Objective To study the influence of two- step sintering method on the sintering property, mechanical properties and microstructure of zirconia ceramic. Methods The nano- size zirconia powder were compacted and divided into two groups, one group for one- step sintering method, another group for two- step sintering method. All samples sintered at different temperature. The relative density, three- bend strength, HV hardness, fracture toughness and microstructure of sintered block were investigated. Results Two- step sintering method influenced the sintering property and mechanical properties of zirconia ceramic. The maximal relative density was 98.49% at 900 ℃/1 450 ℃ sintering temperature. There were significant difference of mechanical properties between one- step sintering and two- step sintering, the three - bend strength and fracture toughness declined, hardness increased at two - step sintering. The three- bend strength, HV hardness and fracture toughness reached to maximum value as 1 059.08 MPa±75.24 MPa, 1 377.00 MPa±16.37 MPa and 5.92 MPa·m1/2±0.37 MPa·m1/2 at 900 ℃/1 450 ℃ sintering temperature respectively. Microscopy revealed the relationship between the porosity and shapes of grains was correlated to strength of the zirconia ceramics. Conclusion Despite of the two- step sintering method influences the properties of zirconia, it also is a promising esthetic all- ceramic dental material.
