What is refractory bricks?

Refractory bricks are refractory products with a certain shape and size.

According to the preparation process, it can be divided into fired bricks, non-fired bricks, fused bricks (fused cast bricks), refractory heat insulation bricks; according to shape and size, it can be divided into standard bricks, ordinary bricks, special-shaped bricks, etc. It can be used as high-temperature building materials and structural materials for building kilns and various thermal equipment, and can withstand various physical and chemical changes and mechanical effects at high temperatures. Commonly used refractory bricks are: refractory clay bricks, high alumina bricks, silica bricks, magnesia bricks, etc.

The characteristics of refractory bricks

1. Chemical composition: the main components determine the quality and characteristics of the refractory

2. Bulk density: the weight per unit volume and the high density indicate that the density is good, the strength may be high, but the thermal conductivity may be large

Commonly used refractory bricks are:

1. High alumina brick: Al2O3 content is more than 75, the refractoriness is higher than that of clay bricks, and the acid and alkali corrosion resistance is good, suitable for cement kiln firing zone, etc.

2. Dolomite brick: The kiln skin has good performance and corrosion resistance, but some bricks contain F-CaO, which is easy to hydrate, difficult to transport and store, and is used less in production.

3. Magnesia-chrome bricks: the kiln skin is good, and it is mostly used in the firing zone. The disadvantage is that the thermal shock resistance is poor, and the positive hexavalent Cr is highly toxic. The number of countries producing and using magnesia-chrome bricks in the world is gradually decreasing. Brick production units find replacements as early as possible

4. Spinel brick: mostly used for excessive belt, good seismic performance, good reduction resistance, but the refractoriness is slightly worse

5. Anti-spalling brick: This brick contains a small amount of ZrO, which undergoes Martensitic transformation to form fine cracks during the heating process. It has strong alkali resistance, good spalling resistance and slag resistance.

6. Phosphate brick: low refractoriness, but high strength and good thermal shock resistance, mostly used in caster coolers, kiln hoods, etc.

7. Silicon carbide bricks: high temperature resistance (about 1800 degrees, softening temperature under load is 1620-1640), small thermal expansion coefficient, good resistance to rapid cooling and rapid heat wear resistance, suitable for cooling zone and kiln mouth

8. Silicon mullite brick: good thermal shock resistance, high strength, good wear resistance, suitable for transition zone.

The main physical indicators of refractory bricks are:

1. Apparent porosity: No specific requirements are made, but as a manufacturer, it is necessary to strictly control the apparent porosity.

2. Load softening temperature: also known as high temperature load starting deformation temperature, this parameter is very important, marking the resistance of the material to high temperature

3. Thermal shock resistance: the ability to resist rapid temperature changes without being damaged

4. Compressive strength: the maximum pressure ability to withstand (normal temperature)

5. Flexural strength: the ability to withstand shear pressure

6. Linear change rate: also called reburning line change or residual line change, which refers to the change of volume expansion and contraction in the same temperature change each time. If the expansion and contraction are the same each time, we define such a linear change rate as 0.

7. Wear resistance: everyone knows that I will not say more, it is one of the best indicators of the quality of refractory materials

8. Thermal conductivity: Under the condition of unit temperature gradient, the heat flow rate through the unit area of ​​the material is related to the porosity

9. Impact resistance: No need to explain, good impact resistance and long service life

10. Slag resistance: the ability to resist the erosion of slag at high temperature without being damaged