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Experimental study on the influences of cutter geometry and material on scraper wear during shield TBM tunnelling in abrasive sandy ground

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第2期16卷 410-425页

作者： Shaohui Tang Xiaoping Zhang Quansheng Liu Qi Zhang Xinfang Li Haojie Wang Key Laboratory of Safety for Geotechnical and Structural Engineering of Hubei Province School of Civil EngineeringWuhan UniversityWuhan430072China State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan430072China

When shield TBM tunnelling in abrasive sandy ground,the rational design of cutter parameters is critical to reduce tool wear and improve tunnelling ***,the influence mechanism of cutter parameters on scraper wear remains unclear due to the lack of a reliable test *** and material optimisation are often based on subjective experience,which is unfavourable for improving scraper geological *** the present study,the newly developed WHU-SAT soil abrasion test was used to evaluate the variation in scraper wear with cutter geometry,material and *** influence mechanism of cutter parameters on scraper wear has been revealed according to the scratch characteristics of the scraper *** geometry and material parameters have been optimised to reduce scraper *** results indicate that the variation in scraper wear with cutter geometry is related to the cutting resistance,frictional resistance and stress *** appropriate increase in the front angle(or back angle)reduces the cutting resistance(or frictional resistance),while an excessive increase in the front angle(or back angle)reduces the edge angle and causes stress *** optimal front angle,back angle and edge angle for quartz sand samples areα=25°,β=10°andγ=55°,*** wear resistance of the modelled scrapers made of different metal materials is related to the chemical elements and *** wear resistances of the modelled scrapers made of 45#,06Cr19Ni10,42CrMo4 and 40CrNiMoA are 0.569,0.661,0.691 and 0.728 times those made of WC-Co,*** the alloy hardness is less than 47 HRC(or greater than 58 HRC),scraper wear decreases slowly with increasing alloy hardness as the scratch depth of the particle asperity on the metal surface stabilizes at a high(or low)***,when the alloy hardness is between 47 HRC and 58 HRC,scraper wear decreases rapidly with increasing alloy hardness as the scratch depth transitions

关键词： Shield TBM Scraper wear Cutter shape metal material Alloy hardness

Microstructure and electrochemical characteristics of nonstoichiometric La-rich AB_5-type alloy for Ni/MH battery electrode

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Rare metals 2005年第1期24卷 65-70页

作者： MAZhihong QIUJufeng CHENLixin LEIYongquan BaotouHengyitongRareEarthsCo. Ltd.Baotou014060China BaotouResearchInstituteofRareEarths Baotou014010China DepartmentofmaterialsScienceandEngineering ZhejiangUniversityHangzhou310027China

The nonstoichiometric La-rich mischmetal (designated by MI)-based hydrogen storage alloy with a composition of MI(Ni0.64Co0.2Mn0.12Al0.04)(4.76) was prepared by arc melting and annealed at 1173 K for 10 h to investigate the effect of annealing treatment on the microstructure and electrochemical characteristics of the alloy. X-ray diffraction analysis showed that annealing can cause a release of the crystal lattice strain and an increase in amounts of the La2Ni7-type second phase in MI(Ni0.64Co0.20Mn0.12Al0.04)(4.76) alloy. Scanning electron microscopy and electron probe microanalysis examinations indicated that annealing leads to disappearance of the dendrite structure in the as-cast alloy, growth of crystal grain, and decrease of composition segregation. The annealing at 1173 K for 10 h flattened and extended the potential plateau and increased the maximum discharge capacity to 328 mA center dot h/g from 310 mA center dot h/g and the cycling life. The mechanism of the improvement in electrochemical characteristics was discussed based on the alloy microstructure change induced by annealing.

关键词： metal material microstructure electrochemical characteristics annealing nonstoichiometric LaNi5-type alloy Ni/MH battery electrode

Heat-treated microstructure and mechanical properties of laser solid forming Ti-6Al-4V alloy

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Rare metals 2009年第6期28卷 537-544页

作者： ZHANG Shuangyin LIN Xin CHEN Jing HUANG Weidong School of materials Science and Engineering State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi＇ an 710072 China

The effects of heat treatment on the microstructure and mechanical properties of laser solid forming （LSF） Ti-6Al-4V alloy were investigated The influences of the temperature and time of solution treatment and aging treatment were analyzed. The results show that the microstructure of LSFed samples consists of Widmanstatten α laths and a little acicular in columnar prior β grains with an average grain width of 300 μm, which grow epitaxiaUy from the substrate along the deposition direction （27）. Solution treatment had an important effect on the width, aspect ratio, and volmne fraction of primary and secondary a laths, and aging treatment mainly affects the aspect ratio and volume fraction of primary α laths and the width and volume fraction of secondary a laths. Globular a phase was first observed in LSFed samples when the samples were heat treated with solution treatment （950℃, 8 h/air cooling （AC）） or with solution treatment （950℃, 1 h/AC） and aging treatment （550℃, above 8 h/AC）, respectively. The coarsening and globularization mechanisms of a phase in LSFed Ti-6Al-4V alloy during heat treatment were presented. To obtain good integrated mechanical properties for LSFed Ti-6Al-4V alloys, an optimized heat treatment regimen was suggested.

关键词： metal material Ti-6Al-4V alloy laser solid forming microstructure mechanical properties heat treatment

Modification mechanism of cerium on the Al-18Si alloy

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Rare metals 2006年第1期25卷 11-15页

作者： ZHANG Henghua DUAN Haili SHAO Guangjie XU Luoping YIN Junlin YAN Biao School of materials Science and Engineering Shanghai University Shanghai 200072 China School of materials Science and Engineering Tongji University Shanghai 200092 China

The effect of the rare earth cerium （Ce） on the hypereutectic Al-Si alloy under different casting states have been studied by optical microscope and quantitative image analysis. It is found that the size and the quantity of primary silicon in castings decrease with the increase of added Ce in the melt. Meanwhile primary silicon changes from branched shape to fine facetted shape. Although the modification on eutectic silicon in castings also improves with the increase of added Ce in the melt, the effect of modification on eutectic silicon away from primary silicon is more obvious than that on eutectic silicon close to primary silicon. The modification mechanism was analyzed in detail by means of scanning electron microscope equipped with energy dispersive analysis of X-ray and thermodynamics analysis, which included the analysis on the change in standard Gibbs energy of reaction and reaction equilibrium.

关键词： metal material modification mechanism thermodynamics analysis rare earth element hypereutectic Al-Si alloy

Electronic Theoretical Study of the Interaction between Rare Earth Elements and Impurities at Grain Boundaries in Steel

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Journal of Rare Earths 2003年第3期21卷 372-374页

作者：刘贵立张国英李荣德 materials Science and Engineering College Shenyang University of Technology

The model of dislocations was used to construct the model of grain boundary (GB) with pure rare earths, and rare earth elements and impurities. The influence of the interaction between rare earth elements and impurities on the cohesive properties of 5.3° low angle GB of Fe was investigated by the recursion method. The calculated results of environment sensitive embeding energy( E ESE ) show that the preferential segregation of rare earth elements towards GBs exists. Calculations of bond order integrals (BOI) show that rare earth elements increase the cohesive strength of low angle GB, and impurities such as S, P weaken the intergranular cohesion of the GB. So rare earth element of proper quantity added in steel not only cleanses other harmful impurities off the GBs, but also enhances the intergranular cohesion. This elucidates the action mechanism of rare earth elements in steel from electronic level and offers theoretical evidence for applications of rare earth elements in steels.

关键词： metal material grain boundary recursion method impurities the interaction between rare earth elements and impurities rare earths

Fabrication of ceramic layer on an Al-Si alloy by MAO process

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Rare metals 2003年第2期22卷 103-106页

作者： SONG Xigui, BIAN Xiufang, QI Xiaogang, and ZHANG JunyanKey Laboratory of Liquid Structure and Heredity of materials, Ministry of Education, Shandong University (Southern Campus), Jinan 250061, China (Received 2002-04-11) Shandong university (Southern Campus) Key Laboratory of Liquid Structure and Heredity of Materials Ministry of Education Jinan 250061 Shandong university (Southern Campus) Key Laboratory of Liquid Structure and Heredity of Materials Ministry of Education Jinan 250061

The MAO (Micro-Arc Oxidation) process is applied to a eutectic Al-Si alloy(Al-12.0 percent Si-l.0 percent Cu-0.9 percent Mg (mass fraction)). The oxide ceramic layer wasfabricated with about 220 mum thickness and 3000 Hv micro-hardness. By XRD (X-ray diffractometry)and DSC (differential scanning calorimetry) analyses, the oxide layer consists of amorphous Al_2O_3,which is distinct from the results reported by the other researchers. The SEM photographs of suchlayer show that the layer is fixed tightly on the substrate alloy. So this alloy can he used in thehigh temperature and friction environment alter it is treated with such process.

关键词： metal material ceramic layer MAO process Al-Si alloy

Influence of solidification rate on the microstructure of (Nd,Dy)_(12.8)(Fe,Co)_(80.7)B_(6.5) cast strips

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Rare metals 2005年第2期24卷 200-204页

作者： LIUHanqiang WANGBiao HANGuangbing GAORuwei SchoolofPhysicsandMicroelectronics ShandongUniversityJinan250100China

The influence of solidification rate on the microstructure of (Nd,Dy)(12.8)(Fe,Co)(80.7)B-6.5 cast strips was reported in this paper. The strips prepared at different wheel speeds were analyzed by X-ray diffraction (XRD). The microstructure of the strips was investigated by backscattered scanning microscope (BSM). The XRD results show that the strips are mainly composed of the main phase (T-1) existing apparent alignment along [00L]. The thickness of T-1 columnar grains is larger when the solidification rate is lower and the over-small isotropic microcrystalline appear on the cooling surface of the strips when the solidification rate is too high. The adequate wheel speed for obtaining the optimum microstructure of the strips is about V = 2.0 m/s. The strip prepared at V = 2.0 m/s possesses suitable thickness and the highest alignment degree of T-1 columnar grains, uniformly distributed Nd-rich phase, and no existence of alpha-Fe phase. This kind of cast strip is an ideal starting material for preparing sintered magnets with high magnetic properties.

关键词： metal material microstructure solidification rate cast strip Nd-Fe-B

Effect of Rare Earths on Corrosion Resisting Properties of Carbon-Manganese Clean Steels

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Journal of Rare Earths 2004年第4期22卷 533-536页

作者：郭锋林勤孙学义 Physical Chemistry Department University of Science and Technology Beijing Beijing 100083 China

Electrochemistry experiments were made on carbon-manganese clean steel with rare earths Ce and La respectively to observe corrosion parameters such as corrosion current i_(corr), and characteristic potential of pitting E_b. The results indicate that the rare earths have effect on corrosion resisting properties of carbon-manganese clean steel, and the optimum contents of La is about 0.011% (mass fraction) and Ce about 0.014% (mass fraction) respectively. The change of corrosion resistance is related to the action of rare earths on microstructure and effect on surface state of samples in the process of polarization.

关键词： metal material corrosion resistance carbon-manganese clean steel electrochemistry rare earths

Computer simulation of interface evolution for an Al-Li alloy during early aging stage

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Rare metals 2004年第3期23卷 279-285页

作者： TANGLiying WANGYongxin CHENZheng LUYanli ZHANGJianjun DepartmentofmaterialsScienceandEngineering NorthwesternPolytechnicalUniversityXi＇an710072China DepartmentofmaterialsScienceandEngineering NorthwesternPolytechnicalUniversityXi＇an710072China

The nucleation of ordered phase was simulated based on microscopic diffusionequation and the assumptions of the classical nucleation theory were examined. The quantitativecalculations of interface thickness evolution were accomplished for the first time. It was foundthat the interfaces between ordered phase and disordered matrix were diffuse. The interfacethickness decreased with time, from the initial 1.2 nm to an equilibrium value 0.6 nm. The ratios ofthe radius of ordered particles and the interface thickness monotonously increased, but they wereof the same order of magnitude all the time. The sharp interface assumption should not be adopted inthis stage. For the Al-10% Li (atom fraction) alloy aged at 192℃, the assumptions of the classicalnucleation theory disagreed with the facts. The phase transformation followed the non-classicalnucleation mechanism and the applicable scope of the classical nucleation should be confined.

关键词： metal material interface computer simulation non-classical nucleationtheory