Effects of Carrier Gas on Melt Protection of High-Quality Mg

초록

Magnesium exhibits poor formability at room temperature, which limits their use because, among other reasons, their crystal structures are hexagonal close-packed(hcp). Thus, magnesium mostly were produced in melt and casting. However, molten magnesium was rapidly ignited in an atmosphere containing oxygen. Therefore, during casting and handling of molten magnesium it is necessary to potect the melt from continuous ignition. The current method of molten magnesium protection utilizes a protective gas mixture that results in the formation of a thin surface film. The protective gas usually contains air and/or CO2, combined with a small amount of an inhibiting agent. However, the increasing cost of SF6 and concern regarding the contribution of SF6 to greenhous effect has resulted in the need for a more detailed examination of the quantity consumed protective gas. In the paper, depending on the type of carrier gas, the quantitative study on the minimum amount of SF6 gas and effects of melt temperature, holding time and concentration SF6 on the surface film of molten magnesium were invstigated. The analysis methods of surface film used XPS/depth profile and SEM/EDS.