Taking The Pressure: Why Aluminum Is A Superhero In Compressor Seal Applications
"Man of Aluminum" just doesn't have the same ring to it that "Man of Steel" has, but no one will deny that aluminum is a superhero in today's industrial world. Versatile, strong, yet malleable, aluminum has replaced a slew of other metals over the last several decades in multiple uses. Compressor seals especially benefit from the use of aluminum, and here's why:
Lighter than the Lightest Feather. Aluminum weighs about a third of its heavier-metal counterparts bronze and steel. This not only translates to lighter equipment that's easier to move, but also means reduced shipping costs and therefore reduced costs to any company buying and selling the material (flat rates only apply up to a certain weight, after all).
Able to Bend in Any Direction in a Single Bound. Part of aluminum's strength comes from the fact that parts can be formed from a single piece of aluminum, removing the need to join two pieces together. Joints and seams tend to be weak spots in a component, so any item made without them will be stronger. The lack of "hills and valleys" associated with joints and seams also makes for a better seal, which makes for a more efficient machine and lower costs to the company in the long run.
Able to Withstand the Harshest Environments. Aluminum is the perfect metal for working in cold environments. Unlike other metals which break down and become brittle in the cold, aluminum actually becomes stronger when exposed to cold. Aluminum can also withstand exposure to various chemical liquids and gases without corroding or becoming pitted (the precursor to corrosion), which makes it an important material in applications ranging from aerospace engineering to soda cans. As an added bonus, it's not affected by magnets or magnetic fields, so it's good for use with electrical components as well.
However, all superheroes have their weaknesses, and mercury is aluminum's kryptonite. The reason why will seem quite odd: It prevents aluminum from rusting. Now, with other metals, rust prevention is a good thing. But aluminum is special. When it rusts, it forms a clear layer of aluminum oxide (better known to jewelry buffs out there as ruby or sapphire) on the surface, preventing corrosion of the rest of the metal. Adding mercury to aluminum prevents this protective layer from forming and allows corrosion to eat its way through.
And swiftly. In a matter of hours, mercury does to aluminum what it takes the normal process of corrosion months or even years to accomplish. Thus the reason why TSA bans mercury from all aircraft; even a small amount of it could decimate a plane in a dangerously short amount of time.
Aluminum is susceptible to other corrosive elements as well, including seawater. For those applications where aluminum may not be the best metal to use, bronze, brass or steel will gladly take its place. Just check to be sure those metals are designed for use in the environments and conditions they will be exposed to.
Since its first use in the 1800s, aluminum has become quite the power player among metals. It works well under adverse conditions, it's easy to bend and shape, and yet it retains as much strength as some of its heavier cousins. Though it has its drawbacks, aluminum is here to stay, and the industrial world is better for it. Click here for more information on aluminum seal.