Effects of Precipitation Hardening Variables on Al–Zn–Mg-Sn Alloy as Sacrificial Anode in Seawater: Experimental and Statistical Analysis

Abstract

This research investigated the effects of tin composition and heat treatment variables on the Al-Zn-Mg alloy as sacrificial anode in seawater using gravimetric technique and statistical analysis. Tin was alloyed with Al-Zn-Mg in varied proportions (0%, 0.01%, 0.05% and 0.1%) to determine the optimum anode efficiency in the marine environment. Precipitation heat treatment was performed by first subjecting the samples to solution treatment at 5380C for 2 hours and later subjected to varying hardening temperatures and times. The samples were hardened for 4, 8 and 12 hours at each of the hardening temperatures of 1300, 1600 and 1900 centigrade. The anode efficiency increases as the tin concentration increases. The experimental result of this study showed that the Al-Zn-Mg alloy with 0.1% tin gives the optimum anode efficiency. It was revealed that the Al-Zn-Mg alloy without tin composition exhibited high output current capacity when hardened at 1900C for 4 hours. Predictive model developed in this work was in consonance with experimental observation except the following; at hardening temperature of 1600C, the model recommended 12 hours as against 4 hours of laboratory experiment and at hardening temperature of 1300C it advocated 8 hours as against 12 hours.Keywords - aluminum alloy, corrosion, precipitation hardening, regression and correlation analysis, and sacrificial anode