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.
Aluminosilicate refractory waste was used to prepare high performance ceramic ball grinding media with 75% Al2O3. The influence of milling time on the particle size of raw materials, the sintering temperature, and per...
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Aluminosilicate refractory waste was used to prepare high performance ceramic ball grinding media with 75% Al2O3. The influence of milling time on the particle size of raw materials, the sintering temperature, and performance of ceramic balls were studied. Results show that with increasing milling time the particle size of the raw materials decreased, resulting in a decrease of ceramic ball sintering temperature and an increase in wear resistance and volume density. The wear rate and volume density of balls prepared by milling the materials for 72 h were 0.01886 %/h and 3.374 g/cm 3, respectively.
Plasma deposition dieless manufacturing is a rapid heating and solidification process, in which how to avoid cracks and distortions is a key problem. To explore the thermal behaviors of this process, the preheated and...
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ISBN:
(纸本)0979497701
Plasma deposition dieless manufacturing is a rapid heating and solidification process, in which how to avoid cracks and distortions is a key problem. To explore the thermal behaviors of this process, the preheated and water-cooled programs were designed and evaluated numerically by finite element method and the watercooled scheme showed lower hot crackability and better formability. Thereafter, evolutions of the temperature and stress field were simulated based on the water-cooled scheme under optimized process conditions. Computational and experimental results confirm that reasonable process-cooled conditions can reduce the temperature and stress gradients and thus ultimately improve the possibly-intended formability.
A peptizing-hydrothermal method to prepare nanometer γ-AlOOH crystal powder with industrial Al(OH)3 as raw materials has been proposed in the present paper. The XRD and TEM results show the product is a pure γ type ...
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A peptizing-hydrothermal method to prepare nanometer γ-AlOOH crystal powder with industrial Al(OH)3 as raw materials has been proposed in the present paper. The XRD and TEM results show the product is a pure γ type nanometer A100H crystal powder with average grain diameter of 70nm. Laser grading analysis indicates the average grain diameters of the product in the solution are 66.52nm in water and 84.33nm in N,N-dimethylformamide, respectively without surface modification and dispersant. The experimental result indicated that polymer/inorganic nano-composite with high content of nanometer AlOOH presents inorganic characteristic of polymer. The wear rate of the alumina ceramic ball sintered at 1465°C from ceramic, which contains 98% alumina (wt), can be reduced up to 40% with addition of 3.5% nanometer AlOOH.
After combining the PVDF and BST powders with different particle sizes, the anti-voltage strengths of composites was tested. Although the concentrates of ceramic were all the same, their anti-voltage strengths were di...
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After combining the PVDF and BST powders with different particle sizes, the anti-voltage strengths of composites was tested. Although the concentrates of ceramic were all the same, their anti-voltage strengths were distinguished. The results showed that the bigger particles or less thickness of material could benefit to the anti-voltage strength and ultimately enhanced the energy storage density of composites. Moreover, the distribution of particle dimension also influenced the strengths of materials. Composite with homogeneous particles performed higher strength than that of composites with inhomogeneous particles.
Si-clathrate compounds, n-type Ba8 Ga16 Znx Si30-x (x = 0, 1, 2, 3, 4), are synthesized by using the solid-state reaction method and the melting method. The effects of the replacement of Si with Zn on the structure an...
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Si-clathrate compounds, n-type Ba8 Ga16 Znx Si30-x (x = 0, 1, 2, 3, 4), are synthesized by using the solid-state reaction method and the melting method. The effects of the replacement of Si with Zn on the structure and the electrical transmission characteristics are investigated for n-type Ba8Ga16Znx Si30-x. The results indicate that the sample with the value of x = 1 has the maximal bond angle distortion Δθ, Δθ = 4.4°. The electrical conductivity of samples with x = 0, 2, 4 is higher than that of samples with x = 1, 3. Among the samples, the electrical conductivity of Ba8 Ga16 Zn1 Si29 is the lowest. The samples with x = 0, 2, 4 exhibit a higher Seebeck coefficient than that of samples with x = 1, 3, and the value of the Seebeck coefficient decreases with the increase of the Zn composition. The power factor of Ba8Ga16Zn2Si28 compound is as large as 1.03 × 10-3 W/(m· K2) at 1000K.
High-energy ball mill method was used to fabricate the stainless steel nanocomposite powder from stainless steel powder, carbon powder and titanium powder as raw materials. The X-ray diffraction, SEM and the BET metho...
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High-energy ball mill method was used to fabricate the stainless steel nanocomposite powder from stainless steel powder, carbon powder and titanium powder as raw materials. The X-ray diffraction, SEM and the BET method were used to evaluate the microstructure of treated samples. The results showed that in vacuum condition, with ball mill time increase, stainless steel powder become more and finer, the grain size can reach nanometer level. At the same time, the nano TiC can be formed during ball milling, the stainless steel-TiC nano composite powder can be obtained.
Using the microwave sintering technology, the samples of WC-10Co cemented carbide were put separately at the pure electric field, the pure magnetic field and the mixture E field and H field in a single-mode TE103 cavi...
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Using the microwave sintering technology, the samples of WC-10Co cemented carbide were put separately at the pure electric field, the pure magnetic field and the mixture E field and H field in a single-mode TE103 cavity. The sintering behaviors of WC-10Co cemented carbide were researched and the effects of these positions on their properties also were analyzed.
Extensive dislocation structure was observed by transmission electron microscopy (TEM) in polycrystalline alumina ceramic sintered under a short-time high temperature 1800°C and pressure 100 MPa. There existed lo...
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Extensive dislocation structure was observed by transmission electron microscopy (TEM) in polycrystalline alumina ceramic sintered under a short-time high temperature 1800°C and pressure 100 MPa. There existed lots of dislocation structures: dislocation coalescence, dislocation arrays and dislocation network. The burgers vector of the dislocation array was determined by diffraction contrast as 1/3 less than or equal 11 over-bar 00>. The dislocation network formation was discussed, and it belonged to basal slip system l/3 less than or equal 112 over-bar 0>. Plastic deformation occured mainly by basal plane slip and prime plane slip.
In the present study, Si2N4 whisker was prepared by thermal decomposition of Si(NH)2, the experimental principles and process were described in detail. Influence factors such as temperature, residual carbon(C), a smal...
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In the present study, Si2N4 whisker was prepared by thermal decomposition of Si(NH)2, the experimental principles and process were described in detail. Influence factors such as temperature, residual carbon(C), a small quantity of oxygen and crucible material that could influence the growth of whisker was analyzed and discussed. The influence degree of each factor and mechanism were explained as well. High quality and modified Si3N4 whisker could be prepared by controlling the influence factors during the experimental process. As a result, it was significant to fabricate batch production of high performance Si3N4 whisker by utilizing this method.
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