A1203/5%SIC nanocomposites were fabricated by pressureless sintering using MgO as a sintering aid and then post hot-isostatic pressed （HIP）, which can subsequently break through the disadvantage of hot-pressing proc...A1203/5%SIC nanocomposites were fabricated by pressureless sintering using MgO as a sintering aid and then post hot-isostatic pressed （HIP）, which can subsequently break through the disadvantage of hot-pressing process. The MgO additive was able to promote the densification of the composites, but could not induce the grain growth of A1203 matrix due to the grain growth inhibition by nano-sized SiC particles. After HIP treatment, A12OJSiC nanocomposites achieved full densification and homogeneous distribution of nano-sized SiC particles. Moreover, the fracture morphology of HIP treated specimens was identical with that of the hot-pressed A1203/SiC nanocomposites showing complete transgranular fracture. Consequently, high fracture strength of 1 GPa was achieved for the A1203/5%SIC nanocomposites by pressureless sintering and post HIP process.展开更多
(Gd,Lu)_(2)O_(3)∶Eu scintillation ceramics have promising applications in the high-energy X-ray imaging.Eu0.1Gd0.6Lu1.3O3 nano-powders with pure phase were prepared from the precursor calcined at 1050℃for 4 h by the...(Gd,Lu)_(2)O_(3)∶Eu scintillation ceramics have promising applications in the high-energy X-ray imaging.Eu0.1Gd0.6Lu1.3O3 nano-powders with pure phase were prepared from the precursor calcined at 1050℃for 4 h by the co-precipitation method.Using the synthesized nano-powders as initial material,Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics were fabri-cated by vacuum pre-sintering at different temperatures for 2 h and hot isostatic pressing(HIP)at 1750℃for 3 h in ar-gon.The influence of pre-sintering temperature on the microstructure,optical and luminescence properties was investi-gated.The Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics pre-sintered at 1625℃for 2 h combined with HIP post-treatment show the high-est in-line transmittance of 75.2%at 611 nm.The photoluminescence(PL)and X-ray excited luminescence(XEL)spectra of the Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)transparent ceramics demonstrate a strong red emission peak at 611 nm due to the^(5)D_(0)→^(7)F_(2) transition of Eu^(3+).The PL,PLE and XEL intensities of the HIP post-treated Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics show a trend of first ascending and then descending with the increase of pre-sintering temperature.The thermally stimulated lumines-cence(TSL)curve of the HIP post-treated Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics presents one high peak at 178 K and two peaks with lower intensities at 253 K and 320 K.The peak at 320 K may be related to oxygen vacancies,and the lumines-cence peak at 178 K is related to defects caused by the valence state changes of Eu^(3+)ions.展开更多
基金Project supported by Pusan National University Research GrantProject(2010-0008-276) supported by National Core Research Center Program through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology
文摘A1203/5%SIC nanocomposites were fabricated by pressureless sintering using MgO as a sintering aid and then post hot-isostatic pressed （HIP）, which can subsequently break through the disadvantage of hot-pressing process. The MgO additive was able to promote the densification of the composites, but could not induce the grain growth of A1203 matrix due to the grain growth inhibition by nano-sized SiC particles. After HIP treatment, A12OJSiC nanocomposites achieved full densification and homogeneous distribution of nano-sized SiC particles. Moreover, the fracture morphology of HIP treated specimens was identical with that of the hot-pressed A1203/SiC nanocomposites showing complete transgranular fracture. Consequently, high fracture strength of 1 GPa was achieved for the A1203/5%SIC nanocomposites by pressureless sintering and post HIP process.
文摘(Gd,Lu)_(2)O_(3)∶Eu scintillation ceramics have promising applications in the high-energy X-ray imaging.Eu0.1Gd0.6Lu1.3O3 nano-powders with pure phase were prepared from the precursor calcined at 1050℃for 4 h by the co-precipitation method.Using the synthesized nano-powders as initial material,Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics were fabri-cated by vacuum pre-sintering at different temperatures for 2 h and hot isostatic pressing(HIP)at 1750℃for 3 h in ar-gon.The influence of pre-sintering temperature on the microstructure,optical and luminescence properties was investi-gated.The Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics pre-sintered at 1625℃for 2 h combined with HIP post-treatment show the high-est in-line transmittance of 75.2%at 611 nm.The photoluminescence(PL)and X-ray excited luminescence(XEL)spectra of the Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)transparent ceramics demonstrate a strong red emission peak at 611 nm due to the^(5)D_(0)→^(7)F_(2) transition of Eu^(3+).The PL,PLE and XEL intensities of the HIP post-treated Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics show a trend of first ascending and then descending with the increase of pre-sintering temperature.The thermally stimulated lumines-cence(TSL)curve of the HIP post-treated Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics presents one high peak at 178 K and two peaks with lower intensities at 253 K and 320 K.The peak at 320 K may be related to oxygen vacancies,and the lumines-cence peak at 178 K is related to defects caused by the valence state changes of Eu^(3+)ions.
