This Friday we will be having the last graduate student seminar for the semester. So come out to see Patrick Trahan talk about “Corrosion Protection of Friction Stir Welded Al 7075 Panels using Cold Gas Dynamic Spray” and Muhammad Faisal Alam talk about “Optimizing the squeeze casting process of carbon fiber reinforced aluminium matrix composites”
Date: Friday April 19, 2013
Location: CBY B205
The abstract talks are below. I hope to see you all there!
Corrosion Protection of Friction Stir Welded Al 7075 Panels using Cold Gas Dynamic Spray
Supervisor: Bertrand Jodoin
Abstract: Friction stir welding (FSW) is a solid-state welding process that allows joining of metals or alloys that cannot be welded with fusion-state welding processes. However, in the case of FSW Al 7075, the weld joint region suffers from greater environmental corrosion than the parent material, resulting in a weaker weld joint over time. The aim of this work is to improve the corrosion resistance of FSW aluminum alloy (AA) 7075 joints. To do this, it was elected to form a protective metallic coating over the weld joint using cold gas dynamic spraying (CGDS). Using CGDS, multiple coatings of Al 7075, Al 5083 or Al 11XX-series (pure) were produced. These coatings were subjected to adhesion and corrosion tests. Results indicate that although the pure aluminum coatings have the lowest adhesion strength, they present the best corrosion resistance properties. The interaction between substrate temperature and coating properties was also analyzed revealing a dependence between substrate temperature and coating thickness.
Optimizing the squeeze casting process of carbon fiber reinforced aluminium matrix composites
Muhammad Faisal Alam
supervisor: Michel Nganbe
Abstract: Aluminium matrix composites are among the most promising candidate materials for light weight and high strength applications such as transportation and armour. In a previous study 6061 aluminum matrix composites reinforced with plain weave carbon fiber preform (AS4 Hexcel) were successfully fabricated by squeeze casting using the laminate fabrication technique. This research aims at optimizing the fabrication process in order to achieve improved strength and mechanical properties. It focuses on the liquid infiltration squeeze casting method. Good mechanical bonding between fiber and aluminium is achieved thanks to improved infiltration and impregnation of the fabric by liquid aluminium. Oxidation products at fiber/aluminium interface and porosity are reduced. As a result, composites are produced with overall improved mechanical properties. The flexural strength is increased by up to 36.08% and 36.7% compared to the laminate approach and the reference 6061 aluminium alloy squeeze cast under identical conditions, respectively. Similarly, overall hardness is improved. However, the impact strength is reduced by 7.76% and 25.78% when compared to casts fabricated by the laminate method and the reference aluminium alloy, respectively. The thesis constitutes a good basis for further research on fiber and particle reinforced aluminium matrix composites with the goal of further improving fracture toughness, particularly for gradient materials used in armour applications.