Refractory materials, as a substance that can maintain its physical and chemical properties in a high-temperature environment, are widely used in various industrial fields. Such as steel, glass, ceramics, etc. The composition of refractory materials is a key factor in determining their performance and application. Here we will take a deeper look at the composition of refractory materials.
The main component of refractory material is the characteristic basis of refractory material, it is the theme component that constitutes the refractory raw material, and its content and nature determine the characteristics of refractory material. The main component can be high melting point oxides, such as magnesium oxide, zirconium oxide, alumina and silica, etc.; it can also be composite oxides, typically magnesium-aluminum spinel (MgO-Al2O3), dolomite (MgO-CaO), etc.; it can also be a number of monomers and non-oxides. According to the content of the main components, refractories can be divided into three kinds.
Silicon (Si): Silicon is one of the most important components in refractories, it can form a dense silicate structure at high temperatures, improving the thermal stability and erosion resistance of the material.
From a chemical point of view, neutral refractories are strictly speaking only carbonaceous refractories, which are not used in the steelmaking process. Tend to neutral refractories are mainly high aluminum and chrome refractories.
High-alumina refractories, the products in the Al2O3> 45%, belonging to the weakly acidic and tend to neutral refractory materials.
Chromium refractories, alkaline and tend to neutral.
Products in the MgO and CaO components account for the absolute majority of refractories called alkaline refractories, mainly magnesium carbon bricks, dolomite bricks, magnesium-calcium sand, magnesium-chromium bricks, magnesium peridotite and spinel refractories, which are strong alkaline refractories mainly magnesium and dolomite refractories.
In the production process of refractory materials, add some small amounts of other components, the purpose is to promote a certain refractory material some performance changes, making the production process simpler. For example, to reduce the sintering temperature and sintering range, optimize the cost structure and improve the performance of the refractory material, add a small amount of ingredients called additive components. Additives can significantly improve the performance of refractory materials and reduce production costs. Common additives in refractories are as follows.
Carbon: Carbon can form carbide in refractory materials to improve the thermal stability and erosion resistance of the material. Carbon also acts as a lubricant and improves the processing properties of the material.
Zirconium: Zirconium forms stable zirconates in refractory materials, which have excellent erosion resistance and thermal stability.
Chromium: Chromium can form stable chromium oxide in refractory materials, which improves the oxidation resistance and thermal shock resistance of the materials.
Impurity composition refers to the limited purity of raw materials during the production and processing of refractory materials. Some of the refractory performance for the use of a small amount of negative impact on the performance of the refractory material into the refractory material, these small amounts of components are called impurity components.
Usually, iron oxide or ferrous oxide, potassium oxide (K20), sodium oxide (Na20) are harmful impurity components in refractory materials. Impurity components have a strong melting effect at high temperatures, and they interact with each other or with the main component, making the temperature of the generated eutectic liquid phase lower or the amount of liquid phase produced increased, thus reducing the performance of f refractories. For example, when the Fe2O3 content in magnesium-chromium bricks is high, when the steel refining atmosphere changes between oxidation and reduction, the transformation between magnesium ferrate (MgO-Fe2O3) and magnesium faujasite causes magnesium-chromium bricks to crack.
The acidic oxides contained in oxide-based alkaline refractories and the basic oxides contained in oxide-based acidic refractories are regarded as impurity components.
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