Houfa SHEN
,
Richard A.Hardin
,
Robert MacKenzie
,
C.Beckermann
材料科学技术（英）
A three-dimensional heat transfer model for continuous steel slab casting has been developed with realistic spray cooling patterns and a coupled microsegregation solidification model that calculates the solidification path for multi-component steels. Temperature and composition dependent properties are implemented in a database for 15 chemical species.Considerable effort is made to accurately model the spray cooling heat transfer. Each spray nozzle position and distribution is considered, including variations of the spray patterns with flow rate,and spray overlap. Nozzle type,layout, nozzle-to-slab distance, and spray span and flux are variable.Natural convection, thermal radiation and contact cooling of individual rolls are computed. The present model provides more comprehensive information and realistic slab surface temperatures than results from a model using the “averaged” treatment of boundary conditions. Cooling operating conditions and parameters of individual spray nozzles can be analyzed to optimize nozzle spray distribution, improve product quality, and troubleshoot issues such as nozzle clogging that may arise during production. One spray cooling correlation is used for the entire machine, achieving as good or better agreement with surface temperature measurements than was found previously for the model using an “averaged” treatment of boundary conditions and using three machine-segment-dependent correlations.
关键词:
Steel
,
null
,
null
Author S.R. Zhou
,
S.R. Qiao
,
S.H. Bai and C.S. Tian Faculty 401
,
Northwestern Polytechnical University
,
Xian 710072
,
ChinaManuscript received 18 October 1998
金属学报(英文版)
The tensile properties of three different carbonfiberreinforced carbon composites (C/C), mat C/C, 2D laminate and 4D C/C, were investigated under the combined influence of temperature and loading rate. From the experiments the following could be concluded: loading rate between 10-1-10 mm/min was valid; the fracture stress of the three kinds of C/C composites increased with increasing temperature in the range from room temperature to 1900, and the initial modulus of 2D laminate C/C composites increased with the increase of temperature up to 2000.
关键词:
tensile testing
,
null
,
null
,
null
孙乐
,
方向青
,
孟广慧
材料科学与工程学报
doi:10.14136/j.cnki.issn 1673-2812.2016.05.027
通过化学气相渗透(CVI)、树脂浸渍/碳化(I/C)的工艺制成多孔的C/C预制件,采用气体压力浸渗方法向预制体中渗入铜,制备出C/C-Cu复合材料.以高密度C/C复合材料(1.9g/cm3)作为对比样,在MM-200型磨损试验机上对其摩擦磨损性能进行测试,并对其微观结构和摩擦磨损机理进行分析.研究结果表明:C/C-Cu的摩擦系数比C/C复合材料的低,这主要与摩擦表面的摩擦膜有关,铜在摩擦力带动下填充摩擦表面的凹坑,并与碳材料共同形成摩擦膜,摩擦膜的碳含量越高,润滑效果越好.当C/C预制件密度为1.59 g/cm3时,C/C-Cu的摩擦系数和磨损量均小于C/C复合材料,摩擦磨损性能良好.
关键词:
C/C-Cu
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摩擦磨损
,
摩擦膜
Physical Review B
We report the electronic transport properties of a composite system comprising zero dimensional superconducting NbC(C) nanocapsules and carbon nanofiber matrix. DC susceptibility measurements of the nanocomposite indicate that the critical temperature (T-C) of NbC nanocrystals is 10.7 K. The temperature dependence of electrical resistivity of the specimen pellet follows the Mott's T-1/4 law in a temperature range between T-C of NbC and 300 K, owing to a strong degree of structural disorder in the carbon matrix. Below the T-C of NbC, when the change of its electrostatic energy Delta E is far greater than the thermal energy, an electron will be localized on an isolated NbC nanocrystal at very low temperatures, leading to "Coulomb Blockade." As a result, a collective behavior of the single-electron tunneling effect takes place in a three-dimensional granular superconductors' network composed of the NbC/carbon/NbC tunneling junctions. The superconducting gap of NbC crystals is not found in the current-voltage curves, due to the suppression of surface superconductivity through the contact between NbC and carbon shells.
关键词:
zero-dimensional superconductor;granular metal-films;particles;conduction;nanocapsules;percolation;samples
材料科学技术（英）
Oxidation behavior of C/C-SiC gradient matrix composites and C/C composites were compared in stationary air. The results show that oxidation threshold of C-SiC materials increases with the amount of SiC particles in the codeposition matrix. Oxidation rate of C/C-SiC gradient matrix composites is significantly lower than that of C/C material. The micro-oxidation process was observed by SEM.
关键词:
carbon carbon composites
Jingyi DENG
,
Wenchuan LIU
,
Haifeng DU
,
Huiming CHEN
,
Yiyi LI
材料科学技术（英）
Oxidation behavior of C/C-SiC gradient matrix composites and C/C composites were compared in stationary air. The results show that oxidation threshold of C-SiC materials increases with the amount of SiC particles in the codeposition matrix. Oxidation rate of C/C-SiC gradient matrix composites is significantly lower than that of C/C material. The micro-oxidation process was observed by SEM.
关键词:
李波
,
崔园园
,
李爱军
,
周春节
,
张家宝
,
白瑞成
上海金属
综述了C/C-SiC摩擦材料的研究现状,以及C/C-SiC摩擦材料的发展历程.详细分析C/C-SiC摩擦材料的摩擦磨损性能影响因素及机理,介绍了C/C-SiC摩擦材料的改性及应用现状,并对未来的研究重点进行了展望.
关键词:
C/C-SiC摩擦材料
,
摩擦磨损性能
,
机理
,
改性
ZHOU Qianli DU Ting Central Iron and Steel Research Institute
,
Ministry of Metallurgical Industry
,
Beijing
,
China DU Ting Senior Engineer
,
Laboratory No.16
,
Central Iron and Steel Research Institute
,
Ministry of Metallurgical Industry
,
No.76 Xueyuannanlu
,
Beijing
,
China
金属学报(英文版)
The influence of Sb on the C solubility in liquid Fe was measured under 1300,1400 and 1500℃.The C solubility decreases with the increase of Sb content in liquid Fe.The tem- perature dependences of the first order interaction coefficients in C-saturated liquid Fe were determined as follows: *e_C~(Sb)=11.309/T+0.0025 *e_(Sb)~C=128.023/T-0.0219 The temperature dependences of interaction coefficients between Sb and C in dilute liquid Fe were given to be: e_C~(Sb)=14.204/T+0.025 e_(Sb)~C=120.541/T+0.227 ε_C~(Sb)=ε_(Sb)~C=6026.75/T+11.958 The interaction coefficients at 1600℃ are *e_C~(Sb)=0.0085,e_C~(Sb)=0.033,*e_(Sb)~C=0.295, ε_C~(Sb)=ε_(Sb)~C=15.36.The first order interaction coefficients vary slightly with the temperature.
关键词:
Fe-C-Sb solution
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null
,
null
,
null
