Working with Metals: Titanium and Composites

Children don't dream of being general aviation pilots with nice sensible Cessnas. They want to fly screaming fighter jets that tear gaping holes in the sky, and touch the edge of space. And when the military builds the most sophisticated attack plane out of exotic materials, adult children naturally attempt to produce their own fighter jet, at least one for the ground, by using those same materials in their cars. Is this just a silly dream, to put these high tech parts on cars? Or is there a real advantage to using ultra-modern parts in your old restoration project?


First of all, lets be clear on our definition of an exotic material. For something to be exotic, it has to be rare, or at least unusual in its class. Since the last two articles dealt entirely with metals, we will concentrate here on exotic metals, however, we will make mention of some exotic non-metals as well.

Talented Titanium
One of the first metals that may come to mind when you think of exotics is titanium. Titanium is not derived from iron, so it is considered non-ferrous. The qualities of this material are really quite amazing. It is very resistant to corrosion, whether by chemicals, and saltwater. Even more impressive is that it has the highest strength-to-weight ratio of any known metal at normal room temperature. This means that a rod of titanium that is 12 inches long and weighs one pound will be stronger than any other piece of metal with the same dimensions. It is almost as lightweight as aluminum, but can withstand much higher loads than most kinds of steel.


So should everything be made of titanium? Well, it could, but not many of us would be able to afford it. The processes used to manufacture raw titanium are very time consuming and expensive. Reaching over 3000 degrees Fahrenheit is required to liquefy titanium, and at that point it likes to absorb hydrogen, oxygen and nitrogen gases. These gases are all very common in the air that we breathe, so titanium must be kept in an airtight environment when it is made. If this sounds a little complicated, then we can move on to the fact that after it is made it is still quite difficult to machine when compared with steel or aluminum.


Where might you find titanium used? Besides the treads of Soviet tanks and the engines of fighter aircraft, there is a growing trend in the use of titanium in making the intake and exhaust valves of commercially available engines. Really though, this is most common in racing applications.