Effect of grain boundary segregation on aging resistance and mechanical properties of tetravalent element-doped 3Y-TZP ceramics for dental restoration

In the humid oral environment, 3Y-TZP ceramics always suffer from low-temperature degradation (LTD) for a long time, which results in the degradation of mechanical properties and catastrophic failure. The low-temperature degradation (LTD) and mechanical properties of low-cost tetravalent (Ge4+, Ti4+) element-doped 3Y-TZP were investigated by analysing grain boundary segregation in samples with deferent contents. The results show that GeO2 is superior to TiO2 in limiting LTD but results in lower flexural strength and fracture toughness when the content is ≥1.5 mol%. This dilemma can be improved by adding only 0.1%-0.5 wt% Al2O3, and the flexural strength and fracture toughness of 0.25 wt% Al2O3 zirconia are then increased to 898 MPa and 4.68 MPa·m1/2 compared with 1Ge-3Y, respectively. This work is expected to provide an effective reference for the development and application of budget dental materials.