检索结果-南通市图书馆

Precise Determination of the MgAlON/(AlN+MgAlON) Phase Bound- ries in the MgO-AlN-Al_2O_3 Ternary System at 1600℃ and 1700℃

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2005年第2期21卷 277-280页

作者： HouxingZHANG YanruoHONG YongHUANG JialinSUN GraduateSchoolatShenzhen TsinghuaUniversityShenzhen518057China//UniversityofScienceandTechnologyBeijingBeijing100083China universityofscienceandtechnologybeijing Beijing100083China DepartmentofMaterialScienceandEngineering TsinghuaUniversityBeijing100084China

The accurate phase boundary of MgAION/(AIN+MgAION) in MgO-AIN-Al2O3 ternary system, has not been determined precisely so far. In the present study, the lattice parameters of MgAION solid solution with various compositions were determined precisely with X-ray powder diffraction. According to the relationship between the lattice parameters of MgAION solid solution and the contents of AIN and MgO, the phase boundaries of MgAION/(AIN+MgAION) in MgO-AIN-AI2O3 ternary system at 1600℃ and 1700℃ were precisely determined.

关键词： Phase boundary MgAlON X-ray diffraction Lattice parameter

Analytical solutions to a compressible boundary layer problem with heat transfer

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2期11卷 120-122页

作者： LiancunZheng XinxinZhang JichengHe AppliedScienceSchool UniversityofScienceandTechnologyBeijingBeijing100083China MechanicalEngineeringSchool UniversityofScienceandTechnologyBeijingBeijing100083China ThermalEngineeringDepartment NortheasternUniversityShenyang110006China

The problem of momentum and heat transfer in a compressible boundary layerbehind a thin expansion wave was solved by the application of the similarity transformation and theshooting technique. Utilizing the analytical expression of a two-point boundary value problem formomentum transfer, the energy boundary layer solution was represented as a function of thedimensionless velocity, and as the parameters of the Prandtl number, the velocity ratio, and thetemperature ratio.

关键词： compressible boundary layer momentum and heat transfer analytical solution

Effect of Mn on microstructure of as-cast Ti47A18Nb(1～2)Mn alloys

在线全文

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2002年第5期12卷 818-821页

作者：许敬文林均品王艳丽陈国良 StateKeyLaboratoryforAdvancedMetalsandMaterials UniversityofScienceandTechnologyBeijingBeijing100083China

The microstructures of Ti47Al8NbxMn (mole fraction, %) alloy with x=1 or 2 were studied on as-cast, as-HIPped and on heat-treated samples. The results showed that Mn element is β phase stabilizer and promotes the formation of β(B 2) phase. B 2 phase exists at the dendrite cores of the as-cast microstructures. This phase is metastable and can completely decompose into α and(or) γ during 1 200 ℃, 200 MPa, 4 h HIP process. In the as-HIPed alloy with 1% (mole fraction) Mn addition, the α 2+γ lamellae structure is interrupted and decomposed resulting in grain refined near gamma microstructure. The α 2+γ lamellae structure near interdendritic regions decomposes almost completely into γ grains, but near dendrite cores incompletely into γ grains with a small amount of α 2 particles or needles around or in it. However, compared with the alloy with 1% (mole fraction) Mn, more α 2 phase is retained in the alloy with 2% (mole fraction) Mn. α 2 phase contains more Mn and is more stable in the alloy with 2% (mole fraction) Mn than in that with 1%(mole fraction) Mn. This makes its grain refinement more difficult. The amount of α 2 phase decreases following (1 250 ℃, 7 h-1 150 ℃, 15 h) for 3 cycles heat treatment.

关键词：铸造高铌钛铝合金显微结构锰元素

Effect of coolant inhibitors on AZ91D

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2004年第3期23卷 255-259页

作者： I.M.Baghni WUYinshun ZHANGWei LIJiuqing MechanicalEngineeringDepatartment EngineeringCollegeofTajouraLibya CorrosionandProtectionCenter UniversityofScienceandTechnologyBeijingBeijing100083China

The inhibition effects of sodium vanadate along with inorganic coolantinhibitors were examined on corrosion of AZ91D in ASTM D1384-80 corrosive water by polarizationmeasurements. The galvanic corrosion of AZ91D coupled to 3003, 6063, and 356 Al alloys were alsotested. An effective combination of inhibitors containing (but not limited to) sodium vanadate,silicate, and nitrate was proposed for inhibition of AZ91D and prevention of galvanic corrosion.

关键词： failure and protection of materials inhibitors potentiodynamicpolarization coolant AZ91D magnesium alloy

Analysis of the thermal profile of work rolls in the hot strip rolling process

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2期11卷 173-177页

作者： XuanliZhang JieZhang XiaoyanLi HaixiaLi GangchengWei MechanicalEngineeringSchool UniversityofScienceandTechnologyBeijingBeijing100083China MechanicalEngineeringSchool UniversityofScienceandTechnologyBeijingBeijing100083China／WuhanIron＆Steel（Group）CorporationWuhan430083China

A 2-dimension axisymmetric model was developed by the finite-differencemethod, which can be used to predict the transient temperature field and thermal profile of workrolls in the hot strip rolling process. To demonstrate the accuracy and reliability of the solutiondeveloped, the calculation results were compared with the production data of a 1700 mm hot striprolling mill and good agreement was found between them. The effect of strip width and roll shiftingon the thermal expansion of the work rolls was studied. It is found that the strip width has markedeffect on the efficient thermal crown. Initially, when the rolling strip changes from narrow towide, a bigger efficient thermal crown can be quickly achieved; afterwards, when the rolling stripchanges from wide to narrow, not only the influence of uneven wear can be reduced but also theexcessive efficient thermal crown can be avoided. It is also found that the work roll shifting has adeterminate but not obvious effect on the reduction of the efficient thermal crown, and will makethe strip shape unstable without being used properly.

关键词： hot strip rolling temperature field thermal crown finite-difference method

Fuzzy optimization of space frame

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 2002年第2期9卷 145-148页

作者： ZaigenMu ZheWu 等 CivilandEnvironmentEngineeringSchool universityofScienceandTechnologyBeijingBeijing100083China BeijingUniversityofAeronauticsandAstronautics Beijing100083China

Fuzzy concepts are introduced into structural optimization to solve fuzzyoptimization problems with a crisp objective function and fuzzy constraints, also a non-membershipfunction is used to convert fuzzy constrains into crisp constrains. Two models are discussed wherethe objective function considered is the volume of space frame and the fuzzy constrains are designlimits by the axial strength, slenderness, deflection, thickness and diameter of space frame member.

关键词： space frame fuzzy optimization geometric non-linearity

Failure analysis of corrosion cracking and simulated testing for a fluid catalytic cracking unit

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 2005年第2期12卷 172-177页

作者： HuaChen XiaogangLi ChaofangDong MingLi JinwenYang MaterialsScienceandEngineeringSchool UniversityofScienceandTechnologyBeijingBeijing100083 MaterialsScienceandEngineeringSchool UniversityofScienceandTechnologyBeijingBeijing100083／／StateKeyLaboratoryforCorrosionandProtectionInstituteofMetalResearchChineseAcademyofSciencesShenyang110016China JiujiangBranchCorp.ofSINOPEC Jiujiang332000

The failure of a fluid catalysis and cracking unit (FCCU) in a Chinese refinery was investigated by using nondestructive detection methods, fracture surface examination, hardness measurement, chemical composition and corrosion products analysis. The results showed that the failure was caused by the dew point nitrate stress corrosion cracking. For a long operation period, the wall temperature of the regenerator in the FCCU was below the fume dew point. As a result, an acid fume NOx-SOx-H2O medium present- ed on the surface, resulting in stress corrosion cracking of the component with high residual stress. In order to confirm the relative conclusion, simulated testing was conducted in laboratory, and the results showed similar cracking characteristics. Finally, some sug- gestions have been made to prevent the stress corrosion cracking of an FCCU from re-occurring in the future.

关键词： stress corrosion cracking fluid catalytic cracking unit dew point failure

Simulative analysis for deep seabed mining lifting systems

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 2002年第3期9卷 161-165页

作者： JilingMao YanhuaShen 等 CivilandEnvironmentalEngineeringSchool universityofScienceandTechnologyBeijingBeijing100083China CivilandEnvironmentalEngineeringSchool universityofScienceandTechnologyBeijingBe

Computer simulation was used for hydraulic lifting systems. Based on theoryof multiphase flows and their applications on the lifting systems, mathematical models for pumplifting and air lifting were built and simulative analysis programs for them were developedrespectively. Corresponding lifting behaviors and system parameters were analyzed and optimum matchof the parameters for future pilot mining tests and commercial mining production was predicted.

关键词： simulative analysis deep seabed mining polymetallic nodule liftingsystem multiphase flow

Promoting sludge granulation by putting xonotlite into the UASB reactors during starting-up stage

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4期10卷 7-11页

作者： WenNi HongweiDuan XiaolingAi JianpingLi CivilandEnvironmentalEngineeringSchool UniversityofScienceandTechnologyBeijingBeijing100083China BeijingDevelopmentCenterforAdvancedMaterials Beijing100083China

Four reactors of up-flow anaerobic sludge blanket (UASB) were concurrentlyoperated to examine the effects of the xonotlite secondary particles on promoting the sludgegranulation during the starting-up stage at room temperature. The results show that the putting ofthe xonotlite secondary particles into the UASB reactors can increase the basicity of the reactingliquid significantly. The particles can act as the media for biomass accumulation. Thus, thegranulation process of the sludge within the reactor can be largely promoted by the specialperformances of the particles both in physical and chemical aspects.

关键词： UASB xonotlite secondary particle sludge granulation