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在氧气中焙烧C/γ-Al2O3复合物快速制备α-Al2O3微粉 总被引:1,自引:0,他引:1
提出了一种快速制备α-Al2O3微粉的方法, 以淀粉为碳源、γ-Al2O3为前体制备了C/γ-Al2O3复合物, 然后在800℃、氧气氛中焙烧制备α-Al2O3微粉. N2物理吸附及SEM分析结果表明, 所制得的α-氧化铝颗粒细小, 约为2μm. 该方法具有焙烧温度低、焙烧时间短的优点, 同时, 淀粉及γ-Al2O3均为廉价的工业原料, 且该方法所需淀粉量较少, 最少仅需0.3g/g γ-Al2O3, 对应的C/γ-Al2O3复合物碳含量约为6wt%, 因而极具工业化应用前景. 相似文献
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晶种对氢氧化铝转相和热压烧结氧化铝晶形变化的影响 总被引:3,自引:0,他引:3
以氢氧化铝为初始原料,通过球磨过程中高纯氧化铝磨介的磨屑作为晶种引入氢氧化铝中.引入的α-Al2O3品种使氢氧化铝于1100℃×2h的条件下转变为α相氧化铝.而且随着α-Al2O3品种引入量的增加,煅烧后氧化铝颗粒的平均粒径减小,颗粒尺寸分布均匀.煅烧得到的氧化铝超细粉经热压烧结后,Al2O3晶粒形貌随品种的引入量的不同而发生变化.未引入α-Al2O3品种的条件下,晶粒形状主要为等轴状;晶种引入后,晶粒发育成六角片状;而且随着晶种引入量进一步增加时,六角片状晶粒尺寸减小,当晶种数量增加到20wt%以上时,晶粒发育生长为长柱状. 相似文献
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以高纯α-Al2O3粉体为原料,MgO-Y2O3为烧结助剂,采用常压烧结法制备亚微米晶Al2O3陶瓷。研究了烧结温度、烧结助剂对Al2O3陶瓷的致密化过程、显微结构及力学性能的影响。结果表明:添加一定量的复合助剂MgO-Y2O3可起到促进Al2O3陶瓷致密化,细化显微结构,并改善其力学性能的作用。经1450℃常压烧结1h可获得相对密度达99.6%、平均晶粒尺寸约0.71μm的亚微米晶Al2O3陶瓷,其维氏硬度和断裂韧性分别为18.5GPa和4.6 MPa·m1/2。 相似文献
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以高纯α-Al2O3粉体为原料,MgO-Y2O3为烧结助剂,采用常压烧结法制备亚微米晶Al2O3陶瓷。研究了烧结温度、烧结助剂对Al2O3陶瓷的致密化过程、显微结构及力学性能的影响。结果表明:添加一定量的复合助剂MgO-Y2O3可起到促进Al2O3陶瓷致密化,细化显微结构,并改善其力学性能的作用。经1450℃常压烧结1h可获得相对密度达99.6%、平均晶粒尺寸约0.71μm的亚微米晶Al2O3陶瓷,其维氏硬度和断裂韧性分别为18.5GPa和4.6 MPa·m1/2。 相似文献
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以TiO2、Al、C(石墨)为原料,首先采用高能球磨引导铝热反应合成了Al2O3-TiC 纳米复合粉体,然后采用放电等离子体烧结纳米复合粉体制备了Al2O3-TiC复合材料.结果表明,在氩气氛围下高能球磨3h后,原料粉末就发生了铝热反应,合成的Al2O3-TiC复合粉体粒子尺寸大约在100nm左右.采用SPS技术在1450℃保温4min烧结的试样致密度达99.6%,并且结构精细(大部分晶粒<1μm),两相分布比较均匀,有较好的力学性能和电导性能,抗弯强度为650±21MPa.,硬度为19.1±0.2GPa,断裂韧性为4.5±0.2MPa·m1/2,电导率为2.3828×105Ω-1·m-1. 相似文献
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Yuanyuan LI Xiaoqiang LI Yan LONG Wei XIA Min ZHU Weiping CHEN College of Mechanical Engineering South China University of Technology Guangzhou China 《材料科学技术学报》2006,22(2):257-260
Fe-2Cu-2Ni-lMo-0.8C (wt pct) elemental mixed powders were rapidly sintered within 6 min by spark plasma sintering, and the effects of sintering parameters on the densification degree and performance of the assintered materials were investigated. Results showed that when a proper combination of pulse electric current and constant electric current was employed for sintering, the density and bend strength of the as-sintered material reached the maxima, being 7.61×103 kg/m3 and 1540 MPa, respectively. Its corresponding fracture morphology was characterized as the mix of ductile, intergranular and cleavage fractures. 相似文献
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Um Tae-Young Abe Toshihiko Sumi Shinichi 《Journal of Materials Synthesis and Processing》1999,7(5):303-309
The characteristics of spark plasma sintering, a new method of powder processing, were investigated. Four systems of intermetallic compounds—Ti-Al, Ti-Al-Cr, Mo-Si, and Mo-Si-Nb—were fabricated, and the formation process of compounds, the formed phases, and the microstructure of samples were observed. During the sintering of all the compositions of mixed powders, most of the compounds were formed by combustion reaction which occurred at almost the same temperature as the conventional combustion reaction temperature. The fabricated samples were well densified, however, the relative densities of the Mo-Si samples were lower than the Ti-Al samples. Ultrasonic images show that no internal defects were found in any sample and the grain size became finer with the increase in the Cr content in the Ti-Al system and Nb content in the Mo-Si system. The formed phases of Ti:Al=1:1 composition samples were TiAl and Ti3Al phases, and Ti-Al added Cr samples consisted of TiAl, Ti3Al, Cr2Al, and Cr9Al17 phases. The sample synthesized with Mo:Si=1:2 mixed powders had only MoSi2 phases, and Mo-Si samples with added Nb consisted of four phases: MoSi2 with a small amount of Mo5Si3 phases in the matrix and Nb5Si3 with unreacted Nb for dispersed phases. 相似文献
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T. Rodriguez-Suarez L.A. Díaz R. Torrecillas S. Lopez-Esteban W.-H. Tuan M. Nygren J.S. Moya 《Composites Science and Technology》2009
In the present work, the parameters controlling the alumina/W nanopowders Spark Plasma Sintering (SPS) process are studied. The important and crucial role of C diffusion from the SPS die in the microstructure, fraction of porosity and new phases formation (W2C) is discussed. It is also pointed out the importance of the processing parameters of the starting powder on the density and mechanical properties of the final compacts. In this regard, dense alumina/nW compacts containing 4 vol.% W with a hardness value as high as 24.6 ± 0.9 GPa were obtained. 相似文献
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Isabel Alvarez‐Clemares Gustavo Mata‐Osoro Adolfo Fernández Sonia Lopez‐Esteban Carlos Pecharromán Javier Palomares Ramón Torrecillas José Serafín Moya 《Advanced Engineering Materials》2010,12(11):1154-1160
The influence of oxides (such as MgO, TiO2, CaO, etc.) on the transparency of polycrystalline alumina compacts are widely studied in the literature. In this work, a completely different approach is developed, consisting of precipitating 0.5 wt.‐% CeO2 nanoparticles (< 5 nm) on the surface of the starting alumina nanopowder (d50 approximately 170 nm) using cerium(III) acetate as precursor. It is shown that the ceria nanoparticles strongly enhance the transparency of the spark plasma sintered compacts due to: i) the ceria nanoparticles acting as powder lubricant, increasing by around 15% the initial density of the powder in the SPS die, and, ii) the CeO2 nanoparticles, having a very low solid solubility in the alumina grains, locating at grain boundaries, hindering alumina grain growth by pinning during SPS sintering at 1 430 °C, 80 MPa for 2 min. This effect is found to be effective only under SPS vacuum conditions. In order to explain the light scattering behavior in the near‐infrared and visible range, a light scattering model under the Rayleigh‐Gans‐Debye approximation for polycrystalline alumina is used. This model offers an additional and simple tool for a completed bulk evaluation of the SPS compacts microstructure. 相似文献
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本文报道分别以Ti/Si/C,Ti/SiC/C为原料,采用放电等离子烧结工艺制备Ti3SiC2材料的研究结果.以元素单质粉为原料,掺加适量Al作助剂能加速Ti3SiC2的反应合成并提高材料的纯度,在1200~1250℃的温度下能制备出经XRD、SME和EDS表征不含TiC和SiC等杂质相的纯净TiSiC2材料.而以Ti/SiC/C为原料时,有无Al作助剂都难以制备出纯净的Ti3SiC2,其反应合成温度明显高于以元素单质粉为原料的. 相似文献
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采用金属钛粉和碳化硼为初始粉料,利用SPS放电等离子烧结技术制备了致密的纳米结构TiB2/TiC复合材料.并借助XRD、SEM考察了复合材料的相组成和显微结构,利用压痕法和小样品力学性能测试方法(MSP)测定了室温显微硬度、断裂韧性和MSP强度.研究结果表明:利用一步法直接升温至1550℃并保温6 min制备的复合材料,其晶粒尺寸大于1μm,MSP强度为833 MPa.而采用两步法升温至1550℃,然后迅速降低保温温度至1450℃,并保温6 min条件下使金属钛粉和碳化硼同步完成反应、烧结、致密化,生成晶粒细小的TiB2/TiC复合材料,晶粒尺寸大约为200 nm,并且所制备的复合材料力学性能更好,MSP强度达到1095 MPa. 相似文献