Toughening Zirconia Ceramic
Zirconia ceramics have unique physical and chemical properties, such as high hardness, low thermal conductivity, high melting point, high temperature, and corrosion resistance. They also have chemical inertness and amphoteric properties. These qualities develope in the application of electronic ceramics, functional ceramics, structural ceramics, and ZTA ceramics.
Toughening method of ceramics, including the versatile zirconia ceramic processes, is quite varied. These methods enhance the durability and functionality crucial to zirconia ceramics.
- Phase change toughening
Phase change toughening refers to the phase change of the metastable tetragonal phase t—ZrO2 under the action of the stress field at the crack tip. This leads to forming a monoclinic phase and generating volume expansion. As a result, compressive stress forms on the crack, hindering the crack propagation, and playing a toughening role.
- Particle toughening
Particle toughening involves using particles as a toughening agent, added to zirconia ceramics powder. Though the effect is not as good as whiskers and fibers, if the particle type, particle size, content, and matrix material properly select, there is a certain strong effect. The advantage is that it is easy to implement. The toughening leads to improved high-temperature strength and high-temperature creep properties. The toughening mechanism mainly includes refining the matrix grain and crack steering bifurcation within zirconia ceramic structures.
- Fiber toughening
The principle of fiber and whisker toughening is that the closing stress add to the crack surface due to deformation in the crystal close to the crack tip. This counteracts the external stress of the crack tip and passivates the crack propagation, thus playing a toughening role. Additionally, when the crack propagates, the columnar crystal should also overcome friction when pulling out. This will further play a toughening role within the realm of zirconia ceramics. Welcome inquiry.