Plant engineering and processes
- Wet chemical shaping methods
- Special characterization methods
- Sintering facilities (inert gas/vacuum)
Wet chemical shaping methods
Wet chemical shaping methods generally refers to technologies in which a suspension, a paste, or a slip is processed into components, structures, or coatings on the basis of powder particles. This category also includes techniques with which a sol is processed.
IEK-1 has a wide range of thick- and thin-film techniques that serve to produce both flat and three-dimensional structures as well as both dense and porous structures.
Apart from plant engineering, methods are available for characterizing the fluid precursors, as well as the layers and components. These include particle size analysis, BET surface, rheological properties, topography, light, confocal, and scanning electron microscopy, and X-ray diffractometry.
After the structures have been produced and coated, diverse drying and sintering technologies are available (oven up to 2000 °C; air, vacuum, inert gases).
Powder injection moulding
Two-component injection moulding machine: Arburg, 370U 2-component ALLROUNDER 700-100-100; processing of two injection-moulded materials in one machine by using a suitable tool with two cavities.
Hot isostatic pressing
Manufacturer: EPSI, max. temperature: 2000 °C, max. pressure: 350 MPa, max. dimensions: Ø = 150 mm, h = 400 mm, compressed gases: Ar, N2, Ar/O2 (20 Vol% O2), heating elements: graphite, Mo, Kanthal
Tape casting and micro-tape castin
With tape casting, depending on the machine, two-dimensional extensive continuous structures can be created in various casting thicknesses. Sintering thicknesses are in the range of approx. 5 µm to 1000 µm. The method is used to produce substrates for solid oxide fuel cells (SOFCs) and gas separation membranes.
Machines: Pilot machine manufactured by SAMA; micro-tape casting bench: under purchase
Screen printing can be used to apply ceramic and metallic coatings at thicknesses of approx. 10 µm to 100 µm to porous or dense substrates.
The method is currently used to manufacture functional layers of solid oxide fuel cells (anode, electrolyte, cathode) and intermediate layers (mesoporous layers) for membrane technology.
Roll coating involves continuously coating flat components with a paste over rollers. Layer thicknesses between 10 and 100 µm can be achieved. Here too, areas of application include solid oxide fuel cells (SOFCs) and gas separation membranes.
Wet powder spraying
With wet powder spraying (WPS), coatings can be applied to flat, round, and three-dimensionally structured (not undercut) components. The WPS technique can create layer thicknesses between 5 µm and approx. 150 µm (multilayer coating). Currently, WPS is used to coat the metallic interconnects of the solid oxide fuel cell with protective and contact layers.
Ink jet printing
With ink jet printing, a suspension, a solution, or a sol is applied to a substrate by means of a print head with a large number of jets.
It is best suited for coating very thin layers (< 1µm) and can only coat flat components.
Vacuum slip casting
Vacuum slip casting is based on a filtration process. This means that flat, porous substrates can be coated using a suspension. The solvent is taken up through the porous substrate by negative pressure on the opposite side, while the powder particles form a filter cake on the substrate. The functional layer is subsequently produced by a sintering process. Layer thicknesses are typically between 5 µm and 20 µm. Facilities: several machines constructed at Forschungszentrum Jülich for various substrate sizes up to 200 mm x 200 mm.
SPIN AND DIP COATING
Spin coating entails the coating of flat structures using a sol or a suspension via rotation of the component to be coated. Achievable layer thicknesses are generally below 2 µm. With dip coating, the component is either dipped vertically into a suspension/sol or using a partly circular movement into the coating medium. This method is also primarily suited for layers that are no thicker than a micrometre.
At IEK-1, warm pressing is used for compressing and shaping powders surrounded by a binder. The pressing pressures are in the range of 1 MPa, with temperatures around 100 °C. With this method, flat, relatively thick components can be produced that can be used as substrates. The substrate thickness is between 1 and 4 mm. Warm pressing is used for the fabrication of substrates for solid oxide fuel cells and membrane substrates. Equipment: Forschungszentrum Jülich construction for component sizes up to 350 mm x 350 mm
Special characterization methods
MCR301 rheometer manufactured by Anton Paar with cylinder and plate, parallel plate, and cone and plate systems; heating element
Component and layer topography
CT 300 laser topograph (special construction) manufactured by CyberTechnologies. Bilateral laser topograph for determining film thicknesses, component warpage and roughness; diverse laser detectors manufactured by Keyence
VK 9700 confocal microscope manufactured by Keyence
Sintering facilities (inert gas/vacuum)
Manufacturer: Thermal Technology, max. temperature 1650 °C, max. dimensions 300 mm x 300 mm x 300 mm, inert gas Ar, H2, Ar/H2, vacuum, suction device for debindering, heating element Mo.
Manufacturer Gero, HV-HTK 25 Mo/16-2G, max. temperature 1600 °C, max. dimensions 250 mm x 400 mm x 250 mm, inert gas Ar, vacuum, suction device for debindering, heating element Mo.
Substrate and coating materials (selection)
- Oxide ceramics
e.g. ZrO2, Y2O3-ZrO2, NiO, perovskites such as La-Sr-Mn-, La-Sr-Fe-Co- and Ba-Sr-Co-Fe-Oxide, spinels
e.g. Crofer 22 APU, Ni, stainless steels
(APS: atmospheric plasma spraying, CVD: chemical vapour deposition, HVOF: high-velocity oxy-fuel spraying, IJP: ink jet printing, PVD: physical vapour deposition, RC: roll coating, SP: screen printing, SPS: suspension plasma spraying, TC: tape casting, VPS: vacuum plasma spraying, VSC: vacuum slip casting, WPS: wet powder spraying)