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How are resin-bonded
crucibles far superior to crucibles bonded otherwise?
The constant technological gains demand improvement in industrial
materials and in this connection, mention may be made of refractory products: these
represent the most important group of industrial materials in this area. Their improvement
has permitted realization of key break through and this evolution has been coupled with
the introduction of novel high quality binder system called Phenolic resin binding.
By the abandonment of ceramic bonding in favor of carbon bonding, the modern method of
carbon bonding is to employ Phenolic resins. These offer a variety of advantages such as
good wetting of silicon carbide and graphite, curability, high strength and a high carbon
yield –which renders them particularly appropriate for this use. The structure of
this carbon is quoted as “glassy carbon” and is chemically inert. It consists of
stacks of two-dimensional ribbon like molecules reminiscent of the fibrils in the
crystalline polymer. This structure is often referred to as “curly carbon”
confers higher strength to the final refractory.
Why is resin bonding considered
ideal for refractory products like crucibles and superior to all other bondings?
They exhibit high specific adhesion to
crucible raw materials like graphite, oxides and silicon carbide.
The strength and erosion characteristics
of resin bonded crucibles are considered to be superior to those based upon other bonding
agents such as clay, tar and pitch etc., thus resulting in longer life.
During the polymerization of Phenolic
resin, the carbon yields is much higher when using resins (55-65%) when compared to pitch
@11-16%, this gives higher thermal conductivity and thus enhances the thermal shock
resistance. This is of special advantage in crucibles where the product is continuously
under the heating/ cooling cycles while in use at the foundry.
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©2003M.P.Carbon Pvt Ltd.. All rights reserved.
Revised: August 07, 2003 |
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