Application of Huntsman Araldite AV 170 for Dissimilar Material Structural Bonding in Automotive Lightweighting

With the popularization of automotive lightweight technology, automobile manufacturers widely adopt the combination of aluminum alloy and carbon fiber reinforced plastic (CFRP) to produce body brackets and engine compartment components. Due to the large difference in coefficient of linear thermal expansion between the two materials, ordinary adhesives are prone to debonding, cracking and strength attenuation under long-term alternating high and low temperatures and vibration conditions. A commercial vehicle component manufacturer adopted Araldite AV 170 one-component heat-curing epoxy structural adhesive for mass production bonding of carbon fiber engine compartment brackets and aluminum alloy frames, achieving reliable practical application.

The bonding substrates in this project are aerospace-grade carbon fiber composite materials and 6063 aluminum alloy. Surface pretreatment was carried out in strict accordance with product specifications: the surfaces were thoroughly degreased with acetone to remove oil, grease and dust, followed by sand blasting for mechanical roughening. A second degreasing treatment was conducted after roughening, and the parts were fully dried to ensure excellent interfacial adhesion. Araldite AV 170 is a thixotropic paste with no sagging during application, suitable for both manual and automatic dispensing. The adhesive thickness was controlled at 0.05–0.10 mm to balance lap shear strength and uniform bonding. It can fill gaps up to 3 mm, which well accommodates the machining tolerances of parts.

The curing process adopted the standard schedule of 60 minutes curing at 150℃, enabling full cross-linking of the adhesive. After curing, the lap shear strength reached 28–30 N/mm² at 23℃, and the roller peel strength was 5.8 N/mm. Its high toughness effectively relieved internal stress caused by thermal expansion and contraction of dissimilar materials. After 100 thermal cycles from -30℃ to 70℃ and long-term vibration tests, no delamination or cracks were found on the bonded joints, with strength retention rate above 94%. The long-term service temperature of the cured adhesive is up to 120℃, which perfectly adapts to the high-temperature environment of engine compartments. It also features excellent resistance to motor oil, unleaded gasoline, lubricating oil and other chemicals, meeting the service requirements for the whole life cycle of vehicles.

In terms of storage and mass production, the adhesive has a shelf life of 2 years when stored at 2–8℃, and can be stably used for 6 months at 15–25℃ after being taken out from cold storage, which fits the stock preparation and continuous production of industrial assembly lines. Up to now, the bonded components of this batch have been in service on vehicles for more than 2 years without any bonding failure, proving to be a mature solution for structural bonding of dissimilar materials in the automotive industry.