Thermal conductivity is the property of a material to conduct heat.
Heat transfer occurs at a lower rate across materials of low thermal conductivity than across materials of high thermal conductivity. Materials of low thermal conductivity are used as thermal insulation. The thermal conductivity of a material may depend on temperature.
The thermal conductivity of refractories is a property required for selecting their thermal transmission characteristics. Users select refractories to provide specified conditions of heat loss and cold face temperature, without exceeding the temperature limitation of the refractory. This test method establishes the testing for thermal conductivity of refractories using the calorimeter.
This procedure requires a large thermal gradient and steady state conditions. The results are based upon a mean temperature.
The data from this test method are suitable for specification acceptance, and design of multi-layer refractory construction.
The hot wire technique is a transient, intermittent isothermal method for measuring thermal conductivity. A thin platinum wire is placed between two appropriately prepared 9" bricks of same density. Heat generated by current applied to the wire is conducted away from the wire at a rate dependent on the thermal conductivity of the material.