Nano-scale 8mol% titania doped yttria stabilized zirconia (8TiYSZ) powders were prepared by coprecipitation combined with azeotropic distillation process. Powder X-ray diffraction, BET method and TEM were performed to...
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Nano-scale 8mol% titania doped yttria stabilized zirconia (8TiYSZ) powders were prepared by coprecipitation combined with azeotropic distillation process. Powder X-ray diffraction, BET method and TEM were performed to characterize the powder properties. The relative density of 8TiYSZ sample sintered by spark plasma sintering technique at 1150°C for 3min reached 99%. The electrical conductivity of sintered pellet was much higher than the reported one.
The effects of glass flit on the sintering and electric properties of PMN-PT textured ceramics were investigated. The glass frits, including PbO, Bi2O3 and ZnO, were selected since liquid phase sintering lowered the P...
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The effects of glass flit on the sintering and electric properties of PMN-PT textured ceramics were investigated. The glass frits, including PbO, Bi2O3 and ZnO, were selected since liquid phase sintering lowered the PMN-PT sintering temperature. The piezoelectric properties of PMN-PT ceramics with glass frit addition are strongly dependent on the densification. The addition of glass frits into PMN-PT matrix reduced the sintering temperature to 1 100℃ instead of 1 150 ℃ for samples without glass. The piezoelectric coefficients （d33） of PMN-PT textured ceramics achieved 568 pc/N with 1 wt% excess PbO.
Dense SnO2 based ceramics are widely used. In this paper, 95SnO2-5MnO2 ceramics were prepared by pressureless sintering in air at different temperatures. Phase compositions and microstructures are examined by XRD, SEM...
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Dense SnO2 based ceramics are widely used. In this paper, 95SnO2-5MnO2 ceramics were prepared by pressureless sintering in air at different temperatures. Phase compositions and microstructures are examined by XRD, SEM and EDX, respectively. The SEM results show that different morphologies exist at the SnO2 grain boundary of ceramic, which compose of manganese oxidation, testified by EDX. The different manganese oxides phases, found by XRD, are the source of oxygen concentration at the grain boundary during heating and oxygen dissipation when cooling. However, solid solutions of Mn, Sn and O are not observed. The density of 95SnO2-5MnO2 ceramics decreases with increasing the sintering temperature, due to the evaporation of SnO and decreasing concentration of oxygen at grain boundary in the cooling process. Densification of the ceramic is promoted with inhibiting the decomposition of SnO2 by increasing oxygen concentration in the heating process, but it is limited by the dissipation of oxygen at the grain boundary in the cooling process.
A series of zirconia porous ceramics with different density are fabricated with commercial zirconia powder and zirconia hollow balls by pressureless sintering technology. The microstructure and phase transformation ar...
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A series of zirconia porous ceramics with different density are fabricated with commercial zirconia powder and zirconia hollow balls by pressureless sintering technology. The microstructure and phase transformation are characterized respectively by SEM and XRD testing methods. The result indicates that the density and compressive strength depend greatly on zirconia powder content at the same sintering temperature, and elevating sintering temperature just has a little effect on the density and compressive strength for the samples of the same zirconia powder content. The XRD diffraction patterns analysis shows that elevating sintering temperature is helpful to eliminate monoclinic zirconia and the best sintering temperature should be beyond 1700°C.
MoSi2 is one of the few intermetallics to have potential for farther systems. However, the use of MoSi2 has been hindered due to the brittle nature of the material at low temperatures, inadequate creep resistance at h...
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MoSi2 is one of the few intermetallics to have potential for farther systems. However, the use of MoSi2 has been hindered due to the brittle nature of the material at low temperatures, inadequate creep resistance at high temperatures, accelerated (pest) oxidation at temperatures between 450-550°C. In this investigation Mo(Al,Si2)/Ti 3SiC2 composites has been prepared by reaction hot-pressing from Mo, Si, SiC, Ti, Al powder mixture under different temperatures. XRD results show that the main products are Mo(Si,Al)2 and Ti3SiC2. Part of TiC and SiC also appeared at low treating temperature. With the treating temperature increasing SiC disappeared. No evidence show lattice change of Mo(Si,Al)2. It must be the results of sufficient Al added. The electrical conductivity properties were also investigated. Samples treating under different temperatures showed different changes. Samples under high treating temperature showed a near linear change ranging from 27∼800°C and Samples under low treating temperature showed a nonlinear change.
The reaction mechanism of silicon and iron composite powders was clarified during the fabrication of high silicon iron sheet with the Si-content of 6.5wt% by Direct Powder Rolling (DPR) technique. The changes of phase...
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The reaction mechanism of silicon and iron composite powders was clarified during the fabrication of high silicon iron sheet with the Si-content of 6.5wt% by Direct Powder Rolling (DPR) technique. The changes of phase composition and structure evolvement were mainly studied, It is found that a local graded structure, Fe-Fe(Si)-Fe3Si(Si)-Si, forms when sintering at 950-10007deg;C, which plays an important role in the DPR process. Fe 3Si(Si) phase keeps higher content of Si, and Fe(Si) phase remains the state with much lower Si-content, thus provides good mechanical proprieties of rolling and cutting. Then, the subsequent sintering at about 1200C improves the density and makes the distribution of Si homogeneous in the final high silicon iron sheets.
Translucent AlN ceramics were fabricated using spark plasma sintering (SPS) technique with 3wt% CaF2 as sintering additive. The samples achieved 52.4% maximum transmittance in medium IR region after 10 min holding tim...
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Translucent AlN ceramics were fabricated using spark plasma sintering (SPS) technique with 3wt% CaF2 as sintering additive. The samples achieved 52.4% maximum transmittance in medium IR region after 10 min holding time by spark plasma sintering at 1800°C and 30 MPa pressure in N2. The results from XRD, SEM, TEM and EDX showed that the sintered bodies were densely compacted and highly pure with fine grain size and uniform microstructures. No secondary phases were observed at the grain boundaries and triple grain junctions, which guaranteed good optical property of the sintered bodies.
In the present study, α-Si3N4 is prepared by using MgO and Al2O3 as the sintering additives and spark plasma sintering (SPS) technique. The SPS sintering mechanism is discussed. The relationship between the content o...
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In the present study, α-Si3N4 is prepared by using MgO and Al2O3 as the sintering additives and spark plasma sintering (SPS) technique. The SPS sintering mechanism is discussed. The relationship between the content of sintering additives, sintering temperature and relative densities of the samples is analyzed. The results suggest that when the sintering temperature is 1300-1500°C, the content of sintering additives is 6wt.%-10wt.%, the relative density of sintered samples is 64%-96%. When the sintering temperature reaches 1400°C, the content of sintering additives is 10%, the samples can be fully dense sintered and the relative density can be up to 95%. The sintering mechanism is liquid phase sintering. The bending strength of the sintered samples is 50-403MPa and has a close correlation with the relative density.
Potassium lithium niobate (KLN: K3Li2Nb5O15) films have been deposited on quartz glass by Pulsed laser deposition (PLD) technique using a stoichiometric KLN target as starting materials. By investigating the effects o...
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Potassium lithium niobate (KLN: K3Li2Nb5O15) films have been deposited on quartz glass by Pulsed laser deposition (PLD) technique using a stoichiometric KLN target as starting materials. By investigating the effects of both the oxygen pressure and the substrate temperature on the structure of KLN films, optimum parameters have been identified for the growth of high-quality KLN films. At 10Pa oxygen ambient pressure, tetragonal tungsten-bronze-type structure of KLN films with (310) preferred orientation can be achieved at substrate temperatures in the range of 700-800°C Optical studies indicate that the films are highly transparent in the visible-near-infrared wavelength range.
In this study, SnO2-based ceramics, with 0.5%CuO as sintering aid and Sb2O3 as activator of the electrical conductivity, was obtained by pressureless sintering at 1450°C for 5 h. Densification behavior and micros...
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In this study, SnO2-based ceramics, with 0.5%CuO as sintering aid and Sb2O3 as activator of the electrical conductivity, was obtained by pressureless sintering at 1450°C for 5 h. Densification behavior and microstructure development strongly depend on Sb2O 3. The characteristization of microstructures on Sb2O 3 concentrations are analyzed by SEM. A small amount of CuO improves densification;Sb2O3 retards the densification of SnO 2-based ceramic. The electrical resistivities of SnO 2-based ceramics with different contents of Sb2O 3 are measured by the standard four probe method and varied in a wide range. The electrical resistivity arrives the minimal value of 4.964×10-2 Ω·cm for 99%SnO2+0.5%CuO +0.5%Sb2O3. More content of Sb2O3 than that of CuO causes the degression of density and the increasing of electrical resistivity of ceramics.
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