Extrusion

Extrusion is a well-known and established ceramic shaping method. It is especially used for the production of tubular or other long parts with a wide variety of cross-sections. Ceramic honeycombs for diesel particulate filters and  catalyst carriers or multi-channel tubes for ceramic membranes , for example, are made by extrusion of cold-plastic ceramic masses based on oxide and non-oxide powders. The rheological properties of ceramic masses strongly depend on the preparation (mixing, kneading) and composition of the mass. Flowability and process parameters must be adjusted exactly to the particular extruded profile to obtain defect-free parts also at high capacities.

 

Products and services offered

 

• Development of complete technology for extrusion of  ceramic masses preferably
  
• Development of ceramic masses based on aqueous and non-aqueous binder systems for cold- and warm-plastic extrusion 
  
• Detailed heological characterization of extrusion masses
  
• Extrusion of tubes, solid profiles, multi-channel elements and honeycombs
  
• Studies on abrasive and chemical wear of extruder screws and dies
  
• Development of concepts and realization in pilot scale for the process chain: mass preparation - extrusion - cutting to length - drying - separating - post treatment for specific profile geometries

 

Technical Equipment

 

• Measuring kneaders 50 ml and 350 ml, temperature-controlled from 0 °C to 95 °C
  
• Measuring kneaders 350 ml, temperature-controlled up to 200 °C
  
• Rotational viscosimeter (for visco-elastic measurements, oszillation)
• Double-Z-kneaders with 2 l, 5 l, 10 l 20 l, 35 l chamber volume,  temperature-controlled from 10 °C to 80 °C
  
• Vacuum screw extruders with 19 mm, 50 mm, 80 mm and 100 mm cylinder diameter, temperature-controlled from 10 °C to 80 °C
  
• Piston extruder with 80 mm cyclinder diameter

 

Examples and references

 

• Development of cold-plastic extrusion masses based on silicon nitride and silicon carbide, oxide and silicate-ceramic
  
• Development of warm-plastic masses based on non-aqueous binder systems
  Technology development for extrusion of honeycombs (from 35 to 325 cpsi)  from silicon carbide, sintermetal, oxide- and silicate ceramics
  
• Technology development for fabrication of support tubes for ceramic membranes with various tube sizes and numbers of channels from corundum, titanium oxide and mullite 
  
• Extrusion of silicon carbide honeycombs (100-300 cpsi)
  
• 7-channel tubes from silicon carbide
  
• Solid profiles from silicon nitride
  
• Tubes from aluminium nitride
  
• Development of technology and equipment for  plugging (alternating sealing of channels) of  extruded honeycombs with 200 and 300 cpsi