Cadmium-Free Zinc-Based Alloy, its Use as a Sacrificial Anode, a Sacrificial Anode, and a Method for Cathodic Protection of Corrosion-Threatened Constructions in Aggressive Environment

Abstract

A cadmium-free, zinc-based alloy suitable as a sacrificial anode substantially consists of 0.4-0.6% by weight of aluminum, 0.02-0.03% by weight of indium, max. 0.001% by weight of cadmium, maximum 0.005% by weight of copper, maximum 0.006% by weight of lead, maximum 0.0005% by weight of tin, maximum 0.10% by weight of other metals, in particular nickel and thallium, and balance zinc having a purity of about 99.995% The alloy shows advantageous properties with respect to resistance to cracking and breaking during post machining of the casting, especially when producing sacrificial anodes having relatively small dimensions.

1 . A zinc-based alloy, characterized in that it substantially consists of
 0.4-0.6% by weight of aluminum,   0.02-0.03% by weight of indium,   maximum 0.001% by weight of cadmium,   maximum 0.005% by weight of iron,   maximum 0.005% by weight of copper,   maximum 0.006% by weight of lead,   maximum 0.0005% of tin,   maximum 0.10% by weight of other metals, in particular nickel and thallium, and   balance zinc having a purity of about 99.995%.   
     
     
         2 . An alloy according to  claim 1 , characterized in that it substantially consists of
 0.45-0.55% by weight of aluminum,   0.02-0.03% by weight of indium,   maximum 0.001% by weight of cadmium,   maximum 0.005% by weight of iron,   maximum 0.005% by weight of copper,   maximum 0.006% by weight of lead,   maximum 0.0005% of tin,   maximum 0.10% by weight of other metals, in particular nickel and thallium, and   balance zinc having a purity of about 99.995%.   
     
     
         3 . An alloy according to  claim 1 , characterized in that it substantially consists of
 0.4-0.6% by weight of aluminum,   0.024-0.026% by weight of indium,   maximum 0.001% by weight of cadmium,   maximum 0.005% by weight of iron,   maximum 0.005% by weight of copper,   maximum 0.006% by weight of lead,   maximum 0.0005% of tin,   maximum 0.10% by weight of other metals, in particular nickel and thallium, and   balance zinc having a purity of about 99.995%.   
     
     
         4 . A zinc-based alloy according to  claim 1  for use as the active part of a sacrificial anode. 
     
     
         5 . The use of an alloy according to  claim 1  as the active part of a sacrificial anode. 
     
     
         6 . A sacrificial anode, characterized in that its active part is a zinc-based alloy according to claim. 
     
     
         7 . A method for the cathodic protection of corrosion-threatened constructions in aggressive environment, characterized in that the constructions are protected by using a sacrificial anode according to  claim 6 .