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Vibration-assisted material damage mechanism:From indentation cracks to scratch cracks

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Chinese Journal of Aeronautics 2024年第8期37卷 527-546页

作者： Bingrui LV Bin LIN Tianyi SUI Chunyan LIU Jinshuo ZHANG Longfei WANG Xuhui CHEN Jingguo ZHOU key laboratory of advanced ceramics and machining technology Ministry of EducationTianjin UniversityTianjin 300072China key laboratory of Mechanism Theory and Equipment Design of Ministry of Education Tianjin UniversityTianjin 300072China Science and technology of advanced Functional Composite laboratory Aerospace Research Institute of Materials and Processing TechnologyBeijing 100076China

Vibration-assisted grinding is one of the most promising technologies for manufacturing optical components due to its efficiency and quality ***,the damage and crack propagation mechanisms of materials in vibration-assisted grinding are not well *** order to elucidate the mechanism of abrasive scratching during vibration-assisted grinding,a kinematic model of vibration scratching was *** influence of process parameters on the evolution of vibration scratches to indentation or straight scratches is revealed by displacement metrics and velocity ***,scratch and vibration scratch experiments were performed on quartz glass,and the results showed that the vibration scratch cracks are a combination of indentation cracks and scratch *** scratch cracks change from indentation cracks to scratch cracks as the indenter moves from the entrance to the exit of the workpiece or as the vibration frequency changes from high to low.A vertical vibration scratch stress field model is established for the first time,which reveals that the maximum principal stress and tensile stress distribution is the fundamental cause for inducing the transformation of the vibration scratch cracking *** model provides a theoretical basis for understanding of the mechanism of material damage and crack propagation during vibration-assisted grinding.

关键词： Vibration assisted grinding Indentation Vibration scratch Material removal mechanism Stress field model Crack propagation mechanism

Porous metal oxides in the role of electrochemical CO_(2) reduction reaction

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Journal of Energy Chemistry 2024年第1期88卷 373-398,I0009页

作者： Ziqi Zhang Jinyun Xu Yu Zhang Liping Zhao Ming Li Guoqiang Zhong Di Zhao Minjing Li Xudong Hu Wenju Zhu Chunming Zheng Xiaohong Sun School of Chemical Engineering and technology Tianjin Key Laboratory of Green Chemical Technology and Process EngineeringState Key Laboratory of Separation Membrane and Membrane ProcessesTiangong UniversityTianjin 300387China School of Materials Science and Engineering Key Laboratory of Advanced Ceramics and Machining TechnologyMinistry of EducationTianjin UniversityTianjin 300072China

The global energy-related CO_(2) emissions have rapidly increased as the world economy heavily relied on fossil *** paper explores the pressing challenge of CO_(2) emissions and highlights the role of porous metal oxide materials in the electrocatalytic reduction of CO_(2)(CO_(2)RR).The focus is on the development of robust and selective catalysts,particularly metal and metal-oxide-based *** metal oxides offer high surface area,enhancing the accessibility to active sites and improving reaction *** tunability of these materials allows for tailored catalytic behavior,targeting optimized reaction mechanisms for CO_(2)*** work also discusses the various synthesis strategies and identifies key structural and compositional features,addressing challenges like high overpotential,poor selectivity,and low *** on these insights,we suggest avenues for future research on porous metal oxide materials for electrochemical CO_(2) reduction.

关键词： CO_(2)reduction Carbon dioxide Transformation Porous metal oxides Electrocatalysis

Corrosion behavior of Gd_(2)Zr_(2)O_(7)thermal barrier coatings under Fe-containing environmental sediment attack

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Journal of advanced ceramics 2024年第4期13卷 447-462页

作者： Lei Guo Yanyan Li Kai Yan School of Materials Science and Engineering Tianjin UniversityTianjin 300072China Tianjin key laboratory of advanced Joining technology Key Lab of Advanced Ceramics and Machining Technology of Ministry of EducationTianjin 300072China key laboratory of Special Equipment Safety and Energy-saving for State Market Regulation China Special Equipment Inspection&Research InstituteBeijing 100029China

Environmental sediments mainly consisting of CaO–MgO–Al_(2)O_(3)–SiO_(2)(CMAS)corrosion are a serious threat to thermal barrier coatings(TBCs),in which Fe element is usually ***_(2)Zr_(2)O_(7)TBCs are famous for their excellent CMAS *** this study,the characteristics of Fe-containing environmental sediments(CMAS-Fe)and their corrosiveness to Gd_(2)Zr_(2)O_(7)coatings were *** types of CMAS-Fe glass with different Fe contents were *** melting points were measured to be 1322–1344℃,and the high-temperature viscosity showed a decreasing trend with increasing Fe *** corrosion behavior of four types of CMAS-Fe to Gd_(2)Zr_(2)O_(7)coatings at 1350℃was *** the initial corrosion stage(0.1 h),anorthite was precipitated in CMAS-Fe with a high Ca:Si ratio,while Fe-garnet was formed in the melt with the highest Fe *** the corrosion time resulted in the formation of a reaction layer,which exhibited an interpenetrating network composed of Gd-oxyapatite,ZrO_(2),and residual *** spinel was precipitated within the reaction *** 1 h or even longer time,the reaction layers tended to be stable and compact,which had comparable hardness and fracture toughness to those of Gd_(2)Zr_(2)O_(7)*** the cyclic CMAS-Fe attack,the residual CMAS-Fe in the interpenetrating network provided a pathway for the redeposited CMAS-Fe infiltration,resulting in the continuous growth of the reaction *** a result,the Gd_(2)Zr_(2)O_(7)coatings had a large consumption in the thickness,degrading the coating ***,the Gd_(2)Zr_(2)O_(7)coatings exhibit unsatisfactory corrosion resistance to CMAS-Fe attack.

关键词： thermal barrier coatings(TBCs) Gd_(2)Zr_(2)O_(7) Fe-containing CaO-MgO-Al2O3-SiO_(2)(CMAS) corrosion resistance reaction layer

Hydroxyapatite/palmitic acid superhydrophobic composite coating on AZ31 magnesium alloy with both corrosion resistance and bacterial inhibition

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Frontiers of Materials Science 2024年第1期18卷 71-83页

作者： Hang Zhang Shu Cai Huanlin Zhang Lei Ling You Zuo Hao Tian Tengfei Meng Guohua Xu Xiaogang Bao Mintao Xue key laboratory for advanced ceramics and machining technology of Ministry of Education Tianjin UniversityTianjin 300072China Department of Orthopedic Surgery Spine CenterChangzheng HospitalNaval Medical UniversityShanghai 200003China

The coating-modified magnesium(Mg)alloys exhibit controllable corrosion resistance,but the insufficient antibacterial performance limits their clinical applications as degradable *** coatings show excellent performance in terms of both corrosion resistance and inhibition of bacterial adhesion and *** this work,a hydroxyapatite(HA)/palmitic acid(PA)superhydrophobic composite coating was fabricated on the Mg alloy by the hydrothermal technique and immersion *** HA/PA composite coating showed superhydrophobicity with a contact angle of 153°and a sliding angle of 2°.The coated Mg alloy exhibited excellent corrosion resistance in the simulated body fluid,with high polarization resistance(77.10 kΩ·cm^(2))and low corrosion current density((0.491±0.015)μA·cm^(-2)).Meanwhile,the antibacterial efficiency of the composite coating was over 98% against *** and *** in different *** results indicate that the construction of such superhydrophobic composite coating(HA/PA)on the Mg alloy can greatly improve the corrosion resistance of Mg alloy implants within the human body and avoid bacterial infection during the initial stages of implantation.

关键词： superhydrophobic coating hydroxyapatite corrosion resistance antibacterial

Editable semiconductor photo-electrodes for sustainable ammonia synthesis

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Nano Research 2024年第4期17卷 3107-3112页

作者： Ning Lan Kun Du Erling Zhao Wei Zhao Tao Ling key laboratory for advanced ceramics and machining technology of Ministry of Education Institute of New-EnergySchool of Materials Science and EngineeringTianjin UniversityTianjin 300072China School of Materials Science and Engineering Tianjin Chengjian UniversityTianjin 300384China

Powered by an inexhaustible supply of solar energy,photoelectrochemical(PEC)nitrogen reduction reaction(NRR)provides an ideal solution for the synthesis of green ammonia(NH_(3)).Although great efforts have been made in the past decades,there are still significant challenges in increasing the NH_(3) yields of the PEC-NRR *** addition to the issues of low activity and selectivity similar to electrochemical NRR,the progress of PEC-NRR is also impeded by the limited increase in NH_(3) yields as the electrode is ***,we propose an editable electrode design strategy that parallels unit photo-electrodes to achieve a linear increase in NH_(3) yields with electrode active *** demonstrate that the editable electrode design strategy minimizes the electrode charge transfer resistance,allowing more photo-generated carriers to reach the electrode surface and promote the catalytic *** believe that this editable electrode design strategy provides an avenue to achieve sustainable PEC NH_(3) production.

关键词： editable electrode photoelectrochemical nitrogen reduction reaction parallel electrode ZnSe

Grain growth behavior and properties of high-entropy pseudobrookite(Mg,Co,Ni,Zn)Ti_(2)O_(5) ceramics

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Journal of advanced ceramics 2024年第6期13卷 757-768页

作者： Xiaohui Ma Jinyu Wu Lingyi Meng Jinfeng Zhang Heng Chen Liwen Yan Anran Guo Jiachen Liu key laboratory of advanced ceramics and machining technology of Ministry of Education School of Materials Science and EngineeringTianjin UniversityTianjin 300072China Xiamen key laboratory of Rare Earth Photoelectric Functional Materials Xiamen Institute of Rare Earth MaterialsHaixi InstitutesChinese Academy of SciencesXiamen 361021China

It is well known that the grain size of high-entropy ceramics is quite small owing to the sluggish diffusion effect. However, abnormal grain growth often occurs in high-entropy pseudobrookite ceramics, ultimately resulting in the formation of many abnormally grown grains with a grain size as large as 50 μm. To study this phenomenon, the grain growth behavior of high-entropy pseudobrookite ceramics was systematically investigated in this paper. The results demonstrate that the starting material powders first react with each other to form a high-entropy intermediate phase and calcined TiO_(2) powders (TiO_(2)-1100 ℃), and then as the sintering temperature increases, the formed high-entropy intermediate phase further reacts with TiO_(2)-1100 ℃ to form high-entropy pseudobrookite ceramics. Thus, in this system, in addition to the sluggish diffusion effect, the grain sizes of the high-entropy intermediate phase and TiO_(2)-1100 ℃ also affect the morphology of high-entropy pseudobrookite. Compared to nanosized TiO_(2), micron-sized TiO_(2) has a lower sintering activity. Therefore, the high-entropy intermediate phases (Mg,Co,Ni,Zn)TiO_(3) and TiO_(2)-1100 ℃ prepared with micron-sized starting materials exhibit lower grain sizes, finally resulting in the formation of high-entropy (Mg,Co,Ni,Zn)Ti_(2)O_(5) with small grain sizes. Moreover, nano-indentation and thermal conductivity tests were carried out on high-entropy (Mg,Co,Ni,Zn)Ti_(2)O_(5) with different morphologies. The results show that the hardness of high-entropy (Mg,Co,Ni,Zn)Ti_(2)O_(5) increases from 6.05 to 9.95 GPa as the grain size increases, whereas the thermal conductivity decreases from 2.091±0.006 to 1.583±0.006 W·m^(−1)·K^(−1). All these results indicate that high-entropy (Mg,Co,Ni,Zn)Ti_(2)O_(5) with a small grain size is a potential material for thermal protection.

关键词： grain size sluggish diffusion effect two-step solid phase process high-entropy intermediate phase high-entropy pseudobrookite ceramic

Sabatier principle guiding the design of cathode catalysts for Li-CO2 batteries

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Journal of Energy Chemistry 2024年第10期97卷 585-592页

作者： Haonan Xie Yimin Zhang Biao Chen Chunnian He Chunsheng Shi Enzuo Liu Naiqin Zhao School of Materials Science and Engineering Tianjin Key Laboratory of Composite and Functional Materials Key Laboratory of Advanced Ceramics and Machining Technology (Ministry of Education) Tianjin University National Industry-Education Platform of Energy Storage Tianjin University Joint School of National University of Singapore and Tianjin University International Campus of Tianjin University

The Sabatier principle has been widely used for designing electrocatalysts for energy conversion applications,but it is rarely mentioned in the research of cathode catalyst of *** our work,the "volcanic" relationship between the catalytic activity and the adsorption energy of the catalyst to the intermediates is first demonstrated based on the first-principles calculation,which meets the Sabatier principle and can be used to design the cathode *** increases in the number of nitrogenvacancy in WN shift the d-band center and increase the interaction with the *** catalytic activity increases first and then decreases with the increase of adsorption energy,which was proved in the *** optimal catalyst for moderate adsorption of intermediate makes the thin LiaCO3distribute *** exhibits a median voltage difference of 0.68 V and an energy efficiency of 84.33% at20 μA cm-2with a limited capacity of 200 μA h cm-2.

关键词： Bidirectional catalyst Li-CO2 batteries Nitrogen-vacancy Sabatier principle Transition metal nitrides

Advancing electrochemical drilling process via coupling of flow field and electric field in pulsating state generated by a novel tube tool

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Chinese Journal of Aeronautics 2024年第4期37卷 542-555页

作者： Liang CHENG Xiaolei CHEN Zhisen YE Yongjun ZHANG State key laboratory of Precision Electronic Manufacturing technology and Equipment Guangdong University of TechnologyGuangzhou 510006China Guangdong key laboratory of advanced Manufacturing technology of Marine Energy Equipment Guangdong University of TechnologyGuangzhou 510006China Guangzhou key laboratory of Nontraditional machining and Equipment Guangdong University of TechnologyGuangzhou 510006China

This paper introduces an improvement to electrochemical drilling process by coupling flow field and electric field in pulsating state. A novel tube with half-wedged shape at the end(HW-tube) is prepared, with both sidewall and wedged part of the HW-tube insulated. Only the flat part is utilized to provide electric field for electrochemical drilling. By rotating the HW-tube, both flow field and electric field in pulsating state are generated, alternating in different positions within the inter-electrode gap(IEG). The pulsating flow field enhances the mass transfer process, while pulsating electric field disperses material dissolution process and distribution of electrolytic byproducts. Both pulsating fields are coupled at the same frequency, further enhancing the electrochemical drilling process. Simulation results indicate that both flow field and electric field in pulsating state are generated. Compared to the traditional tube, the HW-tube significantly reduces the number of residual particles in IEG, and this number is further reduced by increasing the rotation speed. Experimental results reveal that the surface quality and dimensional uniformity of small hole are improved with HW-tube. With feed rate of 2.22 mm/min, a small hole with diameter of 1.52± 0.017 mm is drilled, resulting in a surface roughness of 0.331 μm.

关键词： Small holes Electrochemical drilling Tools Pulsating flow field Pulsating electric field

Spontaneous anchoring Cl intoα-Co(OH)_(2) as efficient and stable oxygen reduction electrocatalysts for seawater battery

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Rare Metals 2024年第7期43卷 3074-3083页

作者： Wang Zheng Xue-Rong Zheng Qi Lu Yan-Hui Cao Yang Wang Hai-Peng Fu Jin-Feng Zhang Yi-Da Deng Wen-Bin Hu School of Materials Science and Engineering Key Laboratory of Advanced Ceramics and Machining Technology of Ministry of EducationTianjin UniversityTianjin 300072China State key laboratory of Marine Resource Utilization in South China Sea School of Materials Science and EngineeringHainan UniversityHaikou 570228China key laboratory of Electromagnetic Processing of Materials Ministry of EducationNortheastern UniversityShenyang 110819China

Seawater battery is an advanced energy storage system that enables conversion of chemical energy to electricity by consuming metals,dissolved oxygen and seawater in anode,cathode and electrolyte,***,the oxygen reduction reaction(ORR)activity and stability of electrocatalysts can be easily deactivated due to the severe Cl~-permeation and corrosion in seawater ***,we developed a structural buffer engineering strategy by spontaneously anchoring Cl~-intoα-Co(OH)_(2) as efficient and stable ORR electrocatalysts,in which the ultrathinα-Co(OH)_(2) nanosheets were synthesized using an ultrafast solution high-temperature shock(SHTS)*** large lattice space(~0.8 nm)of layeredα-Co(OH)_(2) ensured the spontaneously penetration of Cl~-into the lattice structure and replaced part of OH~-to formα-Co(OH)_(2-x)Cl_*** continuous leaching and compensating of saturated Cl inα-Co(OH)_(2-x)Cl_x could enhance the Cl~-corrosion resistance and modulate electronic structure of Co metallic sites,thus improving the ORR electrocatalytic activity and stability in seawater ***α-Co(OH)_(2-x)Cl_x seawater batteries display superior onset and half-wave potentials of 0.71 and 0.66 V,respectively,which are much better than the counterparts ofα-Co(OH)_(2) and ofβ-Co(OH)_(2) with no Cl~-penetrating and no buffer ***α-Co(OH)_(2-x)Cl_x-based seawater batteries display stable open-circuit potential of 1.69 V and outstanding specific capacity of 1345 mAh·g^(-1).

关键词： Seawater battery Oxygen reduction electrocatalyst Solution high-temperature shock Structural buffer engineering