluating surface fracture toughness of thermal barrier coatings

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Applied Mathematics and Mechanics(English Edition) 2023年第5期44卷 693-710页

作者： Haoran BAI Zhanyu WANG Sangyu LUO zhaoliang qu Daining FANG Institute of Advanced Structure Technology Beijing Institute of TechnologyBeijing 100081China

The surface fracture toughness is an important mechanical parameter for studying the failure behavior of air plasma sprayed(APS)thermal barrier coatings(TBCs).As APS TBCs are typical multilayer porous ceramic materials,the direct applications of the traditional single edge notched beam(SENB)method that ignores those typical structural characters may cause *** measure the surface fracture toughness more accurately,the effects of multilayer and porous characters on the fracture toughness of APS TBCs should be *** this paper,a modified single edge V-notched beam(MSEVNB)method with typical structural characters is *** to the finite element analysis(FEA),the geometry factor of the multilayer structure is *** to the narrower V-notches,a more accurate critical fracture stress is *** on the Griffith energy balance,the reduction of the crack surface caused by micro-defects is *** MSEVNB method can measure the surface fracture toughness more accurately than the SENB method.

关键词： thermal barrier coating(TBC) surface fracture toughness modified single edge V-notched beam(MSEVNB)method multilayer structure micro-defect

Review on mechanics of ultra-high-temperature materials

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Acta Mechanica Sinica 2021年第9期37卷 1347-1370,I0001页

作者： Daining Fang Weiguo Li Tianbao Cheng zhaoliang qu Yanfei Chen Ruzhuan Wang Shigang Ai Institute of Advanced Structure Technology Beijing Institute of TechnologyBeijing100081China College of Engineering Peking UniversityBeijing100871China College of Aerospace Engineering Chongqing UniversityChongqing400044China School of Metallurgy and Materials Engineering Chongqing University of Science and TechnologyChongqing401331China

Ultra-high-temperature materials have applications in aerospace and nuclear *** are usually subjected to complex thermal environments during *** mechanical properties of materials in ultra-high-temperature environments have been attracted increasing ***,the characterization and evaluation of ultra-high-temperature mechanical properties of materials are still challenging *** article presents a review on the mechanical properties of materials at elevated *** experimental results and techniques on the ultra-high-temperature mechanical properties of materials are *** constitutive models of materials at elevated temperatures are *** recent research progress on the quantitative theoretical characterization models for the temperature-dependent fracture strength of advanced ceramics and their composites is also given,and the emphasis is placed on the applications of the force-heat equivalence energy density *** thermal–mechanical-oxygen coupled computational mechanics of materials are ***,the outlook and concluding remarks are highlighted.

关键词： Ultra-high-temperature materials Mechanical properties Mechanical testing Theoretical characterization Numerical simulation

In-situ X-ray computed tomography tensile tests and analysis of damage mechanism and mechanical properties in laser powder b e d fused Invar 36 alloy

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Journal of Materials Science & Technology 2024年第8期175卷 29-46页

作者： Qidong Yang Shuo Yang Shiyu Ma Junhan Zhou Ye Zhou Rongzheng Huang Kai Wei zhaoliang qu Xujing Yang Key Laboratory of Advanced Design and Simulation Techniques for Special Equipment Ministry of EducationHunan UniversityChangsha 410082China Institute of Advanced Structure Technology Beijing Institute of TechnologyBeijing 100081China State Key Laboratory of Precision Manufacturing for Extreme Service Performance Central South UniversityChangsha 410083China

Laser powder bed fusion(LPBF)is a potential additive manufacturing process to manufacture Invar 36 alloy components with complicated *** it inevitably introduces specific microstructures and pore defects,which will further influence the mechanical ***,aiming at exploring the LPBF process-related microstructures and pore defects,and especially their influences on the damage mechanism and mechanical properties,Invar 36 alloy was manufactured by LPBF under designed different laser scanning *** microstructure observations reveal that higher scanning speeds lead to equiaxed and short columnar grains with higher dislocation density,while lower scanning speeds result in elongated columnar grains with lower dislocation *** pore defects analyzed by X-ray computed tomography(XCT)suggest that the high laser scanning speed gives rise to numerous lamellar and large lack-of-fusion(LOF)pores,and the excessively low laser scanning speed produces relatively small keyhole pores with high ***,the insitu XCT tensile tests were originally performed to evaluate the damage evolution and failure ***,high laser scanning speed causes brittle fracture due to the rapid growth and coalescence of initial lamellar LOF pores along the scan-ning *** laser scanning speed induces ductile fracture originating from unstable depressions in the surfaces,while metallurgical and keyhole pores have little impact on damage ***,the process-structure-property correlation is *** presence of high volume fraction of lamel-lar LOF pores,resulting from high scanning speed,leads to inferior yield strength and ***,specimens without LOF pores exhibit larger grain sizes and lower dislocation density at decreased scanning speeds,slightly reducing yield strength while slightly enhancing *** understanding lays the foundation for widespread applications of LPBF-processed Invar 36 alloy

关键词： Invar 36 alloy Laser powder bed fusion Microstructure Pore defects Mechanical property X-ray tomography in-situ tensile test

碳纤维增强碳基复合材料抗氧化涂层的微米压痕力学性能表征

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中国科技论文 2019年第4期14卷 363-366,377页

作者：于泽军曲兆亮北京大学经济学院北京100871 华夏幸福产业投资有限公司北京100027 北京理工大学先进结构技术研究院北京100081

为测试得到抗氧化涂层的本征力学性能,利用微米压痕技术研究了涂层的力学行为。通过低压化学气相沉积工艺在碳纤维增强碳基复合材料表面制备得到了碳化铪/碳化硅(HfC/SiC)抗氧化涂层,利用微米压痕技术在HfC/SiC抗氧化涂层表面开展了一... 详细信息

为测试得到抗氧化涂层的本征力学性能,利用微米压痕技术研究了涂层的力学行为。通过低压化学气相沉积工艺在碳纤维增强碳基复合材料表面制备得到了碳化铪/碳化硅(HfC/SiC)抗氧化涂层,利用微米压痕技术在HfC/SiC抗氧化涂层表面开展了一系列不同最大压入载荷的压痕试验,提取得到了压痕载荷位移曲线。并根据Oliver-Pharr方法分析得到了试样材料的弹性模量。研究发现,试样材料弹性模量的数值和离散程度均随最大压入载荷的增大而逐渐减小。综合考虑基底效应和表面粗糙度的影响,确定最大压入载荷为5N时,对应的模量为HfC/SiC抗氧化涂层的本征模量,数值为(29.67±4.72)GPa。微米压痕技术相较于纳米压痕技术,与涂层材料的作用区域更大,可覆盖涂层表面更多的微结构,可以更加真实地表征涂层的整体力学性能,而非微结构的局部性能。

关键词：材料学炭/炭复合材料抗氧化涂层微米压痕技术力学性能表征弹性模量

Lymphatic vessel:origin,heterogeneity,biological functions,and therapeutic targets

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Signal Transduction and Targeted Therapy 2024年第2期9卷 442-478页

作者： zhaoliang Hu Xushi Zhao Zhonghua Wu Bicheng qu Minxian Yuan Yanan Xing Yongxi Song Zhenning Wang Department of Surgical Oncology and General Surgery The First Hospital of China Medical UniversityKey Laboratory of Precision Diagnosis and Treatment of Gastrointestinal Tumors(China Medical University)Ministry of Education155 North Nanjing StreetHeping DistrictShenyang 110001China

Lymphatic vessels,comprising the secondary circulatory system in human body,play a multifaceted role in maintaining homeostasis among various tissues and *** are tasked with a serious of responsibilities,including the regulation of lymph absorption and transport,the orchestration of immune surveillance and *** vessel development undergoes a series of sophisticated regulatory signaling pathways governing heterogeneous-origin cell populations stepwise to assemble into the highly specialized lymphatic vessel ***,as defined by new lymphatic vessels sprouting from preexisting lymphatic vessels/embryonic veins,is the main developmental mechanism underlying the formation and expansion of lymphatic vessel networks in an ***,abnormal lymphangiogenesis could be observed in many pathological conditions and has a close relationship with the development and progression of various *** studies have revealed a set of lymphangiogenic factors and cascades that may serve as the potential targets for regulating abnormal lymphangiogenesis,to further modulate the progression of ***,an increasing number of clinical trials have demonstrated the promising interventions and showed the feasibility of currently available treatments for future clinical *** lymphangiogenic promoters or inhibitors not only directly regulates abnormal lymphangiogenesis,but improves the efficacy of diverse *** conclusion,we present a comprehensive overview of lymphatic vessel development and physiological functions,and describe the critical involvement of abnormal lymphangiogenesis in multiple ***,we summarize the targeting therapeutic values of abnormal lymphangiogenesis,providing novel perspectives for treatment strategy of multiple human diseases.

关键词： therapeutic origin specialized

Low-content and highly effective zoned Rh and Pd three-way catalysts for gasoline particulate filter potentially meeting Euro 7

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Journal of Rare Earths 2023年第6期41卷 905-916,I0004页

作者： Ying Xin Hanxue Zhang Pan Li Ningning qu Ahui Tang Fuzhen Yang Dongxu Han Junxiu Jia Jin Wang Lirong Zheng zhaoliang Zhang School of Chemistry and Chemical Engineering Shandong Provincial Key Laboratory of Fluorine Chemistry and Chemical MaterialsUniversity of JinanJinan 250022China Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China Institute of Catalysis for Energy and Environment College of Chemistry and Chemical EngineeringShenyang Normal UniversityShenyang 110034China

The next-generation Euro 7 standard proposed much lower pollutant limits from gasoline vehicles,specifically for CO and NO_(x),which would be challenging for the three-way catalysts(TWCs)utilized commercially to eliminate these *** with reductive(Rh)and oxidative(Pd)active components on gasoline particulate filters(TWC on GPF)play importantly auxiliary roles in the remediation of CO and NO_(x)downstream the close coupled TWCs to meet their emission ***,a low-content Rh-based TWC(0.17 wt%)zoned with a less expensive Pd-based TWC(0.29 wt%)for GPF applications(cGPF)is reported using improved colloidal deposition *** supporting of Rh on Y-stabilized ZrO_(2)rather than on CeO_(2)-ZrO_(2)inhibits the formation of inactive Ce rhodate species,while Pd on CeO_(2)-ZrO_(2)not only guarantees the high oxygen storage capacity(OSC)but also enhances catalytic *** layout of the front one-fifth in volume being 0.29 wt%Pd on Ce_(0.43)Zr_(0.5)7O_(2)and the rear four-fifths being 0.17 wt%Rh on Zr_(0.85)Y_(0.15)O_(2)prevents the possible alloying of Rh with *** highly effective zoned Rh and Pd TWCs show synergistic three-way activity before and after severe hydrothermal aging at 1000℃with 10%water for24 h,which could be potential choices for close coupled GPF application to satisfy the upcoming stringent emission standards,such as Euro 7 and China 6b.

关键词： Three-way catalyst Zoned catalyst Ultra-low platinum group metal loading Gasoline particulate filter Oxygen storage capacity Rare earths

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时空克里金评估河套灌区土壤盐分时空格局

干旱区研究 2023年第2期40卷 182-193页

作者：孙贯芳高照良朱焱杨金忠屈忠义西北农林科技大学水土保持研究所陕西杨凌712100 武汉大学水资源与水电工程科学国家重点实验室湖北武汉430072 内蒙古农业大学水利与土木建筑工程学院内蒙古呼和浩特010018

区域土壤盐分时空变异性大,采用经典统计和地统计方法无法准确判断取样时间不规则、空间位置不一致的土壤盐分的时空变化趋势。本文以内蒙古河套灌区隆胜研究区68个监测点0~1.8 m土壤剖面4582个土壤盐分数据为基础,利用时空地统计方法... 详细信息

区域土壤盐分时空变异性大,采用经典统计和地统计方法无法准确判断取样时间不规则、空间位置不一致的土壤盐分的时空变化趋势。本文以内蒙古河套灌区隆胜研究区68个监测点0~1.8 m土壤剖面4582个土壤盐分数据为基础,利用时空地统计方法分析区域土壤盐分时空变化特征,比较时空克里金较传统空间克里金插值的精度提升效果,并验证时空地统计方法在监测点减少50%情况下预测区域盐分时空动态的能力。结果表明:(1)该研究区土壤盐分空间变异系数的变化范围是0.43~1.14,为中强变异,0~0.6 m根系层生育期积盐、非生育期脱盐,0.6~1.8 m土壤剖面生育期脱盐、非生育期积盐、农田土壤盐分有明显的季节性规律。(2)和度量模型能较好拟合盐分时空经验半方差,各层土壤盐分预测值和观测值间的均方根误差RMSE均小于0.21 dS·m^(-1),较传统空间克里金的RMSE小0.02~0.09 d S·m^(-1)。(3)采用该方法在减少50%监测点情况下确定的土壤盐渍化分布与所有取样点确定的结果一致性较高,0~0.6 m和0.6~1.2 m土壤盐分面积间的相对误差MRE分别为-13.20%和-8.35%,RMSE为466.67hm2和494.43 hm2,决定系数R2为0.79和0.72。时空克里金同时利用了土壤盐分时间和空间上的更多信息,实现了稀疏盐分监测点数据集土壤盐分时空动态的精确估计,可极大提高区域土壤盐分时空格局监测的效率。

关键词：土壤盐分时空克里金河套灌区时空格局和度量模型

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河套灌区根系层-深层土壤盐分动态及适宜控盐埋深

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农业工程学报 2024年第21期40卷 91-100页

作者：孙贯芳翟明飞王春语朱焱屈忠义李永红高照良西北农林科技大学水土保持研究所杨凌712100 武汉大学水资源工程与调度全国重点实验室武汉430072 内蒙古农业大学水利与土木建筑工程学院呼和浩特010018

浅地下水埋深诱发的土壤次生盐碱化是干旱灌区面临的重要生态环境问题。为探讨河套灌区根系层-深层土壤盐分动态及适宜控盐埋深,该研究基于内蒙古河套灌区隆胜研究区68块灌溉农田连续2 a生育期初和生育期末0~1.80 m的土壤盐分、地下水... 详细信息

浅地下水埋深诱发的土壤次生盐碱化是干旱灌区面临的重要生态环境问题。为探讨河套灌区根系层-深层土壤盐分动态及适宜控盐埋深,该研究基于内蒙古河套灌区隆胜研究区68块灌溉农田连续2 a生育期初和生育期末0~1.80 m的土壤盐分、地下水埋深、地下水盐分的监测和作物种植类型的调查,分析了根系层-深层土壤盐分时空动态、季节性平衡机制、多个因素(如气象条件、地下水埋深、地下水矿化度、作物类型和生育期初土壤盐分等)间相互作用对生育期土壤盐分变化的影响,探明了土壤盐分对地下水年际和季节性埋深的响应。结果表明,根系层土壤盐分均在生育期积盐,休耕期脱盐;深层土壤盐分均在生育期脱盐,休耕期积盐。作物类型、生育期初(5月初)地下水埋深、生育期地下水埋深、地下水盐分及生育期初根系层土壤盐分均对生育期根系层土壤盐分变化有显著影响(P<0.05)。地下水状况与其他各因素的相互作用对生育期根系层土壤盐分变化的影响与水文年型有密切的关系。生育期初根系层土壤盐分随着地下水埋深的增大而指数减小,土壤盐分小于均值的取样点地下水埋深不小于1.60 m。当年均地下水埋深小于2.50 m,不同土层的盐分值和盐分降低速率随地下水埋深的增加而降低。在地下水埋深小于2.50 m的条件下,以概率分布法得出根系层土壤盐分中位数对应的年均适宜临界控盐地下水埋深为1.77 m,土壤盐分远大于中位数或均值的取样点的地下水埋深均小于该埋深。因此,从控盐角度考虑,建议该研究区地下水埋深生育期初应不小于1.60 m,年均地下水埋深应不小于1.77 m。研究结果可为河套灌区通过灌溉制度的设计和排水措施的合理布局控制地下水埋深提供理论依据。

关键词：土壤盐分作物河套灌区地下水埋深