steel and aluminium
steel and aluminium
(OP)
Hi,
Should bolting a steel plate to an aluminium surface cause corrosion problems?
I recently had an ABS problem on a car and traced the fault to the gap between the sensor and the wheel rotor. The gap had increased due to corrosion build up.
The sensor is mounted onto a steel plate at the rear of the wheel hub. The wheel hub is made from aluminium and the corrcsion had built up between the two materials to such a degree, that it pushed the steel plate away from the hub; thus increasing ABS sensor gap.
Thanks
Should bolting a steel plate to an aluminium surface cause corrosion problems?
I recently had an ABS problem on a car and traced the fault to the gap between the sensor and the wheel rotor. The gap had increased due to corrosion build up.
The sensor is mounted onto a steel plate at the rear of the wheel hub. The wheel hub is made from aluminium and the corrcsion had built up between the two materials to such a degree, that it pushed the steel plate away from the hub; thus increasing ABS sensor gap.
Thanks





RE: steel and aluminium
RE: steel and aluminium
I dont believe either surface had any kind of a finish on it.
The corrosion - is it due to differences in electrcical properties of the two dis-similar materials you think?
RE: steel and aluminium
RE: steel and aluminium
I'm convinced "galvanic corrosion" is what i'm dealing with here. But it strikes me odd that a car manufacturer has taken no preventitive measures ?!?!
What finish would you suggest using?
RE: steel and aluminium
A very common problem in the boating world.
Perhaps a check with a boat place or an electronics place may provide a suitable product.
HTH, Cheers , Pete.
RE: steel and aluminium
I don't recall the name of the coating though, the studs came pre-coated.
I've seen where a washer with heavy zinc coating is used between joints of dis-similar metals. The zinc becomes a sacrificial anode and is eroded while the other materials are protected.
regards,
Hydroformer
RE: steel and aluminium
Nick
I love materials science!
RE: steel and aluminium
Regards,
Cory
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RE: steel and aluminium
I should have mentioned, in my stainless stud application, the
steel stamping was e-coated prior to stud insertion. Further more, a teflon (stretched mesh) bushing was used which had to maintain electrical continuity through the joint.
At our tech-center we had one of a very few all aluminum Sables. Under the hood were various labels warning mechanics to use ONLY organically coated fasteners.
regards,
Hydroformer
RE: steel and aluminium
thanks very much for the input. I've got a lot to work with.
regards
nick93
RE: steel and aluminium
Cheers
Greg Locock
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RE: steel and aluminium
Salt spray doesn't reach the thermostat/block area as readily as it does the suspension area, which reduces corrosion risk.
As far as internal corrosion due to coolant as the electrolyte, coolants are produced with additives to prevent corrosion of the Al parts (especially the radiators) along the coolant path.
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: steel and aluminium
i'm left thinking that two dissimilar metals joined would coorode on their own without an electrolyte, and that having an electrolyte (water)would accelerate the corrosion.
RE: steel and aluminium
RE: steel and aluminium
RE: steel and aluminium
The cell works by transfer of electrons. The transfer of electrons requires conductivity. The force driving the transfer of electrons is the difference in affinity for electrons of the two substances connected by the electrolyte. I am digging deep into the memory cells on this one, so I might be way off base, but it seems logical.
Regards
eng-tips, by professional engineers for professional engineers
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RE: steel and aluminium
RE: steel and aluminium
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: steel and aluminium
Regards
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: steel and aluminium
Going back to my original problem layed out at the start, would GROUNDING the "wheel hub"/"steel backing plate" assembly to chassis potential disipate all electrical potential held within the different metals?
RE: steel and aluminium
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: steel and aluminium
What profession are you in?
RE: steel and aluminium
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: steel and aluminium
"Water with the slightest salt content, or acid from dissolved gasses is an electrolyte"
Rain, for example.
Just a few years back, Ford ran a little science experiment by putting aluminum decklids on Lincolns. It was a short-lived experiment, as the steel hinges contacting the aluminum skin prompted the aluminum to corrode right through, usually in a year's time or sligthly more.
They've since done quite a bit of study of galvanic corrosion...
RE: steel and aluminium
Once again thaks for all the input. I'l echo a point i made earlier on in that this has been an interesting topic research.
If anyone is interested, see my final case study WWW.HIBTECH.COM then FERRARI 456 ABS part 2.