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AlPO 4 Coating on Alumina/Mullite Fibers as a Weak Interface in Fiber‐Reinforced Oxide Composites ‡
Author(s) -
Bao Yahua,
Nicholson Patrick S.
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.1551-2916.2005.00751.x
Subject(s) - materials science , mullite , composite material , fiber , isoelectric point , coating , composite number , precipitation , particle (ecology) , oxide , amorphous solid , aluminium oxides , ceramic , metallurgy , chemistry , crystallography , catalysis , biochemistry , physics , oceanography , meteorology , enzyme , geology
A sol of amorphous aluminum orthophosphate (AlPO 4 ) nano particles (30–100 nm) was synthesized by co‐precipitation of Al 3+ and HPO 4 2− with urea at 95°C. A narrow particle size distribution was achieved when [Al 3+ ]≤0.1 M . The isoelectric point of the synthesized powder is pH∼4.7. Alumina/mullite fibers (Nextel™ 720) were pretreated with cationic polyelectrolyte to render them of opposite charge to the AlPO 4 particles, and the latter were then coated by electrostatic‐attraction dipcoating. A uniform, continuous coating formed after several cycles, and its effectiveness as the weak layer between the fibers and the Al 2 O 3 matrix of a hot‐pressed composite was reported. Significant fiber pullout was noted.