The explanation of how it works has just appeared in a letter by Graham Webster, Treasurer of the BMAA, in 'Popular Flying'. In fact the tip first appeared in the previous issue of the magazine, it was written in an article by a friend of mine and refered to the engine of another friend.
It says that most fizzy drinks contain Phosphoric Acid, H3PO4 (mmm, nice...) and is there as a flavouring to give the tartness. Rust jams nuts and studs because Iron Oxide (rust) takes up more space than the iron did before it got oxidised. The Phosphoric Acid reacts with the Iron Oxide to form Iron Phosphate and water. The Phosphoric Acid reacts more quickly with the Iron Oxide than it does with the un-rusted iron, but all traces of the acid i.e. the Tizer/Coke should be washed off after the de-rusting is completed. The result of the reaction is a deposit of Iron Phosphate on the nut/stud which actually inhibits further rusting.
With thanks to Graham Webster,
John
__________________
Johnef
|