Study on Various Chemical Systems for the Preparation and Application of Nickel Nanopastes for Joining Processes

Nanojoining, which utilizes nanoparticles for joining applications, is an interesting method that stands out from conventional processes by combining relatively low joining temperatures with high service temperatures. To use the nanoparticles for this purpose, it has proven useful to process them as a paste. The chemical composition of such a nanopaste has a certain influence on the properties ultimately achieved by the joint. While nickel nanoparticles represent the metal content of the here investigated nanopastes, a variety of substances can be utilized as organic components to form the actual paste-like suspension. Derived from the literature on nanoparticle synthesis, a variety of candidates were identified from which numerous paste compositions were developed for this work. So, high metal content (70 wt.%) nickel nanopastes were prepared from these solvent-stabilizer systems by ultrasound-enhanced mixing. The study evaluates the pastes in terms of manufacturability and handleability. The findings reveal insights into the effects of different chemical substances. Additionally, joining tests using the mild steel DC01 are presented, demonstrating the impact of the paste composition on the joining strength and the microstructure of the joint as well. Within this study, a paste consisting of terpineol and KD4 was the most favorable.