粉体粒度及预烧结升温速度对口腔再生氧化锆陶瓷性能的影响

Effects of powder size and pre-sintering heating rate on dental recycled zirconia

目的探讨预烧结工艺及粉体粒度对口腔再生氧化锆性能的影响。方法将口腔再生氧化锆粉体筛分为大颗粒(粉体粒度>50 μm且≤125 μm)及小颗粒(粉体粒度≤50 μm)两种,并分别压制成试样。将再生氧化锆粉坯依据预烧结升温速度分为A、B、C组,设置预烧结升温速度分别为2、5、8 ℃/min。以商用氧化锆预烧结体为对照,检测预烧结体的相对密度、显气孔率及切削面边缘缺口宽度。按厂家终烧结参数对各组氧化锆预烧结体进行终烧结,比较终烧结体的相对密度、显气孔率、线性收缩率及弯曲强度。通过扫描电镜观察终烧结体断裂面形貌,并用X射线衍射分析各组物相组成。结果相同粉体粒度下(大颗粒或小颗粒),A、B、C组再生氧化锆预烧结体的相对密度及显气孔率差异均无统计学意义(P>0.05)。对照组终烧结体弯曲强度为(988.4±129.8)MPa,显著大于大颗粒A、B、C组[分别为(421.2±54.7)、(444.2±70.1)、(427.5±68.4)MPa]和小颗粒A、B、C组[分别为(750.1±74.1)、(777.2±95.5)、(746.7±73.0)MPa](P<0.05);小颗粒A、B、C组弯曲强度均分别显著大于相应大颗粒A、B、C组(P<0.05)。结论与大颗粒再生氧化锆粉体相比,小颗粒再生氧化锆粉体可有效改善再生氧化锆终烧结体的弯曲性能,预烧结升温速度对再生氧化锆性能没有影响。

Objective To evaluate the effects of pre-sintering heating rate and powder size on dental recycled zirconia.Methods Recycled zirconia powders were sieved to obtain the large(50μm<particle diameter≤125μm)and small(particle diameter≤50μm)particles,these powders were then formed into green bodies.According to the pre-sintering heating rates,the recycled-zirconia green bodies were divided into 3 groups:group A,pre-sintering heating rate of 2℃/min;group B,pre-sintering heating rate of 5℃/min;group C,pre-sintering heating rate of 8℃/min.The relative density open porosity and machinability of the recycled zirconia pre-sintered bodies were evaluated and compared with the commercial zirconia pre-sintered bodies.Zirconia pre-sintered bodies were then fully sintered according to the manufacturer′s instructions.The relative density,open porosity,linear shrinkage and flexural strength of fully sintered zirconia were further compared.The microstructure of fracture surfaces and the crystalline structure were analyzed by scanning electron microscope and X-ray diffractometer,respectively.Results With the same particle size,the recycled zirconia pre-sintered at different heating rates showed no significant differences in the relative densities,and the open porosities(P>0.05).When the pre-sintering heating rates were 2℃/min,5℃/min,and 8℃/min,the flexural strengths of the large-particle recycled zirconia were(421.2±54.7),(444.2±70.1)and(427.5±68.4)MPa,the flexural strengths of the small-particle recycled zirconia were(750.1±74.1),(777.2±95.5)and(746.7±73.0)MPa,respectively.The flexural strength of commercial zirconia was(988.4±129.8)MPa.The flexural strengths of the recycled zirconia were significantly lower than that of the commercial zirconia(P<0.05).At the same pre-sintering heating rate,the flexural strengths of the small-particle recycled zirconia were significantly higher than that of the large-particle recycled zirconia(P<0.05).Conclusions Compared with the large particles,small-particle recycled zirconia powders can effectively improve the properties of recycled zirconia,while the pre-sintering heating rate has no effect on the properties of the recycled zirconia.