Wang Hao1,2 Shi Zhiming2 Yang Ke3 (1.Faculty of Engineering and Surveying,University of Southern Queensland2.School of Engineering,The University of Queensland3.Institute of Metal Research,Chinese Academy of Sciences)
2008(S1): 213-215.
摘要:Drawbacks associated with permanent metallic implants lead to the search for degradable metallic biomaterials. Magnesium alloys have been highly considered as Mg has a high biocorrosion potential and is essential to bodies. In this study, corrosion behaviour of pure magnesium and magnesium alloy AZ31 in both static and dynamic physiological conditions (Hank’s solution) has been investigated. It is found that the materials degrade fast at beginning, then stabilize after 5 days of immersion. High purity in the materials reduces the corrosion rate while the dynamic condition accelerates the degradation process. In order to slow down the degradation process to meet the requirement for their bio-applications, an anodized coating is applied and is proved as effective in controlling the biodegradation rate.
摘要:A comprehensive mathematical model has been developed to describe the interaction of the multiple physics fields during the conventional DC casting and LFEC (low frequency electromagnetic casting) process. The model is based on a combination of the commercial finite element package ANSYS and the commercial finite volume package FLUENT, with the former for the calculation of the electromagnetic field and the latter for the calculation of the magnetic driven fluid flow, heat transfer and solidification. Moreover, the model has been verified against the temperature measurements obtained from two 7XXX aluminum alloy billets of 200mm diameter, cast during the conventional DC casting and the LFEC casting processes. In addition, a measurement of the sump shape of the billets were carried out by using addition melting metal of Al-30%Cu alloy into the billets during casting process. There was a good agreement between the calculated results and the measured results. Further, comparison of the calculated results during the LFEC process with that during the conventional DC casting process indicated that velocity patterns, temperature profiles and the sump depth are strongly modified by the application of a low frequency electromagnetic field during the DC casting.