Some Industrial Examples of Accelerated Curing Using Curie Particles

The aim of this paper is to assess the potential of accelerating the curing of epoxy adhesives by means of induction and ferromagnetic curie particles in the electronic and the automotive industries. Commercially available Araldite 2011 and Jowat 690 epoxy adhesives were considered, while Mn-Zn-Ferrite particles were considered for the modification of the adhesives. Induction experiments were performed at frequencies ranging from 188 to 262 kHz, and with particle weight content of 16.7 and 30%. The effects of the induction frequency and the particle content on the temperature of the adhesive were investigated. In addition, the effect of the particle content on the lap shear strength of bonded joints was also studied. Moreover, a comparison between the lap shear strength of inductively cured joints and reference oven cured joints was performed. Results showed that the temperature of the adhesive increased with increasing both the induction frequency and the particle content. However, the lap shear strength of joints with Araldite 2011 was reduced by 17% when increasing the particle content to 30%. No impact on the strength was observed in the case of the Jowat 690 at 16.7 and 30% particle contents. This suggests that increasing the induction frequency is more efficient in increasing the adhesive temperature without compromising the lap shear strength of the brittle adhesive. Furthermore, the inductively cured samples of the Araldite 2011 with 30% particles achieved a substantial 120% of the reference lap shear strength of oven cured samples in 8% of the curing time. For samples with Jowat 690 with 30% particles, the inductively cured samples achieved 43% of the reference lap shear strength of oven cured samples in 8% of the curing time. This shows a high potential of accelerating the curing time for industrial applications by induction and ferromagnetic curie particles, to reach either high strength as in case of Araldite 2011 or the handling strength as in case of Jowat 690.