Magnesium-calcium Carbon Brick Performance
Magnesium-calcium carbon brick performance
In order to adapt to the development of refining technology outside the furnace, MgO-CaO-C bricks have gradually developed into a series of products. Since the type of MgO-CaO-C brick is more complicated than that of calcined magnesia-calcium brick, the performance of the MgO-CaO-C brick used is listed below for the typical outdoor refining furnace LF, LF-VD, GOR, etc.
In addition to the characteristics of magnesia-calcium bricks, magnesia-calcium carbon bricks have better vacuum stability and thermal shock resistance than magnesia-carbon bricks.
(1) Vacuum stability
The decomposition pressure of CaO under high temperature vacuum is much smaller than that of MgO, and the equilibrium pressure of CaO and C under high temperature vacuum is less than that of MgO and C. The former is two orders of magnitude lower than the latter. Therefore, MgO-CaO-C bricks are more stable than MgO-C bricks at high temperatures, and are more suitable for smelting conditions under high temperature vacuum.
(2) Thermal shock resistance
The relationship between thermal stress and temperature of MgO-C brick and MgO-CaO-C brick is shown in Fig. 6. It can be seen that when the temperature is higher than 700 °C, the thermal stress of MgO-C brick is larger than that of MgO-CaO-C brick. Therefore, the ability of MgO-CaO-C brick to buffer thermal stress is better than that of MgO-C brick.
The performance of MgO-CaO-C bricks depends on the content of CaO and its introduction mode and content of C. The higher the CaO content, the stronger the anti-flaking performance, the better the effect of purifying the molten steel; the higher the C content, the stronger the anti-slag erosion and anti-flaking performance. When smelting ultra-low carbon steel, it is required that the content of brick C in the molten pool is low, otherwise it will pollute the molten steel, but the C content is low and the peeling resistance is poor. In order to compensate for this defect, the content of CaO must be increased.