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Defect Formation during Supercritical Extraction of Binder from Green Ceramic Components
Author(s) -
Shende Rajesh V.,
Redfearn Trent R.,
Lombardo Stephen J.
Publication year - 2004
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.1151-2916.2004.tb07719.x
Subject(s) - materials science , supercritical fluid , supercritical carbon dioxide , green body , ceramic , composite material , supercritical fluid extraction , slurry , barium titanate , extraction (chemistry) , chemical engineering , chromatography , chemistry , organic chemistry , engineering
Supercritical extraction in carbon dioxide has been used to remove binder consisting of 60 wt% poly(vinyl butyral) and 40 wt% dioctyl phthalate from multilayer ceramic capacitors containing barium titanate as the dielectric. The amount of binder removed increases as both the temperature and pressure of the supercritical fluid increases; a maximum of ∼50% of the binder can be removed using carbon dioxide in 3 h at 75°C and 40 MPa. During depressurization from the supercritical state, defects such as fracture and delamination were occasionally observed in the green body. The occurrence of defects is related to the rate of depressurization, the permeability of the body, and the green strength of the body. The origin of the defects is discussed, and ways to mitigate them are presented.