Aluminium corrosion

This actually is a story good ending, but let’s start from beginning.

Having balloon glued and ready I couldn’t resist and started with its filling. First step was to prepare a new electrolyte and I have to say that it really feels good to have practically unlimited supply of KOH now.

Adding water to ~2kg of KOH we’ve witnessed a beautiful exothermic reaction again reaching and measuring it with our thermometer we’ve been able to get values even over 120C. Beautiful.

Next stage was to use Veronika’s vacuum cleaner to deflate our balloon. Sebi happily took care of that.

Finally we could kick of hydrogen production and balloon filling again.

Everything went beautifully and I’ve been able to do first 4,5 hrs run without any problems. All functioning beautifully – generator, cooling pump and balloon – ballooning.

That was two days back. Yesterday I came back to start another session and when turning on the generator I’ve noticed some sort of smoke coming out of it, however that was too early as electrolyte wasn’t hot enough to generate any steam. Having a closer look it came to me that I was terribly wrong and worries I had weeks ago about that aluminium lid materialised.

Apparently Aluminium is generally quite sensitive to number of corrosive effects – Atmospheric, Galvanic, Pitting, Crevice, Intergranular, Exfoliation, General, Deposition, Stress corrosion cracking, Erosion corrosion, Corrosion fatigue, Filiform corrosion and Microbiological induced corrosion. Good reading on all of those for example here.

Interestingly the picture above actually show how is aluminium actually doing pretty good job of resisting corrosion. The thin coating of aluminium oxide forms a protective shield that inhibits further corrosion. However, salts are extremely corrosive and our generator causes this film to worn out. Apparently there’s an easy way to protect aluminium from salt water and prevent unsightly corrosion – a powder coating, but it is too late for our lid here.

I also took a video, where it perfectly demonstrate how is that aluminium being eaten away.

Well, that was quite a drawback in our project and pretty much ruined my evening. Feeling quite down about it I shared pictures and video with Serge & Vlada and Serge instantly offered his help with replacing our aluminium lid with a new one made of formica.

Just a tiny quote from Wikipedia: Formica is pretty much also know as bakelite and was invented in 1912 by Daniel J. O’Conor and Herbert A. Faber, while they were working at Westinghouse, resulting in a patent filing on 1 February 1913.

Serge came precisely 19hrs later since reporting the problem and started cutting and drilling a new lid for me.

I’ve been almost feeling silly when Serge did everything on his own – like a live Robot.

No longer then 30 minutes, all setup was back in action and looked splendid!

Thank you Serge, you saved my day again!

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