Protective coatings for light-weight metallic components
Lowering the weight of metallic components while enhancing physical, chemical and mechanical properties provide tremendous benefits in industries such as the automotive and aerospace sectors. Such characteristics lead to reductions in energy consumption and increased lifetime of components in the face of environmental pressures and overall wear and fatigue. Aluminium and titanium are two metals with low densities, meaning low weight per volume. They are also corrosion-resistant and capable of withstanding relatively high temperatures. Titanium aluminide (TiAl) is an alloy formed by the combination of these two. Among the three major compounds it forms, gamma TiAl has received the most attention, in particular from the aerospace industry. However, despite its exciting potential and progress made in processing and engineering, widespread use has been limited in part due to insufficient performance under severe environmental conditions and temperatures exceeding 800 degrees Celsius as well as to its brittleness or limited ductility. European researchers initiated the Innovatial project to develop protective coatings for gamma TiAl materials and meet the growing market demand. Four different types of ultra-performance nano-scale–structured thin films were developed: nano-scale multilayers, nanocomposites, intermetallic coatings and thermal barrier coatings (TBCs). In addition to developing new coatings, the Innovatial consortium utilised a novel process for applying the coatings, namely high-power impulse magnetron sputtering (HIPIMS), a method for physical vapour deposition (PVD) of thin films. HIPIMS has the advantage of producing higher density films with increased toughness, particularly important in increasing the attractiveness of gamma TiAl. Innovatial coatings demonstrated enhanced performance for long-term protection of gamma TiAl components. Commercialisation has the potential to help gamma TiAl meet the growing demand from the aerospace, automotive and energy sectors for lightweight, high-performance materials subjected to elevated temperatures and extended dwell times.
