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Bag M.,National Institute of Technology Rourkela | Adak S.,TRL Krosaki Refractories Ltd. | Sarkar R.,National Institute of Technology Rourkela
Ceramics International | Year: 2012

Development of low carbon containing MgO-C refractories has been studied containing a fixed 0.9 wt% of nano carbon and 1-9 wt% of flake graphite. Refractory compositions were prepared and processed as per the conventional manufacturing techniques of MgO-C refractory. Properties of the different compositions were evaluated and also compared against the conventional MgO-C refractory containing 10 wt% graphite prepared under exactly similar conditions. Addition of 3 wt% of flake graphite in combination with 0.9 wt% of nano carbon black was found to be optimum and resulted in better/comparable properties to that of conventional MgO-C refractory. © 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Source


Bag M.,National Institute of Technology Rourkela | Adak S.,TRL Krosaki Refractories Ltd. | Sarkar R.,National Institute of Technology Rourkela
Ceramics International | Year: 2012

Development of nano carbon containing magnesia carbon refractories has been studied to reduce the total carbon content, thereby reducing the heat loss from the metallurgical process and producing more eco-friendly refractories. The carbon contamination from refractory to liquid metal will be minimized using low amount of nano carbon. Different percentages of nano carbon are used in combination with graphite as carbon source and the total carbon is maintained below the half of the total carbon of the conventional MgO-C refractories. The compositions were processed as per the conventional manufacturing techniques and the properties were evaluated and compared against the conventional refractory prepared under exactly similar conditions. Also elemental mapping of carbon was done to study the distribution of the nano carbon in the matrix. © 2011 Elsevier Ltd and Techna Group S.r.l. Source


Mukhopadhyay S.,TRL Krosaki Refractories Ltd. | Chattopadhyay A.K.,TRL Krosaki Refractories Ltd. | Das G.C.,Jadavpur University | Maitra S.,India.gov.in
InterCeram: International Ceramic Review | Year: 2012

The effect of the Al 2O 3/MgO ratio on the expansion behavior (permanent linear change, PLC) of a resin-bonded alumina-magnesia- carbon (AMC) based spinel refractory has been studied as a function of sintering time and Al 2O 3/MgO ratios. Spinelization in the system at the interface of Al 2O 3 and MgO grains has also been evaluated quantitatively from SEM. In addition, kinetics for spinelization has also been studied in the AMC system. The mechanism of the spinelization has been found to be diffusion controlled. The activation energy for spinelization was computed and the value is around ∼135 KJ/mole, which is fairly high and indicates the kinetics of spinelization to be small. Source


Mukhopadhyay S.,TRL Krosaki Refractories Ltd. | Chattopadhyay A.K.,TRL Krosaki Refractories Ltd. | Das G.C.,Jadavpur University | Maitra S.,India.gov.in
InterCeram: International Ceramic Review | Year: 2012

Carbon, in the form of graphite, is one of the major constituents of the Al2O3-MgO-C refractory (AMC) used for steel ladles. The thermal expansion property of the AMC refractory is the most important property, which depends on the amount of MgAl2O4 in-situ spinel, formed due to the reaction between Al2O3 and MgO on heating. The spinelization depends on the quantity of MgO in the composition, the grain size of MgO, the firing temperature and the soaking time. Laboratory studies report that the carbon percentage also affects the expansion characteristics, but no quantitative study has been reported. As such, carbon does not play any chemical role in spinelization, but it covers a part of the MgO or Al2O 3 grain surface area (TSAA), reducing the physical contact between grains. So, when the graphite surface area (TSAG) increases, the chance of covering such an area increases, as a result the probability of spinel formation decreases, thereby resulting in reduction of thermal expansion. Spinelization in the system at the interface of Al2O3 and MgO grains has been also studied from XRD, image analysis and SEM results. When the activation energy for spinelization was determined, it was established that it has a strong relationship with TSAG/TSAA factor. Source


Mukhopadhyay S.,TRL Krosaki Refractories Ltd. | Chattopadhyay A.K.,TRL Krosaki Refractories Ltd. | Das G.C.,Jadavpur University
International Journal of Applied Ceramic Technology | Year: 2014

The effect of MgO grain size on the permanent linear change behavior of resin bonded alumina-magnesia-carbon refractory has been studied in relation to the formation of spinel phase in these refractories as a function of firing time and temperature. From scanning electron microscopic studies, spinelization at the interface of Al2O3 and MgO grains has also been studied to determine the reaction kinetics for gaining insight into the process. © 2013 The American Ceramic Society. Source

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