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Early-age Hydration Characteristics of Composite Binder Containing Graphite Powder
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作者 HE Wei SONG Shaomin +2 位作者 MENG Xia ZHANG Pengchong SUN Xu 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2022年第6期1252-1261,共10页
The early-age hydration characteristics of composite binder containing graphite powder(GP)with two different finenesses were investigated by determining the hydration heat,thermo gravimetric,morphology of hardened pas... The early-age hydration characteristics of composite binder containing graphite powder(GP)with two different finenesses were investigated by determining the hydration heat,thermo gravimetric,morphology of hardened paste as well as the compressive strength of mortar.The experimental results show that:replacing 2%-6%of cement with graphite powder significantly improves the piezoresistive effect of early age mortar,can be used to monitor accidental loads caused by dropped objects,collisions,or other accident events,and thus avoids initial damage.Some GP provides additional nucleation sites that lead to a fast formation of hydration products(nucleation-site effect).However,due to the almost hydrophobic water contact angle,most of the GP causes a large number of micro-cracks in the hydrated paste(gap effect).Because of the lamellar shape and high surface energy,GP is easily balled and can not be uniformly distributed in the composite,resulting in clumping together and wrapping some of the cement particles(barrier effect).Due to nucleation-site effect,when the dosages of coarse and fine GP reached 2%and 4%,1 d strength were increased by 9.1%and 9.6%,respectively.At 3 days,as the interior damage caused by the gap effect gradually increased,and the retarding effect on cement hydration caused by barrier effect was enhanced.GP has an obvious negative effect on compressive strength.However,micro-cracks caused by fine GP are less,so its negative effect on 3 d compressive strength is lower. 展开更多
关键词 graphite powder Portland cement early-age hydration piezoresistive effect comprehensive strength
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Research on graphite powders used for HTR-PM fuel elements
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作者 ZHAO Hongsheng LIANG Tongxiang ZHANG Jie LI Ziqiang TANG Chunhe 《Rare Metals》 SCIE EI CAS CSCD 2006年第z1期347-350,共4页
Different batches of natural graphite powders and electrographite powders were characterized by impurity, degree of graphitization, particle size distribution, specific surface area, and shape characteristics. The gra... Different batches of natural graphite powders and electrographite powders were characterized by impurity, degree of graphitization, particle size distribution, specific surface area, and shape characteristics. The graphite balls consist of proper mix-ratio of natural graphite, electrographite and phenolic resin were manufactured and characterized by thermal conductivity, anisotropy of thermal expansion, crush strength, and drop strength. Results show that some types of graphite powders possess very high purity, degree of graphitization, and sound size distribution and apparent density, which can serve for matrix graphite of HTR-PM. The graphite balls manufactured with reasonable mix-ratio of graphite powders and process method show very good properties. It is indicated that the properties of graphite balls can meet the design criterion of HTR-PM. We can provide a powerful candidate material for the future manufacture of HTR-PM fuel elements. 展开更多
关键词 high temperature gas-cooled reactor graphite powder design criterion
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Kinetics of Reduction of Iron Oxide in CaO-SiO_2-Al_2O_3-Fe_tO Slags with Graphite Powder
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作者 Yang Xuemin Huang Dianbing +3 位作者 Kong Lingtan Yang Tianjun Xie Yusheng Wang Daguang 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 1998年第1期21-27,共4页
The reduction rate of Fe^tO in CaOSiO_2Al_2O_3Fe_tO slags with graphite powder has been determined in an alumina crucible at 1 673-1 823 K. The effects of temperature, slag basicity and Fe_tO content on the reduc... The reduction rate of Fe^tO in CaOSiO_2Al_2O_3Fe_tO slags with graphite powder has been determined in an alumina crucible at 1 673-1 823 K. The effects of temperature, slag basicity and Fe_tO content on the reduction rate have also been discussed. Test results show that the reduction rate increases with the increase of temperature or Fe_tO concentration in slags, and the reduction rate has a parabolic relation with slag simple basicity or optical basicity. The maximum reduction rate is observed around CaO/SiO_2=1.5 of molten slags. The reaction order is 1.26 or 1.31, and the reduction activation energy is 126.8 or 129.7 kJ/mol respectively in regard to Fe_tO content or Fe_tO activity calculated by using regular solution model. The reduction rate of Fe_tO in CaOSiO_2Al_2O_3Fe_tO slags with graphite powder is in the range of 0.15×10^-4-0.86×10^-4 molO/cm^2·s. 展开更多
关键词 CaOSiO_2Al_2O_3Fe_tO slags reduction rate graphite powder Fe^tO activity KINETICS
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Rapid Extraction and Analysis of Essential Oil from Cinnamomum Cassia Presl. 被引量:4
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作者 WANG Lu WANG Zi-ming +3 位作者 LI Tie-chun ZHOU Xin DING Lan ZHANG Han-qi 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2008年第3期275-280,共6页
An improved solvent-free microwave extraction(ISFME) was used for the extraction of essential oil from dried Cinnamomum cassia Presl. Two kinds of solid microwave absorption media[carbonyl iron powder(CIP) and gra... An improved solvent-free microwave extraction(ISFME) was used for the extraction of essential oil from dried Cinnamomum cassia Presl. Two kinds of solid microwave absorption media[carbonyl iron powder(CIP) and graphite powder(GP)] were used. When ISFME was applied, the heating rate was enhanced and the extraction time was obviously shorter than that consumed in conventional solvent-free microwave extraction(CSFME). Twenty-eight kinds of compounds in the essential oil were identified, and the total content fractions of the compounds obtained by CIP-ISFME, GP-ISFME, CSFME, and hydrodistillation(HD) were 96.65%, 96.06%, 97.22%, and 96.29%, respectively. The compounds in the essential oil obtained from Cinnamomum cassia Presl. by ISFME, CSFME, and HD were compared and the quantity of the essential oil was almost the same. The ISFME has been proved to be a feasible way to extract essential oil from dried samples, and there are several obvious advantages in ISFME over those of HD and CSFME, for example, shorter extraction time(30 min) and lower energy consumption. 展开更多
关键词 Solvent-free microwave extraction Cinnamomum Cassia Presl. Essential oil Carbonyl iron powder graphite powder
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In-situ formation of Ni-Al intermetallics-coated graphite/Al composite in a cold-sprayed coating and its high temperature tribological behaviors 被引量:3
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作者 Chunjie Huang Wenya Li +2 位作者 Marie-Pierre Planche Hanlin Liao Ghislain Montavon 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2017年第6期507-515,共9页
In this study, cold spraying(CS) was used to deposit a mixture of nickel-coated graphite and 40 vol.% Al powder(Ni-Gr/Al) on a steel substrate aiming to effectively preserve a certain volume fraction of graphite i... In this study, cold spraying(CS) was used to deposit a mixture of nickel-coated graphite and 40 vol.% Al powder(Ni-Gr/Al) on a steel substrate aiming to effectively preserve a certain volume fraction of graphite in the deposited Ni-Gr/Al composite coating. The microstructure of the as-sprayed coating and the effect of post-spray heat-treatment(PSHT) temperatures on the in-situ formation of Ni-Al intermetallic phases in coating were studied. The tribological behaviors of the as-sprayed coating and the PSHTed coating under 450?C were tested at 25?C, while the as-sprayed coating was tested at 450?C for comparison.As a result, the Ni-Gr particles showed a homogenous distribution in the coating. The multilayer Ni-Al intermetallics-coated graphite/Al composite coating was achieved in situ after the PSHT of 450?C, where the graphite did decompose at 550?C leaving big pores in the coating. The coefficients of friction(COF)of the CSed coating and the PSHTed coating were measured at 450?C as well as 25?C, which showed a similar tendency, much higher than that of the CSed coating tested at 25?C. The lubrication phase(graphite) improved the formation of a graphite film during sliding friction and decreased the COF, while the hard Ni-Al intermetallic phases contributed to the increase of COF. 展开更多
关键词 Cold spraying Ni-coated graphite powder Post-spray heat-treatment Intermetallics Tribological performance
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Au nanospheres modified boron-doped diamond microelectrode grown via hydrogen plasma etching solid doping source for dopamine detection 被引量:4
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作者 Kaili Yao Xiaojun Tan +7 位作者 Bing Dai Jie Bai Qiaoyang Sun Wenxin Cao Jiwen Zhao Lei Yang Jiecai Han Jiaqi Zhu 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2020年第14期42-46,共5页
Boron doped diamond(BDD)electrode is a promising electrochemical material for detecting dopamine level in the human’s body.In this work,we developed a new doping source-graphite and solid boron oxide powders to synth... Boron doped diamond(BDD)electrode is a promising electrochemical material for detecting dopamine level in the human’s body.In this work,we developed a new doping source-graphite and solid boron oxide powders to synthesize BDD film with microwave plasma chemical vapor deposition,so as to avoid using toxic or corrosive dopants,such as boroethane and trimethylborate.The synthesized BDD film is pinhole free and with high doping density of 8.44×10^20 cm^-3 calculated from the Raman spectroscopy.Subsequently,Au nanospheres were decorated on the surface of BDD film to improve electrochemical performance of the BDD film.The Au nanoparticles modified BDD electrode demonstrates an excellent electrochemical response,a high sensitivity(in the range of 5μM-1 m M),and a low detection limit(~0.8μM)for detecting dopamine. 展开更多
关键词 Boron doped diamond graphite powders Boron oxide powders Optical emission spectroscopy DOPAMINE
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