Influence of Ageing on the Corrosion Resistance of the ZnAl22Cu3 and ZnAl40Cu3 Alloys

Abstract

Subject of examinations were ZnAl22Cu3 and ZnAl40Cu3 alloys. The samples after solutionizing 3850C/10h and ageing 1750C/10h and for comparative purposes, in the initial state (just after casting) have been studied. Corrosion tests were carried out in “acid rain” solution. The scope of the examinations included potentiodynamic and potentiostatic tests , examination of the surface and structure of the samples after corrosion. The research found that corrosion of ZnAl22Cu3 and ZnAl40Cu3 alloys in the "acid rain" environment leads to a depletion of zinc in the upper surface layer and its enrichment in aluminium and copper resulting in decreasing the corrosion rate. Depending on the parameters (temperature, time) solutioning and ageing of ZnAl22Cu3 and ZnAl40Cu3 alloys can lead to an increase or decrease of the corrosion resistance in the "acid rain" environment.