The formula calculation of refractory materials is similar to that of ceramic materials. Here we mainly talk about the matters that need to be paid attention to in the design of refractory formula.
The blank for producing refractory materials is a mixture made by mixing raw materials in a certain proportion and particle size composition, adding water or other binders, and mixing in a mixer. It has the properties required for blank molding, such as plasticity, bonding, fluidity and filling. According to the performance requirements and process characteristics of refractory products, the process of mixing materials of different materials and different particle sizes in a certain proportion is called the batching of refractory materials. When determining the proportion of blanks, the composition and performance requirements of the products are mainly considered to ensure that the products meet the specified performance indicators; after mixing, the blanks have the necessary molding properties. At the same time, attention is also paid to the rational use of raw material resources to reduce costs.
Determination of the material composition of blanks: including the determination of the types and proportions of the main raw materials, auxiliary components and additives of refractory products. The category of the main raw materials is mainly determined according to the process requirements and the performance indicators of the products. The main raw materials are required to withstand sufficiently high operating temperatures and good resistance to environmental erosion. The introduction of auxiliary ingredients and additives is often to improve the performance of products, facilitate the preparation of products or benefit the composition, structure and performance control of products. The types and quantities of introduction are determined on the basis of certain theoretical guidance and experiments.
When preparing molding materials with high plasticity requirements, more raw materials with high plasticity are used. Since the raw materials have not been heat-treated, the instability caused by heating is higher than that of clinker. Therefore, under the condition that the plasticity is not greatly affected, adding more clinker can reduce the cracking or deformation of products during firing. In plastic molding materials, the amount of raw materials added does not exceed 50% of the total amount of raw materials. For semi-dry molding materials, the amount of raw materials added generally accounts for about 10% to 59% or less of the total amount of raw materials. Raw materials with high plasticity have good bonding in molding materials, which can improve the strength of green billets, and are also conducive to the transmission of molding pressure and facilitate molding. Raw materials are generally added in the form of fine powder. Raw materials have greater reactivity, which can promote the sintering of billets and help improve the strength of products. Ingredient particles
The following aspects should be considered in the determination of composition.
1. It can ensure that the blank has a reasonable stacking density.
2. Meet the performance requirements of the product, such as products with good thermal shock resistance. The number of particle parts and the critical particle size should be appropriately increased in the blank. For products with good slag resistance, the particle stacking should meet the most compact stacking to obtain a dense sintered body.
3. Impact on the production process, such as in the silicon brick blank, more fine particles are required to make the brick easy to undergo polycrystalline transformation during firing, while too many fine particles in the magnesium brick blank are easy to hydrate, which is not good for the product.
4. Meet the process requirements of subsequent processes. Different molding methods have very different requirements for the particle composition of the mud. In addition, it should also be considered to facilitate the firing of the product and obtain the required microstructure and composition. Methods for preparing blanks: generally there are two methods: volumetric method and weight method. Volumetric batching is to batch according to the volume ratio of the material, and various feeders can be used as volumetric batching equipment. Volumetric batching is generally used for continuous batching, and its disadvantage is poor accuracy. The weight method of batching is more accurate, with the general error not exceeding 2%.
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