www.ireng.org


Technical Paper


Figure 11: Backscatter electron micrographs of the protective slag coating 4: Conclusion and Outlook


Laboratory corrosion trials revealed that slag penetration into MgO-C bricks is reduced when the bricks are doped with a small amount of CMA- additive. Unlike in the CMA-free brick, the carbon bond between the MgO grains remains strong and protected by a slag coating. In steel ladle trials a protective slag coating on the hot surface and a joint sealing effect was observed. Both effects seem to contribute to the improved service life when the CMA-additive is employed in the carbon bonded bricks. It will be further investigated if thermomechanical effects and/or thermochemical mechanisms are at the source of the joints protection-effect. Since the in-situ formed protective layer improves the resistance against carbon oxidation it allows to reduce the amount of expensive anti-oxidants like Al- and Si-metal. Further industrial trials with the CMA-additive are running to evaluate its efficiency as well in other carbon-containing and carbon-free refractory bricks and monolithics.


REFERENCES [1]


Mater Rev 1999, 44, 77-104.


[3] Musante L, Munoz V, Labadie MH, Tomba Martinez AG. High temperature mechanical behavior of Al2


O3 37, 1473-83.


[4] Nourbakhsh AA, Salarian S, Hejazi SM, Shojaiei A, Golestani-Fard F. Increasing durability of ladle lining refractories utilizing Al2


O3 Osaka, Japan.


[5] Gehre P, Aneziris CG, Berek H, Parr C, Reinmöller M. Corrosion of magnesium spinel-rich refractories by sulphur-containing slag. J Eur Ceram Soc 2015, 35, 1613-20.


addition on the microstructure and properties of MgO-C refractory ceramic composite. Mater Chem Phys, 2017, 189, 230-6.


[6] Ghasemi-Kahrizsangi S, Dehsheikh HG, Boroujerdnia M. Effect of micro and nano-Al2


O3


[7] Wöhrmeyer C, Parr C, Fryda H, Auvrey J-M, Touzo B, Guichard S. New spinel containing calcium aluminate cement for corrosion resistant castables. Unitecr, 2011, Kyoto, Japan.


[8] Aneziris CG, Gehre P. Effects of magnesium aluminate spinel raw materials on the material properties of MgO-C refractories. 59th


Int. Colloquium on Refractories, 2016,


Aachen, Germany. [9] Dudczig S, Aneziris CG, Emmel M, Schmidt G, Hubalkova J, Berek


Figueiredo Jr A, Bellandi N, Vanola A, Zamboni I. Technological evolution of magnesia-carbon bricks for steel ladles in Argentina. Iron Steel Technology 2004, 1, 42-7.


[2] Lee WE, Zhang S. Melt corrosion of oxide and oxide-carbon refractories. Int H.


Characterization of carbon-bonded alumina filters with active or reactive coatings in a steel casting simulator. Ceram Int, 2014, 40, 16727-42.


[10] Pagliosa C, Souza PV, Hama N, Wöhrmeyer C, Zetterström C, Evangelista P. Improvement of MAC bricks for steel ladle with CaO-MgO-Al2O3 aggregate: A new perspective for cement application. Unitecr, 2017, Santiago, Chile.


-MgO-C bricks. Unitecr, 2003, -MgO-C refractories for steelmaking use. Ceram Int 2001,


Figure 12: MgO-C bricks with 2.5% Antioxidants after 47 heats (LF47) (left) and MgO-C bricks with 5% CMA and 1.5% antioxidants after 55 heats (LF51) in metal zone of a 70 t steel ladle


November 2018 Issue ENGINEER THE REFRACTORIES 21


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32