Investigation and synthesis of multifunctional graphene-nanocomposite coatings on magnesium alloys

Magnesium alloys with hexagonal close-packed lattice are difficult to deform mechanically at room temperature due to their limited numbers of slip system. Comparing with Al, magnesium possesses low mechanical strength, poor creep and corrosion resistance. Despite these shortcomings, light-weight magnesium alloys have attracted increasing attention in automotive and aerospace industries. The aerospace industry has long recognized the benefits of high-performance magnesium alloys for reducing weight in fuselage structures and aircraft skins, interior appliances, aero engine frames and components, helicopter transmissions and aircraft wheels. When magnesium alloys are used in lubricated or chemically active environments, they are susceptible to mechanochemical effects. These environments provide suitable conditions for phenomenon such as tribocorrosion to accelerate the material degradation. The existing methodologies for studying material degradation largely treat wear and corrosion as separate phenomena. This is problematic because wear-corrosion synergism causes accelerated material degradation, which is higher than the effects of wear or corrosion considered separately. Though there are many forms of nanocomposite coatings that can enhance preferentially the wear or corrosion behavior, there are very few that can provide resistance to wear-corrosion synergistic effects. Nickle and graphene are some of the most widely known forms of materials that can provide wear and corrosion resistance when coated on a surface or used as an additive. However, to provide tribological enhancements, specifically wear-corrosion resistance under variable working conditions it is necessary to synthesize composite coatings that involve compatibility with the substrate material. The present study aims to investigate and understand the wear-corrosion synergistic behavior of electrodeposited nanocomposite surface coatings on magnesium alloys.