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Effect of Polystyrene Addition on Freeze Casting of Ceramic/Camphene Slurry for Ultra‐High Porosity Ceramics with Aligned Pore Channels
Author(s) -
Koh YoungHag,
Lee EunJung,
Yoon ByungHo,
Song JuHa,
Kim HyounEe,
Kim HaeWon
Publication year - 2006
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.1551-2916.2006.01311.x
Subject(s) - materials science , porosity , slurry , ceramic , polystyrene , camphene , composite material , polymer , chemical engineering , mineralogy , chemistry , chromatography , essential oil , engineering
We investigated the effect of polystyrene (PS) addition on the freezing behavior of a very dilute alumina/camphene slurry with an initial solid loading of 5 vol% for the fabrication of ultra‐high porosity ceramics with aligned pore channels. To accomplish this, slurries with various PS contents (10, 20, and 30 vol% in relation to the alumina powders) were prepared by ball milling at 60°C and then cast into molds at a constant temperature of 20°C. After removing the frozen camphene, the samples were heat treated to burn out the organic phases and sinter the alumina walls. The addition of the PS binder remarkably enhanced the green strength of the sample, making it possible to handle it without difficulty. All of the sintered samples showed ultra‐high porosities of >88% without the collapse of the porous structure, wherein the pore channels were completely interconnected. Three distinctive zones having different pore structures were observed, viz. the outer shell with elongated pores, the inner zone with long aligned pore channels, and the center with equiaxed pores. The content of the PS polymer significantly affected the pore morphologies in the three distinctive zones. In addition, it was found that the addition of the PS polymer was highly beneficial to the alignment of the pore channels.