ZHANG Qiyun
,
LIU Shuqi
,
XU Yaping Peking University
,
Beijing
,
China professor
,
Department of Chemistry
,
Peking University
,
Beijing
,
100871
,
China
金属学报(英文版)
The features of Cu_6Sn_5 growing slowly at lower temperature and growing rapidly up over 350℃,and or Cu_3Sn growing at higher temperatures,bave been detailedly observed under SEM.The increase of Pb content seems to inhibit sequentially the growth of Cu_6Sn_5 in Pb-Sn alloy.
关键词:
Cu
,
null
,
null
,
null
,
null
By ZHANG Yi WANG Yingxia HUA Tongwen Institute of Chemical Metallurgy
,
Academia Sinica
,
Beijing
,
100080
,
China.Department of Chemistry
,
Peking University
,
Beijing
,
100871
,
China.To whom correspondence should be addressed.
材料科学技术（英文）
The kinetics of α-FeO(OH) formation in weak acidic medium was studied.The effects of the initial concentration,temperature,pH value,partial pres- sure of oxygen,air flow rate and agitating intensity on the oxidation rate of Fe(OH)_2 suspensions have been investigated.It is confirmed that the reaction order for Fe(Ⅱ) is zero at the stage of α-FeO(OH) seeds formation,and about 0.5 at the stage of the seeds growth,and in the whole process partial pres- sure of oxygen appears in first order.The activation energy is determined.The dissolution-oxidation equilibrium which exists in the process of seeds formation has been suggested,by which the zero order reaction for Fe(Ⅱ) and the plateau in the pH-t curve were explained.Physical process is the rate-determining step of the heterogeneous reaction.The study on the kinetics of α-FeO(OH) formation may provide some fundamental informa- tion for the reactor design,the engineering amplifi- cation and the optimization control in the industrial process.
关键词:
kinetics
,
null
,
null
,
null
Zhiyu QIAO Xianran XING Shuzhen DUAN University of Science and Technology Beijing
,
Beijing
,
100083
,
ChinaChaogui ZHENG Beijing University
,
Beijing
,
100871
,
China
材料科学技术（英文）
A new geometric asymmetric model for predicting the thermodynamic properties of ternary system from three sub-binaries is presented in this paper.Its analytical expression with good calculating ac- curacy is most simple in all asymmetric models.The new model was applied to predict the enthalpies of mixing of the Bi-Ga-Sn.Au-Ag-Sn and NaCl-KCl-CaCl_2 ternary systems which were in good agreements with experimental data.Based on thermodynamic principles,the importance of the choice of asymmetric component is also discussed.The error analysis indicates that in the case of judging the asymmetric component in ternary system according to the thermodynamic criterion the deviation is minimum.It is of great significance to improve the calculating accuracy for predicting thermodynamic properties of ternary solution phase from the sub-binary ones.
关键词:
thermodynamic properties
,
null
,
null
