Multi-material car body construction by means of low-temperature brazing of laser-structured and metal-coated fiber-reinforced plastic composites (MuMaK)

1.Application example (node of a car body) with cross section, metal pipe soldered to the coating; 2. cross section consists of (from bottom to top): laser structured FRP, metal coating, solder, metal tube)
© Fraunhofer IWS Dresden
1.Application example (node of a car body) with cross section, metal pipe soldered to the coating; 2. cross section consists of (from bottom to top): laser structured FRP, metal coating, solder, metal tube)

On April 1, 2019, the joint project started with the aim of developing a new joining technology for even lighter and more loadable vehicle bodies. The project investigates technological solutions for high-strength and long-term joining of fiber-reinforced plastics and metal components.

Brief description

Surface pretreatment of the fiber reinforced plastic composite (FRP) with pulsed laser radiation
© Fraunhofer IWS Dresden
Surface pretreatment of the fiber reinforced plastic composite (FRP) with pulsed laser radiation
Thermal spraying for metal coating deposition
© Fraunhofer IWS Dresden
Thermal spraying for metal coating deposition
Mask-free coated FRP sheet
© Fraunhofer IWS Dresden
Mask-free coated FRP sheet

The goal of the Fraunhofer IWS subproject is the process development for laser structuring of fiber-plastic composites (FRP). This surface pre-treatment achieves an optimal bonding of the subsequently generated metallic spray coating. It provides the necessary conditions for the final joining of FRP and metal components using a soldering process.

Within the planned research project, laser-pre-structured fiber composites are to be surface-functionalized by thermal coating with metal layers. The possibility of thermally depositing firmly adhering layers on notch-free substrates opens up a wide range of possible applications - even beyond the joining process being addressed in this project. For example, plastic-based components can be provided with metal surface properties to increase wear resistance, media resistance or electrical conductivity. Subsequent joining processes enable metallized lightweight structures (FRP-based) to be joined with metal components.

Laser surface pretreatment or functionalization can be implemented both locally and on large areas. For the economic processing of large areas, it is necessary to scale up the structuring process. Within the scope of this research project, therefore, a parallelization of the process by means of diffractive optical elements (DOE) is to be implemented, thereby significantly reducing the processing time.