Properties of refractories

Properties of refractories

1. Refractoriness
It is the ability of a material to withstand very high temperature without softening or deformation under particular service condition.

How to measure refractoriness
Since most of the refractories are mixtures of several metallic oxides, they do not have a sharp melting points. So the refractoriness of a refractory is generally measured as the softening temperature and is expressed interms of Pyrometric cone Equivalent (PCE).

Pyrometric cone Equivalent (PCE)
Pyrometric cone equivalent is the number which represents the softening temperature of a refractory specimen of standard dimension (38 mm and 19 mm triangular base) and composition.

Objectives of PCE Test
1. To determine the softening temperature of a test refractory material.
2. To classify the refractories.
3. To determine the purity the refractories .
4. To check whether the refractory can be used at the particular servicing temperature.

Measurement
Refractoriness is determined by comparing the softening temperature of a test cone with that of a series of segar cones. Segar cone (also called pyrometric cones) are pyramid shapes.
A test cone is prepared from a refractory, for which the softening temperature to be determined as same dimensions of segar cones. Then test cone is placed in an electric furnace along with segar cones. The furnace is heated at a standard rate of 10° C per minute during which softening of segar cone occur along with test cone. The temperature at which the apex of the cone touches the base is softening temperature.