No adhesion without pretreatment at novel magnesium/plastic hybrid componentsFriday (10.11.2017) 09:15 - 09:35 Part of:
The joining of magnesium with plastic opens the possibility of a beneficial combination of different properties to a hybrid material. The new developed material compound, which is generated by deep drawing of a novel magnesium wrought alloy (innomag® 20 = Mg-2Mn-SE; SE= rare earth elements) and back injection molding of a glass fibre reinforced thermoplastic material, is leading to a cost efficient production of light weight and resilient structures with a high functional integration. For the manufacturing of the magnesium sheets by extrusion of an open tube and expanding to a flat material a process route was developed, which allows the production of semi finished parts with different wall thicknesses (tailored sheets) by the geometry of the extrusion tool.
Novel pretreatment processes
In the combination of magnesium with plastic also after corrosion impact the bond strength is playing a crucial role. The newly developed pretreatment process based on JUBOcoat 1060 offers excellent corrosion protection and adhesion properties. An important part is a special magnesium etch, which can lead to etch rates up to 600 g/m2*h. This chemistry provides a specific adjustment of etch rates in acceptable process time frames to remove impurities, which are influencing the corrosion protection negatively, also in deeper layers. Beside this special etch chemistry for a better corrosion protection different passivations were developed to improve the adhesion to the plastic. First results showing for the combination of magnesium and polyamide an improvement of the bond strength by factor 3.
In the project „Entwicklung hybrider Kunststoff/Magnesium-Werkstoffverbunde für Ultraleichtbauanwendungen – KuMag“ (support code: EFRE-0800145) the recent experiences will be used to modify the magnesium surfaces in the magnesium/plastic hybrid, which is produced by deep drawing of a magnesium wrought alloy and the back injection moulding of plastic. Involved partners are IKV (RWTH Aachen), IUL (TU Dortmund), JUBO Technologies GmbH (Wuppertal), KODA Stanz- und Biegetechnik GmbH (Dortmund) and TWI GmbH (Dortmund).