Quick Links
- Mechanical Properties of Ceramic Materials
- Thermal Properties of Ceramic Materials
- Chemical Properties of Ceramic Materials
- Electrical Properties of Ceramic Materials
- Physical Properties of Ceramic Materials
|
Characteristic |
Ceramic material |
|||||
|
|
Oxide ceramic |
Non-oxide ceramic |
Special functional ceramics |
|||
|
|
Al2O3 |
ZrO2 |
SiC |
Si3N4 |
AlN |
BaTiO3 |
|
Density |
3.95-3.98 g/cm³ |
5.68-6.1 g/cm³ |
3.1-3.2 g/cm³ |
3.2-3.3 g/cm³ |
3.26 g/cm³ |
5.85 g/cm³ |
|
Flexural strength |
300-630 MPa |
800-1500 MPa |
350-550 MPa |
600-900 MPa |
300-450 MPa |
– |
|
Compressive strength |
2000-4000 MPa |
2000-2500 MPa |
2000-3500 MPa |
2500-3500 MPa |
– |
– |
|
Elastic modulus |
380-400 GPa |
200-210 GPa |
410-440 GPa |
300-320 GPa |
310-320 GPa |
– |
|
Thermal conductivity |
20-30 W/(m·K) |
2-3 W/(m·K) |
80-150 W/(m·K) |
15-50 W/(m·K) |
170-200 W/(m·K) |
– |
|
Coefficient of thermal expansion |
8.0×10⁻⁶/°C |
10.5×10⁻⁶/°C |
4.0×10⁻⁶/°C |
3.0×10⁻⁶/°C |
4.5×10⁻⁶/°C |
6.0×10⁻⁶/°C |
|
Maximum operating temperature |
1750°C |
2400°C |
1600°C |
1400°C |
– |
– |
|
Hardness (Vickers) |
15-19 GPa |
12-14 GPa |
22-28 GPa |
14-16 GPa |
– |
– |
|
Fracture toughness |
3.5-4.5 MPa·m½ |
6-10 MPa·m½ |
3-4 MPa·m½ |
5-8 MPa·m½ |
– |
– |
|
Dielectric constant |
– |
– |
– |
– |
8.8-9.0 |
1500-6000 |
|
Piezoelectric constant d33 |
– |
– |
– |
– |
– |
190 pC/N |
|
Resistivity |
– |
– |
– |
– |
>10¹⁴ Ω·cm |
10¹⁰ Ω·cm |
|
Hardness (Vickers) |
– |
– |
– |
– |
12 GPa |
5 GPa |
Mechanical Properties of Ceramic Materials
Hardness and wear resistance
Ceramic materials have excellent hardness and wear resistance. For example, alumina (Al2O3) has a Mohs hardness of 9, which is three times the hardness of stainless steel. This high hardness comes from the strong ionic and covalent bond structure of ceramic materials. Because of its excellent hardness, ceramic materials perform well in applications that require resistance to wear.
Compression strength and compression resistance
Compression strength and compression resistance are another outstanding feature of ceramic materials. Ceramic materials have strong compressive strength. The compressive strength of some engineering ceramics reaches 2000-4000MPa, far exceeding most metal materials.
This excellent compressive resistance gives ceramic materials unique advantages in engineering applications that withstand high pressure in some building components and mechanical parts.
Brittleness and fracture characteristics
Of course, due to the characteristics of the crystal structure, ceramic materials are prone to brittle fracture when stretched or impacted. This fracture is often sudden and there is no obvious plastic deformation process. The expansion of micro cracks is the main cause of the fracture of ceramic materials.
There are also ceramic materials with strong fracture toughness, such as yttria-stabilized zirconia, which has stronger fracture toughness than general ceramic materials.
Elastic modulus and stiffness
Most ceramic materials have a high elastic modulus, which makes it difficult for them to produce large deformations when subjected to force. For example, the elastic modulus of alumina reaches 380GPa. This high stiffness property allows ceramic materials to maintain dimensional stability.
Thermal Properties of Ceramic Materials
High temperature resistance
Most ceramic materials have extremely high melting points, such as alumina (Al2O3) with a melting point of 2072°C, and zirconium oxide (ZrO2) with a melting point of 2715°C.
Their excellent high temperature resistance mainly comes from strong chemical bonding and stable crystal structure. Even in extreme temperature environments, ceramic materials can maintain the stability of physical and chemical properties.
Thermal conductivity
The thermal conductivity of ceramic materials is diverse, which provides you with choices for different application scenarios. Some ceramic materials such as aluminum nitride (AlN) have high thermal conductivity (170-200 W/m·K), which can help you quickly dissipate heat in electronic products and are excellent electronic packaging materials. Zirconia, on the other hand, has low thermal conductivity (2-3 W/m·K) and is an ideal heat shielding and insulation material.
Thermal expansion properties
Ceramic materials usually have low thermal expansion coefficients. For example, alumina has a linear thermal expansion coefficient of about 8×10-6/℃, which is much lower than most metal materials. This allows it to maintain dimensional stability in high-temperature applications. This property is extremely important in applications in some precision instruments and optical systems.
Thermal shock resistance
The thermal shock resistance of ceramic materials is relatively weak, and you need to pay special attention to it in various applications. When ceramic materials are subjected to rapid temperature changes, due to their poor thermal conductivity and anisotropic thermal expansion coefficient, thermal stress is easily generated inside, resulting in cracking or damage.
Chemical Properties of Ceramic Materials
Chemical stability
This is one of the most notable features of ceramic materials. This stability comes from strong chemical bonding forces, especially the combined effects of ionic bonds and covalent bonds. Alumina (Al2O3) exhibits extremely high chemical stability over a wide temperature range from room temperature to 1000°C. Even in extremely harsh environments, it can maintain the stability of its chemical structure and performance.
This stability of ceramic materials makes them particularly suitable for chemical applications.
Corrosion resistance
Ceramic materials have excellent corrosion resistance and can resist erosion by various corrosive media such as acids, alkalis, and salts. Zirconium oxide (ZrO2) is a very typical example. It can maintain good stability in strong acid and alkali environments and is an ideal material for various chemical equipment and pipeline systems.
The excellent corrosion resistance of ceramic materials is mainly attributed to the dense protective layer formed on the surface of ceramic materials, which effectively prevents further erosion by corrosive media.
Oxidation resistance
Anti-oxidation is another outstanding chemical property of ceramic materials. Many ceramic materials are oxides, such as aluminum oxide and zirconium oxide, which makes them naturally stable in high-temperature oxidizing environments. Even non-oxide ceramics, such as silicon carbide (SiC) and silicon nitride (Si3N4), will form a protective oxide film at high temperatures, further providing oxidation resistance.
Chemical inertness
The chemical inertness of ceramic materials enables them to remain stable in various chemical environments and not easily react chemically with the surrounding medium. For example, alumina is extremely inert and not easy to react with other chemicals, making it an ideal material for chemical reaction containers and laboratory utensils.
Electrical Properties of Ceramic Materials
Insulation properties
Most ceramic materials exhibit excellent electrical insulation properties. Aluminum oxide is a typical example, its resistivity can reach 1015 Ω·cm, which is much higher than most materials. This excellent insulation performance is due to its stable electronic structure and wide bandgap characteristics, which makes it difficult for electrons to jump to the conduction band. The insulation properties make ceramic materials extremely important insulating components for electrical equipment.
Dielectric properties
Ceramic materials have the characteristics of high dielectric constant and low dielectric loss. Barium titanate (BaTiO3) is a typical high dielectric constant material with a dielectric constant of thousands, which is an ideal material for making capacitors.
The dielectric properties are mainly derived from the special crystal structure and polarization mechanism, which can produce a strong polarization effect under the action of an electric field.
Semiconductor properties
Some ceramic materials can exhibit unique semiconductor properties, such as zinc oxide (ZnO) and titanium oxide (TiO2), two transition metal oxides, which can exhibit semiconductor properties through doping or defect control.
The conductivity of these materials can be controlled by temperature and doping concentration, providing more possibilities for your electronic device design.
Piezoelectric properties
Piezoelectric properties are one of the most unique electrical properties of some ceramic materials. Common piezoelectric ceramics include lead zirconate titanate (PZT), which can generate electric charge under mechanical stress. This unique property makes piezoelectric ceramics widely used in sensors, actuators and acoustic wave devices.
Physical Properties of Ceramic Materials
Density
In terms of density characteristics, the theoretical density of typical engineering ceramics, such as alumina, is about 3.95g/cm³, while the theoretical density of zirconia can reach 5.68g/cm³. In the actual manufacturing process, it is inevitable that there will be certain pores, which often make the apparent density of the ceramic material lower than the theoretical density.
Porosity
Porosity properties have an important influence on the overall performance of ceramic materials. Porosity not only affects the density of the material, but is also directly related to its mechanical properties, thermal conductivity and permeability. Therefore, we are constantly pursuing lower porosity to obtain better mechanical properties. The porosity of high-temperature sintered ceramics is usually controlled below 5%. Of course, appropriate porosity is sometimes necessary, such as in special applications such as filtration applications and biomedical ceramics, where a controllable porosity of 20-60 needs to be maintained.
Surface properties
Surface properties are a very important physical property of ceramic materials. Ceramic materials have high hardness and chemical stability on their surfaces due to their unique chemical bonding characteristics. Especially when it comes to interface bonding and surface treatment, properties such as surface energy and wettability will directly affect the application performance of ceramic materials.
Many modern ceramic materials often use surface modification technology to achieve special functions such as hydrophobicity, hydrophilicity, and antibacterial properties according to application requirements.
Conclusion
The properties of ceramic materials vary, and each material has its own unique properties. Thank you for reading this article, I hope it can help you.