检索结果-南通市图书馆

Nickel multilayers and their effects on bend fatigue strength of leads

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2004年第2期23卷 157-160页

作者： LIU Feihua WANG Zhanhua SHEN Zhuoshen school of Material science and engineering, university of science and technology beijing, beijing 100083, china school of Material science and engineering University of Science and Technology Beijing 北京 100083

Nickel is commonly coated on the outer leads for T8 metal package. The leadselectrodeposited by conventional dull or bright nickel over 5μm at direct current from Watt bathare hard to pass the bend fatigue test for three times. Nickel electrodeposited at multi waveformcurrent including direct current, single and double pulse from sulfamate bath can improve the bendfatigue strength of leads. Such nickel plating has a multilayer structure, its morphology ofsublayers can be clearly seen in its cross section with SEM. The electrochemical study shows thatthese sublayers have different corrosion potentials. The bend fatigue test of leads with suchplating for T8 metal package shows that the number of bend increases with the decrease of averagecurrent density of multi waveform, which can be attributed to the reduction of every sublayerthickness and the increase of layer numbers under the same condition of total thickness.

关键词： electroplating nickel multilayers multi waveform current bend fatiguestrength corrosion potential metal package

Nonclassical Plane-crystallographic Groups and Their Applications IV

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and materials 1998年第4期12卷 228-232页

作者： Lequan Min Xaodan zhang(Applied science school, school,university of science and technology beijing, beijing 100083,china) Applied science school University of Science and Technology Beijing Beijing 100083 China

Eight kinds of nonclasslcal periodic lattices with locally 8-fold rotational symmetries are *** can be described via nonclassical Planc-crystallographic groups. The periodic lattices may be interpreted bythe projections on the plane of the corresponding unit cells consisting of embedding polyhedrons, respectively. TheFourier-transform patterns of the Periodic lattices have striking approximate'8-fold rotational symmetries', some ofwhich are similar to those displaying in the electrton-diffraction patterns of so-called quasicrystals.

关键词： nonclasslcal crystallographic groups locoally 8-fold symmetry Fourier-transform patterns, quasicrystals

A New Process for Preparing Fine-ceramic-containing Composite Coatings──Flame Spray Synthesis

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and materials 2000年第3期14卷 214-217页

作者： Changsong Liu, Jihua Huang, Sheng Yin (Material science and engineering school, university of science and technology beijing, beijing 100083, china) Material science and engineering school University of Science and Technology Beijing Beijing 100083 China

Flame spray synthesis (FSS), a combination of the flame spray technology and Self-propagation High-temperature Synthesis (SHS) was developed for preparing fine-ceramic-containing composite coatings. It can simplify the preparations of powder to synthesize and deposit the desired materials in one step. The preliminary results obtained from TiC-Fe cermet coatings by FSS process are reported. The peculiar microstructure of the composite coatings, which contains very fine (<1m) and round TiC and alternate TiC-rich (Hv=11€*13GPa) and TiC-poor layers (Hv=3.0 -6.0GPa), is expected to play an important role in their tribological properties.

关键词： Self-propagation High-temperature Synthesis (SHS) flame spray flame spray synthesis (FSS) TiC-Fe cermet coating

TEM Study on Hydrogen-Induced Cracking of Fe_3Al Alloy

在线全文

学校读者我要写书评

暂无评论

Journal of university of science and technology beijing 2001年第1期8卷 35-38页

作者： Biao Gu, Lijie Qiao, Wuyang Chu Material science and engineering school, university of science and technology beijing, beijing 100083, china Univ Sci & Technol beijing Sch Mat Sci & Engn Beijing 100083 Peoples R China

Hydrogen-induced cracking (HIC) of Fe3Al alloy was studied by in situ transmission electron microscope (TEM). Electron transparent specimens were mounted onto a constant displacement device. Stress was applied to the specimen by using a bolt through the device. The results showed that hydrogen enhanced the dislocation emission and motion in Fe3Al alloy. A dislocation free zone (DFZ) was formed following the dislocation emission. Microcrack initiated in the DFZ or at the main crack tip when the emission reached a critical extension. Hydrogen played an important role in the process of brittle fracture of Fe3Al alloy.

关键词： TEM Fe3Al intermetallics hydrogen induced cracking dislocation emission dislocation free zone

Aging Behaviors of W-Ni-Fe Ternary Alloys with High Ni-to-Fe Ratios

在线全文

学校读者我要写书评

暂无评论

Journal of materials science & technology 2003年第6期19卷 631-633页

作者： Ronghua LI, Jihua HUANG, Sheng YIN and Jun ZHAOschool of materials science & engineering, university of science & technology beijing, beijing 100083, china Sch. of Mat. Sci. and Eng. Univ. of Sci. and Technol. Beijing Beijing 100083 China

The hardness variation of two kinds of alloys with 36 wt pct W content and 7/3, 9/1 Ni-to-Fe ratios during strain aging at 800℃ was studied. The microstructures of the aged alloys were analyzed by X-ray diffraction and TEM. The results show that the strain aging hardness of W-Ni-Fe ternary alloy with 7/3 Ni-to-Fe ratio decreases monotonically with the increase of aging time. Under the same conditions, the hardness of 9/1 Ni-to-Fe ratio alloy decreases in the initial aging stage, but then increases as aging process goes on. X ray diffraction and TEM analysis show that there is not any precipitation depositing from the alloy with 7/3 Ni-to-Fe ratio during aging. The monotonic decrease in hardness of this alloy during aging process results from the recovery, recrystallization and solid solubility declining. In the alloy of 9/1 Ni-to-Fe ratio, the fine β phase precipitates dispersively during aging which hardens the alloy. The two different kinds of mechanisms (the softening one and the hardening one) decide the hardness variation of the alloy with 9/1 Ni-to-Fe ratio mentioned above.

关键词： W-Ni-Fe Tungsten heavy alloys Ni-to-Fe ratio Strain aging β phase

Mass transfer coefficients in metallurgical reactors

在线全文

学校读者我要写书评

暂无评论

Journal of university of science and technology beijing 2003年第2期10卷 1-9页

作者： Ying QuMetallurgical engineering school, university of science and technology beijing, beijing 100083, china Univ Sci & Technol beijing Met Engn Sch Beijing 100083 Peoples R China

An overview on the application and achievements of physico-mathematicalmodeling of metallurgical processes in china is briefly declared. The important role of coefficientsin model formulation is shown from our experience. The mass transfer coefficients of the slag-metalreactions and the gas-metal reactions are discussed referring to the flow conditions near theinterface. The influence of the surface-active species on the mass transfer and the interfacialreaction is also discussed briefly.

关键词： mass transfer modeling pyrometallurgy reaction engineering interfacial flow stirring power

Preparation and characterization of nano-crystalline diamond films on glass substrate

在线全文

学校读者我要写书评

暂无评论

Journal of university of science and technology beijing 2004年第3期11卷 216-220页

作者： Fanxiu Lu Wubao Yang Zhilin Liu Weizhong Tang Yumei Tong materials science and engineering school, university of science and technology beijing, beijing 100083, china materials science and engineering school University of Science and Technology Beijing Beijing 100083 China

Adherent nano diamond films were successfully deposited on glass substrate bymicrowave plasma assisted CVD method in H_2-CH_4 and Ar-CH_4 environment. Raman, AFM (Atomic ForceMicroscope), TEM (Transmission Electron Microscope), FTIR, and Nano Indentation techniques were usedfor characterization of the obtained nano diamond films. It was found that the average grain sizewas less than 100 nm with a surface roughness value as low as 2 nm. The nano diamond films werefound to have excellent transparency in visible and IR spectrum range, and were as hard as naturaldiamond. Experimental results were presented. Mechanisms for nano diamond film deposition werediscussed.

关键词： nano diamond films microwave plasma assisted CVD characterization glasssubstrate

Recycling of Spent Nickel-Cadmium Batteries

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and materials 2000年第2期14卷 126-131页

作者： Xanghua Kong Pingnan Wu(Metallurgy school, university of science and technology beijing, beijing 100083, china) Metallurgy school University of Science and Technology Beijing Beijing 100083 China

A technique for recycling spent nickel-cadmium batteries, which makes separaion of cadmium and nickel possible, is developed by laboratory-scale experiments. NH3-H2CO3 aqueous solution was used in this leaching technique. Since neutralization and/or solvent extraction were not required in the separation procedure of nickel and cadmium, the closed systemizaion of the process becomespossible. Experimental results show that, (1) if the NH3 concentraion of leaching solution is sufficiently high and the ratio of H2CO3 toNH3 is properly adjusted, both Ni(OH)2 and Cd(OH)2 react with NH, and quickly dissolve into leaching solution, and (2) Ni(OH)2 can beconverted into insoluble NiO by calcination at 500℃, and CdO from Cd(OH)2 by calcination maintains good solubility in NH3-H2CO3aqueous solution. As a conclusion, the recycling technique characterized by two step leaching can be developed based on such changesin dissolution behavior by calcination. Meanwhile, the yields of 99.8% for nickel and 97.6% for cadmium are obtained, and the puritiesof Recycling of Spent Nickel-Cadmium BatterieRecycling of Spent Nickel-Cadmium Batteries Recycling of Spent Nickel-Cadmium Batteriesrecovered nickel and cadmium are 99.9% and 98.6%, respectively.

关键词： nickel-cadmium batteries recycling, ammonia leaching closed system environmental protection

SEM in-situ Fatigue Observation on Crack Initiation and Growth from Inclusion in P/M Rene95 Superalloy

在线全文

学校读者我要写书评

暂无评论

Journal of university of science and technology beijing 2001年第3期8卷 195-197页

作者： Lina Zhang, Jianxin Dong, Xishan Xie Material science and engineering school, university of science and technology beijing, beijing 100083, china Univ Sci & Technol beijing Sch Mat Sci & Engn Beijing 100083 Peoples R China

A special designed experiment was conducted for observing crack initiation and growth in P/M Rene95 superalloy under tension-tension loading by self-made SEM in-situ fatigue loading stag. Several alumina inclusion particles exposed at the specimen surface were observed carefully. During fatigue test inclusions led to cracks initiation. The cracks can be formed by two mechanisms. Generally, the cracks nucleated at the interface between inclusion and matrix. Sometimes, cracks were also formed inside the inclusion. As the increase of cycles, some cracks at the interface between inclusion and matrix broadened and propagated along the direction about 45 degrees to the loading axis. On the other hand, the cracks inside the inclusion propagated in the inclusion and towards matrix.

关键词： inclusion P/M superalloy LCF SEM in-situ fatigue