Finished refractory brick inspection and defect analysis

The fired refractory brick products need to be selected and tested for physical and chemical properties to identify whether the product meets the expected shape, size, composition and performance requirements. Appearance selection is to check whether the refractory brick products have cracks, deformation, fire moles, molten holes, defects, raw or overburned, tolerances, etc. The chemical composition and microstructure are mainly determined by means of chemical analysis, fluorescent X-ray analysis, X-ray diffraction analysis, and petrographic and metallographic analysis. Determination of some physical properties, including bulk density, porosity, water absorption, refractoriness, load softening temperature, thermal conductivity, linear thermal expansion, thermal shock resistance, resistivity, dielectric constant, dielectric loss, dielectric breakdown, mechanical Strength, hardness, elastic modulus, etc., all have special testing equipment and standard testing methods. As for the chemical stability of products in various chemical environments such as acid, alkali, salt, metal, glass and gas, it is often measured and judged by special means or simulation tests according to the different uses of different refractory brick products. Items that do not meet standards shall be traced back from the manufacturing process. For example, the appearance of refractory bricks has quality problems:

1) For raw firing or over firing, the method of kiln installation, firing temperature and holding time should be traced;

2) Porosity, the sintering quality of the raw materials, the quality of the molded body, the gradation of the mud particles, the firing system, etc. should be traced;

3) The dimensional tolerance is large, and the performance of raw materials, the particle size distribution of mud, the scale ratio of model design, model size, kiln installation method and firing system should be traced back.

4) Deformation should be traced back to the mud material, kiln loading method and firing system, etc.;

5) Cracking should be traced back to the quality of raw material processing, proportion of ingredients and mud moisture, molding quality, drying quality, firing system, etc.;

6) For spalling, the particle size distribution of the mud material, the moisture content of the mud material, and the molding quality should be traced;

7) For missing corners and edges, the quality of the green body after drying, the quality of the model, and the quality of handling should be traced;

8) For karst caves, the low-melt impurities of raw materials, the quality of raw material purification and treatment, and impurities mixed in the production process should be traced;

9) For fire mole, it should be traced back to the way of kiln installation and the thermal working conditions of the firing process.

If there is a problem with the internal indicators of refractory bricks:

1) Chemical components (main components, secondary components, impurities), mineral composition (type, quantity, crystal size distribution, pore size distribution, distribution of liquid phase quantity, etc.) do not meet the expected requirements, the raw material composition should be traced, and whether the proportion of ingredients is appropriate , whether the firing system is reasonable;

2) If the bulk density and porosity are not up to the standard, the quality of the mud material, the quality of the green body, and the firing system should be traced;

3) The air permeability should be traced back to the proportion of ingredients, the quality of the green body, the firing system, etc.;

4) Strength (compressive strength, flexural strength, impact strength), should be traced back to the mud quality, green body quality, firing system, etc.;

5) Resistance and dielectric strength should be traced back to the nature of raw materials, proportion of ingredients, firing system, etc.;

6) The refractoriness should be traced back to the nature of the raw materials;

7) Changes in thermal expansion and refiring line should be traced back to the properties of raw materials, proportions of ingredients, properties of mud, properties of biscuits, firing systems, etc.;

8) The thermal conductivity should be traced back to the properties of the raw materials, the properties of the green body, and the firing system;

9) Thermal shock resistance should be traced back to the properties of raw materials, proportions of ingredients, properties of mud materials, and firing systems;

10) For high temperature and load softening, the properties of raw materials, mud composition and particle size distribution, molding quality, firing system, etc. should be traced.