Which type of ceramic is the most toughness?

Ceramics have extremely high toughness. These varieties are worthy of attention.

The toughness of ceramics

Ceramics are a type of non-metallic inorganic material that is formed at high temperatures. They possess excellent wear resistance, corrosion resistance, and heat resistance. However, due to their brittleness, ceramics are prone to cracking when subjected to strong forces or impact loads. Therefore, the research on how to enhance the toughness of ceramics to meet the requirements of various industrial applications has become a research hotspot.

Strongly resilient ceramic varieties

1. Zirconia ceramic

Zirconia ceramic, usually referred to as ZrO2, is a wear-resistant material. Compared with traditional ceramics, zirconia ceramic has better strength and toughness, and is widely used in the manufacturing of cutting tools, bearings, valves, and mechanical parts, etc.

2. Silicon carbide ceramic

Silicon carbide ceramic, usually referred to as SiC, due to its excellent heat resistance, corrosion resistance, and hardness, has become an engineering ceramic with wide applications. In addition, silicon carbide ceramic has high toughness and anti-wear performance, and can be used to manufacture high-speed cutting tools, etc.

3. Silicon nitride ceramic

Silicon nitride ceramic, usually referred to as Si3N4, is a widely used engineering ceramic. Compared with silicon carbide ceramic, silicon nitride ceramic has higher toughness and better corrosion resistance. Therefore, silicon nitride ceramic is widely used in the manufacturing of bearings, seals, and high-temperature tools, etc.

4. Alumina ceramic

Alumina ceramic, usually referred to as Al2O3, is an engineering ceramic widely used in the manufacturing of mechanical parts, disk drives, and thermal-sensitive electronic devices, etc. Alumina ceramic still has good toughness and wear resistance at high temperatures, and is more resilient than other ceramics, being less prone to cracking.

Strongly resilient ceramic varieties include zirconia ceramics, silicon carbide ceramics, silicon nitride ceramics and alumina ceramics. As people's demands for the material properties in extreme environments such as high temperature and high pressure continue to increase, the development prospects of ceramic materials remain very broad.

What is the toughest ceramic?

The ceramic with the best toughness is zirconia ceramics. Its fracture toughness can reach 15 MPa·m¹/², and this characteristic is mainly attributed to the phase transformation toughening mechanism of tetragonal zirconia.

The toughness characteristics of zirconia ceramics

Zirconia ceramics (especially yttrium-stabilized tetragonal polycrystalline zirconia, Y-TZP) are currently the ceramics with the highest known fracture toughness. By doping with stabilizers such as yttrium oxide (Y₂O₃), the tetragonal phase of zirconia can exist stably at room temperature. When cracks propagate, the stress at the crack tip will induce a transformation from the tetragonal phase to the monoclinic phase. The volume expansion generates compressive stress that can hinder the further propagation of the cracks, thereby achieving phase transformation toughening.

Key performance data:

Fracture toughness range: 7.0 - 15.0 MPa·m¹/² (ordinary zirconia > 7 MPa·m¹/², Y-TZP can reach up to 15 MPa·m¹/²);

Hardness: HV1250, approximately 80% of that of alumina ceramics, but the toughness is more than three times that of the latter;

Thermomechanical strengthening technology: includes phase transformation strengthening, micro-crack strengthening, and zirconia particles reinforcing other ceramic matrices (such as ZTA ceramics).

Comparison with other high-toughness ceramics:

Silicon nitride ceramics: Excellent comprehensive performance (high temperature resistance, self-lubrication, etc.), but the fracture toughness is usually 6 - 8 MPa·m¹/², lower than that of zirconia ceramics;

Silicon carbide ceramics: The toughness can be increased to 16.5 MPa·m¹/² after fiber/whisker reinforcement, but such composites do not belong to a single ceramic category;

Alumina ceramics: The highest hardness (Mohs hardness 9), but the fracture toughness is only 3 - 4 MPa·m¹/², and the wear resistance is only 1/15 of zirconia.