Influence of the de-waxing atmosphere on the properties of A1N ceramics processed from aqueous media

摘要

The influence of binder burnout atmosphere (air or N_2) on surface chemistry of thermo-chemically treated A1N powders processed in aqueous media, and on the final properties of A1N 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 A1N 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 A1N samples. Thermal conductivities of about 140 W/mK were obtained for the aqueous processed A1N samples de-waxed in nitrogen atmosphere and sintered for 2h at 1750 deg C in the presence of 4wt.percent YF_3 + 2wt.percent CaF_2 as sintering additives.