Gold Cools Cars

"Space race" has taken on a whole new meaning at Epner Technologies (www.epner.com). The 93-year-old plating house has already sent its high-tech infrared coatings into space on satellites and various NASA vehicles. But racetracks may be Epner's next frontier.

Company President David Epner believes that Laser Gold, his proprietary electrochemically deposited gold coating, could drastically improve thermal management in Indy and other racecars. With a surface emissivity of 0.02, "the material has been ideal for thermal control of space components," says Epner. It has also seen use in all sorts of imaging optics. Aside from these established uses, Laser Gold has taken a few turns around the track. Epner reports that he has directly coated some heat-sensitive racecar components-including titanium hydraulic fittings and braided stainless steel hose for brake systems.

But to make this coating work as a heat shield material for firewalls and exhaust systems, Epner has recently come out with a new Laser Gold foil. The company creates the foil by applying a 0.25-micron layer of gold to a thin copper foil, with a bit of electroless nickel sandwiched between the two primary materials. Once adhesively bonded to metal or carbon fiber substrates, this foil would offer radiant thermal properties identical to the electroplated version of Laser Gold, according to Epner.

The foil is too new to have proven itself on the track, but Epner has devised a way to test it anyway. To simulate the thermal conditions in a racecar engine compartment, Epner covered one side of an aluminum panel with Laser Gold foil and trained a heat gun on that surface until it reached a steady state, which usually took less than an hour. "We then measured the thermal gain from ambient with a therocouple on the back side of the panel," he says. He performed the same test with a polymer-gold-colored-thermal material commonly used in racing applications.

The results? "Very promising," says Epner. "But we first had to understand how to apply the foil." The metal-to-metal contact of the foil on a firewall or other metal substrate may ward off radiant heat. "But it did nothing to prevent conductive heat transfer," he says. Even so, the Laser Gold foil managed to equal the performance of the polymer heat shield material in Epner's tests. "There was no appreciable difference between the two," he says. Much better results came when Epner paired the Laser Gold foil with some insulation-0.2 inches of high-temperature acrylic foam. With this kind of insulated structure, says Epner, the Laser Gold foil saw a thermal gain of 40 degrees versus 173 degrees for the polymer-based heat shield.

Epner hasn't stopped with tests on aluminum. He has recently been performing similar thermal tests for an IRL racing team that shipped him some of their carbon fiber parts. And he's found another use for the material. During a recent restoration of his 1965 British Racing Green Corvette, he added a layer of Laser Gold foil to some of the upholstery in an attempt to keep the car cooler on hot summer days. As if that car could get any cooler.