Objective To investigate the microstructure of dental zirconia ceramics prepared by two-step sintering.Methods Nanostructured zirconia powder was dry compacted, cold isostatic pressed, and pre-sintered. The pre-sintered discs were cut processed into samples. Conventional sintering, single-step sintering, and two-step sintering were carried out, and density and grain size of the samples were measured. Afterward, T1 and/or T2 of two-step sintering ranges were measured. Effects on microstructure of different routes, which consisted of two-step sintering and conventional sintering were discussed. The influence of T1 and/or T2 on density and grain size were analyzed as well.Results The range of T1 was between 1 450 ℃ and 1 550 ℃, and the range of T2 was between 1 250 ℃ and 1 350 ℃. Compared with conventional sintering, finer microstructure of higher density and smaller grain could be obtained by two-step sintering. Grain growth was dependent on T1, whereas density was not much related with T1. However, density was dependent on T2, and grain size was minimally influenced.Conclusion Two-step sintering could ensure a sintering body with high density and small grain, which is good for optimizing the microstructure of dental zirconia ceramics.
