Papers by Keyword: ZM21

Abstract: Plasma electrolytic oxidation (PEO) is a technique employed to significantly enhance the corrosion and tribological properties of the materials by forming an oxide ceramic film on the surface of the material. In this investigation, ZM21 Mg alloy was subjected to PEO treatment in silicate and phosphate-based aqueous solutions of 5grams and 10 grams per liter concentrations. The oxide film was characterized using SEM, profilometer, thickness meter, and polarization test. Results showed that the oxide film obtained with 10g/L phosphate-based solution offers higher corrosion resistance than the oxide films formed with other solutions.

Abstract: The increasing attention to magnesium alloys in extruded profiles, especially in the transportation industry, is related to their low density associated with good mechanical properties and complete recyclability. This allows to push towards both increasing efficiency and pollution restrictions. However, these advantages are negatively balanced by the production rates drop in relation to dangerous profile temperatures increasing that force to keep low velocities. In this context, a novel porthole die has been purposely designed for magnesium alloys allowing an increasing of the process velocity up to four times with respect to past solutions. The mandrel consisted of three ports made by 120° bridges that created an equal number of seam welds. The extruded tubes, made in ZM21, were 50 mm in diameter and 2 mm in thickness and were tested under different process conditions. In the present work, the quality of the seam welds has been investigated in relation to each process condition by means of the rubber plug testing method that allowed to applied an hydrostatic tensile state.