Influence of the de-waxing atmosphere on the properties of AlN ceramics processed from aqueous media

abstract

The influence of binder burnout atmosphere (air or N-2) on surface chemistry of thermo-chemically treated AlN powders processed in aqueous media, and on the final properties of AlN ceramics was studied. The surface chemistry after de-waxing was accessed by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). X-ray diffraction (XRD), SEM, high-resolution transmission electron microscopy (HR-TEM), were used to identify the phase assemblage and for microstructural analysis. The effects of the residual carbon and oxygen at the surface on the thermal conductivity and sintered density of AlN samples were investigated. The surface C/O ratios were observed to correlate with the sintering behaviour, the composition and distribution of secondary phases, and grain-boundary composition, as well as thermal conductivity of AlN samples. Thermal conductivities of about 140W/rnK were obtained for the aqueous processed AlN samples de-waxed in nitrogen atmosphere and sintered for 2 h at 1750 degrees C in the presence of 4 wt.% YF3 + 2 wt.% CaF2 as sintering additives. (c) 2005 Elsevier Ltd. All rights reserved.

keywords

ALUMINUM NITRIDE; THERMAL-CONDUCTIVITY; ALN(Y2O3) CERAMICS; OXIDATION; BEHAVIOR; CARBON; PHASE; YF3

subject category

Materials Science

authors

Olhero, SM; Miranzo, P; Ferreira, JMF

our authors

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