F. Kashaninia, H. Sarpoolaky, A. R. Bagheri, R. Naghizadeh, M. Zamanipour,
Volume 8, Issue 4 (12-2011)
Abstract
Abstract: There have been lots of studies to control the poor hydration resistance of dolomite refractories one of the
most effective solutions has been the addition of magnesia to doloma. Using a co-clinker of magnesia-doloma as a
starting material would provide more homogeneity in the properties of the product and has been published recently.
On the other hand, addition of iron oxide to doloma has been found to increase the hydration resistance. In this paper,
the effect of iron oxide addition on hydration phase analysis and microstructure of two different magnesia- doloma
samples, one with CaO content of 25 wt% and the other one with that of 35 wt% has been investigated. Ten samples
were prepared by pressing followed by firing at 1750 ºC for 3hrs. Results showed that the hydration resistance of the
samples improved by decreasing the CaO content, because CaO is much more prone to hydration comparing to MgO.
Besides, iron oxide addition lead to the formation of iron-containing phases which increased the hydration resistance
of the samples both by capsulating the CaO and MgO grains and by promoting the liquid phase sintering.
S. Ghasemi-Kahrizsangi, H. Gheisari-Dehsheikh, M. Boroujerdnia,
Volume 13, Issue 4 (12-2016)
Abstract
In this study the effect of nano meter size ZrO2 particles on the microstructure, densification and hydration resistance of magnesite –dolomite refractories was investigated. 0, 2, 4, 6 and 8 wt. % ZrO2 particles that were added to magnesite –dolomite refractories containing 35 wt. % CaO. The Hydration resistance was measured by change in the weight of specimens after 72 h at 25℃ and 95% relative humidity. The results showed with addition of nano meter size ZrO2 particles, the lattice constant of CaO increased, and the bulk density and hydration resistance of the specimens increased while apparent porosity decreased. With the addition of small amount ZrO2 the formation of CaZrO3 phase facilitated the sintering and the densification process. The mechanism of the nano meter size ZrO2 particles promoting densification and hydration resistance is decreasing the amount of free CaO in the specimens.
