New eco-friendly process enhances fatigue life of aluminium alloy used in aerospace components
Vijay Mohan
Tribune News Service
Chandigarh, June 7
Indian Scientists have developed an environment-friendly process that can provide excellent corrosion resistance to high-strength aluminium alloys extensively used in aerospace, textile, and automotive applications.
The process, called micro-arc oxidation (MAO), involves an electrochemical method for the production of an oxide film on the metallic substrate. The electrolyte of the film is alkaline in nature and capable of providing better wear and corrosion resistance compared to the existing process.
High-strength aluminum alloys are extensively used in aerospace, textile, and automotive applications because of their low density and high specific strength. Aerospace components made out of aluminum alloys include landing gear, the main structural part of the wing, fuselage, aircraft skins and pressure cabins.
These parts need resistance against wear and corrosion damages in addition to enhanced fatigue life. The widely used technique for aluminum alloys to improve corrosion resistance at present is called hard anodizing. It involves sulphuric and oxalic-based electrolytes which emit not only toxic fumes but are also hazardous to handle during processing.
To cater to the aerospace segment, extensive research has been carried out at ARCI, and the high-cycle fatigue life of aerospace Al alloys under plain and simultaneous corrosion environments could be significantly improved.
In order to cater to the growing demand for cleaner industrial processes, MAO was developed at the International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), a research and development center under the Department of Science and Technology.
MAO is a high-voltage driven anodic-oxidation process which uses an electrochemical method to produce an oxide film on a metallic substrates. ARCI team has further designed and developed a duplex treatment of ‘shot peening’, a process used to modify the mechanical properties of metals and alloys, followed by coating deposition.
“Systematic investigations conducted at ARCI have shown that the duplex treatment has led to the remarkable enhancement in aerospace aluminum alloys’ fatigue life while retaining the outstanding corrosion and wear resistance of MAO coating,” according to a statement issued by the Ministry of Science and Technology, today.
“The efficacy of duplex treatment has been validated for different aluminum alloys and extended to impart superior corrosion fatigue life. This work has been recently published in the International Journal of Fatigue,” the statement added.
The MAO process developed at ARCI has been patented in India and abroad and the technology is ready for transfer to the industry for commercial production. The process with necessary modifications can be used for wear, corrosion, thermal, and fatigue and corrosion-fatigue life enhancement of a variety of components made out of aluminum, magnesium, titanium and zirconium.
