检索结果-南通市图书馆

Primary School on the Roof

在线全文

学校读者我要写书评

暂无评论

China Today 2005年第6期54卷 40-41页

作者： zhou chao & ke HAO

ONE month has passed since the start of the new semester at Lingzhi Primary School in Wuhan's Jianghan District, but 20 students have yet to return to class. ""Every new semester, we lose more than ten students,"" laments the teacher. ""Some return to their hometown while others study in other schools. It is very difficult to know if they've dropped out or not.""

关键词：武汉市初级中学学校规模教学质量

Microstructural evolution of TiAl base alloy during three-stepped thermo-mechanical treatment

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Central South University of Technology 2001年第1期8卷 9-12页

作者： LIU Yong,LIU Feng xiao,HUANG Bai yun,zhou ke chao,ZHANG Chuan fu (State key Lab for Powder Metallurgy, Central South University, Changsha 410083, China) 1. State key Lab for Powder Metallurgy Central South University 410083 Changsha China

A TiAl base alloy ingot with a height to diameter ratio of 2.2 was broken down by multiple step canned forging. The microstructures after every deformation and subsequent recrystallization were observed by optical microscopy. Results show that at the first step the reduction should be carefully controlled in case of double bulge and crack of the ingot. After the first annealing, recrystallization occurred at the deformed grain boundaries and inside the grain. The recrystallized microstructure is favorable for further deformation. After the second deformation and annealing, coarsening of the lamellae occurred and the microstructure became equiaxed. By the final deformation and subsequent recrystallization, the coarse lamellar colony can be refined to about 20 μm, and homogeneous microstructure was obtained from the ingot with a large initial height to diameter ratio.

关键词： TiAl base alloy hot forging microstructure

Wear map for sliding wear behavior of Cu-15Ni-8Sn alloy against bearing steel under oil-lubricated condition

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2020年第2期27卷 311-324页

作者： CHENG Jin-juan GAN Xue-ping LI zhou LEI Qian zhou ke-chao State key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China School of Materials Science and Engineering Central South UniversityChangsha 410083China

Wear behaviors of a peak-aged Cu-15Ni-8Sn alloy fabricated by powder metallurgy were *** results indicated that the friction coefficients and the wear rates of Cu-15Ni-8Sn alloy within a normal load range of 50−700 N and a sliding speed range of 0.05−2.58 m/s were less than 0.14 and 2.8×10−6 mm3/mm,***-like curve and wear map were developed to describe the oil-lubrication mechanism and wear *** equation of the dividing line between zones of safe and unsafe wear life was *** oil was squeezed into micro-cracks under severe wear *** addition,the lubricating oil reacted with Cu-15Ni-8Sn alloy to generate the corresponding sulfides,which hindered the repair of micro-cracks,promoted cracks growth,and led to *** work has established guidelines for the application of the Cu-15Ni-8Sn alloy under oil-lubricated conditions through developing wear map.

关键词： Cu-15Ni-8Sn alloy oil lubrication wear behavior wear map

Influence of pre-stretching on quench sensitive effect of high-strength Al-Zn-Mg-Cu-Zr alloy sheet

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2021年第9期28卷 2660-2669页

作者： HE ke-zhun LI Qun LIU Sheng-dan ZHANG Xin-ming zhou ke-chao Powder Metallurgy Research Institute Central South UniversityChangsha 410083China Guangxi Alnan Institute of Aerospace Transit Aluminum Alloy and Application Nanning 530031China Guangxi Alnan Aluminium Inc. Nanning 530031China School of Materials Science and Engineering Central South UniversityChangsha 410083China

The influence of pre-stretching on quench sensitive effect of high strength Al-Zn-Mg-Cu-Zr alloy AA 7085 sheet was investigated by tensile testing at room temperature,transmission electron microscopy(TEM)and differential scanning calorimetry(DSC).The water-cooled and aged alloy exhibits higher strength than the air-cooled and aged alloy;2.5%pre-stretching of tensile deformation exerts little effect on strength of water-cooled and aged alloy but increases that of air-cooled and aged one,and therefore the yield strength reduction rate due to slow quenching decreases from about 3.8%to about 1.0%,reducing quench sensitive *** the air-cooled alloy,pre-stretching increases the sizes ofη'strengthening precipitates but also increases their quantity and the ratio of diameter to thickness,resulting in enhanced strengthening and higher strength after *** reason has been discussed based on microstructure examination by TEM and DSC.

关键词： high-strength aluminum alloy pre-stretching tensile properties quench sensitive effect strengthening precipitates

Selective laser melted near-beta titanium alloy Ti-5Al-5Mo-5V-1Cr-1Fe:Microstructure and mechanical properties

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2021年第6期28卷 1601-1614页

作者： HUANG Hua-long LI Dan CHEN chao LI Rui-di ZHANG Xiao-yong LIU Shi-chao zhou ke-chao State key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Shenzhen Research Institute Central South UniversityShenzhen 518057China

In this work,a near-beta Ti-5Al-5Mo-5V-1Cr-1Fe titanium alloy was fabricated by selective laser melting(SLM),and the microstructure evolution together with the mechanical properties was *** as-fabricated alloy showed columnarβgrains spreading over multiple layers and paralleling to the building *** distinct microstructure of as-fabricated alloy was composed of near-β(more than 98.1%)with a submicron cellular *** SLM processing parameters such as hatch spacing could affect the microstructure of as-fabricated alloy,which could thus further significantly affect the mechanical properties of as-fabricated *** addition,the as-fabricated alloy with the distinct microstructure exhibits yield strength of 818 MPa combined with elongation of more than 19%,which shows that SLM is a potential technology for manufacturing near-beta titanium components.

关键词： selective laser melting Ti-5Al-5Mo-5V-1Cr-1Fe near-βandβ-titanium alloy cellular structure precipitation

Tribological behavior of Cu-15Ni-8Sn/graphite under sea water, distilled water and dry-sliding conditions

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2019年第10期26卷 2623-2633页

作者： WANG Yan ZHANG Lei ZHAI Hong-fei GAO Hong-xia zhou ke-chao Henan key Laboratory of Intelligent Manufacturing of Mechanical Equipment Institute of Mechanical and Electrical EngineeringZhengzhou University of Light IndustryZhengzhou 450002China State key Laboratory for Powder Metallurgy Central South UniversityChangsha 410083China

The tribological behaviors of Cu-15Ni-8Sn/graphite composites with the graphite content of 38 vol.%against AISI321 stainless steel under dry-sliding,deionized water and sea water were investigated on a block-on-ring *** results indicated that the friction coefficient was the lowest under dry-sliding,and the highest in deionized *** wear rate decreased to reach the minimum value of 1.39×10-15 m3/(N·m)in sea water and in deionized water,it increased to the maximum value of 5.56×10-15 m3/(N·m).The deionized water hindered the formation of tribo-oxide layer and lubricating film,which resulted in the largest friction coefficient and wear *** sea water,however,the corrosion products comprised of oxides,hydroxides and chlorides were found on the worn surface,and the compacted layer composed of corrosion products and graphite played an important role in keeping the excellent wear *** was elucidated that the tribological behaviors of Cu-15Ni-8Sn/graphite composite were powerful influenced by the friction environments.

关键词： self-lubricating composites tribological behavior compacted layers corrosion products sea water

Vertical gradients of neutral winds observed by ICON and estimated by the Horizontal Wind Model during the geomagnetic storm on August 26−28,2021

在线全文

学校读者我要写书评

暂无评论

Earth and Planetary Physics 2025年第1期9卷 69-80页

作者： JiaWei Wu chao Xiong YuYang Huang YunLiang zhou Department of Space Physics School of Electronic InformationHubei Luojia LaboratoryWuhan UniversityWuhan 430072China

The Michelson Interferometer for Global High-resolution Thermospheric Imaging(MIGHTI)onboard the Ionospheric Connection Explorer(ICON)satellite offers the opportunity to investigate the altitude profile of thermospheric *** this study,we used the red-line measurements of MIGHTI to compare with the results estimated by Horizontal Wind Model 14(HWM14).The data selected included both the geomagnetic quiet period(December 2019 to August 2022)and the geomagnetic storm on August 26-28,*** the geomagnetic quiet period,the estimations of neutral winds from HWM14 showed relatively good agreement with the observations from *** to the ICON observations,near the equator,zonal winds reverse from westward to eastward at around 06:00 local time(LT)at higher altitudes,and the stronger westward winds appear at later LTs at lower *** around 16:00 LT,eastward winds at 300 km reverse to westward,and vertical gradients of zonal winds similar to those at sunrise hours can be *** the middle latitudes,zonal winds reverse about 2-4 h *** winds vary more significantly than zonal winds with seasonal and latitudinal *** to the ICON observations,in the northern low latitudes,vertical reversals of meridional winds are found at 08:00-13:00 LT from 300 to 160 km and at around 18:00 LT from 300 to 200 km during the June *** reversals of meridional winds are found at 04:00-07:00 LT from 300 to 160 km and at 22:00-02:00 LT from 270 to 200 km during the December *** the southern low latitudes,meridional wind reversals occur at 08:00-11:00 LT from 200 to 160 km and at 21:00-02:00 LT from 300 to 200 km during the June *** the December solstice,reversals of the meridional wind appear at 20:00-01:00 LT below 200 km and at 06:00-11:00 LT from 300 to 160 *** the northern middle latitudes,the northward winds are dominant at 08:00-14:00 LT at 230 km during the June *** winds persist until

关键词： horizontal neutral winds vertical gradients Ionospheric Connection Explorer satellite Horizontal Wind Model 14 geomagnetic storm

Cathodic electrophoretic deposition of α-Fe_2O_3 coating

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2015年第6期22卷 2027-2035页

作者：马莉常通李小斌李志友张斗周科朝 School of Metallurgy and Environment Central South University State key Laboratory of Powder Metallurgy (Central South University)

Submicro α-Fe2O3 coatings were formed using electrophoretic deposition(EPD) technique in aqueous media. The zeta potentials of different α-Fe2O3 suspensions with different additives were measured as a function of p H to identify the optimum suspension condition for deposition. Electrophoretic depositions of α-Fe2O3 coatings under different applied electric fields and deposition time were studied and the effects of applied voltages and deposition time on deposition rates and thicknesses were investigated. The particle packing densities of the deposits at various applied voltages and deposition time were also analyzed by a scanning electron microscope(SEM). The results show that crack-free α-Fe2O3 coatings with uniform microstructure and good adherence to the nickel substrates are successfully obtained. Electrophoretic deposited α-Fe2O3 coating from aqueous suspension is a feasible, low-cost and environmental friendly method.

关键词： electrophoretic deposition Fe2O3 coating aqueous solutions zeta potential

Biocompatibility of MIM 316L stainless steel

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University of Technology 2005年第Z1期12卷 9-11页

作者： ZHU Shai-hong WANG Guo-hui ZHAO Yan-zhong LI Yi-ming zhou ke-chao HUANG Bai-yun Transplantation Medical Academy The Third Xiangya HospitalCentral South UniversityChangsha 410013China State key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China

To evaluate the bioeompatibility of MIM 316L stainless steel,the percentage of S-period cells were detected by flow cytometry after L929 incubated with extraction of MIM 316L stainless steel,using titanium implant materials of clinical application as the *** materials were implanted in animal and the histopathological evaluations were carried *** statistical analyses show that there are no significant differences between two groups(P>0.05),which demonstrates that MIM 316L stainless steel has a good biocompatibility.

关键词： 316L stainless steel metal powder injection moulding biocompatibility flow cytometry