[alfa] Re: Magnesium Wheels

["Robert S. Wilkinson" <wilk@xxxxxxxxxxxxxxxxx>]

A few footnotes to Jim Steck's remarks:  Magnesium, like most things, burns
under the right circumstances.  Magnesium "ribbon" is in fact used as a
"fuse" in chemistry labs--one lights it with a match and it burns at a high
temperature--bright white.  It has high surface-to-volume ratio, so heats
quickly to it's ~350 deg C ignition temperature.  With sufficient heat
input (as in a major fire), wheels will burn too--without external heat or
100% oxygen, but they're hard to get started (and, as Jim says, melt at the
same time) and would probably be the last thing to go in the whole car.

Of greater concern is that Mg oxidizes readily.  My 74 turbina spare wheel
was sitting partially under water in a car (before I bought it used).  The
bead over a few inches is rotted away--I must use a tube in it.  

One further point.  Mg alloys are quite varied--some cannot tolerate
remaining unprotected, while some (later) ones are actually more
oxidation-resistant than typical aluminum alloy wheels.

Jim--If I burn up my turbinas, will you replace them with the Dayton wires
(alloy rims, please) that you know I want, instead of more turbinas?

Bob Wilkinson
72 Spider

Jim Steck said: 

If you can make your magnesium wheels burn . . . without a continuous
external heat source, or 100% oxygen atmosphere . . . I'll buy you a new
set. 
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