I know that car mfgs. are constantly trying to reduce the weight of cars, because this means better gas mileage. Indeed, some exotic makes have all-aluminum bodies (Audi A-5, Acura NSX), which make them lighter than the all-steel bodies used now. My question: I read that automakers are using magnesium as well-Audi used some suspension components of magnesium to reduce weight-can this metal be used to replace steel in the body of the car? Magnesium is evemn lighter than aluminum-what are the chances we will see an all-magnesium car in the future?
Dunno what the chances are, but somebody somewhere is sure working on it.
http://www.industrialtechnology.co.uk/2002/jul/keronite.html
Yeah, but if you witness a car fire, you’ll be blind for life.
Do large pieces of magnesium burn in ordinary air?
Who’d have though that magnesium would have its own homepage? The site discusses the use of magesium alloys for use in cars, amongst other things. Hope this helps.
The use of magnesium as an alternative material for car engine blocks and structural has been the business plan of the very originally named Australian Magnesium Corporation .
It’s been a very hard slog as the car magors are hedging their bets that advances in steel technology and pricing will keep magnesium as a niche material. Ford is the automaker with the greatest involvement in ANM.
[and no I’m not a shareholder ;)]
Yup. I used to work with a volunteer firefighter who came to work bitching one day after a VW with a magnesium engine caught fire and he had to stand there and spray water on it in hopes that it would keep the fire from spreading to the gas tank until the block burned itself out.
Anyone for a hydrogen powered magnesium bodied car? Anyone at all?
I reckon it would be magnesium alloys they are using. You can’t use magnesium for an engine without it catching fire.
Only if it has an oxygen-pressurised cabin.
As I understand it, the major problem with magnesium is its durability. It corrodes easily. It must have proper surface protection (anodization, paint, etc.). Also, isn’t the fabrication cost higher? Magnesium isn’t very ductile.
Titanium is a bit hevier but it’s far more resistant to corrosion. It’s very popular with high-end bicycle frames. I think the cost is the only reason for not using it in automobiles.
By the way I wouldn’t mind a magnesium-body hydrogen-power car at all. I don’t see how it would be any more dangerous than a gasoline-powered car with a magnesium engine block (i.e. the Volkswagen Beetle).
Edited excerpt from the site I linked to above:
"For cast metal components from either sand or die casting. This is the area of strongest demand growth for magnesium, particularly in the US automotive market as US car producers attempt to meet current and future fuel economy standards.
The full benefits of the high pressure die casting of magnesium are also being realised as that process is steadily improved, resulting in more dense castings. Combined with the excellent castability of the common magnesium-aluminium alloys, large structural components such as seat frames, steering wheels, support brackets and instrument panels can now be successfully cast, often replacing complex multi-piece steel stampings. " <my bold>
Since magnesium burns on contact with air, I think we can assume they are talking about alloys, not pure magnesium, but that doesn’t mean the alloys aren’t a fire hazard in themselves.
Cite? Everything I’ve read from reputable sources says that pure magnesium doesn’t ignite spontateously on contact with air (or water), and is quite safe to use as a structural material.
Here’s an interesting page on flammability of magnesium and titanium:
http://tis.eh.doe.gov/techstds/standard/hdbk1081/hbk1081c.html
Magnesium is only a fire hazard when finely ground. Large pieces of pure magnesium are dufficult to ignite, and difficult to put out once burning. Depending on the conditions, trying to put out a magnesium fire with water can actually make the fire burn more intensely.
Interestingly enough, some magnesium alloys are easier to ignite than pure magnesium. Alloying of magnesium is done for improved mechanical properties, not to reduce flammability.
Another problem - magnesium is considerably more expensive than steel or aluminum. It also would be a poor choice for car body panels, which are stamped. Steel and aluminum are easily bent to the right shape, but a magnesium body panel would probably shatter if you tried to stamp it.
I suppose the key point from your link is that pyrophoric metals combust spontaneously “when they reach a high specific area ratio (thin sections, fine particles, or molten states). However, the same metals in massive solid form are comparatively difficult to ignite.”
My experience if based on chemistry lab experiments when small pieces of magnesium, sodium and potassium burnt very freely on contact with water and were kept under oil to stop it happening spontaneously.
Another problem - magnesium is considerably more expensive than steel or aluminum. That alone is probably the number one reason it’s not more popular. It has been used in some specialty automotive components - “mag” wheels being one of the most well known, although that term can also mean wheels in the same style made from aluminum - but its cost means that people are more likely to look at cheaper alternatives. Higher strength steel, aluminum, even fiberglass or plastic are usually prefered over particularly exotic materials.
I’m not sure how well magnesium would work for stamped panels like metal car bodies, either. You can’t really cast a 0.040" thick car body, and magnesium is kind of brittle, making bending it difficult.
(sorry if this is a double post, I’m having trouble connecting)
Magnesium doesn’t burn on contact with air. No cite, just my own experience.
Yes, magnesium manufactured into a car does burn.
Back in 1955, Mercedes ran a magenesium-bodied car at Le Mans, driven by Juan Fangio. It crashed into the stands and went up in a fireball. 85 people were killed, one of the worst spectator disasters on the Grand Prix circuit. Mercedes quit the circuit and I suspect magnesium was banned.
I’ve actually got a block of magnesium sitting on our counter right now. Let me check.
Nope. Its not burning.
Magnesium is difficult to service. If you have body work that needs to be done, your average shop is not going to be equipped to weld a magnesium frame. Most won’t even do aluminum.