1. Resistant to slag In order to increase resistance ability to slag and liquid steel penetration, Cr2O3 or chromium corundum is always added into corundum spinel.Cr2O3 has the same crystal structure with a-Al2O3, the adding of Cr2O3 can effectively improve the slag resistance ability of materials, also can improve the gas channel blocking condition caused by liquid steel penetration.
The aluminum-chrome solid solution and independent chrome bearing glass phase which were formed by Cr2O3 fine powder and Al2O3 under high temperature, can form into liquid phase with certain viscosity, when meet with the slag in steel smelting process. This liquid phase can avoid the slag erosion to porous plugs, and also absorb the Iron oxide and magnesium oxide, forming dense spinel on plug's working surface, thus further improve the slag resistance of the plug.
2. Thermal shock resistant
The main damage to porous plug is thermal shock. As the tapping temperature increasing, there existing big temperature gap onto working surface during work and break. After introducing spinel phase into the structure, the thermal resistance of purging plug is increased significantly. The oxide and non-oxide added into porous plug will form into solid solution phase with aggregate under high temperature, which will increase the high temperature strength, air permeability, resistance to slags of the plug. After high temperature burning for the plug, the performance is increased to meet different steelmaking conditions.