J.M Zeng
,
H. Gu and YH. Zhou (Institute of Materials Science
,
Guangxi University
,
Nanning 530004
,
China Department of Materials Science and Engineering
,
Shanghai Jiaotong University
,
Shanghai 200030
,
China)
金属学报(英文版)
In this paper, the mathematical models for mould-filling under counteramvity are derived on the basis of the principle of momentum. Dynamic processes of mould-filling are observed on a perspex model by means of high speed photography. The results indicate that the mould-filling under counterpmvity can be described by the second oofer nonlinear dtherential equations charucterized by damping oscillations. The velocity oscillations amplofy as the pressuring speed increases if the pressure differential functions are of the same type. On the other hand, if the functions are of different type,then the velocity oscillations depend upon whether the functions pmpressively increase or decrease. Velocity oscillations can be diminished dmmatically by increasing the local damping within the gating system.
关键词:
casting
,
null
,
null
J.M. Zeng and Y.H. Zhou 1) Institute of Materials Science
,
Guangxi University
,
Nanning 530004
,
China 2) Department of Materials Science and Engineering
,
Shanghai Jiao Tong University
,
Shanghai 200030
,
China
金属学报(英文版)
In situ observations of the flow morphology during mold filling under counter gravity are conducted on a perspex water model by means of flow visualization, high speed photography and pattern processing. The experimental results indicate that influences of the dynamic factors on flow morphology can be expressed quantitatively with the parameterφ(k). The flow field takes on different morphology with change in values of φ(k). For thick and thin walled castings, the main dynamic factors influencing flow morphology are gravity and surface tension respectively. Under general circumstances, F_r and W_e should be equal in their values to guarantee the similarity between the prototype and the model in simulating mold filling under counter gravity by experiment.
关键词:
casting
,
null
,
null
X.Q. Sun
,
J.M. Zeng and K. W. Zhou Institute of Materials Science
,
Guangxi University
,
Nanning 530004
,
China
金属学报(英文版)
A new method of analyzing solidification miorostructures of MMCp (Metal Matrix Composite Reinforced by Particles) is proposed based on the principle of statistics in this paper. It is shown that the degree of dispersion of particles increases as crystal grain size and dendrite arm spacing (DAS) of the material decrease. The mean square deviance of the spacing between particles can be taken as the parameters for evaluating homogeneous degree of distributions of particles in MMCp.
关键词:
MMCp
,
null
Jingjing SONG
金属学报(英文版)
The reduction process of manganese dioxide in low-grade manganese ore by biomass roasting was investigated. The calcine of manganese oxide ore was further leached by sulphuric acid, the manganese in ore can be converted into manganese sulfate. Effects of the mass ratio of manganese ore to sawdust, roasting temperature and time, leaching temperature and time, leaching agent concentration and liquid-solid ratio were studied. 97.71 % of manganese recovery can be achieved under the optimal conditions: the mass ratio of manganese ore to sawdust of 5:1, roasting temperature at 500 ℃ for 40 min, leaching temperature at 60 ℃ for 40 min, sulphuric acid concentration of 1 mol/L and liquid-solid ratio of 10:1. Other types of low-grade manganese ore like Guilin ore, Nanning ore and Gongcheng ore were tested and the same results were obtained.
关键词:
Reduction roasting
,
biomass
,
sawdust
,
reduction roasting
