Chemical Composition of Silicon-Aluminum Refractory Bricks
Aluminate-silicate refractory products are refractory products whose basic chemical composition is alumina and silica. According to the content of alumina, can be divided into three types: clay, high alumina, and semi-silicon. In addition to the main components, silicon-aluminum refractory bricks products also contain impurities such as Fe2O3, TiO2, CaO, Na2O, and K2O. The presence of these impurities will greatly reduce the refractoriness of the product. Rongsheng refractory manufacturers have rich experience in production and sales and will show you the chemical composition of silicon-aluminum refractory bricks.
Chemical Composition of Silicon-Aluminum Refractory Bricks
Chemical composition is the basis of refractory materials, and the chemical composition of refractory materials is usually divided into two parts according to the content and function of each component. That is, the main component accounts for the absolute majority, and the secondary component accounts for a small amount. Subcomponents are the accompanying inclusions in raw materials and special additives (additions) in process manufacturing.
(1) Principal components. The main component is the component that constitutes the main body of the refractory and is also the basis for determining the characteristics of the product. If you know the main components in the chemical composition, it is easy to know the refractory body.
In addition to the main component of the refractory material made of special raw materials is close to 100%, the silicon-aluminum refractory material made of natural raw materials will inevitably be mixed with a certain number of inclusions. Therefore, the minimum value of the main component is stipulated in the quality regulations of refractory materials.
Even if the composition of the material is above the specified value, the type and quantity of the impurity components and the structure of the product still greatly affect the performance of the refractory brick. For example, when the impurity aluminum content in the production of silica bricks exceeds 1%, although the main component content (SiO2) is above the specified value, the performance of the product will still deteriorate. Therefore, the main component of refractory bricks is only one of the measures to ensure the quality of products, and this alone is not enough.
(2) Subcomponents. In addition to the main components, silicon-aluminum refractory bricks products usually contain a small amount of impurity components. In recent years, with the continuous development of industrial production, the requirements for the use of refractory materials are getting higher and higher. Therefore, the restrictions on the impurity components in the products are becoming more and more strict.
Most of the impurity components in the material act as flux at high temperatures, which seriously reduces the refractory performance of refractory bricks. It is therefore generally considered a hazardous ingredient. Therefore, it should be avoided to exceed the specified limit in actual production. As for the mechanism of the flux effect on the impurity components in the material, there are two views.
1) A low-melting liquid phase is generated due to a chemical reaction.
2) Although the product is not necessarily low-melting, it generates a more liquid phase at the same temperature.
The research on the impact of impurity oxides in the Al2O3-SiO2 (silicon aluminum) system shows that R2O is the most harmful in the impurity components. Even if its amount is very low (<1%), it can make the product form a eutectic liquid phase at about 1000 ° C, which obviously reduces the fire resistance and high-temperature structural strength of the product. Alkali-containing slag or alkali-containing gas has a serious corrosion effect on silicon-aluminum refractory bricks products during use.
The lower the temperature at which the molten liquid phase is formed, the more liquid phase is formed. As the temperature rises, the faster the growth rate, the stronger the flux effect of the impurity components. Therefore, the impact on the fire resistance of the product is also greater.
In addition to the above, the role of impurities in refractory bricks (raw materials) also has the effect of reducing the firing temperature of products (raw materials) and promoting the sintering of products (raw materials). However, it should be noted that some properties of the product will also be reduced at the same time.
In the manufacturing process of silicon-aluminum refractory bricks, in order to promote the high-temperature change of the material and reduce the sintering temperature, sometimes a small amount of additives (additions) are added. According to its purpose and function, it can be divided into: 1) mineralizer; 2) stabilizer; 3) sintering agent, etc. These ingredients are also included in the chemical composition of the product.
When analyzing the chemical composition, the content of ignition loss, A12O3, SiO2, Fe2O3, TiO2, CaO, MgO, K2O, Na2O, etc. are generally mainly analyzed. Special products and raw materials are analyzed on request. The burning loss of refractory raw materials indicates the amount of degassed products (such as CO2) and organic substances that are thermally decomposed in the raw materials. Therefore, it can be judged that the volume shrinkage of the raw material during the heating process determines whether pre-burning is required in production to ensure that the volume of the product is stable.
Aluminum-silicon refractory bricks are refractory products containing Al2O3 and SiO2 and are a series of aluminum-silicon refractory bricks. Aluminum-silicon refractory bricks have a wide range of applications and occupy a very important position in the refractory application industry. Its consumption accounts for more than 40% of the total refractory products. From a definition point of view, aluminum silicon refractory bricks are a series, which includes multiple types of refractory bricks. RS Alumina Bricks is a manufacturer that can provide a variety of high-quality silica-alumina refractory bricks.
Aluminum-silicon refractory bricks are classified according to the order of increasing composition from SiO2 content to Al2O3 content:
It can be seen from the classification that silica bricks, clay bricks, and high alumina bricks are commonly used refractory bricks for kilns, and are often used for masonry kiln working layers and permanent layers.
To purchase high-quality silicon-aluminum refractory bricks products, please choose a strong refractory brick manufacturer. Rongsheng Refractory Material Manufacturer is a refractory material manufacturer with rich experience in production and sales. Our refractory brick products are reliable in quality, and at the same time, we also provide comprehensive design and solutions for refractory lining materials. Customize refractory materials according to different production needs. Contact us for free samples and quotes.
