Influence of Microstructure on Refractories Corrosion
EPSRC research grant GR/L31647
Summary of the final report
Principal Investigator: Professor W E Lee
This project linked refractories producers, a user and the University in research aimed to further our understanding of the effect of microstructure on the nature of chemical (slag) attack of refractories. A significant aspect of the work was to define in situ refractories as being those which respond to the stimulus of the contents by reacting with them beneficially. This concept changed completely our thinking about refractories. Previously, microstructures were designed to limit the changes which occurred in service i.e. to make them as close to equilibrium as possible so that the tendancy towards equilibrium in use at high temperature is limited. Now, however, the microstructures can be designed to react beneficially (or benignly) with the furnace contents to produce the refractory in service. This fits in with the trend over the passed 30 years towards monolithic or unshaped refractories which are installed e.g. by casting or gunning in place. Then they are dried and fired in situ to develop the desired microstructure and properties.
Corrosion mechanisms in a range of model refractories were fully determined during the course of this project including for white fused alumina (WFA), tabular alumina (TA), brown fused alumina (BFA), sintered MgO (SM), fused MgO (FM), doloma, zirconia, sintered magnesium aluminate spinels (S) of varying stoichiometry and fused zirconia-mullite. MgO-C bricks with a range of metal additives and Al2O3-SiO2-SiC-C bricks were also examined. Static and dynamic slag corrosion tests were used along with post mortem analysis of corroded microstructures supported by thermodynamic calculations of expected phase equilibria.
Results from model and test conditions were compared those seen in commercial refractories after use. These were similar in oxide systems but the presence of C complicated the situation in real refractories and makes model and test results less reliable.
Contact:
Prof W E Lee (now Imperial College, London),
Department of Engineering Materials,
University of Sheffield,
Mappin Street, Sheffield S1 3JD
Telephone: 0114 222 5502
Fax: 0114 222 5943