A block of ceramic material used in kilns, fireboxes, lining furnaces, and fireplaces is known as firebrick or refractory brick. A refractory brick is specifically built to withstand high temperatures, but would usually also have low thermal conductivity for greater energy efficiency. We should know what these are before we venture into the specifics of firebricks. Let's have a look.
What are Firebricks?
Firebricks contain refractory characteristics produced from natural mud or clay. It comprises aluminium-containing minerals. It should have a reasonable proportion of silica and alumina. It's really heavy. They are processed and baked to heat resistance at high temperatures. Until they are cut into form, they are soaked in water. Usually, the colour of the fire bricks is white or yellowish-white, each weighing around 3 kg& have a high melting point.
This type of brick is made of fire clay. Without undergoing any visible change in structural properties such as melting or softening, this clay will withstand high temperatures.
High Alumina Bricks
The manufacturing method of high alumina bricks is identical to that of fireclay bricks. But the high alumina bricks use higher proportions of clinker, which hit 90~95 percent, for the variations. Before crushing and firing the clinker at high temperatures that reach up to 1500 ~ 1600 degrees, pick and sieve all the iron slag.
High alumina bricks manufacturers Hyderabad shows that to improve the quality of high alumina brick products, it is important to strictly sieve and store the high alumina clinker in grades and then finely grind the bauxite clinker and bind clay together.
Properties of good refractory bricks:
The refractory bricks must be excellent in quality to fulfil the desired purpose. The following are the properties that good refractory bricks must-have.
• Refractory bricks in the furnace walls and arches must withstand stress produced at high temperatures.
• At high temperatures, they must retain their rigidity.
• At the furnace temperature, irreversible volume changes do not occur. Since shrinkage results in the opening of joints and a leaky furnace result.
• When exposed to a sudden change in temperature, they must avoid the urge to crack and cut fragments off.
• With furnace gases, they must not react.
• They must not easily form slag-based fusible products.
• The weight of refractory bricks should be approximately 150 lbs per cubic ft (cft).
• Compressive strength of around 20000 to 30000 psi should be used.
• When kept in water for 24 hours, they do not consume more than 6 percent of water by wt.
Characteristics of Fire Bricks:
• The fire brick, in general, weighs between 30 - 35 N.
• The absorption rate ranges between 5 and 10%.
• Fire brick's compressive strength is between 200 – 220 kg/cm2.
• They are white or yellowish or white.
• They have a strong tolerance to chemicals.
• They are available in various sizes ranging from 230 X 115 X 75 mm.
Uses of Firebricks:
• These are used for the interior surface of furnaces, kilns&ovens heated by electricity because they regulate heat and absorb it.
• The fire-resistant structures are constructed using fire bricks, thereby reducing the structural risk against fire accidents.
• For the internal lining of the fire-wood chimney.
• Because of their lower thermal conductivity, ovens are an insulating material for furnaces.
The refractory bricks are usually composed of clay, mainly aluminium and silica. Silica is a superb insulator while alumina has reflective qualities. The higher the temperature the brick will be, and the more alumina is present in the mix, the costlier the component. It is always important to emphasize that when designing or building structures that come into contact with fire, attention must be paid to materials used by local regulations. It's a small price to pay to escape material shortages or more severe injuries, experts say.