Reconsideration on the role of the specific heat ratio in Arrhenius law applications

Arrhenius law implicates that only those molecules which possess the internal energy greater than the activation energy Ea can react. However, the internal energy will not be proportional to the gas temperature if the specific heat ratio y and the gas constant R vary during chemical reaction processes. The varying y may affect significantly the chemical reaction rate calculated with the Arrhenius law under the constant γ assumption, which has been widely accepted in detonation and combustion simulations for many years. In this paper, the roles of variable γ and R in Arrhenius law applications are reconsidered, and their effects on the chemical reaction rate are demonstrated by simulating one- dimensional C-J and two-dimensional cellular detonations. A new overall one-step detonation model with variable γ and R is proposed to improve the Arrhenius law. Numerical experiments demonstrate that this improved Arrhenius law works well in predicting detonation phenomena with the numerical results being in good agreement with experimental data.

A new model for evaluating the electrical conductivity of nonferrous slag

Electrical conductivity of molten slag is an important physicochemical property for designing the refming process in electric smelting furnaces. Though conductivities of many slag systems have been measured, the quantitative relationships of conductivity with slag composition and temperature are still very limited. In this article, the Arrhenius law was used to describe the experimental data of conductivities for CaO-MgO-Al2O3-SiO2, CaO-Al2O3-SiO2, CaO-MnO-AlEO3-SiO2, as well as CaO-MgO-MnO- Al2O3-SiO： systems, and it is found that activation energy can be expressed as a linear function of the content of components, where the optical basicity of slag must be within the range of 0.58 to 0.68.

Simple statistical model for predicting thermal atom diffusion on crystal surfaces

A simple model based on the statistics of single atoms is developed to predict the diffusion rate of thermal atoms in （or on） bulk materials without empirical parameters. Compared with vast classical molecular-dynamics simulations for predicting the self-diffusion rate of Pt, Cu, and Ar adatoms on crystal surfaces, the model is proved to be much more accurate than the Arrhenius law and the transition state theory. Applying this model, the theoretical predictions agree well with the experimental values in the presented paper about the self-diffusion of Pt （Cu） adatoms on the surfaces.

Model for Evaluating Density of Molten Slag With Optical Basicity

A new model is proposed to estimate the density of molten slag, in which the temperature dependence of density is described by Arrhenius Law with the activation energy expressed as the linear function of optical basicity. Successful applications to the density calculations of CaO-Al2 O3-SiO2 and Al2 O3-CaO-MgO-SiO2 slag systems show that this formula can give a good description of composition and temperature dependence of density for molten slags. It is also found that the ionic band percentage of M-O band in MOx oxide is the intrinsic origin of the phenomenon that the slag with a high optical basicity has a large sensitivity to temperature.

Diffusion Coefficient of Calcium Ion in CaO-Al_2O_3-SiO_2 Melts

The Nernst-Einstein equation is used to calculate the diffusion coefficient of calcium ion in the CaO-Al2O3-SiO2 system based on the data of the density and electrical conductivity.It is assumed that all the aluminium ions form tetrahedral structure and merge with chain or ring in the case of molar concentration of CaO higher than Al2O3.And in this case,calcium ion is assumed to be the conclusive charge carrier.A formula between the diffusion coefficient and concentration of calcium ion as well as temperature is deduced,which gives an increasing function relation between the diffusion coefficient and the concentration of calcium ions.

Experimental Study of Hygrothermal and Ultraviolet Aging on the Flexural Performance of Epoxy Polymer Mortar

This paper studies the effects of hygrothermal environment at different temperatures and ultraviolet(UV)radiation on the bending properties of epoxy polymer mortar(EPM).The microstructure changes of EPM during aging were studied by scanning electron microscopy,and the bending properties of EPM were predicted by the Arrhenius law.The results showed that the bending properties of EPM were greatly affected by the temperature in the hygrothermal aging,but not evidently affected by ultraviolet radiation in UV aging.The prediction of Arrhenius model shows that the EPM will steadily retain 92.8%,89.1%and 79.4%of the original flexural strength after long-term hygrothermal aging at 40∘C,60∘C and 80∘C,respectively.