Browse Prior Art Database

Injection Molded Polymer Objects with Expendable Polymer Binder

IP.com Disclosure Number: IPCOM000109246D
Original Publication Date: 1992-Aug-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 1 page(s) / 52K

Publishing Venue

IBM

Related People

Cooper, EI: AUTHOR [+4]

Abstract

Fugitive-polymer ceramic bodies often lose their initial shape during the early organic binder removal stage of firing, due in part to copious gas generation by evaporation and burning. A first stage of partial, non-evaporative binder removal is helpful in this regard because it creates open porosity through which subsequent binder removal can proceed with minimal disturbance. Compositions are based on a two-phase polypropylene/wax binder and a cordierite-type glass ceramic powder blended with a rotating V-blender, then melt compounded in a Rheomix 3000 intensive mixer at 160oC. The resulting mass was ground mechanically to pass a 0.5 mm screen before being compressed or extruded and then heat-treated to test for net shape conservation throughout binder-removal and sintering.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 76% of the total text.

Injection Molded Polymer Objects with Expendable Polymer Binder

       Fugitive-polymer ceramic bodies often lose their initial
shape during the early organic binder removal stage of firing, due in
part to copious gas generation by evaporation and burning.  A first
stage of partial, non-evaporative binder removal is helpful in this
regard because it creates open porosity through which subsequent
binder removal can proceed with minimal disturbance.  Compositions
are based on a two-phase polypropylene/wax binder and a
cordierite-type glass ceramic powder blended with a rotating
V-blender, then melt compounded in a Rheomix 3000 intensive mixer at
160oC.  The resulting mass was ground mechanically to pass a 0.5 mm
screen before being compressed or extruded and then heat-treated to
test for net shape conservation throughout binder-removal and
sintering.  Two typical compositions both containing 60 vol% ceramic
solids: a polymer-rich one (81.9% GC, 12.7% PP, 2.1% Carnauba wax,
1.4% paraffin wax, 1.9% stearic acid) and a wax-rich one (81.2% GC,
6.7% PP, 10.2% paraffin wax, 1.8% stearic acid) behave significantly
differently.  Only the second showed significant weight loss by the
desired wicking mechanism (capillary flow into a porous substrate)
and evaporation at 180-190oC.  An extruded wax-rich sample,
quasi-cylindrical in shape (2.8 mm average diameter), when
heat-treated (190o/13h/air) to "wick" out about 1/3 of the binder,
then treated in a regular "fast-firing sche...