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fabrication processing and mechanical properties of Si₃N₄ ceramic turbocharger wheel

CERAMICS INTERNATIONAL 2018年第9期44卷 10596-10603页

作者： Wen, Daosheng Wang, Shouren Wang, Gaoqi Guo, Peiquan Yang, Liying Yang, Xuefeng Univ Jinan Sch Mech Engn Jinan 250022 Shandong Peoples R China

A composite technique was chosen to fabricate Si3N4 ceramic turbine wheel based on modified investment casting (MIC), slip casting (SP) and mold constraint hot isostatic pressing (MCHIP) aided by a near-net dimension using the gypsum mold and multi-piece Y2O3 ceramic mold. The detailed fabrication processing of Si3N4 ceramic turbine wheel was described. And the flexural strength and fracture toughness after different work temperature and speed were discussed. The results showed that owing to occurrence of phase transformation and chemical reaction, excess temperature resulted in interface cracking and interface debonding, flexural strength and fracture toughness decrease. Thermal expansion and centrifugal force under excessive high speed brought many pores in the microstructure and resulted in crack initiation and crack propagation. The critical work temperature was 700 degrees C and critical work speed was 100,000 r/min, which were obtained from the test and simulation results.

关键词： fabrication processing Microstructure Si3N4 Ceramic turbine Mechanical properties

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CAD/CAM machining Vs pre-sintering in-lab fabrication techniques of Y-TZP ceramic specimens: Effects on their mechanical fatigue behavior

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JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS 2017年 71卷 201-208页

作者： Zucuni, C. P. Guilardi, L. F. Fraga, S. May, L. G. Pereira, G. K. R. Valandro, L. F. Univ Fed Santa Maria MSciD PhD Grad Programs Oral Sci Prosthodont Units Santa Maria RS Brazil IMED Merid Fac Sch Dent MSciD Grad Program Passo Fundo RS Brazil

This study evaluated the effects of different pre-sintering fabrication processing techniques of Y-TZP ceramic (CAD/CAM Vs. in-lab), considering surface characteristics and mechanical performance outcomes. Pre-sintered discs of Y-TZP ceramic (IPS *** ZirCAD, Ivoclar Vivadent) were produced using different pre-sintering fabrication processing techniques: Machined-milling with a CAD/CAM system;Polished-fabrication using a cutting device followed by polishing (600 and 1200 SiC papers);Xfine-fabrication using a cutting machine followed by grinding with extra-fine diamond bur (grit size 30 [tin);Fine-fabrication using a cutting machine followed by grinding with fine diamond bur (grit size 46 gm);SiC-fabrication using a cutting machine followed by grinding with 220 SiC paper. Afterwards, the discs were sintered and submitted to roughness (n=35), surface topography (n=2), phase transformation (n=2), biaxial flexural strength (n=20), and biaxial flexural fatigue strength (fatigue limit) (n=15) analyses. No monoclinic-phase content was observed in all processing techniques. It can be observed that obtaining a surface with similar characteristics to CAD/CAM milling is essential for the observation of similar mechanical performance. On this sense, grinding with fine diamond bur before sintering (Fine group) was the best mimic protocol in comparison to the CAD/CAM milling.

关键词： Dental ceramics Yttrium-stabilized tetragonal zirconia polycrystal Machining CAD/CAM fabrication fabrication processing Mechanical properties

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fabrication,microstructure and mechanical properties of Mg matrix composites reinforced by high volume fraction of sphere TC4 particles

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Journal of Magnesium and Alloys 2016年第4期4卷 286-294页

作者： Chun-Lei Zhang Xiao-Jun Wang Xiao-Ming Wang Xiao-Shi Hu Kun Wu School of Materials Science and Engineering Harbin Institute of TechnologyHarbinChina

A novel liquid settling method was investigated and applied to fabricate TC4 spherical particle reinforced AZ91 alloy matrix *** method was called liquid state settling technique in which TC4 particles would settle down under the force of *** volume fraction(50%)particle reinforced AZ91 composites could be easily obtained via this novel *** is difficult to achieve for other traditional liquid fabrication *** addition,there was a good dispersion of TC4 particles in the AZ91 matrix and no clusters were found,which indicate that this method was *** reaction occurred and the reaction product was confirmed to be *** kinds of pre-dispersion technologies were used before the settling process and different interfacial microstructures were *** calculation and experimental results both indicated that the interfacial product which was embedded in the matrix strengthened the composites and improved the tensile strength.

关键词： Magnesium matrix composites TC4 particles fabrication processing Interfacial reaction

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Printed fabric computerized automatic color separating system

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TEXTILE RESEARCH JOURNAL 2011年第7期81卷 706-713页

作者： Kuo, Chung-Feng Jeffrey Shih, Chung-Yang Natl Taiwan Univ Sci & Technol Dept Mat Sci & Engn Taipei 106 Taiwan Kun Shan Univ Dept Polymer Mat Tainan Taiwan

This paper presents an innovative Printed Fabric Computerized Automatic Color Separation System. First, a scanner is used to obtain the digitized color image of printed fabric in RGB (red, green, blue) mode, and the image is then converted to the digitized color image in HSI (hue, saturation, intensity) mode. Next, the genetic algorithms are applied to search the smaller sub-image having the same color distribution as the original fabric for proceeding with the subsequent color separation algorithm. For the color separation algorithm, the FCM-based (Fuzzy C-Means) Region Splitting Method is used to carry out the color segmentation of the printed fabric image. The experimental result shows that the color separation method proposed by this study can quickly and correctly achieve the automatic color separation of the printed fabric.

关键词： fabrication fiber yarn fabric formation fabrication processing

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Recent Advances in Metallic Glass Nanostructures: Synthesis Strategies and Electrocatalytic Applications

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ADVANCED MATERIALS 2019年第7期31卷 1802120-1802120页

作者： Li, Jinyang Doubek, Gustavo McMillon-Brown, Lyndsey Taylor, Andre D. Southwest Jiaotong Univ Sch Mat Sci & Engn Minist Educ Key Lab Adv Technol Mat Chengdu 610031 Sichuan Peoples R China Univ Campinas UNICAMP Sch Chem Engn CINE BR-13083852 Campinas SP Brazil Yale Univ Ctr Res Interface Struct & Phenomena New Haven CT 06520 USA NYU Tandon Sch Engn Dept Chem & Biomol Engn MetroTech Ctr 6 Brooklyn NY 11201 USA

Recent advances in metallic glass nanostructures (MGNs) are reported, covering a wide array of synthesis strategies, computational discovery, and design solutions that provide insight into distinct electrocatalytic applications. A brief introduction to the development and unique features of MGNs with an overview of top-down and bottom-up synthesis strategies is presented. Specifically, the morphology and structural analysis of several examples applying MGNs as electrodes are highlighted. Subsequently, a comprehensive discussion of commonly employed kinetic parameters and their connection with the unique material structures of MGNs on individual electrocatalytic reactions is made, including the hydrogen evolution reaction, oxygen reduction reaction, and alcohol (methanol or ethanol) oxidation reaction. Finally, a summary of the challenges and perspective on the future research and development relevant to MGNs as electrocatalysts is provided.

关键词： amorphous alloys electrocatalysis fabrication processing metallic glass nanostructures synthesis strategies

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Mechanism analysis of ultrasonic treatment on SU-8 swelling in UV-LIGA technology

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MICRO & NANO LETTERS 2011年第11期6卷 900-903页

作者： Du, Liqun Liu, Yaping Li, Chengbin Dalian Univ Technol Key Lab Micro Nano Technol & Syst Liaoning Prov Dalian 116024 Peoples R China Dalian Univ Technol Minist Educ Key Lab Precis & Nontradit Machining Technol Dalian 116024 Peoples R China

In SU-8 UV-LIGA technology, the precision and controllability of electroformed metal structure are not satisfied because of SU-8 photoresist swelling during electroforming process. To reduce SU-8 swelling and further improve the dimensional precision of electroformed microstructure, the authors originally introduce ultrasonic treatment in the fabrication process of SU-8 mould. The experimental results indicate that the swelling property of cross-linked cured SU-8 varies with ultrasonic time. SU-8 swelling is diminished when it is treated less than 15 min by ultrasonic, but the swelling is increased if the ultrasonic time is extended to 20 min. To explore ultrasonic treatment mechanism of SU-8 swelling, the contact angle between SU-8 and electroforming solutions in different ultrasonic time was measured, and the result presents that SU-8 surface hydrophilicity is affected by ultrasonic treatment. Besides, the contact angle trend is consistent with the curve of SU-8 swelling removal ratio in different ultrasonic time. Subsequently, ultrasonic treatment mechanism of SU-8 swelling is proposed based on ultrasonic mechanical scission of polymer chain and moisture diffusion mechanism.

关键词： resins SU-8 photoresist swelling diffusion Structure of polymers, elastomers, and plastics SU-8 swelling curve swelling swelling property hydrophilicity contact angle polymer chain Nondestructive testing: acoustic methods ultrasonic treatment mechanism SU-8 moulding electroforming solutions Microstructure SU-8 surface hydrophilicity ultrasonic materials testing fabrication processing LIGA electroforming processing electroforming cross-linked cured SU-8 moisture diffusion mechanism ultrasonic mechanical scission electroformed microstructure photoresists polymer structure SU-8 UV-LIGA technology electroformed metal structure

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Excess low-frequency flux noise in dc SQUIDs

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IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 1997年第2期7卷 2882-2885页

作者： Huber, ME Cromar, MW Ono, RH SUPERCONDUCTING CORE TECHNOL GOLDENCO 80401 NATL INST STAND & TECHNOL BOULDERCO 80303

We have fabricated dc superconducting quantum interference devices (SQUIDs) incorporating Nb/Al-oxide/Nb Josephson junctions in both stripline and washer geometries. Low-frequency noise in excess of the predicted by the resistively-shunted junction model is present in both geometries and is demonstrated to be flux noise. This flux noise is no environmental. Improvements in fabrication processing over the past four years have reduced the level of this flux noise. SQUIDs are now fabricated with PdAu resistors, Nb wiring layers, and SiO2 interlayer dielectric. In our best well-coupled SQUIDs, the white-noise energy sensitivity is 5 x 10(31) J.s, with a 1/f knee below 0.1 Hz. We believe further reduction in the flux noise might be obtained with the use of on-chip flux shielding and/or trapping structures.

关键词： 0.1 to 100 Hz 1/f knee 1/f noise aluminium compounds dc SQUIDs excess low-frequency flux noise fabrication processing Geometry Interference Josephson effect Josephson junctions Low-frequency noise magnetic shielding Nb wiring layers Nb-AlO-Nb Nb/Al-oxide/Nb Josephson junctions Niobium Noise reduction on-chip flux shielding PdAu PdAu resistors resistively-shunted junction model SiO/sub 2/ SiO/sub 2/ interlayer dielectric SQUIDs stripline geometry Superconducting device noise superconducting device testing Superconducting devices trapping structures washer geometry white noise white-noise energy sensitivity Working environment noise

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Improvement of turn-off energy loss (E_off) variations by low Mg doping in p-GaN gate power devices

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ELECTRONICS LETTERS 2017年第3期53卷 196-198页

作者： Choi, H. -S. Chosun Univ Dept Elect Engn 309 Pilmun Daero Gwangju South Korea

In p-GaN gate AlGaN/GaN power devices, turn-off energy loss (E-off) variations in die-level uniformity are observed because of the thickness variations of remained p-GaN in the ungated region. These E-off variations can be reduced by negative turn-off gate voltages. However, this method can induce new burden in circuit design because of the negative voltages. Therefore, we focus on fabrication processes such as Mg doping in p-GaN gate. Using low Mg doping in p-GaN gate, E-off variations mostly disappear, but threshold voltage (V-th) is approximately 0.3 V decreases. In addition, dynamic on-resistance (dynamic R-ds,R-on) is slightly increased.

关键词： aluminium compounds gallium compounds III-V semiconductors wide band gap semiconductors magnesium semiconductor doping power semiconductor devices p-GaN gate power device doping turn-off energy loss improvement die-level uniformity variation negative turn-off gate voltage circuit design fabrication processing AlGaN-GaN:Mg

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Thermal stress analysis of mesoporous perovskite solar cell by finite element method 16

Thermal stress analysis of mesoporous perovskite solar cell ...

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16 int conf elect packaging technology

作者： Zhou, Ying Liu, Sheng Wang, Guoping Chen, Peng Jiang, Hao Zhan, Shannan Huazhong Univ Sci & Technol China EU Inst Clean & Renewable Energy Wuhan Peoples R China Wuhan Univ Sch Power & Mech Engn Wuhan Peoples R China Shanghai Jiao Tong Univ Sch Mech Engn Shanghai Peoples R China Huazhong Univ Sci & Technol Sch Mech & Engn Wuhan Peoples R China

ISBN: (纸本)9781467379991

For nearly five years, the photoelectric conversion efficiency of the perovskite-based solar cells are extraordinarily developed at a high speed, showing a good application prospect. It is necessary to further optimize the devices and make them industrially feasible. The different temperature requirements of perovskite solar cells during the preparation process will result in undesirable thermal stresses. There have already existed a number of papers concerning methods to improve power conversion efficiency of perovskite-based solar cell. However, the thermal properties of laminated structure of solar cell, which significantly affect the long-time reliability of solar cell packaging, have rarely been discussed. Different temperature loads in preparation process are taken into account to obtain the resulting thermal stresses in this paper. The fabrication processing is reproduced in FEM simulations which are able to directly analyze the internal stresses within and between solar cell layers. The goal is to develop a systematic understanding of thermal behavior of perovskite solar cell during the fabrication process. The study figures out that the maximum Mises stresses are located in central area for the upper layers. But the maximum stress on the bottom layer occurs at the fringe of the etching groove. The large accumulated plastic strain at the center will cause a crack initiation at this location and then the crack may continue to grow to the etching groove or even cause delamination. Due to the mismatch of the coefficient of thermal expansion, warpage is evident for alumina film and molybdenum oxide film, which had a bad influence on the uniformity of the following encapsulation process. It is meaningful to provide a reference for the continuous improvement of efficiency. The encapsulation of perovskite-based solar cells also will be discussed to reduce the resulting internal loads to a minimum value.

关键词： perovskite solar cell FEM thermal stress fabrication processing encapsulation

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SUPERPLASTIC ALLOY DIAPHRAGM FORMING OF FRTP BY CONVENTIONAL HEAT OVEN

SUPERPLASTIC ALLOY DIAPHRAGM FORMING OF FRTP BY CONVENTIONAL...

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22ND INTERNATIONAL TECHNICAL CONF OF THE SOC FOR THE ADVANCEMENT OF MATERIAL AND PROCESS ENGINEERING - ADVANCED MATERIALS : LOOKING AHEAD TO 21ST CENTURY

作者： MATSUNAGA, N AZEYANAGI, K YOSHIDA, H Janome Sewing Machine Co. Ltd. Research Lab Tokyo Japan

ISBN: (纸本)0938994549

A conventional heat oven was employed for superplastic alloy diaphragm forming of continuous carbon fiber reinforced thermoplastic. In an innovative pilot scale pressure vessel design, specially formed parts were cooled by an air/water jet. Thus, it is possible to control the crystallinity of semi-crystaline polymer matrix. The objective of this investigation was to establish the processing criteria required to economically form complex, large scale curved parts without causing shear-buckling. Female hemispherical section parts with varying depths were formed by applying gaseous pressure across a superplastic alloy sheet. Part quality, and fiber placement were inspected. An investigation was performed to study the pressurization forming cycle and it's relation between cooling rates with the air/water jet and impact damage by the drop weight test.

关键词： CERAMICS COMPOSITES POLYMER MATRIX EQUIPMENT fabrication processing MOLDING POLYETHERETHERKETONES REINFORCEMENT CARBON TESTING

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