Studies On Zirconia Ceramics Toughened By Lanthanum Oxide And Nano Silicon Dioxide And Its Correlational Mechanical Properties

Objective: By adding different proportion of lanthanum oxide?La₂O₃?and nano silicon dioxide?SiO₂?to the zirconia ceramic powders,explore the optimal adding proportion,in order to make the fracture toughness,bending strength,vickers hardness and volume density of zirconia ceramics best,and by scanning electron microscopy?SEM?,to observe micro-morphology of rupture surface of specimens,to explore the change of the material density.Methods: The content of La₂O₃ and nano SiO₂ were 0,0;0.5wt%,0;1wt%,0;0,0.5wt%;0,1wt%;0.5wt%,0.5wt%;0.5wt%,1wt%;1wt%,0.5wt% as well as 1wt%,1wt%,respectively.Followed by A group,B₁ group,B₂ group,C₁ group,C₂ group,D₁ group,D₂ group,D₃ group,D₄ group.A group as the control group,B₁,B₂,C₁,C₂,D₁,D₂,D₃,D₄ group as the experimental group.Mill with ball bead,blend,dewater,dry Mixed powder,compress powder into the standard shape With cold isostatic pressing machine,Two sections of sintering process is adopted to start the pressureless solid phase sintering.Get fracture toughness specimens of 25 mm x 2.5 mm x 5 mm specification,and bending strength and hardness of the specimens of 35 mm x 3 mm x 4 mm specification,grind up and down surface of specimens in polishing machine,clean specimens with ultrasonic wave in anhydrous ethanol and acetone,dry specimens,set aside,test fracture toughness,flexural strength,vickers hardness and bulk density,randomly observe microscopic morphology of fracture surface of fracture toughness specimens with scaning electron microscopy?SEM?to determine its density.Results: In addition to the D₃ and D₄ group,the data of the rest of the groups are significant differences?p<0.05?;by comparing the B and C group,found La₂O₃ is better than that of nano SiO₂ in improving the zirconia ceramics performances;and C₂ group is better than C₁ group;B₁ group is better than B₂ group;D₂ group is the best.Scanning electron microscopy?SEM?observation shows,D₂ group grains uniform and closely arrange.Density of D₃,D₄ group is lower than that of A group,The rest of the groups are better than that of A group,the rest of the groups are lower than D₂.Conclusions: In improving the zirconia ceramics performances,La₂O₃ and nano SiO₂ create synergies,La₂O₃ is better than nano SiO₂.When the content of La₂O₃ is 0.5wt %,the adding amount of nano-SiO₂ is 1wt %,the mechanical properties of zirconia ceramics is the best.