When The Zinc Comes Down...

[jbltzpflk]

Some exhaust pipes are made from aluminized steel (like galvanized but it's an aluminum coating instead of zinc). Probably because of the low boiling point of zinc. The aluminum is there as a sacrificial metal - when the iron rusts from road salt etc, the aluminum cements the iron back on.

 

[awbrew]

Hi jbltzpflk,
Sorry I haven't replied sooner, But the email ended up in the spam folder. I just seen it reading all the other threads. But thats good to know, and it makes more sense on a cheap vehicle, that more expensive stainless metal. Besides if you've ever tried cutting stainless exhaust with a sawsaw blade. Well you know it will kill a new blade quick. cool info about the alum being a sacrifricial metal. I love reading on this board and there always something to be learned... Thanks again

 

[Traveller11]

You say the HCl/Clorox leach will dissolve PGM's? I thought it only dissolved gold.

 

[butcher]

Chlorine gas is generated when you mix hydrochloric acid and sodium hypochlorite; it is this chlorine gas in solution that oxidizes the gold or some of the platinum group metals that then can form metal chlorides from the HCl acid.

Hydrochloric acid and concentrated hydrogen peroxide will also generate chlorine gas in solution and will also dissolve these valuable metals into solution.