Sustainable Shaping of Ceramics and Hardmetals by Water-Based Extrusion

Water-based cold plastic extrusion is established as an efficient and sustainable forming process in technical ceramics. It enables large-scale industrial production of complex ceramic components such as cordierite catalyst substrates, diesel particulate filters, ceramic membrane filters and thermal insulators. As such it makes a key contribution to low-emission mobility, air pollution control and energy efficiency.

In the manufacturing process, ceramic powders are first plasticized in a mixing and kneading step using environmentally compatible additives such as cellulose ethers, along with small quantities of organic processing aids. The extrusion compound is then degassed and shaped into the desired geometry using screw or ram extruders. Optimized interaction between rheological properties, process parameters and die design ensures the dimensional stability and shape accuracy of the extrudates. Shaping is followed by cutting to length, drying and further material-specific processing steps. Water-based cold plastic extrusion does not require organic solvents and uses only small amounts of additives: this reduces environmental impact and energy consumption while at the same time enabling robust, cost-effective, and resource-efficient production. As a result, the process makes a vital contribution to the sustainable transformation of industrial value chains.

In the hardmetal industry, blanks for round tools are still predominantly extruded using solvent- or wax-based systems. The NANO-PRO project at Fraunhofer IKTS (funding code: KK.01.2.01.0079) involved the development of water-based extrusion compounds based on WC–10Co and nanostructured tungsten carbide. Tailored drying regimes enable the production of thick-walled tubes with a high degree of dimensional stability. After sintering, the extruded components exhibit densities and magnetic properties comparable to those of conventionally pressed blanks. Water-based extrusion therefore eliminates hazardous substances and avoids the need for complex drying and debinding processes.

The technology can also be applied to other non-oxide ceramics. The EBeA project with TU Bergakademie Freiberg involved the development of heater components made of zirconium carbide (ZrC). ZrC can replace strategically critical materials such as tungsten, tantalum and molybdenum. Pressureless sintering of the water-based, highly plastic, formable extrusion compound enables the cost-effective production of U-shaped heating elements. Another application of the technology is the fine extrusion of silicon carbide (SSiC), enabling the manufacture of precise capillaries with outer diameters of 1.55 ± 0.03 mm and inner diameters of 0.56 ± 0.02 mm after approximately 20 % shrinkage.

These developments demonstrate how innovative materials and process technologies can enhance the sustainability of established industrial manufacturing, reduce energy consumption and boost technological sovereignty.

Services offered
 

• Technology development for the extrusion of ceramic and cemented carbide compounds using sustainable binder raw materials
• Rheological characterization
• Transfer from laboratory scale to pilot production
• Evaluation of process chains at customer sites