Study On β-sialon Combining Zirconia Composites

Zirconia ceramic has attracted widelyattention by scholars from different countries due to its strength high-toughness, high hardness and good chemical stability and so on. At present, as its thermal shock resistance ispoor that limited their application in certain areas. Therefore, one alternative for improvement of thermal shockresistance properties of Zirconia is the addition of Sialon as a second reinforced phase with high strength, goodchemicalandthermalstability.Sialon material has been prepared by metal reduction-nitridation method and nonhydrolytic sol-gelcombining reduction-nitridation method. β-Sialon/ZrO₂compound materials were prepared by different ways.TheeffectofadditionsandZvaluesofβ-Sialonpowderonthepropertiesofthecompositeswereinvestigated.β-SialonwithdifferentZvalues（1,2and3）waspreparedbymetalreduction-nitridationmethod.β-Sialonpowderwaspreparedbythenonhydrolyticsol-gelcombiningcarbothermalreductionnitridationmethods.β-SialonbondedZrO₂composites were prepared by reaction sintering process using β-Sialon and CaOstabilized ZrO₂powders as raw materials. The results show that the samples with10wt%of β-Sialon additionhadthelowestapparentporosity（29.80%）andthehighestofflexuralstrength（68.70MPa）.Incarbonprotectionregimes,thethermalshockresistanceofthecompositescouldbeimprovedbyaddtionof5wt%β-Sialon.Itmaybe relative with that the sample had the lowest thermal expansion coefficient in vacuum. The samples with Z=2ofβ-Sialonadditionhadthehighestofflexuralstrength（71.46MPa）.ThesampleswithZ=1ofβ-Sialonadditionhad highest of thermal shock resistance and the lowest thermal expansion coefficient. The main crystallinephasesareβ-Sialon,m-ZrO₂,c-ZrO₂incomposites.β-SialonbondedZrO₂composites were prepared by nitridation in the flowing nitrogen atmosphere, usingSi powder,Al powder,Al2O3and ZrO₂as starting materials. Results show that the samples with10wt%of β-Sialon had the lowest apparent porosity and the highest of flexural strength. In carbon protection regimes, thethermal shock resistance of the composites with content of5wt%β-Sialon were the best, and the Residualflexuralstrengthretentionrate wereimproved30%comparedwiththe ZrO₂.ThesampleswithZ=3ofβ-Sialonhad the highest of flexural strength （84.37MPa）. The samples with Z=1,2of β-Sialon addition had the highestthermalshockresistance.Themaincrystallinephasesincompositesareβ-Sialon,m-ZrO₂,c-ZrO₂,ZrN.