Fabrication And Properties Of Yttria-Stabilized ZrO₂?YSZ?Transparent Ceramics

Yttria-stabilized ZrO2 transparent ceramics have a refractive index of 2.16 in the visible wavelength range,which is higher than traditionally optical glasses and resins.YSZ transparent ceramics can be used as optical lens,which satisfies the development trends to miniaturization and increased viewing angle of modern optical devices,such as microscopes,digital cameras and telescopes.In addition,YSZ transparent ceramics also have potential for the transparent armors,infrared windows and domes due to the excellent optical and mechanical properties.High-quality YSZ transparent ceramics have been successfully fabricated in some foreign research institutes using commercially available YSZ powders(Tosoh Corporation,Japan)as the starting materials However,the domestic researches on YSZ transparent ceramics are basically still in the stage of powder synthesis and small-sized samples,and the transmittance in the visible wavelength range is still far from that of foreign samples.Therefore,we need to explore the powder synthesis process to prepare YSZ nanopowders with good dispersion and high sinterability,and then optimize the sintering process to fabricate YSZ transparent ceramics with high transparency.Based on the above background,the main contents of the thesis are as follows1.Y0.16Zr0.84O1.92 nanopowder was synthesized by the co-precipitation method using low-cost and well-sourced zirconium oxychloride and yttrium nitrate as raw materials,and ammonia was used as the precipitant.The phase and morphology of the Y0.16Zr0.84O1.92 nanopowder calcined at 800? for 4 h were investigated.The results showed that the Y0.16Zr0.84O1.92 nanopowder was cubic YSZ and weak-agglomerated.Using this nanopowder as starting material,Y0.16Zr0.84O1.92 ceramics were successfully fabricated by air pre-sintering combined with HIP post-treatment without sintering additives.In-line transmittance of the ceramics with the thickness of 1.0 mm reached 65.3%at 800 nm2.In order to further optimize the dispersion of Y0.16Zr0.84O1.92 nanopowders,the influences of terminal pH value on the properties of Y0.16Zr0.84O1.92 precursors,calcined powders and ceramics were systematically investigated.It was found that the Y0.16Zr0.84O1.92 nanopowder with terminal pH=9.0 showed the lowest agglomeration,indicating the best dispersion and sinterability.With the increase of terminal pH value,the transmittance of ceramics increased firstly and then decreased The Y0.16Zr0.84O1.92 ceramics with terminal pH=9.0 had the homogeneous microstructure and best transparency,and in-line transmittance of the ceramics with the thickness of 1.0 mm reached 67.8%at 800 nm3.In order to further enhance the transmittance of Y0.16Zr0.84O1.92 transparent ceramics,the influences of pre-sintering temperature on the microstructure and optical quality of Y0.16Zr0.84O1.92 ceramics were systematically studied.The results showed that the HIP-treated Y0.16Zr0.84O1.92 ceramics pre-sintered at 1300? showed the best transparency,and in-line transmittance of the ceramics with the thickness of 1.0 mm reached 67.8%at 800 nm,which was close to the theoretical transmittance.