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The main performance indicators of refractories are:     1. Refractory: refractoriness is the resistance of refractory to melting at high temperatures. The refractoriness depends primarily on the chemical composition of refractory materials and the con

Date:2017-06-15 11:31 From:Zhengzhou Sunrise Refractory Author:admin
The main performance indicators of refractories are:
    1. Refractory: refractoriness is the resistance of refractory to melting at high temperatures. The refractoriness depends primarily on the chemical composition of refractory materials and the content of fusible impurities (such as FeO, NaO, etc.) in the material. Refractory does not represent the actual use of refractory humidity, because the high temperature load under the softening temperature of the refractory material will be reduced, so the actual allowable use of refractory temperature is higher than the refractory. The refractoriness is generally determined by experiment. Refractor degree greater than 1580 ℃ of the material can be called refractory material.
    2. High temperature structural strength: high temperature structural strength refers to the refractory products under high temperature to withstand the pressure without deformation of the resistance. Often with the weight of softening temperature to assess. The so-called weight softening temperature refers to the refractory products at 0.2 pressure, at a certain heating rate of heating, the sample began to deformation of the temperature and compression deformation of 4% or 40% of the temperature. The temperature of the former is called the weight loss softening start humidity, the latter is called weight softening 4% or 40% softening point.
    3. Thermal stability: thermal stability refers to the rapid changes in resistance to humidity without cracking or flaking ability, sometimes referred to as resistance to rapid cooling. It is determined by heating the refractory product to a certain temperature (850 ° C) and then cooling it with flowing cold water until the weight of the part is peeled off by 20% of the original weight. Thermal stability of the indicators.
    4. Volume stability: volume stability refers to the refractory products at a certain temperature repeated heat, cooling volume change percentage. Generally under repeated high temperature, refractory products within the composition of the occurrence of recrystallization and further sintering, will produce residual expansion or contraction phenomenon. The permissible residual expansion or contraction should not exceed 0.5-1.0%.
    5. High temperature chemical stability: high temperature chemical stability refers to refractory products at high temperatures, resistance to metal oxides, molten salt and furnace gas erosion ability. Commonly used to assess the slag resistance, this property depends mainly on the composition of refractory products itself, the chemical characteristics and physical structure, such as porosity, bulk density and so on.
    6. Bulk density, porosity, permeability: Bulk density refers to the total unit of refractory products, including the weight of units, the unit is g / cm3. Porosity (%) is divided into porosity and true porosity. The apparent porosity is the ratio of the volume of the hole to the total volume of the refractory product to the atmosphere. The true porosity is the ratio of the volume of the hole to the total volume that does not communicate with the atmosphere.
    Permeability is often assessed by the permeability coefficient, the air permeability coefficient is 9.8Pa under the pressure difference, within 1h through the thickness of 1m, an area of ​​1m2 refractory products, the amount of air.
    7. Thermal conductivity, specific heat capacity, thermal expansion: thermal conductivity that the thermal conductivity of refractory materials, often with the symbol "λ" said. Its physical meaning is when the temperature difference of 1K, the unit time through the thickness of 1m, an area of ​​1m2 refractory products of heat, the unit is W / (m.K)
    Specific heat capacity reflects the thermal storage capacity of refractories, in units of kJ / (kg * ℃), its value increases with increasing temperature. The coefficient of thermal expansion is usually expressed as the percentage of linear expansion "α", that is, the length L of the refractory article at t ° C and the length L at 0 ° C. The difference between the value of L. Percentage of the ratio.

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