Aluminum Body Panel Conductivity.
Supposedly my new Chevy Silverado has an aluminum hood. I haven't verified with a magnet yet but I have noticed an interesting phenomenon: The snow melts off the hood and front fenders when the eng...
Forum Discussion
Got me going back to college books and did a quickie search to refresh
Cadmium plated fasteners are preferred over SS fasteners for aluminum,
but many will use SS, which does NOT have the grades available like steel
fasteners
Aluminum has about 5 times the thermal conductivity over steel...dependent
on alloy
Aluminum has about half the electrical conductivity of copper (don't
ever remember any comparison to steel)...as steel is NOT considered
an electrical wiring conductor because it is NOT as flexible. Aluminum
can be made to have a higher electrical conductivity, but that then
makes it more dense and not as flexible
Aluminum is anodic (sacrificial) to the other metal toward cathodic (noble or inert)
The farther away, the more active (sacrificial, or electron flow) the
aluminum will be. Meaning the aluminum will rot away when electrically
connected to the cathodic metal. There is a voltage generated in
doing this and the higher the voltage...the more electrons are flowing
and therefore metal molecules moved from anodic metal to cathodic metal
"Electrically connected" meaning water and the dissolved minerals...like
salt or whatever is used to de-ice
A hood does NOT see the amounts of road salts as does anything 'down
there' does....and that is where the potential issue(s) will be
Of course the designers will or should have had materials classes
and here are some of the generalized info for those who wish to bone
up on that aspect of this topic:
Galvanic corrosion
Steel Aluminum Galvanic Corrosion
The real potential problems are the road salt build up and the body
shop that uses the wrong materials. Biggie is the wrong fasteners
and most will think SS will be the best...yes it is the best for NOT
corroding the fastener, but the aluminum will be sacrificial to the SS
Cadmium plated fasteners are preferred over SS fasteners for aluminum,
but many will use SS, which does NOT have the grades available like steel
fasteners
Aluminum has about 5 times the thermal conductivity over steel...dependent
on alloy
Aluminum has about half the electrical conductivity of copper (don't
ever remember any comparison to steel)...as steel is NOT considered
an electrical wiring conductor because it is NOT as flexible. Aluminum
can be made to have a higher electrical conductivity, but that then
makes it more dense and not as flexible
Aluminum is anodic (sacrificial) to the other metal toward cathodic (noble or inert)
The farther away, the more active (sacrificial, or electron flow) the
aluminum will be. Meaning the aluminum will rot away when electrically
connected to the cathodic metal. There is a voltage generated in
doing this and the higher the voltage...the more electrons are flowing
and therefore metal molecules moved from anodic metal to cathodic metal
"Electrically connected" meaning water and the dissolved minerals...like
salt or whatever is used to de-ice
A hood does NOT see the amounts of road salts as does anything 'down
there' does....and that is where the potential issue(s) will be
Of course the designers will or should have had materials classes
and here are some of the generalized info for those who wish to bone
up on that aspect of this topic:
Galvanic corrosion
Steel Aluminum Galvanic Corrosion
The real potential problems are the road salt build up and the body
shop that uses the wrong materials. Biggie is the wrong fasteners
and most will think SS will be the best...yes it is the best for NOT
corroding the fastener, but the aluminum will be sacrificial to the SS
