ZHUO Xiaojun
,
WOO Daehee
,
WANG Xinhua
,
LEE Haegeon
钢铁研究学报(英文版)
Ascast CC slabs of microalloyed steels are prone to surface and subsurface cracking. Precipitation phenomena initiated during solidification reduce ductility at high temperature. The unidirectional solidification unit is employed to simulate the solidification process during continuous casting. Precipitation behavior and thermal stability are systematically investigated. Samples of adding titanium and niobium to steels have been examined using field emission scanning electron microscope (FESEM), electron probe Xray microanalyzer (EPMA), and transmission electron microscope (TEM). It has been found that the addition of titanium and niobium to highstrength lowalloyed (HSLA) steel resulted in undesirable large precipitation in the steels, ie, precipitation of large precipitates with various morphologies. The composition of the large precipitates has been determined. The effect of cooling rate on (Ti,Nb)(C,N) precipitate formation is investigated. With increasing the cooling rate, titaniumrich (Ti,Nb)(C,N) precipitates are transformed to niobiumrich (Ti,Nb)(C,N) precipitates. The thermal stability of these large precipitates and oxides have been assessed by carrying out various heat treatments such as holding and quenching from temperature at 800 and 1 200 ℃. It has been found that titaniumrich (Ti,Nb)(C,N) precipitate is stable at about 1 200 ℃ and niobiumrich (Ti,Nb)(C,N) precipitate is stable at about 800 ℃. After reheating at 1 200 ℃ for 1 h, (Ca,Mn)S and TiN are precipitated from CaAl oxide. However, during reheating at 800 ℃ for 1 h, CaAlTi oxide in specimens was stable. The thermodynamic calculation of simulating the thermal process is employed. The calculation results are in good agreement with the experimental results.
关键词:
carbonitride;microsegregation;dendritic region;unidirectional solidification;heat treatment;thermal stability
涂政文
,
李宏
,
徐建生
,
高万振
,
赵源
材料保护
doi:10.3969/j.issn.1001-1560.2002.11.005
利用四球试验机考察了二聚酸-3-氯-2-羟基丙单酯(DAE)在4种成品油中的摩擦学性能.试验结果表明:DAE添加剂在L-HM68液压油和L-DAB100空压机油中具有良好的适应性,使其承载能力增强,摩擦系数降低及耐磨性增强;DAE在L-CKE涡轮蜗杆油中使耐磨性增强;DAE在L-CKC150齿轮油中虽使承载能力提高,减磨性增强,但有使耐磨性减小的趋势,说明DAE在不同的油中有不同的性能.
关键词:
润滑油添加剂
,
摩擦磨损
,
磨损自补偿
解旭斌
,
王维城
,
王栋
工程热物理学报
本文以HFC134a和HCFC22为工质对光管及两种不同槽型的强化传热管(DAE-2管与DAEC管)的水平管内凝结换热进行了对比实验研究。研究发现，DAE-2管平均换热系数比光管提高了140%170%, 而单位长度阻力损失增加了50%100%, DAEC管平均换热系数比光管提高了160%200%, 同时单位长度阻力损失增加了70%130%。此外，本文给出了DAE-2管和DAEC管平均换热系数及阻力损失的计算关联式,可用于冷凝器设计
关键词:
强化传热
,
水平管
,
管内
,
凝结换热
,
制冷剂
章莎
,
周益春
材料导报
应用纳米压痕法测量残余应力的2种理论模型对5种电沉积镍镀层中的残余应力在不同压痕深度处进行了测量,并与X射线衍射法的测量结果进行了比较.结果表明,压深位于薄膜/基底界面处的2种压痕法测量结果与X射线衍射法的测量结果相近,且Yun-Hee模型与其符合得更好.
关键词:
纳米压痕法
,
电沉积镍镀层
,
残余应力
,
X射线衍射法
YL. Chen(Department of Materials Science and Engineering
,
Zhejiang University
,
Hangzhou 310027
,
China)
金属学报(英文版)
Some thermodynamic parnmeters of Pd-In alloys with 2 to 70 at. H indium have been determined in the temperuture range 800 to 1000℃ from e.m.f measurements ongalvanic cells with an onsen-cotzducting solid electrolyte. Heats of tnising calculated hem the activities are in excellent agreement with calorimetric data. The relative partial excess hee enengy of indiurn assumes unnsually larpe negative values ap to-174kJ/mol for Pd-rich alloys. Two efficts are discussed to account for the non-idealproperties: The rise Of Fermi enerpy as the valence electron8 of indium enter the 4dand 5sP bands of the alloy and the lattice distortion brought about by the differentmolar volumes of the cofnponents. The rise of the Fermi enerpy, as determlned fromthe activity data, indicates a strict adherence of the alloys to the rigid band model.
关键词:
galvanic cell
,
null
,
null
,
null
,
null
