Study On Magnesia-calcium Bricks Surface Modification

The MgO-CaO refractories have a series of excellent performance. But, thanks to the problem of its hydration, which has a negative impact on the production, storage and transport. In order to make the MgO-CaO refractories develop and apply well, this problem of hydration must be solved, so we will use CO₂ to deal with the surface of the MgO-CaO refractories and obtain optimal technological parameters, and analysis the material of the surface and reaction layer thickness by scanning electron microscopy. Applying boiling experiment tests waterproof effect of samples, and analysis reaction mechanism using kinetic theory. we get the following conclusions:(1) we obtained optimal technological parameters: reaction temperature is 700℃, reaction time is 180 minutes, suitable water vapour temperature is 40℃, and the appropriate CO₂ flow is in the 4L·min-1. At this time, the hydration resistance of MgO-CaO refractories is best.(2) The material of the surface of MgO-CaO refractories dealing with CO₂ is CaCO₃ by scanning electron microscopy, and with the reaction time longer, reaction layer thickness of the sample surface generally shows an increasing trend. When reaction time is 180 min, the reaction layer thickness of the sample surface is 110.5μm. At this time, the hydration resistance of MgO-CaO refractories is best. (3) The waterproof reaction mechanism of MgO-CaO refractories: First, CaO carbonation reaction control speed, and then by water vapor and CO₂ gas through the product layer diffusion speed control.