There are several main methods to improve the toughness of alumina ceramics:
1. Zirconia toughening: This is the most commonly used toughening method. When an appropriate amount of zirconia (ZrO2) is added to alumina, its toughness can be significantly improved. The toughening effect mainly comes from mechanisms such as the refinement of the alumina grain matrix, the phase transformation toughening of zirconia, microcrack toughening, and crack steering and bifurcation.
2. Whiskers and fiber toughening: Whiskers are ceramic single crystals with a high aspect ratio, and the fiber length is several times longer than ceramic whiskers. They can all be added to alumina ceramics as toughening reinforcements. The addition of whiskers or fibers can increase the fracture surface, that is, increase the crack propagation channel. When the crack extends to the fibers (whiskers), pull-out, debonding, and fracture of the fibers (whiskers) will occur, thereby consuming fracture energy and improving the toughness of the ceramic.
3. Particle toughening: Adding particles with high elastic modulus (such as SiC, TiC, TiN, etc.) to alumina materials can cause cracks to deflect and bifurcate when the material fractures, consuming fracture energy, thereby improving toughness. Although the toughening effect of particles is not as good as that of whiskers and fibers, the uniform mixing of raw materials and sintering densification are simpler and easier than fiber and whisker composites.
4. Alumina self-toughening: Ceramics prepared from nanoscale alumina powder show excellent superplasticity at low temperatures. This nanomaterial can improve the shape and grain boundary properties of ceramic grains, thereby increasing its toughness.
5. Introduce the second phase: Introduce the second phase into the matrix of alumina ceramics so that it fills the grain boundaries of alumina, which is beneficial to blocking the propagation of cracks and thereby improving the fracture toughness of the ceramics. For example, zirconia-toughened alumina uses this method.
6. Adding alumina seed crystals: The addition of alumina seed crystals can promote the anisotropic growth of crystal grains and form flaky or columnar crystal grains, similar to whiskers, which can cause crack deflection, grain pull-out, and connection toughening of ceramics. role.
These methods can be used alone or in combination to improve the toughness of alumina ceramics. The specific choice depends on required performance, cost and application scenarios. Now ZTA toughed alumina ceramics from Chemshun Ceramics manufacturer can effectively meet your higher toughness requirement
Post time: May-10-2024