Recently, many people have asked me if the ceramic processing is what they imagine is the bowl processing. In fact, it is not. Ceramic processing mainly refers to products like zirconia ceramics. The physical and chemical properties of zirconia ceramics, such as high hardness, low thermal conductivity, high melting point, high temperature corrosion resistance, chemical inertia and amphoteric properties. The disadvantage of zirconia ceramics is that it is too brittle. As long as the toughness of zirconia materials is strengthened, its reliability and service life can be increased, so that zirconia ceramics can become a widely used new material. So the toughening technology of zirconia ceramics has been very popular. Here I introduce the toughening methods and applications of zirconia ceramics for you.

   The toughening methods of ceramics include phase transformation toughening, particle toughening, fiber toughening, self-toughening, dispersion toughening, synergistic toughening and nano-toughening. 

1.Composite toughening.

   It refers to the toughening of ZrO2 ceramics by using several toughening mechanisms at the same time. In practice, toughening mechanism is selected according to the different functions of zirconia ceramics. 

2. Phase transformation toughening

   Phase transformation toughening refers to the metastable tetragonal t-ZrO_2 phase transformation under the action of the crack top stress field, forming monoclinic phase, expanding the crack volume, then forming compressive stress on the crack, hindering the crack growth, and playing a toughening role. In addition, external

conditions (such as laser shock, fatigue cracking resistance, low temperature, grain size and content, critical change energy, etc.) have a great influence on phase

transformation toughening of zirconia ceramics. If the stress and volume change of phase transformation occurs, the products will crack easily. Therefore, in the production process, the influence of external factors on phase transformation toughening of zirconia ceramics should be prevented. 

3. Micro-crack toughening 

   Micro-crack toughening refers to the addition of tough materials when the crack stress is maximum, so that micro-cracks can occur and reach the intent of the 

scattered stress, reduce the motive force of the crack, and then add the toughness of the material. The residual strain energy effect and microcracks often occur 

when the material undergoes phase transformation. Therefore, the effect of phase change toughening is obvious. 

4. Particle Toughening

   Particle toughening refers to adding particles to ZrO 2 ceramic powders as toughening agent. Although the effect is not as good as whiskers and fibers, it still has toughening effect if the particle type, particle size, content and matrix material are selected properly. Its advantage is that the method is simple, toughening at the same time will bring high temperature strength and high temperature creep function improvement. The toughening mechanism of particle toughening mainly includes grain refinement and crack steering bifurcation.

5. DISPERSION TOUGHENING

   DISPERSION TOUGHENING mainly refers to the toughening of ceramic matrix by tetragonal ZrO2 particles. Besides the mechanism of phase transformation toughening, there is also the mechanism of dispersion toughening of second phase particles. Before crack propagation, the residual strain energy of the ceramic itself must be overcome, and then the intention of toughening can be reached. 

6. Fiber Toughening

   Fiber and whisker toughening principle is to add closing stress to the crack surface because of deformation, cancel the external stress at the crack top,passivate

the crack growth, and then play a toughening role. In addition, when crack growth, the cylindrical crystal also has to overcome the frictionforce when pulling out, which will also play a toughening role. 

7. Self-toughening

   Because of the existence of columnar crystals in zirconia ceramics, crack initiation and deflection will occur during the cracking process of zirconia ceramics, and the way of crack propagation will be changed and added. Then passivation crack adds the resistance of crack propagation to achieve the purpose of toughening.