Aluminum’s relatively low cost and availability makes it a very popular material for food manufacturers. It is also twice as abundant as Iron. But does rust from this cheap metal find its way into our food? This puzzled Assistant Professor of Applied Chemical Engineering, Feyisayo Victoria Adams and inspired her to investigate the popular notion that aluminum is wholly corrosion-resistant.
The fact that aluminum is widely used for packaging in the food industry, automobiles, and aerospace made the research even more intriguing.
At the School of Engineering Seminar held on February 21, 2020, Dr. Adams presented her findings on Corrosion of Aluminum Alloys. Aluminum is very soft, has a high electrical and thermal conductivity, and has high mechanical stability. An interesting fact about aluminum is that once it is exposed to the conditions which make other metals rust, it instead forms aluminum oxide which prevents further rusting.
Dr. Adams explained that it shows good corrosion resistance due to the formation of a resistive oxide layer. However, this stable metal could still corrode beyond expectation under conditions like the chloride environment. Her research work was a comparison study of the corrosive properties of three aluminum alloys in nitric and acetic acid.
"Acetic and nitric acid which are the focus of this work is present in most foods because they are organic; they are used in pickling for fish and vegetables and can also be present in the atmosphere."
"Alloy AA1200 has the highest corrosion resistance in both acid media. Alloy AA8011 has the least corrosion resistance in acetic acid solution and alloy AA44017, on the other hand, has the highest corrosion rate in nitric acid."
Chairman/HOD of the Division of Engineering, Dr. Abubakar Sadiq Hussaini, was curious to know if there is any standard for aluminum use as packing materials in the food industry. He learned from the presenter that they must have passed through stress and corrosion tests before they are approved to be used as such materials.
Reported by Omorogbe Omorogiuwa