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International Journal of minerals,Metallurgy and Materials 2009年第5期16卷 534-539页

作者： T.A.Daniel Sagayaraj S.Suresh M.Chandrasekar Department of Mechanical engineering National Institute of Technology Tiruchirappalli-620015Tamil NaduIndia

The experimental investigations on the effect of the fly ash particle size, velocity, impingement angle, and feed rate were done with an emphasis on the effect of erosion on annealed SA 210 GrA1 （A） and normalized SA 210 GrA1 （N） carbon steel economizer-tube materials. Erosion rates were evaluated with different impingement angles ranging from 15° to 90°, at four different velocities of 32.5, 35, 37.5, and 40 m/s, and at four different feed rates of fly ash particles of 2, 4, 6 and 8 g/min. The erodent used was fly ash particles, sizes ranging from 50-250 μm of irregular shapes. Erosion rate is found to be the maximum at the impingement angle of 30°. Erosion rates of the carbon steel tube in different heat treatment conditions, annealed and normalized, at a constant velocity of 32.5 m/s with different angles were studied. In all cases of feed rates, impingement angles, particle sizes, and velocities of fly ash particles, it has been found that the erosion rate of the annealed tube is less than that of the normalized tube. Empirical correlations for erosion rate relating the velocity, size, feed rate, and impingement angle of the particles and elongation property of the target materials were arrived. Morphologies of the eroded surface were examined by scanning electron microscope （SEM）.

关键词： erosion rate economiser tubes annealing normalizing

Effect of stoichiometry and Cu-substitution on the phase structure and hydrogen storage properties of Ml-Mg-Ni-based alloys

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International Journal of minerals,Metallurgy and Materials 2015年第1期22卷 86-93页

作者： Yuan Li Yang Tao Quan Huo Hebei Key Laboratory of Applied Chemistry School of Environmental and Chemical EngineeringYanshan University

To improve the electrochemical properties of rare-earth-Mg-Ni-based hydrogen storage alloys, the effects of stoichiometry and Cu-substitution on the phase structure and thermodynamic properties of the alloys were studied. Nonsubstituted Ml0.80Mg0.20（Ni2.90Co0.50-Mn0.30Al0.30）x （x=0.68, 0.70, 0.72, 0.74, 0.76） alloys and Cu-substituted Ml0.80Mg0.20（Ni2.90Co0.50-yCuyMn0.30Al0.30）0.70 （y=0, 0.10, 0.30, 0.50） alloys were prepared by induction melting. Phase structure analysis shows that the nonsubstituted alloys consist of a LaNi5 phase, a LaNi3 phase, and a minor La2Ni7 phase;in addition, in the case of Cu-substitution, the Nd2Ni7 phase appears and the LaNi3 phase vanishes. Ther-modynamic tests show that the enthalpy change in the dehydriding process decreases, indicating that hydride stability decreases with in-creasing stoichiometry and increasing Cu content. The maximum discharge capacity, kinetic properties, and cycling stability of the alloy electrodes all increase and then decrease with increasing stoichiometry or increasing Cu content. Furthermore, Cu substitution for Co ame-liorates the discharge capacity, kinetics, and cycling stability of the alloy electrodes.

关键词： hydrogen storage alloys electrode materials stoichiometry substitution phase structure thermodynamic properties electro-chemical properties

Lateral growth rate of δ phase during solidification of Fe-0.15wt%C-0.8wt%Mn steel

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International Journal of minerals,Metallurgy and Materials 2012年第4期19卷 312-316页

作者： Guo-wei Chang Shu-ying Chen Qing-chun Li Xu-dong Yue Guang-can Jin School of Materials Science and engineering Liaoning University of Technology Jinzhou 121001 China

Taking Fe-0.15wt%C-0.8wt%Mn steel as the research object, in situ observations of the 8 phase growth process during solidifica- tion were conducted by using a high-temperature confocal scanning laser microscope （HTCSLM）. The effects of the solid/liquid （S/L） inter- face＇s shape, temperature, and curvature radius on the lateral growth rate of 6 phase were investigated in detail, and the relational expression among the lateral growth rate of 5 phase, temperature, and curvature radius of column-shaped ~ phase was deduced for the carbon steel dur- ing solidificatiorL The results indicate the growth rate of the concave-shaped S/L interface is larger than that of the convex-shaped S/L inter- face during the beginning growth of ~ phase, but these two kinds of growth rates gradually approach with proceeding in solidification. The calculated lateral growth rate of 6 phase is consistent with the experimental result at a cooling rate of 0.045℃/s.

关键词： carbon steel solidification ferrite growth rate interfaces

Effect of Al^(3+) on Tobermorite Crystallinity

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International Journal of minerals,Metallurgy and Materials 2000年第2期14卷 79-81页

作者： Fengmei Liu Deping Chen Wen Ni Zhenyuan Cao(Resource engineering School, University of Science and Technology Beijing, Beijing 100083, China) Resource engineering School University of Science and Technology Beijing Beijing 100083 China

The difference between the systems of CaO-SiO2,-H2O and CaO-SiO2-Al(OH)3,-H2O, was studied, especially the effect of Al3+on the crystallinity of tobermorite was focussed. As a result, in the system of CaO-SiO2-H2O, tobermorite formed early, however, withreaction time forward, tobermorite was replaced by xonotlite. So far as CaO-SiO2-Al(OH)3,-H2O was concemed, hydrothermal reactionwas cdried out under the same condition as CaO-SiO2-H2O to study the morphological changes of tobermorite crystals. It was found thatAl3+ accelefated the crystal growth of tobermorite to some extent and was in faVor ofplaty crystals. Moreovef, with the Al3+ content in-creasing in the starting material, the morphology of tobermorite did not change magnificently, but platy crystals became more and moreeminent. As soon as the Al2O3 content was over 15.6%, synthetic mineral greatly changed in smicthe and haled into hibschite differentfrom 1 .1 nm tobermorite. Obviously, xonotlite was not apt to form in the presence of Al3+.

关键词： calcium silicate hydrate xonotlite 1.1 nm tobermorite hibschite

Development of Mg based biomaterial with improved mechanical and degradation properties using powder metallurgy

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Journal of Magnesium and Alloys 2020年第3期8卷 883-898页

作者： Ajit Kumar Pulak M.Pandey Department of Mechanical engineering Indian Institute of TechnologyDelhi110016India

In the present work,biocompatible materials such as niobium(Nb),zinc(Zn)and calcium(Ca)have been blended with magnesium(Mg)to develop a novel biomaterial(BM)with improved mechanical and corrosion resistant *** metallurgy(PM)technique was used to fabricate Mg based *** powder of all aforementioned materials were mixed homogenously in specific quantities to create a uniform composite *** order to analyse the influence of process parameters on the mechanical properties of the fabricated part,experiments were performed considering central composite design(CCD).The effect of powder metallurgical parameters namely percentage Nb,compaction pressure,heating rate,sintering temperature and soaking time on the ultimate compressive strength(UCS)and sintered density was studied in the present *** was found that the UCS and sintered density increased with increase in compaction pressure,heating rate and sintering *** results also revealed that the increase in soaking time and percentage Nb,increased sintered density and UCS to a certain *** increase in these two parameters,sintered density and UCS *** electron microscopy(SEM)images of the fabricated samples showed reduction in porosity with the increase in heating ***,X-ray diffraction(XRD)results revealed that no other phase or impurities were found during sintering of Mg based *** optimum process parameters were obtained to develop Mg based BM for maximum UCS and sintered ***,the Mg based BM samples fabricated at optimum process parameters were used for corrosion testing in simulated body fluid(SBF)solution at a temperature of 37±0.5℃.The Mg based BM yielded improved mechanical properties with reduced corrosion rates as compared to pure Mg.

关键词： Biomaterials Powder metallurgy Magnesium Corrosion Metal matrix composite

Internal energy transfer phenomenon and light-emission properties of γ-LiAlO_2 phosphor doped with Mn^(2+)

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International Journal of minerals,Metallurgy and Materials 2013年第7期20卷 678-683页

作者： Bai-Bin Wang Chi-Fen Chang Wein-Duo Yang Department of Chemical and Materials engineering Kaohsiung University of Applied Sciences Electronics Testing Center

γ-LiAlO2 phosphor was synthesized using the cellulose-citric acid sol-gel method, and its light emission and energy transfer properties were investigated. Excitation and emission spectrum analysis revealed a decrease in intensity of the spectrum as the amount of Mn2＋ doping increased. Blasse＇s equation determined the maximum distance for energy transfer between Mn2＋ ions as 4.3142 nm. Dexter＇s theory verifies that the mechanism of energy transfer between Mn2＋ ions conforms to an electric dipole and electric quadrupole interaction.

关键词： phosphor energy transfer light emission sol-gel process doping

Characterization and wear behavior of WC-0.8Co coating on cast steel rolls by electro-spark deposition

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International Journal of minerals,Metallurgy and Materials 2009年第6期16卷 707-713页

作者： Jian-sheng Wang Hui-min Meng Hong-ying Yu Zi-shuan Fan Dong-bai Sun School of Materials Science and engineering University of Science and Technology Beijing Beijing 100083 China

To prepare high wear resistance and high hardness coatings, electro-spark deposition was adopted for depositing an electrode of a mixture of 92wt%WC＋8wt%Co on a cast steel roll substrate. The coating was characterized by classical X-ray diffractometer （XRD） and scanning electron microscopy （SEM） with energy dispersive X-ray analysis （EDX）. The results indicate that the coating shows nanosized particulate structure and dendritic structure including columnar structure and equiaxed structure. The primary phases of the coating contain Fe3W3C, Co3W3C, Fe2C and Si2W. The coating has a low friction coefficient of 0.13, its average wear-resistance is 3.3 times that of the cast steel roll substrate and the main mechanism is abrasive wear. The maximum microhardness value of the coating is about 1573.9 Hv0.3. The study reveals that the electro-spark deposition process has the characteristic of better coating quality and the coating has higher wear resistance and hardness.

关键词： electro-spark deposition (ESD) WC-Co coatings microstructure wear resistance

Suppression of Surface Burn in Grinding of Titanium Alloy TC4 Using a Self-inhaling Internal Cooling Wheel

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Chinese Journal of Aeronautics 2011年第1期24卷 96-101页

作者： LI Xun CHEN Zhitong CHEN Wuyi School of Mechanical engineering and Automation Beijing University of Aeronautics and Astronautics Beijing 100191 China

Based on analysis of surface average temperature and burn degree, this article obtains the threshold temperature of surface burn in grinding titanium alloy with cup wheels. Meanwhile, the impact of the burn degree on the metallographic structure of workpiece surface and metallurgical phase transformations is investigated. In order to reduce the grinding temperature and improve the grinding efficiency, a self-inhaling structure cup segmented wheel is developed to generate internal cooling effect. The internal cooling technology is compared with traditional cooling conditions in the grinding experiments on TC4 （Ti-6Al-4V）. The results indicate that the self-inhaling internal cooling wheel can reduce the grinding surface temperature by 30% or more, and the grinding efficiency doubles. Utilizing water-based semi-synthetic coolant, the segmented wheel with the self-inhaling structure can further reduce the grinding temperature by about 50%.

关键词： grinding temperature measurement surface burn internal cooling self-inhaling

Preparation of long alumina fibers by sol-gel method using tartaric acid

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International Journal of minerals,Metallurgy and Materials 2011年第6期18卷 691-694页

作者： Hong-bin Tan School of Materials Science and engineering Shaanxi University of Technology Hanzhong 723003 China

Long alumina fibers were prepared by sol-gel *** spinning sol was obtained by mixing aluminum nitrate,tartaric acid,and polyvinylpyrrolidone with a mass ratio of 10∶3∶***-differential scanning calorimetry （TG-DSC）,Fourier transform infrared （FT-IR） spectra,X-ray diffraction （XRD）,and scanning electron microscopy （SEM） were used to characterize the properties of the gel and ceramic fibers.A little of α-Al2O3 phase is observed in the alumina precursor gel fibers sintered at 1273 *** fibers with a uniform diameter can be obtained when sintered at 1473 K,and its main phase is also indentified as α-Al2O3.

关键词： alumina fibers sol-gel process polyvinylpyrrolidone

Inverse Modeling of Nonlinear Systems and Application

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International Journal of minerals,Metallurgy and Materials 1999年第4期13卷 302-305页

作者： Jianping Wei Huade Li Datai Yu(Information engineering school, University’ of Science and Technology’ Beijng, Beijing 1 00083, China) Information engineering School University of Science and Technology Beijing Beijing 100083 China

Inverse modeling is discussed based on neural networks. U-D factorization Kalman filter learning algorithm is introduced totrain a feed forward multilayer neural network, which is used as inverse models. A scheme of D... 详细信息

关键词： neural network modeling control DC EAF