Effect of the Consolidation Technique on the Sintering Ability and Thermal Properties of AlN Processed from Aqueous Suspensions


Article Preview

In this work, two different consolidation techniques were used to obtain AlN samples: slip casting and dry pressing of granules obtained from aqueous suspensions by freeze granulation. The green samples were sintered at a temperature (1750°C) lower than those usually used (>1800°C), using CaF2 and YF3 as sintering aids. The microstructural features were analysed by scanning electron microscopy (SEM) and the crystalline phases formed were identified by X-ray (XRD). Full dense AlN-based ceramics were obtained from both consolidation techniques; however the thermal conductivity values were quite different. The presence of carbon in the samples derived from the freeze granulated powder containing organic processing additives de-waxed in an inert atmosphere revealed to be helpful in the cleaning of oxygen present at the grain boundaries and consequently, for enhancing the thermal conductivity.



Materials Science Forum (Volumes 514-516)

Edited by:

Paula Maria Vilarinho




S. M.H. Olhero and J. M. F. Ferreira, "Effect of the Consolidation Technique on the Sintering Ability and Thermal Properties of AlN Processed from Aqueous Suspensions", Materials Science Forum, Vols. 514-516, pp. 1531-1535, 2006

Online since:

May 2006




[1] Jackson, T., Barrett, Virkar, A.V., More, K.L., Dinwiddie, R.B. & Cutler, R.A., High-thermalconductivity aluminium nitride ceramics: the effect of thermodynamic, kinetic and microstructural factors. J. Am. Ceram. Soc., 1997, 80.

[6] 1421-1435.

[2] Collange, A., Grosseau, P., Guilhot, B., Disson, J.P. & Joubert, P., Thermal conductivity of compacted AlN samples. J. Europ. Ceram. Soc., 1997, 17, 1897-(1900).

DOI: 10.1016/s0955-2219(97)00084-8

[3] M. Oliveira, S. Olhero, J. Rocha, J.M.F. Ferreira, Controlling hydrolysis and dispersing AlN Powders in aqueous media, Journal of Colloid and Interface Science, 261, 456-463, (2003).

DOI: 10.1016/s0021-9797(03)00065-1

[4] Olhero S.M., Novak S., Krnel K., Kosmac T., Ferreira J.M.F., Thermo-chemical Surface Treatment of AlN Powder Towards Aqueous Processing of AlN Ceramics, Journal of Materials Research, 19.

DOI: 10.1557/jmr.2004.19.3.746

[3] 746-751, (2004).

[5] S.M. Olhero, M.I.L.L. Oliveira and J.M.F. Ferreira, Successful strategies for aqueous colloidal shape-forming of nitride-based ceramics, Transworld Research Network, Kerala India, Recent Devel. Coll. Inter. Res. 2 (2004) pg. 65-89.

[6] Nyberg B., Carlstrom E., Carlsson R., Euro-ceramics II, Vol. 1 Basic Science and Processing of Ceramics, ed. By G. Ziegler and H. Hausner, Deutsche Keramische Gesellschaft, (1993) pp.447-451.

[7] Virkar A. V., Barret Jackson T., Cutler R. A., Thermodynamic and kinetic effects of oxygen removal on the thermal conductivity of aluminium nitride, J. Am. Ceram. Soc., 72.

[11] 2031-2042, (1989).

[8] Olhero S.M. and J.M.F. Ferreira, Effect of the de-waxing atmosphere on the final properties of the AlN samples prepared from aqueous media, submitted to J. Europ. Ceram. Soc. C-DP 15 µµµµm C-SC 15 µ15 µ15 µ15 µm.

Fetching data from Crossref.
This may take some time to load.