Fully stabilized zirconia ceramics belong to the cubic fluorite type structure. Due to the existence of oxygen octahedral voids in the fluorite structure, this relaxed structure is conducive to the diffusion and migration of cations, and has strong solid electrolyte conductivity, especially solid solution. After incorporating the stabilizer, a large number of oxygen vacancies are formed, resulting in good oxygen ion conductivity.
At present, fully stabilized zirconia oxygen sensors doped with yttrium oxide have been used as the basic means of oxygen quantitative analysis in many work analysis processes, and the operating temperature is between room temperature and 900 °C. The particularity of the working conditions requires the material to have a certain thermal shock resistance. However, the fully stabilized zirconia ceramic itself has a large thermal expansion coefficient and low thermal conductivity. After being impacted, the strength decreases rapidly, and the product will fail after micro-cracks or macro-cracks appear inside. Generally, the oxygen sensor for automobiles is replaced once a year, and some industrial oxygen sensors for measuring molten steel fail even after one use. Therefore, the development of fully stabilized zirconia with high thermal shock resistance is extremely important.
The main feature of the fully stabilized zirconia product is that the product includes a matrix and whiskers distributed throughout the matrix. The matrix is yttria-doped fully stabilized zirconia, the whiskers as described above are alpha alumina whiskers with an average length of 1-50 μm, and the doped molar percentage of yttria (accounting for the total matrix) is 4- 12 mol %, and the weight percentage of the alumina whiskers is 5-25 wt %. In addition, the ceramic material may also contain 0-3 wt% of one or more sintering aid components of MgO, SiO2, CaO and Al2O3.
