Papers by Keyword: Diffusion Process

Abstract: Diffusion chromizing of tool steel has been investigated, using a powder method modified by the use of low pressure during the process for the avoidance of the oxidation of the batch. Innovative chromizing novel processes have been carried out in a hot-wall vacuum oven. The processes have been performed in a chromium chloride atmosphere at a low pressure range from 1 to 800 hPa, with treatment temperatures of 850 to 950°C. Studies of layer thickness, its phase composition, and Cr, Fe, and C depth profiles in the diffusion zone of chromized layer have been conducted. The effect of the process parameters, such as time and temperature, on the growth kinetics of diffusion layers has also been investigated. A comparison was made between the layer thickness produced on the tool steel surface using the novel chromizing method, under low pressure, and a traditional chromizing process, by the pack powder method. Chromizing conducted at low pressure was found to be more effective for maximizing the growth rate of diffusion layers than that for chromizing by the traditional pack cementation method.

Abstract: Assessing the vulnerability of critical infrastructure objects is of major concern when dealing with the process of dependability and risk management. Special attention is paid to the objects of higher interest, such as nuclear power plants. In spite of the protection of these objects, there is still a certain level of a potential threat. The aim of the paper is to describe a possible way of assessments of the consequences when attacking on an object of critical infrastructure. Several characteristics of the impacts outcomes were obtained. For this reason, as well as for modelling of adversary ́s behaviour impact, fuzzy logic tools have been used.

Abstract: Chitosan is an abundant, natural polysaccaride obtained from fishing industry waste and films of chitosan also provide an efficient oxygen barrier. However, they are a poor water vapor barrier, which can be improved by incorporation of a hydrophobic compound, forming a emulsified film. Chitosan films were produced with the addition of palmitic acid lipid analysis and then the process in parallel with the diffusive permeability to water vapor. The objective of this work was to characterize the diffusion and water vapor permeability behavior of chitosan films and chitosan emulsified films.

Abstract: Intermetallic compounds layer will be formed at the interfaces between alloy layer and matrix in the diffusion process of hot dip aluminized steel, which is beneficial to enhance the binding ability of alloy layer with matrix. However, when the thickness of intermetallic compounds exceeds the certain value, the vast extending force of interfacial void will cause the crack of intermetallic compounds and greatly weaken the spall resistance of aluminized layer. Therefore it is very important for the applications of hot dip aluminized steel to research and control the formation of intermetallic compounds at the interfaces. According to the characteristics of diffusion process of hot dip aluminized steel, the growing model of intermetallic compounds were established in the paper. The computed results were in accord with the experimental value. It can provide reference to the choice of the diffusion parameters of hot dip aluminized steel.

Abstract: This document shows the equations and some calculation results of two new Diffusion parameters. The Diffusion parameters assist the calculation of different temperature or time values for equivalent diffusion processes. The Diffusion parameters include temperature dependent and temperature independent factors. The document shows that the introduced Diffusion parameter is suitable for the accurate calculations of the temperature and time values for equal simple diffusion processes. The document shows, that the frequently used Larson-Miller parameter (LMP) does not give accurate results if we use the temperature and time values of equal simple diffusion equations for the LMP calculations.