The method for measuring refractoriness of materials

Refractoriness of materials

Refractoriness of materials is also called refractoriness. Refractoriness of material is not a physical constant of a substance, but a technical index and its level are determined by the chemical composition of the material, the degree of dispersion, the proportion of liquid phase in it, and the viscosity of the liquid phase. 

Refractoriness of materials

The refractoriness of some common refractory raw materials and products are as follows:

Crystalline silica 1730~1770℃ High alumina brick>1770~2000℃

Silica brick 1690~1730℃ Magnesium brick>2000℃

Hard clay 1750~1770℃ Dolomite brick>2000℃

Clay brick 1610~1750℃

The method for measuring refractoriness of materials

The test material is made into a truncated triangular cone of a specified size, and when heated at a certain heating rate, it gradually bends due to its own weight, and the test cone bends to the point where the top of the test cone is in contact with the chassis. The temperature is the refractoriness of the test materials.

The bending degree of the refractory test cone at high temperature mainly depends on the number ratio of the liquid phase to the solid phase, the viscosity change of the liquid phase, and the dispersion of the high melting point crystal phase. Usually, when the cone reaches the refractoriness, most of them contain about 70~80% liquid phase, and the liquid phase viscosity is about 10~50Pa•s, which varies with different materials. Therefore, it can be considered that the level of refractoriness of refractories is mainly controlled by the chemical and mineral composition of the material in addition to the measurement conditions, especially the particle size composition and heating rate of the test cone, and the measurement atmosphere of some materials. For refractory materials composed of various single and two components, it mainly depends on the melting point of the compound. For refractories composed of multiple components, it depends on the quantity ratio of the main component and other components. Impurities can seriously reduce the refractoriness of the material.