Slags thermal conductivity

The interelectrode insulators, an integral part of the electrode wall stmcture, are required to stand off interelectrode voltages and resist attack by slag. Well cooled, by contact with neighboring copper electrodes, thin insulators have proven to be very effective, particularly those made of alumina or boron nitride. Alumina is cheaper and also provides good anchoring points for the slag layer. Boron nitride has superior thermal conductivity and thermal shock resistance. 

Bricks of silicon carbide, either recrystaUized or clay-bonded, have a high thermal conductivity and find use in muffle walls and as a slag-resisting material. 

Thermal property is another critical property for furnace slag. Because of their more porous structure, blast furnace slag aggregates have lower thermal conductivities than conventional aggregates. Their insulating value is of particular advantage in applications such as frost tapers (transition treatments in pavement subgrades between frost-susceptible and nonfrost-susceptible soils) or pavement base courses over frost-susceptible soils. 

An investigation was carried out on concrete containing up to 30% of PE foam waste in order to optimise the thermal conductivity of the concrete. An amorphous aggregate of ash-slag waste was utilised to decrease the thermal conductivity of the concrete. 5 refs. 

Properties High heat resistance, great strength, high thermal conductivity, high resistance to attack by acids and acid slags, porosity about 25%, low permeability. 

Heat is transferred through slags by a variety of mechanisms which include convection, radiation and various thermal conduction processes, viz. thermal ("phonon") conductivity, (k ), electronic conductivity (kg ) and radiation conductivity (k ). Methods for estimating the various physical properties involved in these processes are considered below. 

Heat is transferred by phonons which are quanta of energy associated with each mode of vibration in the sample. Scattering of the phonons causes a decrease in the thermal conductivity and thus the conductivity (kc) is sensitive to the structure of the slag and... 

Heat Transfer and Thermal Conductivity of Coal Slags... 

Electronic conductivity It has been reported that glasses which contain significant concentrations of Fe ions behave in a similar manner to semi-conductors and hence thermal conduction via conduction electrons, holes, etc could be significant, according to Fine et al -I. Little is known of this mechanism in relation to the heat transfer in slags and consequently the contribution of k. to the measured thermal conductivities has been ignored in this review. 

---