Water mixture, environment-alloy

General corrosion damage was the cause of failure of an A1 alloy welded pipe assembly in an aircraft bowser which was attacked by a deicing-fluid — water mixture at small weld defects . Selective attack has been reported in welded cupro-nickel subjected to estuarine and seawater environments . It was the consequence of the combination of alloy element segregation in the weld metal and the action of sulphate reducing bacteria (SRB). Sulphide-coated Cu-enriched areas were cathodic relative to the adjacent Ni-rich areas where, in the latter, the sulphides were being continuously removed by the turbulence. Sulphite ions seemed to act as a mild inhibitor. 

Many chemical reactions and virtually all biological processes take place in an aqueous environment. Therefore, it is important to understand the properties of dilferent substances in solution with water. To start with, what exactly is a solution A solution is a homogeneous mixture of two or more substances. The substance present in a smaller amount is called the solute, whereas the substance present in a larger amount is called the solvent A solution may be gaseous (such as air), solid (such as an alloy), or hqrrid (seawater, for example). In this section we will discuss only aqueous solutions, in which the solute initially is a liquid or a solid and the solvent is water. 

---