Alumina ceramic is a type of porous ceramic. Its core characteristic lies in the formation of a large number of pores within the matrix through a specific process, combining the high-temperature resistance, corrosion resistance and other properties of alumina ceramics with the unique structural advantages of porous materials.

Specific characteristics of alumina ceramic

The porous structure of alumina ceramic is mainly achieved through the following methods:

l Porogenic agent method ‌

By adding solid porogenic agents (such as organic substances), when the ceramic is sintered at high temperature, the porogenic agents decompose to form pores.

l Organic foam impregnation method

Using a network of organic foam to impregnate the ceramic slurry, after sintering, the foam structure is retained to form a material with a high porosity.

Porous alumina ceramics, hailed as one of the outstanding materials in the field of "energy conservation and emission reduction", have achieved remarkable success in various fields due to their high hardness, high temperature resistance, wear resistance, excellent electrical insulation, and corrosion resistance. The raw materials are widely available and the prices are affordable, and the production process is relatively simple, making it highly cost-effective. As a result, porous alumina ceramics are widely used in purification and separation, immobilized enzyme carriers, sound absorption and vibration reduction, and sensor materials, etc. Especially in the aerospace, energy, and petroleum industries, their application prospects are immeasurable. Moreover, the types and structures of the pores in porous ceramics also have a profound impact on their performance and applications. Among them, the size of pores, pore structure, and pore volume are all key factors.

Types and classifications of pores in porous ceramics

The types and classification of pores in porous ceramics have a significant impact on their properties and applications. Based on the connectivity of the pores, porous ceramics can be divided into open-pore and closed-pore types. Closed pores refer to the pores inside the ceramic that are not connected to the outside, while open pores are connected to the outside of the ceramic and are classified as semi-open pores and through pores. Semi-open pores only exist on the surface of the ceramic and cannot penetrate internally; through pores can be connected to the outside and the internal pores are interconnected, allowing gases, liquids, and even solids to pass through.

In addition, porous ceramics can also be classified according to pore size. Large-pore porous ceramics have pore sizes larger than 100 μm and are often used in sound absorption and physical filtration fields; mesoporous and microporous porous ceramics have pore sizes ranging from 50-100 μm and less than 50 μm, respectively, and are suitable for beneficial bacteria cultivation, electrolytic cells, and vacuum suction cups, etc.

The diverse structure of porous ceramics

On the other hand, the pore structure of porous ceramics also exhibits diversity. Common structures include cross-linked rod-shaped, honeycomb-shaped, biological structure-shaped, and foam-shaped. These different pore structures of porous ceramics have their own characteristics in performance and application, providing flexible options for various needs.

Types and Applications of Porous Ceramics

Types of Porous Ceramics

Porous ceramics refer to ceramic materials with a porosity higher than 30%. Depending on different preparation methods and compositions, porous ceramics can be classified into the following categories:

1. Alumina ceramics: Made from alumina, with pore diameters ranging from 0.1 to 500 micrometers, the pore diameters are uniform and the pore channels are interconnected. They have excellent thermal stability, corrosion resistance, and mechanical strength, and are widely used in gas filtration, catalytic carriers, separation membranes, etc.

2. Zirconia ceramics: Made from zirconia, with pore diameters ranging from 0.1 to 100 micrometers, they have advantages such as high-temperature stability, corrosion resistance, and high wear resistance. They are widely used in high-temperature catalysis, high-speed abrasives, etc.

3. Silicon-nitrogen-carbon ceramics: Made from a ternary compound of silicon, nitrogen, and carbon, with pore diameters ranging from 0.1 to 500 micrometers, they have excellent thermal stability, chemical stability, and mechanical properties. They are widely used in catalyst carriers, gas separation materials, anti-corrosion coatings, etc.

Applications of Porous Ceramics

Porous ceramics possess the advantages of uniform pore distribution, adjustable pore size, heat resistance, and corrosion resistance, and are widely used in industry. The following lists the applications of porous ceramics in some typical fields:

1. Filtration: Porous ceramics can be used as filtration materials for high-temperature and high-pressure gases and liquids, and are widely applied in industrial exhaust gas, smoke, and particulate matter filtration.

2. Adsorption: Porous ceramics can be used as adsorption materials to adsorb organic substances, heavy metal ions, etc., and are widely used in environmental protection fields.

3. Catalysis: Porous ceramics can be used as catalyst carriers and are widely applied in petrochemicals, chemical reactions, and other fields.

4. Separation: Porous ceramics can be used as separation materials and are widely applied in gas separation and liquid separation fields.

In summary, porous ceramics have extensive applications in various fields, and with the continuous development of materials science, their application fields will become increasingly extensive.