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bending strength and fracture surface topography of natural fiber-reinforced shell for investment casting process

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China Foundry 2016年第3期13卷 211-216页

作者： Kai Lü Xiang-dong Liu Zhao-xin Du Yan-fen Li School of Materials Science and Engineering inner Mongolia University of Technology Hohhot 010051 China Key Laboratory of Materials Processing & Control Engineering of Inner Mongolia Autonomous Region Hohhot 010051 China

In order to improve the properties of silica sol shell for investment casting process, various contents of cattail fibers were added into the slurry to prepare a fiber-reinforced shell in the present study. The bending strength of fiber-reinforced shell was investigated and the fracture surfaces of shell specimens were observed using SEM. It is found that the bending strength increases with the increase of fiber content, and the bending strength of a green shell with 1.0 wt.% fiber addition increases by 44% compared to the fiber-free shell. The failure of specimens of the fiber-reinforced green shell results from fiber rupture and debonding between the interface of fibers and adhesive under the bending load. The micro-crack propagation in the matrix is inhibited by the micro-holes for ablation of f ibers in specimens of the f iber-reinforced shell during the stage of being fired. As a result, the bending strength of specimens of the fired shell had no significant drop. Particularly, the bending strength of specimens of the fired shell reinforced with 0.6wt.% fiber reached the maximum value of 4.6 MPa.

关键词： fiber-reinforced shell investment casting bending strength fracture surface topography

Thermal conductivity and bending strength of SiC composites reinforced by pitch-based carbon fibers

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Journal of Advanced Ceramics 2022年第2期11卷 247-262页

作者： Liyang CAO Yongsheng LIU Yunhai ZHANG Yejie CAO Jingxin LI Jie CHEN Lu ZHANG Zheng QI Science and Technology on Thermostructural Composites Materials Laboratory Northwestern Polytechnical UniversityXi’an 710072China Science and Technology on Space Physics Laboratory Beijing 100076China

In this work,pitch-based carbon fibers were utilized to reinforce silicon carbide(SiC)composites via reaction melting infiltration(RMI)method by controlling the reaction temperature and resin carbon *** conductivities and bending strengths of composites obtained under different preparation conditions were characterized by various analytical *** showed the formation of SiC whiskers(SiC_(w))during RMI process according to vapor–solid(VS)***_(w) played an important role in toughening the C_(pf)/SiC composites due to crack bridging,crack deflection,and SiC_(w) *** in reaction temperature during RMI process led to an initial increase in thermal conductivity along in-plane and thickness directions of composites,followed by a *** reaction temperature of 1600℃,thermal conductivities along the in-plane and thickness directions were estimated to be 203.00 and 39.59 W/(m×K),*** these conditions,bending strength was recorded as 186.15±3.95 *** in resin carbon content before RMI process led to the generation of more SiC *** conductivities along in-plane and thickness directions remained stable with desirable values of 175.79 and 38.86 W/(m×K),*** comparison,optimal bending strength improved to 244.62±3.07 *** sum,these findings look promising for future application of pitch-based carbon fibers for reinforcement of SiC ceramic composites.

关键词： pitch-based carbon fiber continuous carbon fiber reinforced silicon carbide matrix composites(C/SiC) thermal conductivity bending strength

Construction of continuous heat conductive channel,a double harvest strategy to enhance thermal conductance and bending strength of C/SiC composites

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Journal of Materials Science & Technology 2022年第10期105卷 101-108页

作者： Yunhai Zhang Yongsheng Liu Liyang Cao Xutong Zheng Yejie Cao Jing Wang Qing Zhang Science and Technology on Thermostructural Composite Materials Laboratory Northwestern Polytechnical UniversityXi’an 710072China

The development of efficient and quick method to prepare structure-function integrative C/SiC composites is always a major challenge in this ***,the thermal conductivity and bending strength of C/SiC composites were enhanced simultaneously via continuous high heat conductive channels constructed by continuous wave laser machining and pitch-based high thermal conductivity carbon fber in thickness *** revealed that the thermal conductivity of the modifed C/SiC composites is three times higher than that of referential C/SiC composites due to its highly ordered heat conducive channel in the thickness ***,the bending strength of modifed C/SiC composites increased to *** better understand the enhance mechanism,the micro-structure for both the composites and heat conductive channel was systematically *** results demonstrated that the rivet effect of heat conductive channel and the formed two phases structure on the fbers dispersed partial of load and fnally enhanced the property of the *** a word,this method holds a nice applicable future in constructing structure-function integrative C/SiC composites.

关键词： C/SiC composites Structure-function integrative Thermal conductivity bending strength Heat conductive channel

Subsurface damage and bending strength analysis for ultra-thin and flexible silicon chips

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Science China(Technological Sciences) 2023年第1期66卷 215-222页

作者： JIAN Wei WANG ZhaoXian JIN Peng ZHU Longji CHEN Ying FENG Xue Key Laboratory of Applied Mechanics of Ministry of Education Department of Engineering MechanicsTsinghua UniversityBeijing100084China Center for Flexible Electronics Technology Tsinghua UniversityBejing 100084China Institute of Flexible Electronics Technology of Tsinghua University Jiaxing Jiaxing314000China Qiantang Scienceand Technology Innovation Center Hangzhou310016China

Subsurface damage(SSD) is an unavoidable problem in the precision mechanical grinding for preparing ultra-thin and flexible silicon chips. At present, there are relatively few studies on the relationship between SSD and the bending strength of ultra-thin chips under different grinding parameters. In this study, SSD including amorphization and dislocation is observed using a transmission electron microscope. Theoretical predictions of the SSD depth induced by different processing parameters are in good agreement with experimental data. The main reasons for SSD depth increase include the increase of grit size, the acceleration of feed rate, and the slowdown of wheel rotation speed. Three-point bending test is adopted to measure the bending strength of ultra-thin chips processed by different grinding conditions. The results show that increasing wheel rotation speed and decreasing grit size and feed rate will improve the bending strength of chips, due to the reduction of SSD depth. Wet etching and chemical mechanical polishing(CMP) are applied respectively to remove the SSD induced by grinding, and both contribute to providing a higher bending strength, but in comparison, CMP works better due to a smooth surface profile. This research aims to provide some guidance for optimizing the grinding process and fabricating ultra-thin chips with higher bending strength.

关键词： ultra-thin chip flexible chip subsurface damage bending strength mechanical grinding

Relationships among Preparative Technique,Phase Composition and bending strength of Bauxite Porcelain

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Chinese Journal of Structural Chemistry 2007年第1期26卷 79-83页

作者：任强武秀兰何选盟朱振峰 School of Material Science and Engineering Shaanxi University of Science and Technology

Bauxite porcelain can be sintered to make its bending strength reach 179Mpa by using sintered bauxite, clay and potash feldspar and albite as the main raw materials in oxidation atmosphere under the normal pressure. XRD, SEM and so on are utilized to study the relationships between factors like the composition of ingot, reduction particle size and heat insulating time at sintering temperature and the phase composition, microstructure and bending strength of ceramic body. The results show that the main phases in bauxite porcelain are corundum, mullite and glass, and the mullite is composed of two parts： primary mullite formed by clay conversion and secondary mullite whiskers precipitating from high temperature melt. The bending strength of ceramic body can be improved by enhancing the content of sintered bauxite in the formula： the smaller the particle size of the ceramic body is, the higher the bending strength will be. The high-temperature heat insulating technique is beneficial to the precipitation of certain quantitative secondary mullite whiskers so as to remarkably improve the strength of glass phase and ceramic body.

关键词： bauxite porcelain mirocstructure mullite whiskers bending strength

The Influence of Mineral Admixtures on bending strength of Mortar on the Premise of Equal Compressive strength

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Journal of Wuhan University of Technology(Materials Science) 2012年第3期27卷 586-589页

作者：王强阎培渝 Department of Civil Engineering Tsinghua University

The influence of mineral admixtures on bending strength of mortar on the premise of equal compressive strength was investigated. Three mineral admixtures （fly ash, ground granulated blast-furnace slag and steel slag） were used. The adding amount of mineral admixture in this study ranges from 22.5% to 60%, and the water-to-binder ratio ranges from 0.34 to 0.50. With equal compressive strength, different mortars can be arranged in such a descending order with their bending strength： cement-fly ash mortar, cement mortar, cement-GGBS mortar, and cement-steel slag mortar. With the same compressive strength, the higher the steel slag content and water-to-binder ratio, the lower the bending strength of mortars. However, the effect of mineral mixture content and water-to-binder ratio on the bending strength of cement-fly ash mortar and cement-GGBS mortar is far inconspicuous.

关键词： mineral admixtures bending strength compressive strength

Influence of Characteristics on bending strength of Layered Steel Fiber Reinforced Concrete

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Wuhan University Journal of Natural Sciences 2005年第5期10卷 883-886页

作者： DAI Shao-bin SONG Ming-hai HUANG Jun Design Institute Wuhan University of Technology Wuhan 430070 Hubei China

The influence of two main characteristics of steel fiber, the aspect ratio （Df） and volume fraction （ρf）, on the bending strength of Layered Steel Fiber Reinforced Concrete （LSFRC） is investigated by using orthogonal test. Via the variance analysis on the experimental results and trend analysis on the two characteristics, Df is found significantly related to the bending strength of LSFRC. The influence ratio is 63.3%. The bending strength of LSFRC increases if Df increases, makes better when Df reaches 100. ρf has ordinary influence on the bending strength of LSFRC. The influence ratio is 29.2%. Other characteristics, such as the shape of steel fiber and the mix proportion, have less influence. The best ρf contributing to the bending strength of LSFRC is 1.5 %. If ρf is greater than 1.5%, it has negative influence on the bending strength of LSFRC. So, ρf makes a limited contribution to the bending strength of LSFRC.

关键词： LSFRC bending strength orthogonal test influence ratio

EFFECT OF CORROSION ON BOND BEHAVIOR AND bending strength OF REINFORCED CONCRETE BEAMS

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2001年第3期2卷 59-69页

作者：金伟良赵羽习 Department of Civil Engineering Zhejiang University Hangzhou China

There is growing concern for corrosion damage in reinforced concrete structures with several decades’ service. Pullout tests and beam tests were carried out to study the effect of reinforcement corrosion on the bond behavior and bending strength of reinforced concrete beams. The bond strength of plain bars and concrete initially increases with increasing corrosion, then declines. The turning point depends on the cracking of the concrete cover. The bond strength of deformed bars and concrete increases with corrosion up to a certain amount, but with progressive increase in corrosion, the bond strength decreases, and the cracking of the concrete cover seems to have no effect on the bond strength. On the basis of test data, the bond strength coefficient recommended here, which, together with the bond strength of uncorroded steel bars and concrete, can be used to easily calculate the bond strength of corroded steel bars and concrete. The bond strength coefficient proposed in this paper can be used to study the bond stress\|slip relationship of corroded steel bars and concrete. The bending strength of corroded reinforced concrete beams declines with increasing reinforcement corrosion. Decreased bending strength of corroded RC beam is due to reduction in steel bar cross section, reduction of yield strength of steel bar, and reduction of bond capacity between steel bar and concrete.

关键词： reinforced concrete beam corrosion bond behavior bond strength coefficient bending strength coordination coefficient

Interfacial reactions and bending strength of SiC/A356/FeNi50 composite fabricated by gas pressure infiltration

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Transactions of Nonferrous Metals Society of China 2013年第8期23卷 2229-2235页

作者：马春雪于家康薛晨张志庆西北工业大学凝固技术国家重点实验室西安710072

The SiC/A356/FeNi50 composite was fabricated by gas pressure infiltration. The interfacial region of the SiC/A356/FeNi50 composite consisted of FeNi50 reaction layer, A1 reaction layer and A1 alloy matrix. The main intermetallic compounds were （Fe,Ni）a（A1,Sih3 and （Fe,Ni）2（A1,Si）5 at the A1 reaction layer and FeNi50 reaction layer, respectively. The bending behavior versus different infiltration temperatures and holding times was also investigated. The bending strength at 670 ~C was the highest and close to the bending strength of A1 alloy （223 MPa）, and 46% of SIC/A356. The brittle intermetallic compounds existing at the interface induced the decreasing of the bending strength. The pores were reduced by adequate heating time due to the homogeneous temperature of preform, which was beneficial to improve the bending strength of the composite.

关键词： infiltration metal matrix composites bending strength interracial reactions