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Aetiology of Defects in Large Ceramic Moldings
Author(s) -
Krug Steffen,
Evans Julian R. G.,
Maat Johan H. H.
Publication year - 1999
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1999.tb02046.x
Subject(s) - materials science , sintering , molding (decorative) , polyoxymethylene , ceramic , composite material , mold , particle (ecology) , polymer , oceanography , geology
This study is an attempt to identify the causes of defects that appear in large ceramic injection molded bodies after sintering. It asks the question: are such defects established at the injection molding stage or are they caused by the debinding process or by sintering? Moldings with ascending thickness were prepared using a mold cavity with replaceable tool faceplates. Control over pressure during solidification was compared by using conventional molding and a novel molding technique that uses an insulated sprue. The organic vehicle is polyoxymethylene, which can be displaced by catalytic degradation in the solid state. This is a shrinking unreacted core process with a clearly defined reaction boundary in which there is no provision for particle movement in the liquid state. This study tracks the development of defects at each stage and concludes that the defects apparent after sintering have their origin in injection molding, even though they do not mature until a later stage.