The Effect of Titanium Oxide Additions on the Phase Chemistry and Properties of Chromite-Magnesia Refractories

Ceramics

Delphin Mulange¹  AndrieMariana Garbers-Craig²  JohanPR De Villiers² 

[1] Metallurgical Engineering, University of Pretoria, Pretoria 0002, South Africa;;Department of Materials Science &

关键词: chromite-magnesia brick;    refractory;    spinel;    tio₂;   

DOI  :  10.3390/ceramics3010013

来源: DOAJ

【 摘 要 】

The microstructure of a direct-bonded chromite-magnesia refractory brick, typically used in copper and platinum converters, was modified by adding different amounts of nano-size TiO₂ to the raw material mixture. Bricks with 0, 1, 3, 5, and 7 mass% TiO₂ were produced and compared in terms of spinel formation; the role of the tetravalent cation Ti⁴⁺ in the bonding phase; as well as changes in density, porosity, thermal expansion, and internal stress. This was done through a comprehensive XRD and SEM-EDS study. It was found that Ti is accommodated in the secondary spinel that has formed, where Mg in excess of unity in the tetrahedral site combines with an equal amount of Ti in the octahedral sites to maintain charge balance. The 1 mass% TiO₂ brick had the lowest bulk density (but not significantly different from the original chromite-magnesia brick), the smallest difference in unit cell volumes between the primary and secondary spinels, and the lowest stress arising from the smallest difference in linear thermal expansion coefficients of the phases present. The calculated porosities correspond well with experimentally determined apparent porosity values, whereas the linear thermal expansion coefficients calculated at 1392K are similar to the values measured from 293 to 1273 K.

【 授权许可】

Unknown