The quality inspection standards of silicon brick mainly include the following aspects. These standards and inspection methods can comprehensively evaluate the performance and quality of silicon brick and ensure its reliability and stability in high temperature environment.

I. Chemical composition detection

Silicon dioxide (SiO) content: the main component of silicon brick, usually requires that the SiO content should be not less than 94%, and the SiO content of high-quality silicon brick should reach more than 96%.

Impurity content: The content of impurities such as Fe₂O₃, Al₂O₃, CaO, KO and Na₂O should be strictly controlled. For example, the Fe₂O₃ content is generally less than 1.4%, and the requirements for high-quality silicon bricks are even lower.

Testing standard: The testing of chemical components is based on GB/T 6901-2008 or GB/T 21114-2007 standards.

II. Physical performance testing

True density: it is an important index to judge the degree of crystal transformation of silicon brick, which is generally required to be below 2.38 g/cm³, and high-quality silicon brick should be below 2.35 g/cm³.

Apparent porosity: it is usually required to be less than 24%, and the apparent porosity of high-quality silicon bricks is even lower.

Cold compressive strength: the compressive strength at room temperature is an important index to measure the mechanical properties of silicon bricks, which is usually required to be ≥19.6 MPa.

Softening temperature under load: The softening temperature under load of silicon brick is the key index to keep its structural stability at high temperature, which is generally required to be ≥1640℃.

Thermal expansion rate: The thermal expansion rate at 1000℃ is usually required not to exceed 1.30%.

Testing standard: Physical performance is tested according to GB/T 2997-2000, GB/T 5071-2013, GB/T 5072-2008 and other standards.

III. Fire resistance test

Refractory degree: Refractory degree is the temperature at which the silicon brick does not melt at high temperature, which is generally required to be ≥1700℃.

Permanent linear change after heating: the permanent linear change rate after heating at 1450℃ for 2 hours is usually required to be within 0.3%.

Testing standard: The testing of fire resistance is based on GB/T 5988-2007 and other standards.

IV. Other testing items

Thermal shock resistance: the thermal shock resistance of silicon brick is poor, which is usually evaluated by the number of water cooling cycles, generally 1-4 times.

Acid corrosion resistance: Silicon brick has good acid slag corrosion resistance, which is one of its important characteristics.

Detection methods: including X-ray fluorescence spectrometry, thermogravimetric analysis, differential scanning calorimetry, universal material testing machine and so on.

V. Testing standards and specifications

GB/T 2608-2012: This is the national standard for silicon bricks, which stipulates the classification, technical requirements, test methods, quality evaluation procedures, packaging, marking, transportation, storage and quality certificate of silicon bricks.

GB/T 2992.1-2011 and GB/T 2992.2-2014: The shape and size of refractory bricks and the terms of brick shape and masonry are specified respectively.

Through the above standards and testing methods, the quality and performance of silicon bricks can be comprehensively evaluated to ensure their reliable application in industrial equipment such as high-temperature furnaces.