Landolt-Börnstein - Group VIII Advanced Materials and Technologies

Forming of binder treated powders

Abstract

This chapter discusses forming of binder treated powders. Sometimes it is necessary to blend the metallic ingredients with organic binders in larger volumetric fractions in order to make use of forming processes which have traditionally not been used in powder metallurgy. Metal injection molding requires fine powders with typical particle sizes below about 25 µm. Binder assisted extrusion differs from metal injection molding in that a highly viscous feedstock of powder and binder is continuously forced through an orifice forming a profiled bar of constant cross-section. The type of binder can be very similar to those used for injection molding and can contain solvents, surfactants, deflocculants, coagulants, lubricants, plasticizers and preservatives. Ram or piston extruders are used more for very high pressures and most complex cross-sections, and screw extruders more for large production volumes. In a further step in the direction to added shape capability, metal powders can be converted into castable liquids, a logical step from the pliable pasty condition with injection molding and extrusion. Slurry is prepared for tape and slip casting and is pressureless cast into molds where the carrier fluid is partially extracted, leaving behind a moist structural part with sufficient strength to be handled for further drying, binder burn-out and sintering. Similar to pasty powder processing, where structural parts are made by injection molding or low pressure die casting and continuous cross-sections are extruded, wet powder processing is also capable of manufacturing continuous products in the form of cast ribbons, sheets or tapes.

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Title
Forming of binder treated powders
Book Title
Powder Metallurgy Data
In
3 Forming
Book DOI
10.1007/b88278
Chapter DOI
10.1007/10689123_9
Part of
Landolt-Börnstein - Group VIII Advanced Materials and Technologies
Volume
2A1
Editors
  • P. Beiss Send Email (11)
  • R. Ruthardt Send Email (12)
  • H. Warlimont Send Email (13)
  • Editor Affiliation
  • 11 Professur und Institut für Werkstoffkunde, Rheinisch Westfälische Technische Hochschule (RWTH) Aachen, 52062, Aachen, Germany
  • 12 Aussenstelle Hanau, Deutsche Gesellschaft für Materialkunde e.V., Adalbert-Stifter-Str. 19, 63452, Hanau, Germany
  • 13 Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden, 01069, Dresden, Germany
  • Authors
  • P. Beiss Send Email (101)
  • Author Affiliation
  • 101 Professur und Institut für Werkstoffkunde, Rheinisch Westfälische Technische Hochschule (RWTH) Aachen, 52062, Aachen, Germany
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