COMPARATIVE STUDY OF CORROSION PERFORMANCE OF ALUMINIUM- ZINC COATED, GALVANIZED AND ELECTROPLATED STEELS IN TOMATO JUICE

Abstract

Metallic materials are given prominent considerations in agro-based machinery especially in fruit juice processing, storage and use as disposable cans. Such metallic materials include Electroplated Steel (ES), Galvanized Steel (GS) and Aluminum-zinc coated steel (Aluzinc). This study evaluated the corrosion performance of Aluzinc, GS and ES in tomato juice. The medium was chosen due to its social and economic importance. Samples of Aluzinc, GS and ES were prepared by cutting into 3 x 3 cm² from 1 mm thick plate. Three of each of the prepared samples were used for Potentiostatic Polarization Experiments (PPE) while 18 samples each were used for Weight Loss Method (WLM). Each of the prepared samples for WLM was cleaned, weighed and immersed in the media for 30 days. The samples were removed at the end of immersion, cleaned and reweighed. The results obtained for the corrosion rates in mm/y using PPE in tomato juices were 0.0061, 0.0065 and 0.0148 for Aluzinc, GS and ES respectively. The measured pH values for the media ranged from 4.1 to 8.3. Aluzinc had the lowest corrosion rate in tomato juice followed by GS and ES after 30 days of immersion using WLM.