Thermos Insulating Properties of Refractory Materials
                     Thermos Insulating Properties of Insulating  
Refractory Materials
You can witness the use of refractory materials in 
multiple fields like iron and steel,  ceramics, 
petrochemical, electric power, etc. 
Refractory bricks are also a kind of  refractory 
material.
These are necessary as basic materials to ensure the functioning of several  
industries. Refractory materials are inorganic, nonmetallic materials that have a  
high refractory degree. They include products made by specific processes for  
specific purposes and natural ores.
These materials come with various thermal insulating properties. The bulk 
density  of refractory materials is an important physical property expressed using 
the units
- kilograms per cubic meter or pounds per cubic foot.
Thermos Physical Properties of Insulating Refractory  
Materials
The efficiency of insulating refractory materials is dependent on the thermal  
insulating properties of these materials. Some of the thermos physical properties  
of refractory materials are as follows:
1) Thermal Shock Resistance
A refractory material suffers from frequent temperature changes. These changes  
lead to thermal stresses in the refractory materials, which, in turn, cause the  
expansion and contraction of the material. Two commonly used tests that measure 
 thermal shock resistance include the prism spalling test and the test that checks  
loss of strength.
The prism spalling test is about cycling samples of refractory materials from 2200  
degrees Fahrenheit for around 10 minutes, then put to water for around 2 
minutes,  followed by air for 7 to 8 minutes. This cycle continues till the specimens 
break, or  there have been 40 cycles. The more the number of these cycles, the 
higher the  thermal shock resistance of the refractory insulation materials will be.
In the test that checks the loss of strength, a sample of the insulating refractory  
material is brought from room temperature to 2200 degrees Fahrenheit five times.  
After that, the Modulus Of Rupture ( MOR) is done on cycled, and uncycled  
samples, and then the strength loss is calculated in percentage using the MOR  
values of the cycled and uncycled specimens. It is done 5 times with different  
samples of the refractory material, and the corresponding loss of strength
percentage is calculated. The thermal shock resistance is good if the strength loss  
is minimal.
2) Reversible Thermal Expansion
A refractory material usually expands when it is heated and suffers from  
contraction when cooled. Data sheets show a thermal expansion curve graph,  
which represents the expansion rates of the refractory material at different  
temperatures. The expansion rates are different for various refractory materials.  
Some refractory materials may also become larger than their usual size when they  
are cooled. The reheat tests will demonstrate the linear and volume change.
3) Thermal Conductivity
Thermal conductivity measures the amount of heat flowing from the hotter side  
to the colder face of any refractory lining. This flow of heat depends on the wall  
thickness and the refractory material's conductivity value. The thicker the wall, the  
less the heat flow will be. The thermal conductivity is also directly related to the  
drop in temperature from the hot side to the cold side, the time and the wall's 
area.
There may be various ways to measure thermal conductivity; you must compare  
the results of the same tests to check for the thermal insulating properties such as 
 rockwool insulation.
Final words
The thermal insulating properties play a key role with respect to the refractory  
materials. In this article, we have discussed three such properties.
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materials/