The melting temperature and critical transition temperature Tc of YBa2Cu3O7-δ with deferent content additives of PbO and BaPbO3 were studied. When PbO was doped in YBa2Cu3O7-δ, the melting temperature of YBa2Cu3O7-...The melting temperature and critical transition temperature Tc of YBa2Cu3O7-δ with deferent content additives of PbO and BaPbO3 were studied. When PbO was doped in YBa2Cu3O7-δ, the melting temperature of YBa2Cu3O7-δ was reduced, however its superconductivity was weakened. From the XRD pattern of the sintered mixture of YBa2Cu3O7-δ and PbO, it was known that there was a reaction between YBa2Cu3O7-δ and PbO, and the product was BaPbO3. Hence different contents of BaPbO3 (10mass%, 20mass% and 30mass%) were added in YBa2Cu3O7-δ. It was proved that there were no reactions between YBa2Cu3O7-δ and BaPbO3. And the superconductivity of the mixtures was much better than that of the samples with PbO additive.展开更多
The effects of B2O3 addition, as a sintering agent, on the sintering behavior, microstructure and dielectric properties of CaMgSi2O6 ceramic have been investigated. The CaO-MgO-B2O3-SiO2 glassy phase came forth by add...The effects of B2O3 addition, as a sintering agent, on the sintering behavior, microstructure and dielectric properties of CaMgSi2O6 ceramic have been investigated. The CaO-MgO-B2O3-SiO2 glassy phase came forth by adding B2O3 into CaO-MgO-SiO2 ceramic powders, and it was advantageous to lower the synthesis temperature of CaMgSi2O6 crystalline phase. Moreover, the emergence of CaO-MgO-B2O3-SiO2 glass phase could effectively lower the sintering temperature of CaMgSi2O6 ceramic and promote the CaMgSi2O6 grains growing. With 6 wt pct B2O3 addition, the densification temperature of CaMgSi2O6 ceramic could be effectively reduced from 1300 to 1100℃, and the dielectric constant （εr） and dielectric loss （tanδ） were： εr=7.61 and tanδ=7.4×10^-4 （1 MHz）.展开更多
ZrO2, TiO2 and P2O5 were doped in CaO-B2O3-SiO2 glass-ceramics as nucleating additives. Effects of different nucleating additives on the phase separation and crystalline behaviors were investigated by using gradient t...ZrO2, TiO2 and P2O5 were doped in CaO-B2O3-SiO2 glass-ceramics as nucleating additives. Effects of different nucleating additives on the phase separation and crystalline behaviors were investigated by using gradient temperature furnace, DTA and XRD. Then, sintering process of the glass-ceramics was investigated by testing sintering shrinkage, dielectric constant and loss. The experimental results shows that the glass-ceramics doped with nucleating additives represents higher crystallization, with ZrO2 as an exceptional effective dopant to promote the precipitation of wollastonite crystal. Finally, ZrO2 containing glass-ceramics was chosen to study the influence of sintering temperature and soaking time with the help of X-ray diffraction analysis and density measurement. The glass-ceramics can be well consolidated at 850 ℃ for 10 min, with low dielectric constant （5.87） and loss （3.21×10^-4）, which is desirable for LTCC application.展开更多
To improve the mechanical properties of WC-Al2O3 composites, the effects of trace amount of CeO2 additives on the microstructure and mechanical properties of the WC-Al2O3 composites prepared by hot pressing were inves...To improve the mechanical properties of WC-Al2O3 composites, the effects of trace amount of CeO2 additives on the microstructure and mechanical properties of the WC-Al2O3 composites prepared by hot pressing were investigated. The results revealed that the WC-Al2O3 composites doped with 0.1% CeOz possessed refined microstructure and enhanced mechanical properties compared with that of the undoped WC-Al2O3composites. Trace CeO2 suppressed the decarburization of WC, promoted the microstructural refinement, and improved the interface coherence of the WC matrix and Al2O3. When 0.1% CeO2 was added to the WC-Al2O3 composites, the effect of CeO2 resulted in the achievement of a relative density of 98.82% with an excellent Vickers hardness of 16.89 GPa, combining a fracture toughness of 9.85 MPa. m1/2 with an acceptable flexural strength of 1 024.05 MPa.展开更多
文摘The melting temperature and critical transition temperature Tc of YBa2Cu3O7-δ with deferent content additives of PbO and BaPbO3 were studied. When PbO was doped in YBa2Cu3O7-δ, the melting temperature of YBa2Cu3O7-δ was reduced, however its superconductivity was weakened. From the XRD pattern of the sintered mixture of YBa2Cu3O7-δ and PbO, it was known that there was a reaction between YBa2Cu3O7-δ and PbO, and the product was BaPbO3. Hence different contents of BaPbO3 (10mass%, 20mass% and 30mass%) were added in YBa2Cu3O7-δ. It was proved that there were no reactions between YBa2Cu3O7-δ and BaPbO3. And the superconductivity of the mixtures was much better than that of the samples with PbO additive.
基金supported by the Program for New Century Excellent Talents in University (No. NCET-07-0786)the Nature Science Foundation of Zhejiang Province (No. R406007)the Science Technology of Zhejiang Province (No. 2008C21054)
文摘The effects of B2O3 addition, as a sintering agent, on the sintering behavior, microstructure and dielectric properties of CaMgSi2O6 ceramic have been investigated. The CaO-MgO-B2O3-SiO2 glassy phase came forth by adding B2O3 into CaO-MgO-SiO2 ceramic powders, and it was advantageous to lower the synthesis temperature of CaMgSi2O6 crystalline phase. Moreover, the emergence of CaO-MgO-B2O3-SiO2 glass phase could effectively lower the sintering temperature of CaMgSi2O6 ceramic and promote the CaMgSi2O6 grains growing. With 6 wt pct B2O3 addition, the densification temperature of CaMgSi2O6 ceramic could be effectively reduced from 1300 to 1100℃, and the dielectric constant （εr） and dielectric loss （tanδ） were： εr=7.61 and tanδ=7.4×10^-4 （1 MHz）.
基金Funded by the Shanghai Leading Academic Discipline Project (B502)Shanghai Key Laboratory Project (08DZ2230500)
文摘ZrO2, TiO2 and P2O5 were doped in CaO-B2O3-SiO2 glass-ceramics as nucleating additives. Effects of different nucleating additives on the phase separation and crystalline behaviors were investigated by using gradient temperature furnace, DTA and XRD. Then, sintering process of the glass-ceramics was investigated by testing sintering shrinkage, dielectric constant and loss. The experimental results shows that the glass-ceramics doped with nucleating additives represents higher crystallization, with ZrO2 as an exceptional effective dopant to promote the precipitation of wollastonite crystal. Finally, ZrO2 containing glass-ceramics was chosen to study the influence of sintering temperature and soaking time with the help of X-ray diffraction analysis and density measurement. The glass-ceramics can be well consolidated at 850 ℃ for 10 min, with low dielectric constant （5.87） and loss （3.21×10^-4）, which is desirable for LTCC application.
文摘To improve the mechanical properties of WC-Al2O3 composites, the effects of trace amount of CeO2 additives on the microstructure and mechanical properties of the WC-Al2O3 composites prepared by hot pressing were investigated. The results revealed that the WC-Al2O3 composites doped with 0.1% CeOz possessed refined microstructure and enhanced mechanical properties compared with that of the undoped WC-Al2O3composites. Trace CeO2 suppressed the decarburization of WC, promoted the microstructural refinement, and improved the interface coherence of the WC matrix and Al2O3. When 0.1% CeO2 was added to the WC-Al2O3 composites, the effect of CeO2 resulted in the achievement of a relative density of 98.82% with an excellent Vickers hardness of 16.89 GPa, combining a fracture toughness of 9.85 MPa. m1/2 with an acceptable flexural strength of 1 024.05 MPa.
基金Postdoctoral Science Foundation of China(2012M520605)Research Foundation of Taiyuan University of Technology(tyut-rc201369a,2013Z040)+1 种基金Open Foundation of State Key Laboratory of Coal Conversion(09-102)Natural Science Foundation of Shanxi Province(2013011042-1)
