In modern industrial production, refractories play a vital role, especially in high temperature environment, they can withstand extreme temperature and chemical erosion, and ensure the normal operation of various industrial equipment. As a high-quality refractory raw material, sintered mullite has attracted much attention because of its excellent properties and wide application fields.

I. Characteristics of sintered mullite

The main component of sintered mullite is mullite phase, which gives the material a series of excellent properties. Firstly, it has high mullite phase content, such as M45, M47, M60 and M70 mentioned in this paper, and the mullite content is not less than 55%, 65%, 78% and 78% respectively. High mullite content means that the material has better stability and corrosion resistance at high temperature.

Secondly, the low porosity of sintered mullite is one of its important characteristics. Low porosity means fewer holes in the material, which not only improves the compactness of the material, but also enhances its permeability and erosion resistance. For example, the apparent porosity of M45 and M47 grade sintered mullite is less than 2.0%, while the porosity of M60 and M70 grade is only 2.8%, which makes the material effectively resist chemical erosion and physical wear in high temperature environment.

Sintered mullite also has a high refractoriness, which is a key index to measure the structural integrity of refractories at high temperature. The fire resistance of the four grades of sintered mullite mentioned in this paper reaches 1750℃, 1790℃, 1820℃ and 1850℃ respectively. This means that in high-temperature furnaces and other equipment, sintered mullite can remain stable at extreme temperatures and will not easily melt or deform.

In addition, sintered mullite also has good thermal shock resistance, small high-temperature creep, high softening temperature under load, high bulk density, high hardness and uniform expansion. These characteristics make sintered mullite perform well in complex industrial environment and can withstand frequent temperature changes, mechanical stress and chemical erosion.

II. Chemical composition and physical properties of sintered mullite

The chemical composition of sintered mullite has an important influence on the properties of materials. According to the data provided in this paper, the contents of iron oxide (Fe₂O₃), silicon dioxide (SiO₂), titanium dioxide (TiO₂), potassium oxide (KO), sodium oxide (Na₂O), magnesium oxide (MgO) and calcium oxide (CaO) in different grades of sintered mullite are different. For example, the Fe₂O₃ content in sintered mullite of M45 grade is less than 1.0%, while that of M70 grade is less than 1.30%. The SiO₂₂ content of M45 grade is less than 52%, while that of M70 grade is only 27%. The change of these components will affect the refractoriness, corrosion resistance and thermal expansion coefficient of materials.

In terms of physical properties, the bulk density of sintered mullite also increases with the increase of grade. The bulk density of M45 grade is 2.55g/cm³, while that of M70 grade is 2.80g/cm³. Higher bulk density means that the material is denser and can better resist physical wear and chemical erosion at high temperature.

III. Application fields of sintered mullite

As a high-quality refractory raw material, sintered mullite is widely used to manufacture various high-performance refractory products. In the iron and steel industry, sintered mullite can be used to manufacture steel-lined bricks, tundish-lined bricks, skateboard bricks, etc. These products need to be stable at high temperature, and at the same time bear the chemical erosion and mechanical impact of molten steel. The high refractoriness, low porosity and good corrosion resistance of sintered mullite make it an ideal material choice.

In the glass industry, sintered mullite can be used to make wall bricks and bottom bricks of glass melting furnaces. The working temperature of glass melting furnace is extremely high, and the glass liquid has strong corrosiveness to refractories. The high temperature stability and corrosion resistance of sintered mullite can effectively prolong the service life of kiln and improve production efficiency.

In addition, sintered mullite is also widely used in ceramic industry, petrochemical industry, building materials industry and other fields. In the ceramic industry, it can be used to manufacture kiln furniture of ceramic firing kiln, such as shed board, pillar, etc. In petrochemical industry, it can be used to manufacture wear-resistant lining of catalytic cracking unit; In the building materials industry, it can be used to manufacture the lining of cement rotary kiln.

IV. Quality control, packaging and transportation of sintered mullite

In order to ensure the quality of sintered mullite, production enterprises usually establish a perfect quality control system. It is mentioned in the article that quality inspectors will conduct sampling inspection on all products, and unqualified products will be prohibited from leaving the factory. Quality inspection items include particle size distribution, chemical analysis, physical properties, mineral composition and pH value. These strict inspection measures can ensure the stable and reliable quality of sintered mullite and meet the needs of different customers.

In terms of packaging and transportation, sintered mullite is usually packed in 25kg plastic woven bags or kraft paper bags, and then packed in large bags of 1000-1500kg, or small bags are placed on trays and covered with plastic films. During transportation, a 20-foot container can carry 24 tons and a 40-foot container can carry 28 tons. Reasonable packaging and transportation methods can effectively protect sintered mullite from damage during transportation and ensure that products can reach customers safely and completely.

V. Summary

Sintered mullite plays an important role in the field of refractories because of its high mullite phase content, low porosity, high refractoriness, good thermal shock resistance and corrosion resistance. It is widely used in many industrial fields, such as steel, glass, ceramics, petrochemical industry and building materials, which provides a reliable guarantee for the normal operation of various high-temperature equipment. At the same time, strict quality control and reasonable packaging and transportation measures further ensure the quality and use effect of sintered mullite. With the continuous development of industrial technology, the application prospect of sintered mullite will be broader and make greater contributions to the development of modern industry.