Showing posts with label Black Core. Show all posts
Showing posts with label Black Core. Show all posts

May 4, 2009

‘Black Core’ in Refractory Bricks

What is ‘Black Core’?

As the name suggests these are circular or semi-circular shaped black spots forms around the core or middle portion in non-basic refractory bricks containing good percentage of raw clay. The two reasons attributed to the formation of Black Core are:


=> Presence of Carbonaceous matters in plastic / non-plastic fire clay. Sometimes, too much carbonaceous matters have been found to occur in the fireclays which are available particularly around a Coal-belt.

=> Reducing atmosphere in the kiln during firing of bricks.


Precautions

Following are the few steps to avoid the formation of Black Core in refractory bricks:


=> The firing atmosphere (kiln atmosphere) must be kept oxidizing.

=> Soaking time should be prolonged.

=> If it is not eliminated even after taking the above two steps then the raw clay has to be replaced.


Related Posts:

>> How to Prevent Formation of Iron Spots (Crater) in Refractory Bricks as a Measure of Quality Control [Read]

>> Types of Testing of Refractories [Read]

>> Glimpses of the Growth of Refractory Industry in India [Read]