Discussion in 'General Automotive Questions' started by landyacht, Nov 21, 2017.
Different mechanism. It is identical to electrolysis.
Thank you all for your help, battery had a dead cell in it but was still under warrenty... Unfortunately they stopped carrying the 27 so I had to settle for a 24...
Anyway I tested the new battery and at rest its 12.33 cranking was 10.xx and spun the engine very nicely.
Now I just have to line it back up, stick the distributor back in and we can hopefully start timing it.
What is the difference?
External effect corrosion VS internal effect. External power drives it rather than electrochemical reaction of materials.
From the research I've done, dielectric corrosion doesn't seem to be clearly defined....in nearly every search I've done, it is equated to galvanic corrosion. Searches on electrolysis and galvanic corrosion yield clear and concise definitions. This leads me to believe the term is jargon....maybe urban dictionary knows
? Internal chemical corrosion= Sodium filled valve destroyed from the inside out. Galvanic ? Dissimilar metals corroding bolt threads like a stainless bolt into cast iron or aluminum ? Would external corrosion equal stray electrical current results ? Not dumb, just confused.
Not sure about the sodium filled valve...interesting question.
Dissimilar metals corroding is galvanic corrosion...needs the presence of an electrolyte. Tap water is a weak electrolyte, but enough to allow the electron transfer to take place. Salt water is a better electrolyte. The farther apart the metals are on the galvanic scale, the worse will be the corrosion of the less noble metal. The electrons from the less noble metal get transferred to the electrolyte (metal ions), thus there is a current that results. A driving current can make the situation worse, an opposing one can prevent it.
All professions have their particular jargon, electrical is no exception.
Slang, on the other hand, is what is used by non professionals (urban dictionary).
We deal with corrosion that, while the process is the same as electrolysis, metal is not necessarily transported from one place to another, as in the corrosion that occurs at the base of metal power poles where they contact the ground but not below the ground. This type of corrosion can destroy the metal without oxidation or chemical reaction.
Liquid sodium is very caustic. It will strip any oxygen molecules, even if strongly bound chemically and burn, creating intense local heating. I suspect a faulty stainless alloy that contained bound oxygen.
Stray currents will attack aluminum at any connection that is not dry.
We use stainless nuts and bolts a lot in the industry, I have seen cast iron connections 'hollowed out' inside the bolt hole, but that is high current, high voltage situation. Seizing, where the stainless bolt effectively welds itself to the iron or steel is very common so generally stainless studs are used when bonding to iron and the connector set to the iron with conductive paste.
It is confusing, corrosion can come from many different causes, and often more than one is in play.
That's our world, nothing lasts.
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