Effect Of ZrOCl₂ Solution Soaking On The Properties Of Magnesia Refractories

The magnesia refractories have been widely used in the metallurgical industry, because of their high refractoriness and excellent slag resistance. However, the slag penetration resistance and the thermal shock resistance of the refractories are poor, which restrict their service life.In this paper, ZrO2 was introduced by means of ZrOCl2 solution soaking into the magnesia refractory. The effects of ZrOCl2 solution soaking on the slag resistance, oxidation resistance and thermal shock resistance of the magnesia refractories were studied, and the mechanism was discussed. The obtained results are as follows:(1) Before the temperature reaches 320℃, ZrOCl2·8H2O is decomposed to ZrO2.(2) Because of the introduced ZrO2, the quality of the magnesia refractory increased with the raised concentration of ZrOCl2 solution while the apparent porosity of the magnesia refractory decreased. The introduced ZrO2 was in the pore of the magnesia refractory.(3) As for sample without treatment, CaO and SiO2 in the slag reacted with the magnesia refractory to form CaMgSiO4, while the products of the magnesia refractory soaked in ZrOCl2 solution after corrosion test were CaZr4O9 and ZrO2, besides CaMgSiO4. Far away from the interface between the slag and the refractory, there is an enrichment zone of Zr element, which prevented the magnesia refractory from further corrosion.(4) In the corrosion test, ZrO2 reacted with CaO to form cubic solid solution. The phase transformation occurred during cooling proceeded as following:Cub ss→Mon ss+CaZr4O9 (Cub ss menas cubic solid solution, Mon ss means monocline solid solution).(5) The oxidation resistance and the thermal shock resistance of the magnesia refractories improved after introducing ZrO2.