[nanoPost] New technology for applying micro- and nanostructured composite materials

Research Centre Germany

Tools for the 3D sheet metal forming process in the automotive industry demand highest contour profile accuracy and
surface quality in line with high geometrical complexity. The application of new high-strength steels leads to problematic
forming conditions due to high mechanical load and an increasing wear. This research work aims to develop a new
technology for manufacturing 3D tool surfaces for the novel sheet metal forming processes based on micro- or
nanostructured composite coatings with enhanced functional and structural (tailor-made) properties by employing ultra
fine and nanosized powders. Low specific weight and high reactivity of ultra fine and nanosized powder materials due to
high surface energy require special equipment for the thermal spraying process. Thermico GmbH, Dortmund (Germany)
offers two different HVOF (High Velocity Oxygen Fuel) flame spraying techniques that are specially optimized to spray
such kind of powders. With the ‘Temperature Controlled CJS HVOF-Gun’ the operating flame temperature as well as the
particle velocity can be precisely controlled so that ultra fine particles with grain size < 10 µm can be employed. Another
HVOF technique called ‘ID Cool Flow’ is designed for the coating of interior parts with internal diameters up to 79 mm.
This technique provides low flame temperatures so that an overheating of the substrate can be avoided. Another key
problem for applying nanosized powders is the feeding process. Ultra fine powders have great affinity to moisture that
leads to fast agglomeration. In order to dry the powder material and to stabilise the feeding process the powder feeder
designed by Thermico is equipped with a vacuum pump, a gas-heater and a heating sleeve for the powder hopper.
Nanostructured coatings processed by these technologies offer a smooth and a near-net-shape surface. In addition they
provide outstanding coating characteristics, such as higher hardness combined with enhanced ductility. Therefore they
are not only well-suited to protect forming and machining tools against wear and corrosion, but also offer a great
potential for various other industrial applications. Apart from metallurgical properties as described above feeding of ultra
fine and nanosized metal-matrix-composite powder materials and corresponding adapted thermal spraying process have
to be investigated.