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.
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.
A novel water-based magnetorheological (MR) suspension is based on the poly(ethy1ene glycol)-coated carbonyl iron particles, which is prepared by the co-sol-gel reaction using carbonyl iron particles as raw materials,...
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ISBN:
(纸本)9812771190
A novel water-based magnetorheological (MR) suspension is based on the poly(ethy1ene glycol)-coated carbonyl iron particles, which is prepared by the co-sol-gel reaction using carbonyl iron particles as raw materials, and water without any other additive. The microshucture, anti-oxidation properties, magnetic and magnetorheological properties of the core-shell particles are characterized by scanning electronic microscopy, transmission electronic microscopy, Fourier transform infrared spectroscopy, thermogravimetric- differential thermal analysis, vibrating sample magnetometer, and ARES2000 rheometer, respectively. The results show that the as prepared particles have core-shell structure with a polymer shell of less than 100 nm and its anti-oxidation property is enhanced due to the compound coating. Both the core-shell particles and its based MR suspension exhibit excellent soft magnetic performance. The based MR suspension shows low zero viscosity and high MR effects, especially greatly improved anti-settlement and redispersibility. The phenomena are attributed to the hydrophilic thin shell of the core-shell particles.
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.
This paper was the experimental research of photographic progress on BN-303 photo-resist, in which the ultraviolet light was used in exposure. The surface morphology was observed with SEM. It was discussed that the ef...
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This paper was the experimental research of photographic progress on BN-303 photo-resist, in which the ultraviolet light was used in exposure. The surface morphology was observed with SEM. It was discussed that the effect of soft-baking on 3D structure of MEMS, qualitatively. Finally, the optimized technical parameters obtained through experiments were as follows: soft-baking time was 80°C and soaking time was 30 min, under the condition of cleaning oxidized silicon mask with standard methods, activating sample surface for 30 min at drying temperature 200°C, coating photo-resist at 6000 r/min of rotating speed for 15 s with 17 s of exposure time. The above research results might provide some reliable technical parameters for fabricating micro-device.
Novel mesoporous ZnO-SiO2 (MZS) composites with rod-like morphology were synthesized from coprecipitation method, which was the first time to apply this method in the successful synthesis of ordered mesoporous composi...
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Novel mesoporous ZnO-SiO2 (MZS) composites with rod-like morphology were synthesized from coprecipitation method, which was the first time to apply this method in the successful synthesis of ordered mesoporous composites to our knowledge. This direct-synthesis method was more simple, convenient and efficient, compared with the post-synthesis ones. Structural characterization and spectroscopic study were discussed.
Single-phase n-type (AgIn)xPb1-2xTe compounds were synthesized using the melting reaction method. Influences of (AgIn) substituting for Pb on the constituent phases and thermoelectric properties of the (AgIn)xPb1-2xTe...
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Single-phase n-type (AgIn)xPb1-2xTe compounds were synthesized using the melting reaction method. Influences of (AgIn) substituting for Pb on the constituent phases and thermoelectric properties of the (AgIn)xPb1-2xTe(x=0.01-0.05) were investigated. Results indicate that single phase compound is obtained when the (AgIn) substitution fraction x&le0.04. However, the second phase (AgInTe2) was observed in the sample with x=0.05. The Seebeck coefficient increases gradually with the increasing of the (Agin) substitution fraction x, and the electrical conductivity of the compounds decreases with the increasing of x. Thermal conductivity decreases with the increasing of x. In all of the n-type (AgIn)xPb1-2xTe compounds, (AgIn)0.01Pb0.98Te compound has the greatest ZT value, reaching 1.1 at 800K.
This article introduces a process for the growth of one-dimensional oxide nanomaterials that combines rheological phase reaction and hydrothermal self-assembling process. Fundamentals and practical approaches of hydro...
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This article introduces a process for the growth of one-dimensional oxide nanomaterials that combines rheological phase reaction and hydrothermal self-assembling process. Fundamentals and practical approaches of hydrothermal self-assembling process and rheological phase reaction are briefly described. Particular attention is devoted to the rheological self-assembling for the growth of low dimensional oxide nanomaterials. Many examples are shown that the rheological self-assembling is an effective method to prepare one-dimensional nanomaterials, organic-inorganic hybrids and 1-D nanomaterial array for optical-electronic and electrochemical devices and catalysis. Morphologies, microstructures, properties, and application of one-dimensional oxide nanomaterials are reviewed.
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