A non-aqueous processing route for phosphate-protection of AlN powder against hydrolysis
authors Ganesh, I; Thiyagarajan, N; Sundararajan, G; Olhero, SM; Ferreira, JMF
nationality International
journal JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
author keywords AlN powder; phosphate coating; AL(H2PO4)(3); H3PO4; Y2O3
keywords ALUMINUM NITRIDE POWDER; ASSISTED SOLIDIFICATION; SIALON CERAMICS; BETA-SIALON; SURFACE; BEHAVIOR; Y2O3
abstract A commercial AlN powder was treated in an ethanol with H3PO4 and Al(H2PO4)(3) to passivate its surface against hydrolysis. The treated powder was quite stable in water for >72 h as confirmed by pH measurement, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy dispersive analysis with X-rays. The coating layer was stable up to 1200 degrees C as confirmed by thermogravimetry and differential thermal analysis. The aqueous processing ability of treated AlN powder was tested in aqueous gelcasting of beta-SiAlON reaction precursor mixtures for fabricating dense ceramic bodies and 500 mL thin wall crucibles. The sintered gelcast beta-SiAlON exhibited the following properties: bulk density of 3.07 g/cm(3), apparent porosity of 0.13%, water absorption capacity of 0.04%, linear shrinkage of <16%, beta-SiAlON content of >90%, hardness of 14 GPa and fracture toughness of 3.95 MPa m(1/2). (C) 2008 Elsevier Ltd. All rights reserved.
publisher ELSEVIER SCI LTD
issn 0955-2219
year published 2008
volume 28
issue 11
beginning page 2281
ending page 2288
digital object identifier (doi) 10.1016/j.jeurceramsoc.2008.02.025
web of science category Materials Science, Ceramics
subject category Materials Science
unique article identifier WOS:000257349800021
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journal impact factor 4.495
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