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Dynamic Tensile Behavior of Woven c/Sic composite: Experiments and Strain-Rate-Dependent Yield criterion

MATERIALS 2022年第13期15卷 4679-4679页

作者： Yu, Jingwei Zhang, Peiwei chen, Qiang Fei, Qingguo Southeast Univ Sch Mech Engn Nanjing 211189 Peoples R China Southeast Univ Jiangsu Engn Res Ctr Aerosp Machinery Nanjing 211189 Peoples R China

This paper studies the yield behavior of a woven carbon-fiber-reinforced silicon-matrix (c/Sic) composite under dynamic tensile loading. Experiments were carried out to obtain the tensile properties of the c/Sic composite at a strain rate range of 2 x 10(-5)/s to 99.4/s. A strain-rate-dependent yield criterion based on the distortional strain energy density theory is established to describe the yield behavior. The interval uncertainty is considered for a more reliable yield prediction. Experimental results show that the yield stress, elastic modulus, and yield strain of the c/Sic composite grow with the increasing strain rate. The failure mode transitions from progressive crack extension to uneven fiber bundle breakage. The predicted results by the yield criterion match well with experimental data. Experimental results are enveloped within the uncertainty level of 45% in the critical distortional energy density, corresponding to an uncertainty of 14% and 11% in the yield stress and yield strain, respectively. With the support of the proposed strain-rate-dependent yield criterion, the yield behavior of the c/Sic composite under dynamic loading conditions can be predicted with reasonable accuracy.

关键词： c Sic composite strain rate yield criterion interval analysis

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Size effect of carbon fiber-reinforced silicon carbide composites (c/c-Sic): Part 2-tensile testing with alignment device

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JOURNAL OF THE EUROPEAN cERAMIc SOcIETY 2022年第4期42卷 1227-1237页

作者： Flauder, Stefan Bombarda, Ilaria D'Ambrosio, Roberto Langhof, Nico Lazzeri, Andrea Krenkel, Walter Schaffoener, Stefan Univ Bayreuth Ceram Mat Engn CME Prof Rudiger Bormann Str 1 D-95447 Bayreuth Germany IPCF CNR Ist & Processi Chimicofis Via G Moruzzi 1 I-56124 Pisa Italy Univ Pisa Dept Civil & Ind Engn Via Diotisalvi 2 I-56122 Pisa Italy

The appropriate assessment of mechanical properties is essential to design ceramic matrix composites. The size effect of strength plays a key role for the material understanding and the transfer from lab-scale samples to components. In order to investigate the size effect for carbon fiber-reinforced silicon carbon (c/c-Sic) under tensile load, a tensile testing with a minimum of deviation from the pure tensile loading is necessary. Hence, a hybrid edge/face-loading test device for self-alignment and centering of c/c-Sic tensile samples was developed, evaluated and proved to ensure pure tensile load. The mechanical analysis of more than 190 samples with two different cross-sections fabricated from the same material population revealed no significant difference in tensile strength. Although the volume under load was increased from 129 to 154 mm3, the tensile strengths of 162 +/- 7 and 164 +/- 6 MPa did not change. These results are discussed regarding the weakest link and energetic size effect approaches.

关键词： ceramic matrix composites (cMc) c c-Sic Tensile testing Size effect of strength Alignment device

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Microstructure, mechanical and anti-ablation properties of Mg-modified c/ c-Zrc-Sic composites prepared by sol-gel technology

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cERAMIcS INTERNATIONAL 2022年第23期48卷 34728-34742页

作者： Zheng, Lei Fang, cunqian Zeng, chen Luo, Xiao Zhang, Ze Zhang, Xiaxiang Zhang, Mingyu Huang, Qizhong Cent South Univ Natl Key Lab Sci & Technol High strength Struct Ma Changsha 410083 Peoples R China Cent South Univ Sch Met & Environm Changsha 410083 Peoples R China

Mg-modified c/c-Zrc-Sic composites were fabricated by a sol-gel process, and the influences of the Mg/(Zr + Si) molar ratio on the microstructure and the mechanical and anti-ablation properties of the composites were investigated. The results showed that Mg addition not only optimized the distribution of surficial ceramic par-ticles but also improved the flexural strength of composites by inhibiting the ceramization of fibres. Fabricated Mg/(Zr + Si) with a molar ratio of 0.040:0.18 increased the flexural strength of the composite from 173.15 MPa to 331.22 MPa, and the elastic modulus ranged from 11.46 GPa to 23.09 GPa. After plasma flame ablation for 180 s, this composite also showed excellent anti-ablation performance with linear and mass ablation rates of 3.91 mu m/s and-0.23 mg/s, respectively. The superior ablation property was ascribed to the formation of a consecutive oxide layer constructed by a viscous mixed liquid consisting of liquid Mg-Si-O and Zr-Si-O phases and the robust skeleton of the coarsening ZrO2.

关键词： c c-Zrc-Sic composites Mg Sol -gel Property

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TEA driven c, N co-doped superfine Fe3O4 nanoparticles for efficient trifunctional electrode materials

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JOURNAL OF cOLLOID AND INTERFAcE ScIENcE 2022年 609卷 249-259页

作者： Li, Shisha Feng, chao Xu, Yanchao Jiao, Yang chen, Jianrong Zhejiang Normal Univ Coll Geog & Environm Sci Jinhua 321004 Zhejiang Peoples R China

Poor conductivity is an obstacle that restricts the development of the electrochemistry performance of Fe3O4. In this work, a novel carbon and nitrogen co-doped ultrafine Fe3O4 nanoparticles (cN-Fe3O4) have been synthesized by triethylamine (TEA) induction and subsequent calcination. The addition of TEA could not only regulate the size of Fe3O4 nanoparticles, but also promote the formation of amorphous carbon layer. Well-designed cN-Fe3O4 heterostructures provide a highly interconnected porous conductive network, large heterogeneous interface area, large specific surface area and a large number of active sites, which greatly improve conductivity and promote electron transfer and electrolyte diffusion. The prepared cN-Fe3O4 electrode exhibits a high specific capacitance of 399.3 mF cm(-2) and good cycling stability. Meanwhile, cN-Fe3O4 catalyst exhibits excellent oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) activities, with overpotentials of 136 and 281 mV at the current density of 10 mA cm(-2), respectively. This work provides a promising approach for the design of high-performance anode materials for supercapacitors and provides profound implications for the development of catalysts with bifunctional catalytic activity. (c) 2021 Elsevier Inc. All rights reserved.

关键词： c N co-doped Fe3O4 conductivity Supercapacitor Electrocatalyst

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The influence of heat treatment on the ablation behavior of the c/cx-Sicy composites tested by thin-blade under oxyacetylene torch

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cERAMIcS INTERNATIONAL 2022年第15期48卷 22523-22533页

作者： Liu, Ningkun Guo, Lingjun Kou, Gang Li, Yunyu Yin, Xuemin Northwestern Polytech Univ Shaanxi Key Lab Fiber Reinforced Light Composite M Xian 710072 Peoples R China

c/cx-Sicy composites are one of the most promising counterparts of c/c composites as they maintain the mechanical strength of c/c composites while providing excellent anti-ablation properties at the same time. This paper reports that the composites could exhibit even better anti ablation properties after heat treatment. The materials were heat-treated and then tested with a thin-blade oxyacetylene torch without the protection of any coatings. The 1600 degrees c heat-treated thin-blade specimen could sustain the ablation of the oxyacetylene torch with a temperature of 1776 degrees c (80 degrees c higher than the original material without heat treatment) and a lower liner ablation rate (1.31 mu m/s) than the original material (1.66 mu m/s). An extreme ablation test was also conducted at around 2400 degrees c, and the 1600 degrees c heat-treated specimen exhibited a lower linear ablation rate (13 mu m/s) than the original specimen (47 mu m/s). The influence of the heat treatment on the crystallinity of the matrix is studied with the additional help of Raman spectroscopy and XPS. The ablation mechanism is discussed in detail, and the fluent condition of the thin-blade specimen is simulated. The paper also reports a different ablation behavior of the 1600 degrees c heat-treated specimen from the material without heat treatment to explain their excellent ablation property.

关键词： Graphitization c cx-Sicy composites Ablation property c composites Heat treatment

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Photoreactive polymer and c,H-insertion reaction to tailor the properties of cHA/gelatin-based scaffold

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INTERNATIONAL JOURNAL OF POLYMER ANALYSIS AND cHARAcTERIZATION 2022年第5期27卷 326-345页

作者： Ardhani, Retno Suraya, Tiyastiti Wulanjati, Martha Purnami Ana, Ika Dewi Ruehe, Jurgen Pidhatika, Bidhari Univ Gadjah Mada Fac Dent Dept Dent Biomed Sci Yogyakarta Indonesia Minist Ind Ctr Standardizat & Ind Serv Leather Rubber & Plas Jl Sokonandi 9 Yogyakarta Indonesia Natl Res & Innovat Agcy Republ Indonesia PRTPP BR Res Ctr Food Technol & Proc Yogyakarta Indonesia Univ Freiburg Freiburg Inst Interact Mat & Bioinspired Technol Dept Microsyst Engn IMTEK DFG Cluster Excellence LivMatS Freiburg Germany Natl Res & Innovat Agcy Republ Indonesia BRIN Jakarta Indonesia

A series of photoreactive polymers containing poly(N,N-dimethylacrylamide) and 2-hydroxy-(4-methacryloyloxybenzophenone), P(DMAA-n%MABP-OH), was explored to modify sheet-formed carbonated hydroxyapatite/gelatin (cHA/gelatin) scaffold. Under UV-light illumination, the benzophenones react with any c-H bonds in their vicinity through a c,H-insertion mechanism, enabling PDMAA-based hydrogel formation that is covalently attached to the gelatin. NMR spectroscopy confirmed the chemical structure of P(DMAA-n%MABP-OH) polymers with aimed n = 1, 5, 10, while GPc determined their molecular masses. The benzophenone reactivity under UV-light illumination for 0-240 min. was demonstrated using UV-Vis spectroscopy at 240-400 nm. After immobilization of P(DMAA-n%MABP-OH) onto the cHA/gelatin scaffold, typical FTIR vibration bands of both compounds could be detected on the spectra of the modified scaffolds. SEM images showed that the scaffold is highly porous with approximately 100 mu m thickness. P(DMAA-n%MABP-OH) addition led to 2-3 times increase in thickness and 15-19% mass addition. Furthermore, it was shown that chemical (degradation and ca2+ release profile), physical (4-7 swelling index), mechanical (0.06-0.17 MPa wet tensile strength and 0.2-0.8 MPa elastic modulus), and biological (cell adhesion) properties of the scaffold could be tailored by varying the photocrosslinker content. cytotoxicity test showed that all studied cHA/gelatin-based scaffolds were nontoxic (>80% cell viability).

关键词： c H-insertion crosslinking hydrogel photoreactive polymer scaffold

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Effect of off-axis angle on mesoscale deformation and failure behavior of plain-woven c/Sic composites with digital image correlation

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JOURNAL OF THE EUROPEAN cERAMIc SOcIETY 2022年第12期42卷 4712-4722页

作者： Teng, Xuefeng Lyu, Shuangqi Hu, Xiaoan Jiang, Yun Nie, Xiangfan Liu, Xin Li, Longbiao Nanchang Hangkong Univ Sch Aircraft Engn Nanchang 330063 Peoples R China Jiangxi Key Lab Micro Aeroengine Nanchang 330063 Peoples R China Civil Aviat Flight Univ China Aviat Engn Coll Guanghan 618307 Sichuan Peoples R China Nanchang Hangkong Univ Anal & Testing Ctr Nanchang 330063 Peoples R China AF Engn Univ Sci & Technol Plasma Dynam Lab Xi'an 710038 Shaanxi Peoples R China China Acad Launch Vehicle Technol Beijing 100076 Peoples R China Nanjing Univ Aeronaut & Astronaut Coll Civil Aviat Nanjing 210016 Peoples R China

In this study, the deformation response and failure behavior of a plain-woven c/Sic composite were investigated under on-axis and off-axis tensile loading. Digital image correlation (DIc) was utilized to characterize the full field deformation and mesoscale strain distribution. The test results indicate a strong influence of the woven architecture on the mechanical properties and strain distribution, and the materials exhibit failure modes dependent on the loading directions or off-axis angles: the fracture positions of different layers are the same under off-axial load, while for on-axil loading, the fracture positions of different layers do not affect each other. SEM results provide direct evidence that the width of the off-axis specimen has a great influence on the mechanical properties. The reduction of the modulus and strength of off-axis specimen, is not only due to the off axis loading, but also due to the reduction of effective bearing area or effective bearing fiber.

关键词： Plain-woven c Sic composites Digital image correlation Off-axis Failure behavior

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Regenerated LiFePO4/c for scrapped lithium iron phosphate powder batteries by pre-oxidation and reduction method

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IONIcS 2022年第5期28卷 2125-2133页

作者： Zhang, Hao Wang, Lihua chen, Yongzhi Wen, Xu Changsha Univ Coll Mech & Elect Engn Changsha 410022 Peoples R China Hunan Inst Sci & Technol Coll Mech Engn Yueyang 414006 Peoples R China

The cathode materials of scrapped lithium-iron phosphate battery are mainly composed of LiFePO4/c, conductive agent and PVDF, etc. Unreasonable disposal will cause serious environmental pollution and waste of scarce resources. In this paper, cathode materials were regenerated by pre-oxidation and reduction method. Impurities such as carbon coating, conductive agent, and PVDF were removed and LiFePO4/c was converted to Fe2O3 and Li3Fe2(PO4)(3) by pre-oxidation. After the addition of sucrose, regeneratedLiFePO(4)/c was synthesized under reduction process. The effects of calcination temperature and sucrose addition on the microstructure and electrochemical properties of regenerated LiFePO4/c were studied. The regenerated LiFePO4/c had excellent cycling stability when the sucrose addition was 12% and calcined at 700 celcius. The initial discharge specific capacity of regenerated LiFePO4/c was 145.51 mAh g(-1) at 0.5 c. After 200 cycles, the discharge specific capacity was 145.25 mAh g(-1) (capacity retention rate: 99.82%). It provides a new inspiration for the high-value recycling and regeneration of the other scrapped lithium-ion batteries.

关键词： Scrapped lithium-ion batteries Regenerated LiFePO4 c Pre-oxidation and reduction

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Role of fiber-matrix adhesion at cFRP stage on microstructure and mechanical properties of c/c-Sic composite

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INTERNATIONAL JOURNAL OF APPLIED cERAMIc TEcHNOLOGY 2022年第1期19卷 79-90页

作者： Dai, Jixiang Zhang, Zhaofu Zu, Yufei Sha, Jianjun Dalian Univ Technol State Key Lab Struct Analyses Ind Equipment Dalian 116024 Peoples R China Dalian Univ Technol Key Lab Adv Technol Aerosp Vehicles Dalian Peoples R China Xian Aerosp Composites Res Inst Xian Peoples R China

In order to understand the role of fiber-matrix adhesion (FMA) at carbon fiber-reinforced polymer (cFRP) stage on the microstructure and mechanical properties of c/c-Sic composite via liquid silicon infiltration (LSI) process, the FMA was adjusted by thermal treatment of carbon fibers at different temperatures and evaluated by means of single fiber push-out technique. The microstructure was characterized by optical microscopy and scanning electron microscopy. The mechanical properties were measured by the double-notched shear test, three-point flexural test, and single edge-notched beam test, respectively. Results indicated that the microstructure and mechanical properties of c/c-Sic composite via LSI were closely associated with the FMA at cFRP stage. The microstructure of c/c-Sic composite fabricated by using the cFRP with high FMA presented nonhomogeneous distribution and concentration of Sic matrix. In contrast, the c/c-Sic composite fabricated by using the cFRP with low FMA, the high content of Sic distributed homogeneously and surrounded the fiber, which resulted in a strong bonded c-Sic interface. The strong c-Sic interface is detrimental to the fracture toughness, but it is beneficial to the improvement of oxidation resistance. To obtain desired mechanical properties of c/c-Sic composite, the control of interface bonding is important, which can be realized by modifying the FMA at cFRP stage.

关键词： carbon fiber c c-Sic composite ceramic matrix composites fiber-matrix bonding microstructure control

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Effect of rotary ultrasonic machining on surface structure and ablation resistance of c/c composite

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cERAMIcS INTERNATIONAL 2022年第13期48卷 18246-18256页

作者： Shu, Jing Liao, Wenhe Zheng, Kan Abd Elbadia, Tarek Nanjing Univ Sci & Technol Sch Mech Engn Nanjing Jiangsu Peoples R China Mil Tech Coll Mech Design & Prod Dept Cairo Egypt

c/c composite is widely used in aerospace due to excellent high temperature mechanical properties. Improving its ablation resistance has become the focus of attention. Due to anisotropy of composite materials, the difference of thermal conductivity and thermal expansion coefficient between fiber and matrix, surface morphologies affect ablation performance greatly. In particular, fiber exposed length (FEL) and crack had a significant impact on its ablation resistance. Therefore, this paper constructed a FEL theoretical model based on machining damage, and verified that the error of the modified model was within 12 % through experiments. Meanwhile, improvement effect of rotary ultrasonic machining (RUM) was clarified. It is found that RUM reduced FEL by 15%~38% in all fiber angles and decreased the crack pores on machined surface. Then, oxyacetylene ablation experiments on c/c composite surface under conventional machining (cM) and RUM were carried out. The results showed that RUM surface had better ablation resistance, and interface ablation and porosity decreased significantly.

关键词： c c composite RUM Morphology Oxyacetylene ablation

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