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China Foundry 2024年第1期21卷 11-19页

作者： Wen-ning Liu Wei Zhang Peng-yue Wang Yi-xian Liu Xiang-yi Jiao Ao-xiang Wan Cheng-gang Wang Guo-dong Tong Shou-mei Xiong School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China Key Laboratory for Advanced Materials Processing Technology Tsinghua UniversityBeijing 100084Beijing China FAW Group Co. Ltd.Changchun 130013China China FAW Foundry Co. Ltd.Changchun 130013China

The effect of slow shot speed on externally solidified crystal(ESC),Porosity and tensile property in a newly developed high-pressure die-cast Al-Si alloy was investigated by optical microscopy(OM),scanning electron microscopy(SEM)and laboratory computed tomography(CT).Results showed that the newly developed AlSi9MnMoV alloy exhibited improved mechanical properties when compared to the AlSi10MnMg alloy.The AlSi9MnMoV alloy,which was designed with trace multicomponent additions,displays a notable grain refining effect in comparison to the AlSi10MnMg alloy.Refining elements Ti,Zr,V,Nb,B promote heterogeneous nucleation and reduce the grain size of primaryα-Al.At a lower slow shot speed,the large ESCs are easier to form and gather,developing into the dendrite net and net-shrinkage.With an increase in slow shot speed,the size and number of ESCs and porosities significantly reduce.In addition,the distribution of ESCs is more dispersed and the net-shrinkage disappears.The tensile property is greatly improved by adopting a higher slow shot speed.The ultimate tensile strength is enhanced from 260.31 MPa to 290.31 MPa(increased by 11.52%),and the elongation is enhanced from 3.72%to 6.34%(increased by 70.52%).

关键词： hypoeutectic Al-Si alloy high pressure die casting Porosity externally solidified crystal tensile property

Conversion of polyethylene to gasoline:Influence of Porosity and acidity of zeolites

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Frontiers in Energy 2023年第6期17卷 763-774页

作者： Chunyu LI Haihong WU Ziyu CEN Wanying HAN Xinrui ZHENG Jianxin ZHAI Jiao XU Longfei LIN Mingyuan HE Buxing HAN Shanghai Key Laboratory of Green Chemistry and Chemical Processes School of Chemistry and Molecular EngineeringEast China Normal UniversityShanghai 200062China Beijing National Laboratory for Molecular Sciences CAS Laboratory of Colloid and Interface and ThermodynamicsCAS Research/Education Center for Excellence in Molecular SciencesCenter for Carbon Neutral ChemistryInstitute of ChemistryChinese Academy of SciencesBeijing 100190China School of Chemical Sciences University of Chinese Academy of SciencesBeijing 100049China Institute of Eco-Chongming Shanghai 202162China

Plastic waste is causing serious environmental problems. Developing efficient, cheap and stable catalytic routes to convert plastic waste into valuable products is of great importance for sustainable development, but remains to be a challenging task. Zeolites are cheap and stable, but they are usually not efficient for plastic conversion at a low temperature. Herein a series of microporous and mesoporous zeolites were used to study the influence of Porosity and acidity of zeolite on catalytic activity for plastics conversion. It was observed that H-Beta zeolite was an efficient catalyst for cracking high-density polyethylene to gasoline at 240℃, and the products were almost C_(4)–C_(12) alkanes. The effect of Porosity and acidity on catalytic performance of zeolites was evaluated, which clearly visualized the good performance of H-Beta due to high surface area, large channel system, large amount accessible acidic sites. This study provides very useful information for designing zeolites for efficient conversion of plastics.

关键词： plastics conversion polyethylene zeolites acidity Porosity

Insight to the enhanced microwave absorption of porous N-doped carbon driven by ZIF-8:Competition between graphitization and Porosity

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International Journal of Minerals,Metallurgy and Materials 2023年第3期30卷 474-484页

作者： You Zhou Hongpeng Wang Dan Wang Xianfeng Yang Hongna Xing Juan Feng Yan Zong Xiuhong Zhu Xinghua Li Xinliang Zheng School of Physics State Key Laboratory of Photoelectric Technology and Functional MaterialsNorthwest UniversityXi’an 710127China

Porous carbon-based materials are promised to be lightweight dielectric microwave absorbents.Deeply understanding the influence of graphitization grade and porous structure on the dielectric parameters is urgently required.Herein,utilizing the low boiling point of Zn,porous N-doped carbon was fabricated by carbonization of ZIF-8(Zn)at different temperature,and the microwave absorption performance was investigated.The porous N-doped carbon inherits the high Porosity of ZIF-8 precursor.By increasing the carbonization temperature,the contents of Zn and N elements are decreased;the graphitization degree is improved;however,the specific surface area and Porosity are increased first and then decreased.When the carbonization temperature is 1000°C,the porous N-doped carbon behaves enhanced microwave absorption.With an ultrathin thickness of 1.29 mm,the ideal RL reaches-50.57 dB at 16.95 GHz and the effective absorption bandwidth is 4.17 GHz.The mechanism of boosted microwave absorption is ascribed to the competition of graphitization and Porosity as well as N dopants,resulting in high dielectric loss capacity and good impedance matching.The porous structure can prolong the pathways and raise the contact opportunity between microwaves and porous carbon,causing multiple scattering,interface polarization,and improved impedance matching.Besides,the N dopants can induce electron polarization and defect polarization.These results give a new insight to construct lightweight carbon-based microwave absorbents by regulating the graphitization and Porosity.

关键词： N-doped carbon Porosity dielectric impedance matching microwave absorption

Shale Porosity measurement by the saturated oil method: Removing the contribution from oils dissolved in kerogen

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Petroleum Science 2023年第6期20卷 3273-3279页

作者： Jin-Bu Li Min Wang Hao-Ming Shao Ming Li Liang Liu Shuang-Fang Lu National Key Laboratory of Deep Oil and Gas China University of Petroleum(East China)Qingdao 266580ShandongChina Shaanxi Key Laboratory of Petroleum Accumulation Geology Xi'an 710000ShaanxiChina Key Laboratory of Tectonics and Petroleum Resources(China University of Geosciences) Ministry of EducationWuhan 430074HubeiChina Sanya Offshore Oil&Gas Research Institute Northeast Petroleum UniversitySanya 572025HainanChina

Shale Porosity measurements have crucial scientific and economical applications in unconventionalpetroleum systems. As a standard technique, liquid saturation methods, including water saturation (WS)and oil saturation (OS), have been widely used to measure the Porosity of many rock types. For clay-richshale reservoirs with high organic matter content, it is well known that the WS method may cause clayswelling and induce structural changes in the pore system. The OS method affects the accuracy ofPorosity measurements because of some of the oil being dissolved by kerogen within the shale;however,this has not received sufficient research attention. In this study, we compare the previously reported andnewly tested OS porosities with helium (He) expansion Porosity. Results show that OS Porosity generallyexceeds the He Porosity. Furthermore, the higher the total organic carbon (TOC) content and lower thematurity of shale, the greater the difference between the OS and helium porosities. When using the OSmethod, the effect of kerogen-dissolved oil causes an overestimation of the shale Porosity by ~30%. To thebest of our knowledge, this is the first time to note the kerogen-dissolve oil effects on OS Porosity. Herein,we propose a new, simple, and effective correction method for estimating OS Porosity that involvessubtracting the kerogen-dissolved oil content from raw OS Porosity. In addition, the quantification modelof kerogen-dissolved oil capacity is established, taking into account the abundance and maturity oforganic matter. Taking the He Porosity as the benchmark, the absolute error of the corrected OS Porositydoes not exceed 1% and the average relative error is only ~10%. The obtained results can help improve theaccuracy of shale Porosity evaluation methods.

关键词： Shale Porosity Oil saturation Kerogen-dissolved oil Water saturation

A time−space Porosity computational model for concrete under sulfate attack

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Frontiers of Structural and Civil Engineering 2023年第10期17卷 1571-1584页

作者： Hui SONG Jiankang CHEN Jiangxi Provincial Key Laboratory of Hydraulic&Civil Engineering Infrastructure Security Nanchang Institute of TechnologyNanchang 330099China Zhejiang Provincial Engineering Research Center for the Safety of Pressure Vessel and Pipeline Ningbo UniversityNingbo 315211China Ningbo University Donghai Academy Ningbo 315211China

The deterioration of the microscopic pore structure of concrete under external sulfate attack(ESA)is a primary cause of degradation.Nevertheless,little effort has been invested in exploring the temporal and spatial development of the Porosity of concrete under ESA.This study proposes a mechanical–chemical model to simulate the spatiotemporal distribution of the Porosity.A relationship between the corrosion damage and amount of ettringite is proposed based on the theory of volume expansion.In addition,the expansion strain at the macro-scale is obtained using a stress analysis model of composite concentric sphere elements and the micromechanical mean-field approach.Finally,considering the influence of corrosion damage and cement hydration on the diffusion of sulfate ions,the expansion deformation and Porosity space−time distribution are obtained using the finite difference method.The results demonstrate that the expansion strains calculated using the suggested model agree well with previously reported experimental results.Moreover,the tricalcium aluminate concentration,initial elastic modulus of cement paste,corrosion damage,and continuous hydration of cement significantly affect concrete under ESA.The proposed model can forecast and assess the Porosity of concrete covers and provide a credible approach for determining the residual life of concrete structures under ESA.

关键词： expansion deformation Porosity internal expansion stress external sulfate attack mechanical–chemical coupling model

Effect of thermal induced Porosity on high-cycle fatigue and very high-cycle fatigue behaviors of hot-isostatic-pressed Ti-6Al-4V powder components

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Journal of Materials Science & Technology 2022年第3期98卷 177-185页

作者： Min Cheng Zhengguan Lu Jie Wu Ruipeng Guo Junwei Qiao Lei Xu Rui Yang College of Materials Science and Engineering Taiyuan University of TechnologyTaiyuan 030024China Institute of Metal Research Chinese Academy of SciencesShenyang 110016China

The present work reports the effect of thermal induced Porosity(TIP)on the high-cycle fatigue(HCF)and very high-cycle fatigue(VHCF)behaviors of hot-isostatic-pressed(HIPed)Ti-6Al-4V alloy from gasatomized powder.The results show that the residual pores in the as-HIPed powder compacts present no obvious effect on the HCF life.The regrowth of the residual pores can be observed after solution heat treatment.The pore location ranks the most harmful for the fatigue life compared with the other initiating defects.The maximum stress intensity factors were calculated.The plastic zone size of fine granular area(FGA)is much less than the characteristic size of the microstructure,and the crucial size of the internal pores in this study is about 40μm.The failure types of fatigue specimens in the VHCF regime were classified,and the competition of different failure types was described based on the modified Poisson distribution.

关键词： Titanium alloy Hot isostatic pressing Fatigue life Crack initiation type Porosity

Open-cell mullite ceramic foams derived from porous geopolymer precursors with tailored Porosity

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Journal of Advanced Ceramics 2023年第2期12卷 279-295页

作者： Jiahuan SHAO Chengying BAI Xinyu LI Kun YANG Ting ZHENG Yingjie QIAO Lili ZHANG Hongqiang LI Paolo COLOMBO Key Laboratory of Superlight Materials and Surface Technology Ministry of EducationCollege of Materials Science and Chemical EngineeringHarbin Engineering UniversityHarbin 150001China College of Civil Engineering Hunan UniversityChangsha 410082China Department of Industrial Engineering University of Padovavia MarzoloPadova 35131Italy Department of Materials Science and Engineering The Pennsylvania State UniversityState College 16802USA

Porous geopolymer precursors were firstly prepared by the direct foaming method using bauxite,fly ash(FA),and metakaolin(MK)as raw materials,and porous mullite ceramics were prepared after ammonium ion exchange and then high-temperature sintering.The effects of chemical foaming agent concentration,ion-exchange time,and sintering temperature on porous geopolymerderived mullite ceramics were studied,and the optimal preparation parameters were found.Studies have shown that the concentration of blowing agent had great influence on open Porosity(q)and Porosity and cell size distributions of geopolymer samples,which in turn affected their compressive strength(σ).Duration of the ion exchange had no obvious effect on the sintered samples,and the amount of mullite phase increased with the increase in the sintering temperature.Mullite foams,possessing an open-celled porous structure,closely resembling that of the starting porous geopolymers produced by directly foaming,were obtained by firing at high temperatures.Stable mullite(3Al_(2)O_(3)·2SiO_(2))ceramic foams with total Porosity(ε)of 83.52 vol%,high open Porosity of 83.23 vol%,and compressive strength of 1.72 MPa were produced after sintering at 1400 for 2 h in℃ air without adding any sintering additives using commercial MK,bauxite,and FA as raw materials.

关键词： porous mullite ceramic Porosity porous geopolymer precursor direct foaming nanophase strengthening

Effect of hollow insulation riser on shrinkage Porosity and solidification structure of ingot

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Journal of Iron and Steel Research(International) 2022年第12期29卷 1951-1960页

作者： Ying-jie Liu Chun-lin Peng Wan-ming Li Xiao-lei Zhu Ming-gang Shen Xiang-wei Liao Kun Liu Chong-yi Wei Yusuf Abba Yusuf Ji Yang Chang-you Cai School of Materials and Metallurgy University of Science and Technology LiaoningAnshan 114051LiaoningChina State Key Laboratory of Metal Material for Marine Equipment and Application Anshan 114000LiaoningChina

The thermal insulation performance of riser is very important to the shrinkage Porosity and solidification structure of ingot,but it is difficult to significantly improve due to the limit of thermal conductivity of riser material.A new type of hollow insulation riser was proposed based on the low thermal conductivity of air,which aims to improve the thermal insulation performance of riser.A 14.5-t steel ingot was prepared using the hollow insulation riser,and the casting temperature was 1500°C.The temperature evolution of the external surface of mold during solidification was measured using an infrared temperature instrument.A numerical model was established to simulate the Porosity and solidification structure of ingot.The reliability of numerical simulation was verified by comparing simulation and experimental results.Results show that the insulation performance of the riser can be significantly improved through application of the hollow insulation sleeve.Compared with solid insulation sleeve,the shrinkage cavity depth was decreased and the position of Porosity was raised when hollow insulation riser was applied.

关键词： Hollow insulation riser Solidification Heat transfer Porosity Thermal conductivity

Tuning Porosity of coal-derived activated carbons for CO_(2) adsorption

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Frontiers of Chemical Science and Engineering 2022年第9期16卷 1345-1354页

作者： Zhipeng Qie Lijie Wang Fei Sun Huan Xiang Hua Wang Jihui Gao Guangbo Zhao Xiaolei Fan School of Energy Science and Engineering Harbin Institute of TechnologyHarbin 150001China Department of Chemical Engineering and Analytical Science The University of ManchesterManchester M139PLUK China Datang Corporation Renewable Energy Science and Technology Research Institute Beijing 100052China Energy and Bioproducts Research Institute(EBRI) Aston UniversityBirmingham B47ETUK

A simple method was developed to tune the Porosity of coal-derived activated carbons,which provided a model adsorbent system to investigate the volumetric CO_(2)adsorption performance.Specifically,the method involved the variation of the activation temperature in a K2CO3 induced chemical activation process which could yield activated carbons with defined microporous(<2 nm,including ultra-microporous<1 nm)and meso-microporous structures.CO_(2)adsorption isotherms revealed that the microporous activated carbon has the highest measured CO_(2)adsorption capacity(6.0 mmol∙g^(–1)at 0℃and 4.1 mmol∙g^(-1)at 25℃),whilst ultra-microporous activated carbon with a high packing density exhibited the highest normalized capacity with respect to packing volume(1.8 mmol∙cm−3 at 0℃and 1.3 mmol∙cm^(–3)at 25℃),which is significant.Both experimental correlation analysis and molecular dynamics simulation demonstrated that(i)volumetric CO_(2)adsorption capacity is directly proportional to the ultra-micropore volume,and(ii)an increase in micropore sizes is beneficial to improve the volumetric capacity,but may lead a low CO_(2)adsorption density and thus low pore space utilization efficiency.The adsorption experiments on the activated carbons established the criterion for designing CO_(2)adsorbents with high volumetric adsorption capacity.

关键词： coal-derived activated carbons Porosity CO_(2)adsorption molecular dynamics

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

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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