TherEvoMon

Thermo-mechanic evolutions of monolitics during heating-up – optimization of the sintering behaviour

Submitted to the 21 CORNETcompetition. Realised from 1.01.2017 to 31.12.2018. Positively assessed and settled.

Summary of the Polish part of the project carried out by a team of the Refractory Materials Department of ICiMB led by Dr. Jacek Podwórny

1. Chemical reactions in the corundum castable matrix with the participation of aluminum-calcium cement are diffusive in nature.

2. The coefficient of thermal expansion of spinel decreases with increasing temperature as a result of diffusion of Mg2+ into the corundum grains. The formation of a substechiometric spinel compensates for the thermal expansion of corundum and CA₆.

3. The activation energy of CA, CA₂ and CA₆ in the matrix with the participation of MgO is greater than without its participation. More energy is necessary to transform them; the transformation took place at higher temperatures.

4. Transformations in the sol-gel warp are different than in the cement warp. Initially, MgO enters the solid solution in Al2O3, and above 1380^oC Mg2+ diffuses into amorphous silica, which results in a decrease in the viscosity of the liquid phase and a decrease in thermomechanical properties. Refractory resistance under the load of castable on the sol-gel bond was about 260^oC lower than with cement.

5. It was unexpectedly found that the brittle-plastic transformation of corundum castable with the participation of cement occurs at a relatively low temperature of 1150^oC.

6. From the point of view of castable properties, the most advantageous is the use of bimodal active alumina (0.8 and 3.5μm or 0.8 and 5.5 μm) for the warp.

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