Mathematics model of carbide coating growth kinetics on steel matrix surface in molten system is put forward based on the theory of unsteady diffusion mass transfer and subittics model of regular solution. Experiments of vanadium carbide coating treatment of commercial steels 45,4Cr5MoSiV1,T10,and Cr12MoV in molten V 2O 5—Na 2O—B 2O 3 system reduced by silicon are tested and verified.
With microhardness distribution method, based on one dimension unsteady diffusion model, the diffusion coefficient of hydrogen during EIA treatment is calculated out being D=0.43×10~(-13) m~2s~(-1) at 80℃.
In this article,the existence of hydrogen diffusion was verified with a method of gas eliminating oil. With a microhardness distribution method,according to an one dimension unsteady diffusion model,the diffusion coefficient of hydrogen during EIA treatment was calculated,D=0.43×10~(-13)? m~2s~(-1) at 80?
With microhardness distribution method, based on the model of unsteady diffusion in one dimension, the diffusion coefficient of hydrogen during EIA treatment is calculated out being 0.303×10~(-13) m~2s~(-1) at 60℃. The result not only accord with the theoretical deduction, but also with the diffusion coefficient measurement results obtained with other methods. Therefore the method can be used to test the hydrogen diffusion coefficient in EIA treatment.
Copolymerization of ethylene/1 -hexene under a supported Ziegler-Natta catalyst has been studied. It has been found that the catalyst efficiency in copolymerization is higher than that in ethylene homopolymerization. This phenomenon has been explained in the view of unsteady diffusion kinetics of heterogeneous Ziegler-Natta catalyst.
Moisture unsteady-state diffusion in radial and tangential direction during high temperature drying of Masson’s pine lumber was tested and researched. The conclusions follows: When moisture content above F.
The apparent kinetics of leaching of iron oxides in diasparic bauxite by hydrochloric acid has beenprelirninarily investigated. The results show that the leaching rate of hematite obviously increases with the leaching temperature and slightykly with the hydrochloric acid concentration. The rate processes of leaching canbe dominated by the intefacial chemical reaction for x<0.20 and the unsteady-state diffusion model ofreactants through a liquid film for x=0.20-0.80, respectively.
Based on the system of PAN/DMSO/H2O, the minimum time of gelation has been estimated in certain wet-spinning condition. And using computer, we obtain the numerical solution of non-stable diffusion equation with the help of finite element method and the three-dimensional figures of solvent and coagulant are gained in the processing of coagulation.
It was realized to dry Pinus radiata board in the condition of constant high-temperature in early stage and lowering temperature in late stage by taking temperature of the core layer during high-temperature drying as controlling parameter and choose the appropriate moisture content of starting to lower temperature.
The physical parameters, such as steady state and unsteady state diffusion coefficients, of moisture movement in particleboard are very important for modelling the moisture movement process and preventing the deformation of particleboards.
The methods of determination of steady state and unsteady state diffusion coefficients were studied and the results of those determined coefficients obtained.
Unsteady state diffusion of vapour in a closed tube
The mass transfer coefficient was correlated satisfactorily to unsteady state diffusion theory using measured spreading velocities.
It is shown, by taking potentiostatic measurements, that several time intervals exist where steady-state and non-steady-state diffusion coefficients are realized.
In the initial stage of the process, when regularities of non-steady-state diffusion are fulfilled, a large potential jump is observed.
The utilization, for programmed heating, of Fick's second equation concerning non-steady-state diffusion is discussed.
From these tests, calculations of non-steady-state diffusion coefficients, Dns, have been carried out, resulting that migration tests give results in the same order of magnitude than those obtained from natural diffusion tests.
This relation enables the comparison between different non-steady-state diffusion coefficients.