After capturing the rally world championship and triumphing in saloon car racing, Audi (Ingostadt, German)—for a second year—won one of the most difficult and demanding motor races in the world—the 24 hours of Le Mans. Thanks to Vorsprung durch Technik, the two Infineon Audi R8 cars set the pace from the beginning.

Success is no coincidence for Audi Sport. Success results from years of experience and cooperation with reliable partners. About 100 people at Audi Sport work continuously on improving the vehicles. One example of improvement is a new approach to bonding the aluminum coolant radiator for the 610-hp twin turbocharged V8 engine to the carbon fiber reinforced plastic (CFRP) vehicle frame.

In extreme conditions, the bonded area can be exposed to temperatures as high as 130 C. The different thermal expansion coefficients of aluminum and CFRP led engineers to adhesive bonding as the preferred joining method.

To be suitable for such an application, an adhesive must retain high strength at elevated temperatures, and withstand mechanical stress and vibration. The adhesive must also retain sufficient toughness to compensate for the different thermal expansion coefficients of the bonded substrates across the whole range of operating temperatures.

Audi chose Epibond 1590 A/B from Vantico (Duxford, Cambridge, England) for bonding the radiator to the frame. It is a cold-curing, two-component epoxy paste adhesive that has a glass transition temperature of 140 to 150 C. At 130 C, it still retains shear strength of 10 megapascals. The adhesive also has a low specific gravity—only 1.09 grams per milliliter—which is desirable for such applications.

For more information on adhesives, call 517-351-5900 or visit