Priprava kompozitov Ni-YSZ z uporabo gel-precipitacijske metode: vpliv reakcijskih pogojev na morfološke lastnosti svežih gel-precipitatov ter kemijsko sestavo končnih kompozitov Ni-YSZ
Preparation of Ni-YSZ composites by the gel-precipitation method: morphological characteristics of intermediates and chemical composition of Ni-YSZ composites

slovenian

2001

volume 35, issue 5

zirconium 

Inštitut za kovinske materiale in tehnologije
(Obvezni izvod spletne publikacije)

Ni-YSZ composite materials were prepared by the gel-precipitation method according to the preliminary results on separate zirconia, yttria and nickel hydroxide reaction systems. The average size of the agglomerate in the suspension diminishes with the increasing final pH value as a consequence of the agglomerate surface stabilization. In contrast, an increase in the initial Ni$^2+$:Zr$^4+$ molar ratio favors smaller agglomerate sizes. Similar behavior was observed in methanol and aqueous media. Methanol has a lower dielectric constant and dipole moment than water, therefore the mutual influence of charged particles in the suspension is greater in the methanol. The highest nickel content in the final composite was obtained when the gel-precipitation was carried out up to a final pH value of 8. Below that value the precipitation of nickel hydroxide is in complete, while above a pH value of 8 the already-precipitated nickel hydroxide dissolves again in the excess of ammonia forming a violet soluble complex.

16.09.2009