两次烧结工艺对氧化锆陶瓷性能的影响

Effect of two-step sintering method on properties of zirconia ceramic

目的研究两次烧结工艺对氧化锆陶瓷的烧结密度、机械性能和显微结构的影响。方法将纳米氧化锆粉体静压成型,分别采用一次烧结和两次烧结两种热处理方式,在不同的烧结温度下烧结,对不同烧结方式和烧结温度下材料的烧结密度、三点挠曲强度、维氏硬度和断裂韧性进行测量分析,并通过扫描电镜观察试件的断裂面形貌。结果两次烧结与一次烧结相比,氧化锆陶瓷烧结体的密度、三点挠曲强度、维氏硬度及断裂韧性存在差异。在900℃/1450℃烧结温度时,两次烧结氧化锆陶瓷烧结体相对密度最高(98.49%),机械性能最佳,三点挠曲强度、维氏硬度和断裂韧性分别为1059.08MPa±75.24MPa、1377.00MPa±16.37MPa和5.92MPa·m1/2±0.37MPa·m1/2。两次烧结使氧化锆陶瓷烧结体的内部孔隙略有增多,部分晶粒长大且大小不均匀。结论两次烧结工艺对氧化锆陶瓷的性能虽有一定影响,但材料的各项性能均可满足临床要求。

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 zireonia 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·m^1/2 ± 0.37 MPa·m^1/2 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.