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On the reliability of nanoindentation hardness of Al₂O₃ films grown on Si-wafer by atomic layer deposition

JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A 2014年第1期32卷

作者： liu, xuwen Haimi, Eero Hannula, Simo-Pekka Ylivaara, Oili M. E. Puurunen, Riikka L. Aalto Univ Sch Chem Technol Dept Mat Sci & Engn FI-00076 Espoo Finland VTT Tech Res Ctr Finland FI-02044 Espoo Finland

The interest in applying thin films on Si-wafer substrate for microelectromechanical systems devices by using atomic layer deposition (ALD) has raised the demand on reliable mechanical property data of the films. This study aims to find a quick method for obtaining nanoindentation hardness of thin films on silicon with improved reliability. This is achieved by ensuring that the film hardness is determined under the condition that no plastic deformation occurs in the substrate. In the study, ALD Al2O3 films having thickness varying from 10 to 600 nm were deposited on a single-side polished silicon wafer at 300 degrees C. A sharp cube-corner indenter was used for the nanoindentation measurements. A thorough study on the Si-wafer reference revealed that at a specific contact depth of about 8 nm the wafer deformation in loading transferred from elastic to elastic-plastic state. Furthermore, the occurrence of this transition was associated with a sharp increase of the power-law exponent, m, when the unloading data were fitted to a power-law relation. Since m is only slightly material dependent and should fall between 1.2 and 1.6 for different indenter geometry having elastic contact to common materials, it is proposed that the high m values are the results from the inelastic events during unloading. This inelasticity is linked to phase transformations during pressure releasing, a unique phenomenon widely observed in single crystal silicon. Therefore, it is concluded that m could be used to monitor the mechanical state of the Si substrate when the whole coating system is loaded. A suggested indentation depth range can then be assigned to each film thickness to provide guidelines for obtaining reliable property data. The results show good consistence for films thicker than 20 nm and the nanoindentation hardness is about 11 GPa independent of film thickness. (C) 2014 American Vacuum Society.

关键词： Thin films

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如何做好“高职”招生工作

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潍坊教育学院学报 2003年第4期16卷 34-35页

作者：刘绪文王鲁茜潍坊教育学院招生办潍坊教育学院干训处山东青州262500

随着高校改革的深入发展,高校招生工作要依法治招,坚持抓好常规管理,加强管理队伍建设,提高“高职”招生管理人员素质。

关键词：高校招生工作高职教育常规管理 .管理人员素质依法治招招生管理

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Theoretical Analysis and Numerical Simulation of the Motion of RDX Deflagration-Driven Flyer Plate Based on Laser-Initiated Micro-Pyrotechnic Devices

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MICROMACHINES 2023年第5期14卷 917-917页

作者： Xian, Mingchun Zhao, Kang liu, xuwen Meng, Yangang Xie, Junyao Li, Jingwei Tong, Lele Huang, Meng Wu, Lizhi Nanjing Univ Sci & Technol Sch Chem & Chem Engn Nanjing 210094 Peoples R China Sichuan Aerosp Chuannan Pyrotech Co Ltd Luzhou 646000 Peoples R China Jianghan Univ State Key Lab Precis Blasting Wuhan 430056 Peoples R China

Miniaturized laser-initiated pyrotechnic devices have great application prospects in aerospace and modern weapon systems due to their excellent energy output performance and reliability. In order to develop a low-energy insensitive laser detonation technology based on a two-stage charge structure, it is important to deeply analyze the motion law of a titanium flyer plate driven by the deflagration of the first-stage charge (RDX). The effects of the charge mass of RDX, flyer plate mass, and barrel length on the motion law of flyer plates were studied through a numerical simulation method based on the Powder Burn deflagration model. The consistency between the numerical simulation and the experimental results was analyzed using the paired t confidence interval estimation method. The results show that the Powder Burn deflagration model can effectively describe the motion process of the RDX deflagration-driven flyer plate with a 90% confidence level, and its velocity error is =6.7%. The speed of the flyer plate is proportional to the mass of the RDX charge, inversely proportional to the mass of the flyer plate, and exponentially related to its moving distance. As the moving distance of the flyer plate increases, the RDX deflagration products and air in front of the flyer plate are compressed, which inhibits the motion of the flyer plate. In the optimum state (the mass of the RDX charge is 60 mg, the mass of the flyer is 85 mg, and the length of the barrel is 3 mm), the speed of the titanium flyer reaches 583 m/s, and the peak pressure of the RDX deflagration reaches 2182 MPa. This work will provide a theoretical basis for the refined design of a new generation of miniaturized high-performance laser-initiated pyrotechnic devices.

关键词： laser-initiated deflagration-driven flyer plate powder burn

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Fabrication and properties of MEMS compatible energetic arrays based on carbon-based copper azide

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APPLIED SURFACE SCIENCE 2022年 577卷 150643-150643页

作者： liu, xuwen Hu, Yan Chen, Bingwen Wei, Hai Su, Jiaxin Yang, Caimin Hu, Jiaheng Ye, Yinghua Shen, Ruiqi Nanjing Univ Sci & Technol Sch Chem & Chem Engn Nanjing 210094 Peoples R China Minist Ind & Informat Technol Micronano Energet Devices Key Lab Nanjing 210094 Peoples R China

Copper azide is a promising primary explosive with low toxicity and high energy density. However, due to the extreme electrostatic sensitivity, it does not have many practical applications in the miniaturized pyrotechnics. In this work, we constructed an energetic composite, embedding in oriented carbon nanotubes (CNTs) arrays grown on a silicon substrate, which is compatible with the micmfabrication technique of Micro-Electro-Mechanical Systems (MEMS). Since it has excellent electrical conductivity and mechanical strength, oriented CNTs, as nano-containers of Cu(N-3)(2), can availably reduce the electrostatic sensitivity and bring about the directional output of detonation energy. The oriented CNTs arrays were prepared by magnetron sputtering, anodization and chemical vapor deposition successively. Electrochemical deposition was used to deposit copper nanoparticles in the cavities of CNTs, which were converted into copper azide by subsequent in-situ azide reaction. The electrostatic sensitivity test, thermal performance analysis and laser ignition experiment were conducted on the energetic composite, respectively. The results show that the energetic composite kept safe under an electrostatic stimulation of 3.18 mJ, while original copper azide exploded when subjected to stimulation of 0.05 mJ. The energetic composite opens a new route of introducing hazardous primary explosives into micro-initiators and modern pyrotechnics.

关键词： Composite energetic materials Copper azide Oriented CNTs array Template method Electrochemical deposition Electrostatic safety

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球磨工艺对铜基摩擦材料混合料的影响Ⅰ:对粒度分布的影响

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粉末冶金技术 2016年第6期34卷 444-449页

作者：殷德政石增敏张大勇刘旭文三峡大学材料与化工学院湖北宜昌443000 天津瑞克曼德科技发展有限公司天津300050

采用单因素试验方法,研究了行星式球磨工艺参数如球料比、球磨时间、磨球直径、醇料比等对铜基粉末冶金摩擦材料混合料粒度分布的影响规律。结果表明,随球料比的增加,混合料的平均粒径不断减小,球料比为15∶1时,混合料的平均粒径最小,为... 详细信息

采用单因素试验方法,研究了行星式球磨工艺参数如球料比、球磨时间、磨球直径、醇料比等对铜基粉末冶金摩擦材料混合料粒度分布的影响规律。结果表明,随球料比的增加,混合料的平均粒径不断减小,球料比为15∶1时,混合料的平均粒径最小,为1.345μm;球磨时间对混合料平均粒径的影响规律是随着球磨时间的增加混合料平均粒径先减小后增大;一定范围内的醇料比在湿磨过程中对研磨效率影响不大;相比于刚玉磨球,钢质磨球对于混合料的研磨效率更好。

关键词：铜基摩擦材料粉末冶金球磨工艺粒度分布

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Submarine Continental Slopes Stability Prediction of Natural Gas HydratesBased on Machine Learning

Submarine Continental Slopes Stability Prediction of Natural...

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Offshore Technology Conference, OTC 2025

作者： Chen, Yu He, Yufa Wang, Yixuan Zhou, Yunjian Fu, Qiang Qin, xuwen liu, Dingyuan Tian, Zheng Zhang, Kexin CNOOC Research Institute Ltd State Key Laboratory of Offshore Natural Gas Hydrates Beijing China Huairou Laboratory Beijing China China Aero Geophysical Survey and Remote Sensing Center for Natural Resources Beijing China

ISBN: (纸本)9781959025610

In the process of extracting naturally-occurring oceanic gas hydrates, the dissociation of hydrates can causea reduction in soil strength. This reduction has the potential to trigger slope failure and submarine landslides,which present a catastrophic threat to offshore facilities and hydrate production. This research aims to create a robust and accurate machine-learning model that can efficiently predict stability of submarine continental slopes where gas hydrates are widespread. By collecting and analyzing 144 relevant cases, a comprehensive dataset was constructed, incorporating slope basic data, overlying and underlying layer data, and geological parameters of the hydrate layer. After conducting a correlation coefficient analysis between the characteristic parameters of the dataset and the output, the key characteristic parameters were determined. To model the dataset and assess its performance, four machine learning techniques were employed: Random Forest(RF), XGBoost, K-Nearest Neighbors (KNN), and Support Vector Machine (SVM). Formation physical parameters, geotechnical parameters, and NGH parameters were taken as input parameters, and the stability of NGH slopes was taken as prediction indicator. Evaluation metrics such as the ROC and confusion matrix were employed to comprehensively evaluate these models’ classification ability. Among these algorithms,the RF algorithm achieves the best prediction accuracy and AUC value, demonstrating its potential in submarine continental slopes stability prediction of natural gas hydrates. Additionally, sensitive analysis using Gini impurity calculations revealed that hydrate decomposition degree is the most significant factor affecting slope stability, followed by the burial depth and thickness of the hydrate layer. The slope angle,cohesion, and internal friction angle also have significant impacts. This study provides a new perspective for predicting submarine continental slopes stability with NGH and offers a scientific

关键词： Landslides

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Aluminum oxide from trimethylaluminum and water by atomic layer deposition: The temperature dependence of residual stress, elastic modulus, hardness and adhesion

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THIN SOLID FILMS 2014年第0期552卷 124-135页

作者： Ylivaara, Oili M. E. liu, xuwen Kilpi, Lauri Lyytinen, Jussi Schneider, Dieter Laitinen, Mikko Julin, Jaakko Ali, Saima Sintonen, Sakari Berdova, Maria Haimi, Eero Sajavaara, Timo Ronkainen, Helena Lipsanen, Harri Koskinen, Jari Hannula, Simo-Pekka Puurunen, Riikka L. VTT Tech Res Ctr Finland FI-02044 Espoo Finland Aalto Univ Sch Chem Technol Dept Mat Sci & Engn FI-00076 Aalto Finland Fraunhofer IWS Dresden D-01277 Dresden Germany Univ Jyvaskyla Dept Phys FI-40014 Jyvaskyla Finland Aalto Univ Sch Elect Engn Dept Micro & Nanosci FI-00076 Aalto Finland Aalto Univ Sch Chem Technol Dept Mat Sci & Engn FI-00076 Aalto Finland Aalto Univ Sch Chem Technol Micronova Nanofabricat Ctr FI-00076 Aalto Finland

Use of atomic layer deposition (ALD) in microelectromechanical systems (MEMS) has increased as ALD enables conformal growth on 3-dimensional structures at relatively low temperatures. For MEMS device design and fabrication, the understanding of stress and mechanical properties such as elastic modulus, hardness and adhesion of thin film is crucial. In this work a comprehensive characterization of the stress, elasticmodulus, hardness and adhesion of ALD aluminum oxide (Al2O3) films grown at 110-300 degrees C from trimethylaluminum and water is presented. Film stress was analyzed by wafer curvature measurements, elastic modulus by nanoindentation and surface-acoustic wave measurements, hardness by nanoindentation and adhesion by microscratch test and scanning nanowear. The films were also analyzed by ellipsometry, optical reflectometry, X-ray reflectivity and time-of-flight elastic recoil detection for refractive index, thickness, density and impurities. The ALD Al2O3 films were under tensile stress in the scale of hundreds of MPa. The magnitude of the stress decreased strongly with increasing ALD temperature. The stress was stable during storage in air. Elastic modulus and hardness of ALD Al2O3 saturated to a fairly constant value for growth at 150 to 300 degrees C, while ALD at 110 degrees C gave softer films with lower modulus. ALD Al2O3 films adhered strongly on cleaned silicon with SiOx termination. (C) 2013 Elsevier B.V. All rights reserved.

关键词： Atomic layer deposition Residual stress Elastic modulus Hardness Adhesion Aluminum oxide

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Serum metabolomics reveals the intervention mechanism and compatible regularity of Chaihu Shu Gan San on chronic unpredictable mild stress-induced depression rat model

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JOURNAL OF PHARMACY AND PHARMACOLOGY 2020年第8期72卷 1133-1143页

作者： Zhang, Hongye Huang, Huimin Song, Hui Chin, Bonnie Zheng, Hua Ruan, Junxiang Wu, Fang Cheng, Bang Wu, Jinxia liu, xuwen Liang, Yonghong Song, Fangming Chen, Zhaoni Tang, Chaoling Lu, Shiyin Guo, Hongwei Zou, Zhongmei Su, Zhiheng Guangxi Med Univ Pharmaceut Coll Nanning 530021 Peoples R China Shenyang Pharmaceut Univ Dept Clin Pharm Shenyang Peoples R China Guangxi Med Univ Med Sci Res Ctr Nanning Peoples R China Guangxi Med Univ Chinese Minist Educ Key Lab Longev & Aging Related Dis Nanning Peoples R China Guangxi Med Univ Ctr Translat Med Nanning Peoples R China Chinese Acad Med Sci & Peking Union Med Coll Inst Med Plant Dev Beijing 100193 Peoples R China

Objectives To provide a comprehensive study of the intervention mechanism and compatible regularity of Chaihu Shu Gan San (CSGS) in a chronic unpredictable mild stress (CUMS)-induced depression model. Methods Ethological study and ELISA assay were applied to measure the phenotypes of depression after CUMS stimulate and assess the antidepressant activity of fluoxetine, CSGS and its compatibilities. The serum metabolic profile changes were revealed by untargeted Q/TOF MS-based metabolomics followed by multivariate statistical analysis. Key findings CSGS exhibits an significant intervention effect on CUMS-induced depression. After the multivariate statistical analysis, 17 potential serum biomarkers were identified and 16 of them could be regulated by CSGS. The intervention of CSGS on CUMS-induced depression involved five key pathways. Moreover, each functional unit (monarch, minister, assistant and guide medicine) in CSGS regulates different metabolites and metabolic pathways to achieve different effects on antidepressant;however, their intervention efficacies are inferior to the holistic formula, which may be due to the synergism of bioactive ingredients in the seven herbs of CSGS. Conclusions CSGS produced an obvious antidepressant activity. The comprehensive and holistic metabolomics approach could be a powerful tool to study the intervention mechanism and the compatibility rule of traditional Chinese medicine.

关键词： antidepression Chaihu Shu Gan San chronic unpredictable mild stress-induced depression compatibility serum metabolomics ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry

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Effect of Fe–N–C single atom/cluster catalyst on ORR of PEMFC

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International Journal of Hydrogen Energy 2025年 139卷 718-729页

作者： Li, Ruina Li, xuwen liu, Qingcheng Yue, Hua Meng, Yang Tian, Yuanyuan School of Automotive and Traffic Engineering Jiangsu University Jiangsu Zhenjiang212013 China Research Center of Fluid Machinery Engineering and Technology Jiangsu University Jiangsu Zhenjiang212013 China Zhejiang Shaoxing312000 China Key Laboratory of Chemical Additives for China National Light Industry College of Chemistry and Chemical Engineering Shaanxi University of Science and Technology Shaanxi Xi'an710021 China

With the continuous advancement of fuel cell technology, the exploration and development of highly efficient non - precious - metal catalysts for the oxygen reduction reaction (ORR) have emerged as a focal point of research. Fe–N–C catalysts have attracted much attention due to their excellent performance and low cost, and coupling single-atom catalysts (SACs) with atomic clusters (ACs) is an effective method to improve catalyst activity. This study used the pyrolysis method to synthesize iron atom catalysts (Fe–N–C SACs) and iron cluster coupled catalysts (Fe–N–C SACs/ACs) on ZIF-8 carbon support. It evaluated the catalyst performance through electrochemical testing. The experimental results showed that the introduction of Fe clusters improved the half-wave potential of the catalyst to 0.399 V, which represented an 8.2 % enhancement compared to the SAC catalyst and reached 87.1 % of that of the commercial Pt–C catalyst, and reduced the Tafel slope to 61.47 mV dec−1, effectively improving the ORR activity of the catalyst. We constructed FeN4 single atom catalyst models and FeN4/Fe4N6 single atom cluster catalyst models using density functional theory (DFT), analyzed their electronic structures and reaction mechanisms, and revealed the mechanism of action of iron clusters. DFT calculations showed that iron clusters altered the charge distribution of FeN4 sites, reducing the rate determining step (RDS) (OH desorption) energy to 0.5 eV, which promoted the desorption of products and the re-adsorption of reactants. As a result, the superior electrocatalytic performance of Fe–N–C SAC/AC is attributed to the synergistic effect between iron clusters and single atoms, which is influenced by the coordination environment and provides new ideas for designing efficient ORR catalysts. © 2025 Hydrogen Energy Publications LLC

关键词： Electrolytic reduction

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Thermal and plasma enhanced atomic layer deposition of SiO₂ using commercial silicon precursors

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THIN SOLID FILMS 2014年 558卷 93-98页

作者： Putkonen, Matti Bosund, Markus Ylivaara, Oili M. E. Puurunen, Riikka L. Kilpi, Lauri Ronkainen, Helena Sintonen, Sakari Ali, Saima Lipsanen, Harri liu, xuwen Haimi, Eero Hannula, Simo-Pekka Sajavaara, Timo Buchanan, Iain Karwacki, Eugene Vaha-Nissi, Mika VTT Tech Res Ctr Finland FI-02044 Espoo Finland Aalto Univ Sch Chem Technol Inorgan Chem Lab FI-00076 Espoo Finland Beneq Oy FI-01510 Vantaa Finland Aalto Univ Sch Elect Engn Dept Micro & Nanosci FI-00076 Espoo Finland Aalto Univ Sch Chem Technol Dept Mat Sci & Engn FI-00076 Espoo Finland Univ Jyvaskyla Dept Phys FI-40014 Jyvaskyla Finland Air Prod & Chem Inc Allentown PA 18195 USA

In this paper, we report ALD deposition of silicon dioxide using either thermal or plasma enhanced atomic layer deposition (PEALD). Several aminosilanes with differing structures and reactivity were used as silicon precursors in R&D single wafer ALD tools. One of the precursors was also tested on pilot scale batch ALD using O-3 as oxidant and with substrates measuring 150 x 400 mm. The SiO2 film deposition rate was greatly dependent on the precursors used, highest values being 1.5-2.0 angstrom/cycle at 30-200 degrees C for one precursor with an O-2 plasma. According to time-of-flight-elastic recoil detection analysis measurements carbon and nitrogen impurities were relatively low, but hydrogen content increased at low deposition temperatures. (C) 2014 Elsevier B.V. All rights reserved.

关键词： Atomic layer deposition Plasma-enhanced atomic layer deposition Precursors Silicon dioxide Batch deposition Conformal coating

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