Papers by Keyword: Diffusion Behavior

Abstract: In this paper, fine-grain WC/Co tools were utilized in dry turning of the Ti-6Al-4V alloy. The wear modes of the cutting tools at different cutting speeds were analyzed. The diffusion behavior between the cutting tool and the workpiece was studied in detail based on the Auger electron spectroscopy (AES) depth profile technology. The diffusion wear mechanism was revealed. The results showed that the diffusion layer formed at the interface between the cutting tool and the adhering material. The diffusion ability of C was the strongest, followed by W, the weakest was Co in all the elements of the cutting tool. The chemical reactions took place close to the adhering material, forming the reaction layer. As a diffusion barrier, it was possible to limit the elements diffusion from the cutting tool to the adhering material, decrease the changes in the cutting tool composition and damages. The diffusion layer, which was weakened by diffusion, was worn off and taken away by the fast flowing chip during the cutting process, causing the diffusion wear characterized by a smooth crater formation on the tool surface.

Abstract: Effect of hydrogen trapping and poisons on diffusion behavior of hydrogen in commercial cold-rolled low carbon steel was investigated by means of electrochemical hydrogen permeation techniques. The experimental results reveal that diffusion rate and diffusion flux of hydrogen in the materials gradually increase with increasing the number of hydrogen charging and outgassing, and lag time significantly shortens with them, therefore, hydrogen trapping impede diffusion behavior of hydrogen in the materials. Different poisons in the hydrogen charging solution have also resulted in a certain influence on the assessment of hydrogen diffusion behavior.

Abstract: The research on the decarbonizing behavior of the austenite region of SCM435 steel was carried out. And the experimental results shewed that the relationship between the diffusion coefficient and temperature totally agreed with the Arrhenius equation and that the diffusion constant and the diffusion activation energy were uniform within the temperature range of 900-1100°C. However, when the austenite reached certain temperature, the carbon diffusion coefficient decreased significantly as temperature increased and its relationship with temperature no longer agreed with the Arrhenius equation.

Abstract: To better apply ERP, it is necessary to understand its developing rules and influencing factors in the diffusion process. Firstly, properties of ERP diffusion are analyzed, and its diffusion mechanism is discussed. Secondly, under some assumptions, a nonlinear differential model is constructed, in which three kinds of enterprises are considered, and government is regarded as an important factor. Thirdly, the model is analyzed, and qualitative results are given. Finally, the application of the diffusion model is exemplified and simulated by Vensim, and the parameter influence is given. This study assists enterprises to analyze trends of ERP and make reasonable decisions, and provides theory basis for government strategies.

Abstract: Molecular dynamics simulations are performed to research the diffusion behavior of amorphous silica with hydroxyl group. Muliken analysis is employed for the determination of initial charge status of simulated systems with various hydroxyl contents. Modified BKS potentials for the interactions between introduced hydroxyl groups and other atoms, are adopted in the present molecular dynamics simulations. Short-range atomic arrangement and self diffusion coefficients of hydroxyl-doped amorphous silica systems are calculated and hereafter compared with those of pure amorphous silica. The calculation results suggest that the doped hydroxyl groups play an important role for the mobility of atoms within the system, which can be employed to the theoretical interpretation of the oxidation process of the ceramics such as silicon nitride.