Refractory Ceramics and their Industrial Applications

Abstract:
Traditional and advanced refractory -ceramics or refractories are solid
brittle, polycrystalline, oxide - and/or non-oxide structural ceramic
materials, mainly applied for thermal insulation of industrial furnaces or
kilns. These include varieties of shaped and unshaped, dense and
lightweight, granular and fibrous as well as acidic, neutral and basic
products for application under a wide range of thermo - chemical and
mechanical service conditions up to ~1800oC. Therefore, these products
should withstand effects of service temperatures without loosing th eir shape
and mechanical strength, i.e. volume stability. These should also resist
thermal shock (spalling) due to successive heating -cooling cycles as well as
wear against thermo- chemical and mechanical attack of the in -contact gas,
liquid and solid materials under service conditions. Properties and
performance of the refractory -ceramic products under service conditions
are basically influenced by their chemical and phase composition as well as
microstructure, crystal structure of the co -existing phases and also the
processes applied for their manufacture or fabrication.
The refractory-ceramic products or refractories are consumed with
different rates in lining the different industrial furnaces, equipment and
reactors at 800-1800oC. The main refractory consumer is the steel industry
(~70%) and the rest is distributed in descending order between Portland -
cement and lime, ceramics, including refractories itself, petroleum -refining
and chemical industries, glass and non -ferrous metals (Al, Cu, Zn, Pb, …).
Selection criteria for refractory products adequate for application as back
and/or face linings of the different parts of these furnaces are mainly based
on their thermo- chemical and mechanical service conditions and also on
composition, microstructure and physical properties of the products. Hence,
intimate cooperation should be existed between the process -consumer
technical staff and refractory -manufacturer research team to develop
refractory materials suitable for specific service conditions in the differ ent
furnace parts. This would lead to optimize performance, service life and
consumption of the refractory linings with increasing rate of production
and quality of the fired materials. For instance, service conditions as well as
the technically and economically feasible types of refractory -linings,
recently recommended for application in steel, Portland -cement and
ceramic industries are summarized.