In the field of technical manufacturing, zirconia ceramics and silicon nitride ceramics are two important thermal performance materials. Their chemical properties, physical properties and application fields are significantly different. In this paper, the differences between these two ceramic materials will be analyzed from the aspects of chemical composition, physical properties, thermal mechanical properties and application fields.

1. Chemical composition

Zirconia ceramics (Al₂O₃·nH₂O)

Zirconia ceramics are formed by combining Al₂O₃ with water, the chemical formula is Al₂O·nH₂O. The main component is dialumina, and the most common includ are Al₂O₃·6H₂O(CA) and Al₂O₃·2H₂O(ST).

CA type zirconia ceramics are made of high purity alumina and water, the melting point is about 1677°C, and the Koves strengthening is high.

ST type zirconia ceramics combine with less water in Al₂O₃, have a slightly lower melting point than type CA, and a decomposition temperature of about 1700°C(4H₂O) to 1450°C(2H₂O).

Silicon nitride ceramics (Si₃N₄)

Silicon nitride ceramics are formed by combining silicon (Si) and nitrogen (N). The chemical formula is Si₃N₄. It is a high-performance ceramic material with a six-valent aluminum ion structure and a stable alkaline aluminate structure.

2. Physical properties and thermal properties

Zirconia ceramics

Melting point: Zirconia ceramics have a melting point between 1550°C and 1800°C, depending on their water content. CA type zirconia ceramics have a higher melting point (about 1700°C) and are more resistant to high temperatures.

Hardness: The hardness of zirconia ceramics is moderately high, but the hardness is lower than that of silicon nitride ceramics.

Fracture toughness: zirconia ceramics have a certain degree of fracture toughness, but it is prone to micro-cracks at high temperatures.

Thermal conductivity: The thermal conductivity of zirconia ceramics is better, but not as good as silicon nitride ceramics.

Silicon nitride ceramics

Melting point: The melting point of silicon nitride ceramics is about 2500°C(crystal melting point), and the decomposition temperature is about 1400°C to 1500°C.

Hardness: Silicon nitride ceramics are extremely hard, second only to diamond, and have excellent wear resistance.

Fracture toughness: silicon nitride ceramics have a very low fracture toughness, with a unique "break without cracking" characteristics.

Thermal conductivity: The thermal conductivity of silicon nitride ceramics is poor, but its stability is higher and it is suitable for high temperature environment.

3. Thermal mechanical properties

Zirconia ceramics

Zirconia ceramics have certain thermal expansion strength (CS) and thermal toughness, but micro-cracks are easy to occur at high temperatures. Its thermodynamic properties are suitable for mechanical parts with moderate temperature ranges.

Silicon nitride ceramics

The thermal expansion strength (CS) of silicon nitride ceramics is generally high, but its thermal toughness is poor. It shows better wear resistance and stability at high temperatures, so it is often used in high temperature mechanical parts and shear and torsion materials.

4. Application field

Zirconia ceramics

High temperature mechanical parts: Zirconia ceramics are commonly used in high temperature mechanical parts, such as engine blades, ayar.valley cooling chambers and ball valves.

Medical devices: Zirconia ceramics have good biocompatibility and are widely used in medical devices such as artificial joints and dental implants.

Sensors: Its excellent insulation and electrical conductivity make it an ideal material for sensor packages and capacitors.

Ceramic composites: Zirconia ceramics are often combined with other materials (such as carbon fiber, glass ceramics, titanium alloy) for high-strength, abrsion-resistant structural parts.

Silicon nitride ceramics

Electronic components: Good ceramics suitable for high voltage, high frequency electronic components, with excellent insulation properties and radiation resistance.

Advanced solder: Silicon nitride ceramics are widely used as advanced solder for microelectronic components, especially for high-temperature welding materials.

High-temperature engine parts: As a high-temperature stable ceramic material, it is used in supercharger boiler cover, jet pipe, engine components and other parts.

Corrosion resistant materials: Silicon nitride ceramics exhibit excellent corrosion resistance in high temperature, high purity corrosive environments and are commonly used in chemical processing equipment and industrial pipelines.

5. Select the basis

High mechanical performance requirements: If you need high strength, wear resistance and low fracture rate of materials, it is recommended to choose silicon nitride ceramics.

High requirements for thermomechanical properties: for high temperature parts, zirconia ceramics are more suitable because of their higher melting point.

High requirements for corrosion resistance: silicon nitride ceramics perform well in strong acid, alkali or corrosive environments and are suitable for corrosion resistance.

Limited budget: Compared with silicon nitride ceramics, zirconia ceramics cost less, suitable for low-end applications.

6.Summarize

Zirconia ceramics: suitable for mechanical parts, medical devices, sensors and other fields in medium to high temperature environments.

Silicon nitride ceramics: suitable for high temperature, high strength, high corrosion resistance of electronic components, engine components, advanced solder and other fields.

According to the specific application requirements, choosing the right material is the key. I hope the above analysis can help you in the selection of materials!