两步烧结对牙科氧化锆陶瓷微观组织的影响

Influence on microstructure of dental zirconia ceramics prepared by two-step sintering

目的研究两步烧结工艺对牙科氧化锆陶瓷微观组织的影响。方法纳米氧化锆经过干压、冷等静压成型后预烧，切削加工成试样，采用传统烧结、单步烧结和两步烧结工艺，通过对试样密度和晶粒大小的测定，得出了两步烧结中较高温度T1与较低温度T2的大致范围，对比了两步烧结与传统烧结的微观组织，研究两步烧结中T1、T2对微观组织的影响。结果两步烧结中T1、T2的大致范围分别为1450—1550℃和1250—1350℃；两步烧结相对于传统烧结，密度更高，晶粒更细，组织更均匀；T1主要影响晶粒尺寸，对致密度影响不大；T2主要影响致密度，而对晶粒大小影响不明显。结论两步烧结能够在高致密化情况下细化晶粒，有利于优化牙科氧化锆陶瓷材料的微观组织。

Objective To investigate the microstrucUlre 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 siutering 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 ofT2 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.