MgO和TiO2烧结助剂对凝胶注模成型氧化锆增韧氧化铝陶瓷性能的影响

目的探讨加入氧化锆增韧氧化铝（ZTA）基体粉体质量分数5%的烧结助剂对凝胶注模成型工艺制备牙科ZTA纳米复合陶瓷烧结性能和力学性能的影响。方法将微米氧化铝和纳米氧化锆按质量比4∶1配置体积分数为55%的浆料，同时加入基体粉体质量分数5%的烧结助剂MgO、TiO2，按二者比例的不同分0、1、2、3、4号组。各组凝胶注模成型后，分别在1 150、1 200、1 300、1 400、1 450、1 500、1 600 ℃下保温2 h，冷却后取出抛光，测其三点抗弯强度、线收缩率、相对密度，扫描电镜观察其断面形态。结果添加1%MgO和4%TiO2烧结助剂组（1号组）具有最高的抗弯强度，1 600 ℃保温2 h后达（401.78±19.50）MPa，高于0号组（380.64±44.50）MPa。MgO含量为基体粉体质量分数2%及以上时，对烧结致密后陶瓷的抗弯强度起降低作用，均比0号组低。MgO含量高于2%及以上，含烧结助剂各组相对密度升高的速率没有明显的区别。烧结温度高于1 200 ℃后各组均出现明显的收缩，且含烧结助剂组均高于0号组。结论含1%MgO和4%TiO2烧结助剂的ZTA纳米复合陶瓷具有最佳的力学性能。MgO含量为基体粉体质量分数2%及以上时，对ZTA纳米复合陶瓷相对密度速率的提高没有明显的作用，且对ZTA纳米复合陶瓷的力学性能起降低作用。

Influence of MgO and TiO2 on mechanical properties of zirconia toughened alumina ceramics formed by gel-casting technique

Objective The objective of this study is to investigate the influence of mechanical properties and sintering performance by adding 5% weight percentage aids to nano-compound zirconia toughened alumina（ZTA） ceramics. Methods Micrometer Al2O3 and nanometer ZrO2（quality ratio 4 ∶ 1） were used to get 55% volume percentage slurry. Magnesium oxide and titanium oxide were taken as aids which were 5% weight percentage of the Al2O3 and ZrO2 powder. Five groups（number 0, 1, 2, 3, 4 group） were divided according to different proportion of aids. After gel-casting, the porcelain pieces were sintered at 1 150, 1 200, 1 300, 1 400, 1 450, 1 500, 1 600 ℃ for 2 hours. Static three-point flexure strength, line shrinkage, relative density were measured and scanning electron microscopy（SEM） was used to observe section. Results Number 1（MgO 1%, TiO2 4%） group had the highest bending strength. It was （401.78±19.50）MPa after sintering at 1 600 ℃ for 2 hours and was higher than 0 group （380.64±44.50）MPa. Bending strength became lower than 0 group when MgO was more than 2% or more than that weight percentage of ZTA powder. When MgO content was higher than 2% or more than that weight percentage, there was no difference in relative density raising rate between each sintering assistants groups. When the sintering temperature was higher than 1 200 ℃, all groups showed obvious line-shrinkage and the groups which contained sintering assistants were all was higher than 0 group. Conclusion Adding MgO and TiO2 aids from 1% to 4% weight percentage of ZTA will promote fritting and increase ZTA nano -compound ceramics mechanical properties. Adding 2% MgO aids or more than that weight percent will has no obvious help to increase the relative density raising rate of ZTA nano -compound ceramics and will degrade the mechanical properties of ZTA nano-compound ceramics.