Using agarose as a gel agent to prepare ceramics is a suitable non-toxic gel-casting method. The effects of agarose concentration and addition amount on gel-cast 3Y-ZrO_2 green and sintered bodies were investigated. G...Using agarose as a gel agent to prepare ceramics is a suitable non-toxic gel-casting method. The effects of agarose concentration and addition amount on gel-cast 3Y-ZrO_2 green and sintered bodies were investigated. Green bodies were prepared by gel-casting using an agarose solution of a different agarose mass fraction including 3.0%, 3.5%, 4.0%, 4.5%, 5.0% and 5.5%with an added amount of agarose in the green body at a mass fraction of 0.7%, and using the agarose solution of a mass fraction of4.5% with a different amount of added agarose including 0.6%, 0.7%, 0.8%, 0.9%, and 1.0% in terms of mass fraction. The green bodies were sintered at 1 600 °C for 4 h. The relative density, linear shrinkage, and bending strength of the green bodies, and the density, microstructure, bending strength, and fracture toughness of sintered samples were characterized and analyzed. Results show that comprehensive properties of green bodies made with 4.5%(in terms of mass fraction) agarose solution added to an mass fraction of agarose in the slurry at 0.6% were the best, of which the bending strength was 3.14 MPa, the linear shrinkage was below 4.3%, and the relative density is 57.3%. For sintered bodies, the best fracture toughness was 5.63 MPa m^(1/2), and the optimal density was 5.88 g cm^(-3).展开更多
In the present study,graphite/alumina composites are fabricated via reductive sintering of gel-casted green bodies with structurally controlled cross-linked epoxy polymers for the first time.The cross-linking degrees ...In the present study,graphite/alumina composites are fabricated via reductive sintering of gel-casted green bodies with structurally controlled cross-linked epoxy polymers for the first time.The cross-linking degrees of polymers are tuned by the amount ratio of epoxy monomer/polyvinyl alcohol cross-linker utilized in gel-casting process.Superior electrical properties with respect to 5-fold enhanced electrical conductivity and 2-fold higher carrier mobility are successfully achieved in graphite/alumina composite fabricated from cross-linked epoxy polymer,whose phenomenon is attributed to the excellent conductive path in ceramic matrix established by highly uniform network with improved graphitization degree.展开更多
In this study,Gd and Ca co-doped ceria electrolytes with the compositions of Ce_(0.8)Gd_(0.2-x)Ca_(x)O_(2-δ)(x=0-0.08) were prepared by a novel gel-casting method.The effects of the addition of Ca on the phase compos...In this study,Gd and Ca co-doped ceria electrolytes with the compositions of Ce_(0.8)Gd_(0.2-x)Ca_(x)O_(2-δ)(x=0-0.08) were prepared by a novel gel-casting method.The effects of the addition of Ca on the phase compositions,sintering behavio r,and electrical prope rties of samples were investigated.According to the scanning electron microscope results and relative density measurement results,it is found that the addition of particular quantity of CaO can promote the sintering densification with a uniform grain growth.When the sintering temperature is 1400℃,the sample with 6 mol% addition of Ca has the highest relative density,which reaches 98.5% of the theoretical density.The electrical properties testing results confirm that the electrical conductivity of the samples can be improved significantly by doping appropriate CaO content.The maximum conductivity of 0.082 S/cm can be obtained at 800℃ in the Ce_(0.8)Gd_(0.12)-Ca_(0.06)O_(1.87) sample.It suggests that CaO can be used as an effective sintering aid and a codopant on the optimization of electrical properties for ceria-based electrolytes.展开更多
A series of Bi^(3+)-doped YAG:Ce^(3+), Mn^(2+) ceramics was synthesized successfully by gel-casting method and structurally characterized by XRD and SEM. The doping effect and related mechanism of Bi^(3+) upon the lum...A series of Bi^(3+)-doped YAG:Ce^(3+), Mn^(2+) ceramics was synthesized successfully by gel-casting method and structurally characterized by XRD and SEM. The doping effect and related mechanism of Bi^(3+) upon the luminescent property were studied. It can be assigned to the energy transfer of multipolar interaction from Bi^(3+) to Ce^(3+), leading to the improvement of emission intensity about 58% for 0.0001 Bi^(3+) and 0.05 Mn^(2+) doping. In addition, the emission is significantly red-shifted with the peak at 590 nm for the Y2.9939 Ce0.006 Bi0.0001 Al4.96 Mn0.02 Si0.02 O12 ceramic specimen with in-line transmittance 81.6% at 1100 nm. The LED module assembled from Y2.9939 Ce0.006 Bi0.0001 Al4.96 Mn0.02 Si0.02 O12 ceramic owns correlated color temperature(CCT) of 3960 K and luminous efficiency(LE) of 92 lm/W, implying that doping Bi^(3+) shows a good sensitization effect in the YAG:Ce^(3+), Mn^(2+) ceramic system and further serving as an attracting phosphor candidates for warm WLEDs applications.展开更多
Novel MgO-doped CaO sorbent pellets were prepared by gel-casting and wet impregnation.The effect of Na^(+) and MgO on the structure and CO_(2) adsorption performance of CaO sorbent pellets was elucidated.MgOdoped CaO ...Novel MgO-doped CaO sorbent pellets were prepared by gel-casting and wet impregnation.The effect of Na^(+) and MgO on the structure and CO_(2) adsorption performance of CaO sorbent pellets was elucidated.MgOdoped CaO sorbent pellets with the diameter range of 0.5-1.5 mm exhibited an excellent capacity for CO_(2) adsorption and adsorption rate due to the homogeneous dispersion of MgO in the sorbent pellets and its effects on the physical structure of sorbents.The results show that MgO can effectively inhibit the sintering of CaO and retain the adsorption capacity of sorbents during multiple adsorption-desorption cycles.The presence of mesopores and macropores resulted in appreciable change of volume from CaO(16.7 cm^(3)·mol^(-1))to CaCO3(36.9 cm^(3)·mol^(-1))over repeated operation cycles.Ca2Mg1 sorbent pellets exhibited favorable CO_(2) capture capacity(9.49 mmol·g^(-1)),average adsorption rate(0.32 mmol·g^(-1)·min^(-1)) and conversion rate of CaO(74.83%) after 30 cycles.展开更多
基金Funded by the Science&Technology Pillar Program of Hubei Province(No.2015BAA105)the Natural Science Foundation of Hubei Province(No.2014CFB796)
文摘Using agarose as a gel agent to prepare ceramics is a suitable non-toxic gel-casting method. The effects of agarose concentration and addition amount on gel-cast 3Y-ZrO_2 green and sintered bodies were investigated. Green bodies were prepared by gel-casting using an agarose solution of a different agarose mass fraction including 3.0%, 3.5%, 4.0%, 4.5%, 5.0% and 5.5%with an added amount of agarose in the green body at a mass fraction of 0.7%, and using the agarose solution of a mass fraction of4.5% with a different amount of added agarose including 0.6%, 0.7%, 0.8%, 0.9%, and 1.0% in terms of mass fraction. The green bodies were sintered at 1 600 °C for 4 h. The relative density, linear shrinkage, and bending strength of the green bodies, and the density, microstructure, bending strength, and fracture toughness of sintered samples were characterized and analyzed. Results show that comprehensive properties of green bodies made with 4.5%(in terms of mass fraction) agarose solution added to an mass fraction of agarose in the slurry at 0.6% were the best, of which the bending strength was 3.14 MPa, the linear shrinkage was below 4.3%, and the relative density is 57.3%. For sintered bodies, the best fracture toughness was 5.63 MPa m^(1/2), and the optimal density was 5.88 g cm^(-3).
文摘In the present study,graphite/alumina composites are fabricated via reductive sintering of gel-casted green bodies with structurally controlled cross-linked epoxy polymers for the first time.The cross-linking degrees of polymers are tuned by the amount ratio of epoxy monomer/polyvinyl alcohol cross-linker utilized in gel-casting process.Superior electrical properties with respect to 5-fold enhanced electrical conductivity and 2-fold higher carrier mobility are successfully achieved in graphite/alumina composite fabricated from cross-linked epoxy polymer,whose phenomenon is attributed to the excellent conductive path in ceramic matrix established by highly uniform network with improved graphitization degree.
基金Project supported by the Natural Science Foundation of Anhui Province of China(1708085ME112)。
文摘In this study,Gd and Ca co-doped ceria electrolytes with the compositions of Ce_(0.8)Gd_(0.2-x)Ca_(x)O_(2-δ)(x=0-0.08) were prepared by a novel gel-casting method.The effects of the addition of Ca on the phase compositions,sintering behavio r,and electrical prope rties of samples were investigated.According to the scanning electron microscope results and relative density measurement results,it is found that the addition of particular quantity of CaO can promote the sintering densification with a uniform grain growth.When the sintering temperature is 1400℃,the sample with 6 mol% addition of Ca has the highest relative density,which reaches 98.5% of the theoretical density.The electrical properties testing results confirm that the electrical conductivity of the samples can be improved significantly by doping appropriate CaO content.The maximum conductivity of 0.082 S/cm can be obtained at 800℃ in the Ce_(0.8)Gd_(0.12)-Ca_(0.06)O_(1.87) sample.It suggests that CaO can be used as an effective sintering aid and a codopant on the optimization of electrical properties for ceria-based electrolytes.
基金supported by the grants of CAS Priority Research program(XDB20010300,XDA21010204)Natural Science Foundation of Fujian Province(2017H0048)。
文摘A series of Bi^(3+)-doped YAG:Ce^(3+), Mn^(2+) ceramics was synthesized successfully by gel-casting method and structurally characterized by XRD and SEM. The doping effect and related mechanism of Bi^(3+) upon the luminescent property were studied. It can be assigned to the energy transfer of multipolar interaction from Bi^(3+) to Ce^(3+), leading to the improvement of emission intensity about 58% for 0.0001 Bi^(3+) and 0.05 Mn^(2+) doping. In addition, the emission is significantly red-shifted with the peak at 590 nm for the Y2.9939 Ce0.006 Bi0.0001 Al4.96 Mn0.02 Si0.02 O12 ceramic specimen with in-line transmittance 81.6% at 1100 nm. The LED module assembled from Y2.9939 Ce0.006 Bi0.0001 Al4.96 Mn0.02 Si0.02 O12 ceramic owns correlated color temperature(CCT) of 3960 K and luminous efficiency(LE) of 92 lm/W, implying that doping Bi^(3+) shows a good sensitization effect in the YAG:Ce^(3+), Mn^(2+) ceramic system and further serving as an attracting phosphor candidates for warm WLEDs applications.
基金Financial support by the National Key Research and Development Program of China(Grant No.2017YFB0603300)the Program for New Century Excellent Talents in University(Grant No.NCET-13-0411)are gratefully acknowledged.
文摘Novel MgO-doped CaO sorbent pellets were prepared by gel-casting and wet impregnation.The effect of Na^(+) and MgO on the structure and CO_(2) adsorption performance of CaO sorbent pellets was elucidated.MgOdoped CaO sorbent pellets with the diameter range of 0.5-1.5 mm exhibited an excellent capacity for CO_(2) adsorption and adsorption rate due to the homogeneous dispersion of MgO in the sorbent pellets and its effects on the physical structure of sorbents.The results show that MgO can effectively inhibit the sintering of CaO and retain the adsorption capacity of sorbents during multiple adsorption-desorption cycles.The presence of mesopores and macropores resulted in appreciable change of volume from CaO(16.7 cm^(3)·mol^(-1))to CaCO3(36.9 cm^(3)·mol^(-1))over repeated operation cycles.Ca2Mg1 sorbent pellets exhibited favorable CO_(2) capture capacity(9.49 mmol·g^(-1)),average adsorption rate(0.32 mmol·g^(-1)·min^(-1)) and conversion rate of CaO(74.83%) after 30 cycles.
