2016-Sustainable Industrial Processing Summit
SIPS 2016 Volume 2: Dubois Intl. Symp. / Complex Metallic Systems
| Editors: | Kongoli F, Kobe S, Calin M, Dong C |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2016 |
| Pages: | 130 pages |
| ISBN: | 978-1-987820-38-6 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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The hydrolysis of aluminium nitride powder exploited for advanced materials engineering
Andra Kocjan1;1JOZEF STEFAN INSTITUTE, Ljubljana, Slovenia;
Type of Paper: Regular
Id Paper: 331
Topic: 36
Abstract:
The unusual tendency of aluminium to form quasicrystalline alloys is not the only anomalous property of this metal atom. It has another, i.e., when covalently bonded to nitrogen (aluminium nitride; AlN), its propensity to decompose in humid environments, i.e., the tendency to undergo hydrolysis, which can lead to a complete degradation of the material, is unique in metal nitrides. Although this form of hydrolysis has been known for a long time – about a century ago it was exploited for the production of ammonia – it is generally considered as a nuisance, because it prevents the aqueous powder-processing of AlN-based ceramics. However, we have shown that this hydrolysis can also be exploited.
The present paper will present our recent, in-depth studies of the solid reaction products of the hydrolysis along with its reaction kinetics, which has opened up numerous possibilities for the exploitation of this naturally driven process in the area of advanced materials engineering. On one hand, we can use it in the hydrolysis-assisted solidification (HAS) of ceramic suspensions for the processing of high-performance, porous ceramics. On the other, we can exploit it for the synthesis of hierarchically self-assembled, mesostructured, hydrous aluminium oxide powders and/or coatings. For example, we showed that the coatings are suitable as templates for self-cleaning, super-hydrophobic surfaces or in dentistry as adhesive coatings for cementing, the recently very popular, yttria-stabilized tetragonal zirconia. On the other hand, the hierarchically self-assembled, mesostructured powder can be used either as a precursor for the processing of porous transient alumina monoliths with hierarchical heterogeneities or for the fabrication of the photocatalytically active γ-Al2O3/TiO2 hetero-structures with a superior quantum efficiency.