The main performance index of refractories

1. Refractoriness : The refractoriness is the resistance of the refractory to melting at high temperatures. The refractoriness depends mainly on the chemical composition of the refractory material and the content of susceptibility impurities (such as FeO , NaO, etc. ) in the material. The degree of refractoriness does not represent the actual operating humidity of the refractory material, because the softening deformation temperature of the refractory material under the effect of high temperature load will decrease, so the actual allowable maximum use temperature of the refractory material is lower than the refractoriness. The refractoriness is generally determined by tests. Materials with a refractoriness greater than 1580 °C can be referred to as refractories.

2.
High-temperature structural strength : High-temperature structural strength refers to the resistance of refractory products under high pressure without deformation. It is often assessed by the weight softening temperature. The so-called weight-reducing softening temperature is the temperature at which a refractory product is heated at a certain heating rate under 0.2 pressure, and the temperature at which the sample starts to deform and the temperature at which the compression deformation reaches 4% or 40% are measured. The temperature of the former is called the weight and softens the initial humidity, and the latter is called the weight-bearing softening point of 4% or 40% .

3.
Thermal stability : Thermal stability refers to the ability to resist sharp changes in humidity without breaking or peeling, sometimes also called quenching and rapid heat. It is determined by heating the refractory product to a certain temperature ( 850 °C ) and then cooling it with flowing cold water until it reaches the weight of 20% of the original weight due to the cracking of the product . The alternating number of love hot and cold is Assess thermal stability indicators.

4.
Volume stability : Volume stability refers to the volumetric change percentage of heat and cooling that refractory products are repeatedly added at a certain temperature. Generally, under the action of multiple high temperatures, the internal components of the refractory product will undergo recrystallization and further sintering, resulting in residual expansion or contraction. The general allowable residual expansion or contraction should not exceed 0.5-1.0% .
5.
High-temperature chemical stability: High-temperature chemical stability refers to the ability of refractory products to resist erosion by metal oxides, molten salts, and furnace gases at high temperatures. The slag resistance is commonly used to evaluate this property mainly depends on the chemical characteristics and physical structure of the refractory composition itself, such as porosity, bulk density and so on.

6.
Bulk Density, Porosity, and Air Permeability : Bulk density refers to the weight of unit refractory products including all pores, and its unit is g/cm3.
Porosity ( % ) shows the porosity and true porosity. The apparent porosity is the ratio of the volume of voids in the refractory product to the atmosphere and the total volume. True porosity refers to the ratio of the volume of voids that does not pass through the atmosphere to the total volume.
Permeability coefficient of permeability often assessed permeability coefficient is at a differential pressure of 9.8Pa, a thickness of the inner through 1h 1m, surface 1m2 Gou air amount refractory products.

7.
Thermal conductivity, specific heat capacity, thermal expansion : Thermal conductivity represents the thermal conductivity of a refractory material, often denoted by the symbol “λ” . Its physical meaning is the heat of a refractory product with a thickness of 1m and an area of 1m2 per unit time when the temperature difference is 1K , and the unit is W/ ( mK)
The specific heat capacity reflects the heat storage capacity of the refractories in kJ/ ( kg* °C ), which increases with increasing temperature.
Common thermal expansion percentage linear expansion "α" to indicate that the length of the refractory article deg.] C at the T L, the length L at 0 ℃. The difference L. The percentage of the ratio.

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