- Time:Jul 13, 2023
Hydration of magnesia bricks refers to the process of chemical reaction of magnesia bricks in contact with water to produce hydrates. Magnesia bricks are mainly composed of magnesia (MgO) and other additives. When magnesia bricks encounter water, the following main reasons will cause hydration:
1. Hydration reaction: Magnesium oxide in magnesia bricks undergoes a hydration reaction with water to generate magnesium hydroxide (Mg(OH)2). Hydration reaction is the main process of hydration of magnesia bricks, and it is also the main reason for the volume increase of magnesia bricks.
2. Thermal reaction: Magnesia bricks will release a lot of heat when they react with water. This is due to the fact that the hydration reaction is an exothermic reaction, that is, a process in which heat energy is released. In a high temperature environment, the thermal reaction may lead to rapid evaporation of water and accelerate the hydration reaction.
3. Highly alkaline environment: Magnesium hydroxide produced during the hydration process of magnesia bricks is strongly alkaline. When magnesium hydroxide dissolves in water, it releases hydroxide ions (OH-), making the surrounding environment alkaline. This highly alkaline environment is corrosive to some materials and may cause damage to others.
4. Volume expansion: the hydration reaction causes the volume of magnesia bricks to increase, resulting in volume expansion. Since the hydration product is larger than the original magnesia brick, when moisture enters the interior of the magnesia brick, it will cause expansion and cracking of the material.
5. Moisture penetration: Moisture can enter the interior of the material through the pores and tiny cracks of the magnesia brick. Especially in a high temperature environment, the pore structure of magnesia bricks will become more open, thereby promoting the penetration of water and the hydration reaction.
The hydration process of magnesia bricks will lead to the volume change of the material, the temperature rise, the formation of alkaline environment and other effects, which may cause adverse effects on the structure. In order to alleviate the problems caused by hydration, some measures can be taken, such as considering the expansion of materials in the design, controlling water penetration, selecting additives with strong alkali resistance, etc., to improve the durability and stability of magnesia bricks.
