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Disruption of an Alumina Layer During Sintering of Aluminium in Nitrogen

Pieczonka T.

Archives of Metallurgy and Materials

2017

Vol. 62, iss. 2B

987--992

Aluminium oxide layer on aluminium particles cannot be avoided. However, to make the metal-metal contacts possible, this sintering barrier has to be overcome in some way, necessarily to form sintering necks and their development. It is postulated that the disruption of alumina layer under sintering conditions may originate physically and chemically. Additionally, to sinter successfully non alloyed aluminium powder in nitrogen, the operation of both types mechanism is required. It is to be noted that metallic aluminium surface has to be available to initiate reactions between aluminium and the sintering atmosphere, i.e. mechanical disruption of alumina film precedes the chemical reactions, and only then chemically induced mechanisms may develop. Dilatometry, gravimetric and differential thermal analyses, and microstructure investigations were used to study the sintering response of aluminium at 620°C in nitrogen, which is the only sintering atmosphere producing shrinkage.

Warstwy tlenku glinu na węglikach spiekanych otrzymywane metodą MOCVD

Sawka A., Kwatera A., Juda W., Rakowski W.

Inżynieria Materiałowa

2002

R. XXIII, nr 5

387-389

Warstwy Al2O3 syntezowano metodą MOCVD (Metal-Organic Chemical Vapour Deposition) z użyciem acetyloacetonianu glinu, czystego argonu (99,999% obj.) oraz powietrza. Warstwy te osadzano bezpośrednio na powierzchniach węglików spiekanych bez pośredniej warstwy TiC w zakresie temperatur 800-1000 stopni Celsjusza. Czas ich syntezy wynosił 15-120 min. Niektóre z otrzymanych warstw w 800 stopniach Celsjusza dodatkowo wygrzewano w temperaturze 850-1000 stopni Celsjusza. Warstwy poddano badaniom na mikroskopie skaningowym współpracującym z mikroanalizatorem dyspersji energii promieniowania rentgenowskiego (EDS). Wykonano również analizę rentgenowską, a także przeprowadzono pomiary mikrotwardości oraz badania na przyczepność warstw do podłoża.

Alumina layers were synthesized by the MOCVD (Metal-Organic Chemical Vapour Deposition) method using aluminium acetylacetonate (Al(O2C5H7)3), pure argon (99,999% vol.) and air. Layers were deposited on cemented carbides with no intermediate layer of TiC in the temperature range of 800-1000 degrees centigrade. The time of their synthesis was 15-120 min. Some layers synthesized at 800 degrees centigrade were additionally annealed at 850-1000 degrees centigrade. The obtained layers were examined by scanning electron microscopy with EDS attachement. The phase composition of the layers was also investigated by X-ray analysis. The microhardness of the coats and their adhesion to the substrate were also measured.