A fire brick is a special type of brick made using fire clay and has a good resistance against high temperatures which are used in kilns, lining furnaces, fireplaces and fireboxes. These bricks are manufactured in a way similar to that of normal bricks, except during the burning process- Fire bricks are exposed to very high temperatures.
Types of Fire Bricks: Fire bricks are classified majorly into three types:
1.Acidic fire bricks 2. Basic fire bricks 3.Neutral fire bricks
1. Acidic Fire Bricks
Acidic Fire brick, also called as acid resistant brick is used especially to resist acidic actions of chemicals or weather. Generally, normal fire brick made of natural fire clay is as good as acid brick, but if more acid resistance is needed then an additional amount of silica is added to fire clay which may range up to 97% of its composition. For binding purposes, 1 to 2% lime may be added. Acid bricks are burnt at heavy temperatures for long periods.
2. Basic Fire Bricks
These are good at corrosion resistance and chemical resistance. They contain high amount of magnesia and here also lime is used as a binding material. Different basic fire bricks available are Magnesite bricks, Magnesia-carbon, magnesia-chrome bricks etc.
3. Neutral Fire Bricks
These are good for both acidic and basic lining purposes. They offer good resistance against acidic fumes as well as corrosive actions. Neutral bricks are of two types namely- high alumina bricks and chromites bricks.
High alumina bricks contain alumina in large amounts while chromites bricks contain chromium, iron oxide, silica, bauxite, and iron ore in various proportions.
Uses of Fire Bricks: These are used for Inner surface lining of kilns, furnaces, chimneys etc.
- To build fire-resistant structures thereby reducing the damage of the structure against fire accidents.
- For inner lining of wood-fired ovens.
- As an insulating material for furnaces, ovens because of their lower thermal conductivity.