Does magnesium easily catch fire?

Magnesium in bulk forms is very stable and difficult to ignite accidentally.  As with many metals and materials, in finely divided form (powder or small shavings) magnesium can be readily ignited. We often explain it this way, grain silo’s have been known to ignite explosively,  yet few if any of us are fearful of buying or even toasting bread.  In the late 1940’s and early 1950’s DOW demonstrated how safe bulk forms of magnesium really are.  Below you can see a demonstration of cooking food on a magnesium griddle, placed on magnesium ingots. This is all being cooked with open gas flame.

Dow even produced a video short to demonstrate which forms were dangerous and which ones were safe.  On an annual basis more people are injured or killed by aluminum or titanium explosions. Of course aluminum production is far larger than magnesium production on an annual basis. Consider that magnesium is used in many notebook cases and has experienced far fewer industrial explosions in China than aluminum. Proper safety procedures are the only protection from metal powder fires. Magnesium fires burn very hot and very bright.

Doesn’t magnesium corrode very easily?

Magnesium is far more corrosion resistant than mild steel or iron. Since the late 1930’s it’s been known that high purity alloys offer low corrosion, in many cases lower than many cast aluminum alloys. Specific impurities are prime culprits in increase corrosion. These are Iron, Nickel and Copper, if these are kept to very low limits in the pure magnesium used to make alloys, significant improvements are had in resulting corrosion resistance.  If one considers magnesium like steel rather than aluminum it is easily understood that passivation or anodizing followed by coatings such as paint, of plating offers highly durable all weather performance.

Didn’t they stop using magnesium for wheels because it is brittle?

The history of light alloy wheels is one where for most of automotive history cast aluminum failed to offer the ductility required to make a safe wheel. A few wheels makers in Germany, US, and Italy finally improved aluminum casting technology to the point where it the simultaneous goals of safety and low costs where achieved. Still magnesium wheels offer higher ductility and safety than aluminum wheels, whether forged or cast. Corrosion protection often means polished finishes are not possible, but if painted, these wheels out perform wheels made of any material including carbon fiber reinforced composites.

Isn’t magnesium expensive?

There is often a misinformed assumption that magnesium is more costly than titanium or so rare no one can work with it. In fact magnesium is about the same price per unit volume as aluminum. While processing magnesium can at times be more costly, these costs are on the order of 15-25% higher than aluminum.  As for magnesium’s rarity, it is one of the few metal resources on earth to be considered inexhaustible. We often explain that magnesium is the affordable exotic. It offers strength to weight ratio’s in excess of most aluminum alloys and matches 6-4 titanium. Only beryllium can beat magnesium’s specific stiffness.

What finishing systems can be used for magnesium?

Dozens of magnesium finishing systems exist, most common are passivation, followed by a liquid or powder paint. Systems of anodizing have existed since the 1940’s, often creating a hard and adherent coating, that is quite porous, thereby improving the subsequent finishing systems such as paint or e-coating. Some very new lower cost higher performance finishing systems are now available. Please contact us for details on vendors and performance specifications.

Plating can be applied to passivated or anodizing, chemically,  electrically applied or vacuum deposited. Cold enamels also work very well, as do phenolic resins.