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陶瓷凝胶注模成型工艺是一种新颖的成型工艺,它将高分子化学单体聚合的思路引入到陶瓷的成型工艺中。通过加入分散剂制备了流动性较好的Al2O3浆料,用改性淀粉原位凝胶注模成型技术制备了具有较高强度和均匀性良好的氧化铝陶瓷坯体。研究了不同分散剂在制备低粘度高固相体积分数Al2O3浓悬浮体中的分散作用,并重点考察了添加不同分散剂的Al2O3浆料的粘度随pH值变化的趋势,对比了不同分散剂对Al2O3浆料的分散效果。 相似文献
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本实验采用机械合金化工艺结合热处理工艺制备Fe3Al金属间化合物粉末,并将Fe3Al粉末与Al2O3粉末相混合制备Fe3Al/Al2O3复合粉末,并通过热压烧结工艺制备Fe3Al/Al2O3复合材料块材试样,对Fe3Al/Al2O3复合材料的物相组成,显微结构和力学性能进行研究.结果表明采用机械合金化工艺球磨60h后得到Fe-Al金属间化合物粉末.并经过800℃和1000℃热处理后得到Fe3Al金属间化合物粉末.经过热压烧结后得到的Fe3Al/Al2O3复合材料块材主要有Fe3Al相和Al2O3相.Fe3Al/Al2O3复合材料的显微结构均匀致密.Fe3Al晶粒均匀分布在Al2O3基体中,Fe3Al晶粒的平均颗粒尺寸为3~4μm,而Al2O3基体颗粒尺寸为4~5 μm.随着基体中Fe3Al合金含量的增加,Fe3Al/Al2O3复合材料的密度和相对密度逐渐增加;Fe3 Al/Al2O3复合材料的抗弯强度和断裂韧性逐渐增加;Fe3Al/Al2O3复合材料的洛氏硬度和弹性模量逐渐降低.Fe3Al/Al2O3复合材料具有较高的力学性能是由于复合材料具有均匀致密的显微结构. 相似文献
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Al2O3/SiCp纳米复合材料化学制备工艺研究 总被引:4,自引:0,他引:4
化学工艺是剪裁和控制陶瓷材料显微结构最有效的手段之一。为此详细研究了Al2O3/SiCp纳米复合材料的化学制备工艺,利用非均匀成核法在纳粹SiC粒子表面包覆一层Al(OH)3后,其等电点IEP由pH=3.4移至pH7.5,表现出类似Al2O3的胶态特性,在pH=4.5-5.0之间,包覆型SiC与Al2O3荷电性相同,通过胶态悬浮液混合,将包覆型纳米SiC均匀分散于Al2O3基体中,最后,在不加任何分散剂的条件下,制备出高固相、低粘度的包覆型SiC-Al2O3水基浆料,并成功利用凝胶注模型成型(gelcasting)工艺,制备出显微结构均匀的Al2O3/SiCp纳米复合陶瓷材料素坯。 相似文献
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纳米SiO2包覆Al2O3浓悬浮体制备及其凝胶注模成型 总被引:3,自引:1,他引:2
采用硅溶胶等制备纳米SiO2包覆Al2O3微复合体系,凝胶注模工艺制备莫来石陶瓷,着重研究了低粘度高固含量浓悬浮体系的特性及其凝胶注模成型坯体的性能.研究表明按莫来石理论组成将Al2O3颗粒分散于质量分数为30.3%的硅溶胶中,纳米SiO2胶粒吸附于颗粒表面,形成30~50 nm的SiO2包覆层,其中已形成Si-O-Al-O键.纳米SiO2包覆Al2O3浓悬浮体系的最佳分散条件在pH=9.0左右,利用SiO2包覆层的静电位阻稳定作用,可直接制备低粘度、高固含量浓悬浮体系,固相质量分数为76%的浓悬浮体表观粘度为975 mPa·s;固相质量分数为76%,有机单体质量分数为7.7%,采用凝胶注模工艺,所得坯体结构均匀、致密,相对密度达63%,抗折强度达5.85 Mpa. 相似文献
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《Journal of the European Ceramic Society》2005,25(9):1575-1579
An experimental study on the aluminum oxynitride and aluminum nitride formation by combustion of mixtures of micron-sized aluminum powder (average particle diameter as ∼9.0 μm) and alumina nanopowder (as ∼0.05 μm) of the fixed mass (∼10 g) and different mass ratios (Al/γ-Al2O3 = 0.1–19.0) in air is reported. The formation of aluminum oxynitride (Al3O3N) and aluminum nitride during the combustion of powdery aluminum-based mixtures in air is discussed in this study. The combustion synthesis of Al3O3N and AlN was carried out in self-sustaining way. XPS-FESEM, XRD and chemical analysis were executed on final products of synthesis. The combustion process was also recorded by a video-camera. It was found that powdery mixtures, ignited by local heating, burned in one- or two-stage self-propagating regime. The combustion regime is different for different initial mass ratios Al/γ-Al2O3 and mainly depends on the content of fuel (aluminum powder) in mixture. 相似文献
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真空条件下,以Al2O3和Al为原料,通过Al2O歧化法制备微细Al2O3/Al复合粉体.XRD和SEM分析表明:在反应温度为1200~1400℃时,随着温度的升高,粉体中氧化铝含量升高;冷凝温度约为550~750℃时,复合粉体中的氧化铝包括稳定晶型和不稳定晶型;冷凝温度约为1100~1300℃时,复合粉体中的氧化铝全部为稳定晶型;冷凝温度约为550~650℃时,复合粉体的平均粒径小于0.5μm;冷凝温度约为750℃时,铝熔化、微粒团聚;冷凝温度约为1100~1200℃时,铝形成铝珠,氧化铝为不规则状、平均粒径小于2μm;冷凝温度约为1300℃时,氧化铝为片状.因此,通过选取合适的反应温度、冷凝温度,可以控制Al2O3/Al复合粉体中氧化铝的含量、晶型和粒径. 相似文献
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M.C. Mesa P.B. Oliete R.I. Merino V.M. Orera 《Journal of the European Ceramic Society》2013,33(13-14):2587-2596
Al2O3-Er3Al5O12 and Al2O3-Er3Al5O12-ZrO2 eutectic ceramic rods were directionally solidified using the laser floating zone technique at several growth rates. Binary eutectic microstructure consisted in a three-dimensional interpenetrated network of the eutectic phases whereas the ternary eutectic showed a geometrical microstructure at low growth rates and a nanofibrillar pattern at high rates. The microstructure size was strongly dependent on the growth rate, decreasing when the processing rate increased. The optical absorption was measured in the samples at room temperature and Judd–Ofelt analysis was used to model the optical absorption of the Er3+ ions. Thermal emission of the eutectic rods was studied at temperatures up to 1600 °C. An intense narrow emission band at 1.55 μm matching with the sensitive region of the GaSb photoconverter was obtained. The intensity of the selective emission band is larger for the binary eutectic than for the ternary compound and increases as the microstructural size decreases. 相似文献
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《Ceramics International》2021,47(18):25491-25496
In this study, we developed a novel method for synthesising Al2OC-AlNss using a solid nitrogen source: a Si3N4 mesophase. The two-step sintered Al–Al2O3 and Si3N4–Al–Al2O3 samples were prepared under an atmosphere of nitrogen to investigate the effect of Si3N4 on the formation of Al2OC-AlNss in resin-bonded Al–Al2O3 composites. The samples were investigated via XRD and SEM. The results indicated that the synthesis of Al2OC-AlNss with different morphologies was achieved via the Si3N4 mesophase, and its morphology was influenced by the source of AlN. Both Al2OC-AlNss and Al4O4C were formed in the two-step sintered Al–Al2O3 sample, whereas only Al2OC-AlNss was formed in the two-step sintered Si3N4–Al–Al2O3 sample. Induced by the AlN formed by the nitridation of Al, needle-like Al2OC-AlNss was generated. Compared to that formed by the nitridation of Al, more AlN nuclei were provided by the reaction between Si3N4 and Al. Subsequently, columnar and granular Al2OC-AlNss were formed. Furthermore, fibre-like Al2OC-AlNss was also generated via the VS and VLS mechanism. The reaction model was established in this study. 相似文献
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Al2O3-MgO·1.35Al2O3复合浆料的流变特性研究 总被引:1,自引:1,他引:1
测试了高纯板状刚玉粉(Al2O3)、富铝尖晶石粉(MgO@1.35Al2O3)及其复合粉料(Al2O3-MgO@1.35Al2O3)在水溶液中不同pH值下的ζ电位,三者的等电点分别为7.4、~3和5.3.研究了分散剂三聚磷酸钠对复合浆料的ζ电位和流动性的影响,结果表明外加1 wt%溶剂量的三聚磷酸钠可降低复合浆料的ζ电位约40 mV;制备Al2O3-MgO@1.35Al2O3复合浆料的理想pH值范围为9~11;复合浆料中MgO@1.35Al2O3对流变特性的影响比Al2O3的大. 相似文献
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《Journal of the European Ceramic Society》2005,25(8):1285-1291
The mechanical properties and thermal stability of the Al2O3/Er3Al5O12 (EAG) eutectic ceramics have been investigated at very high temperature. The emissive properties of this eutectic ceramics have also been measured and its possibilities of application to an emitter have been discussed. The present eutectic ceramic has excellent high-temperature strength characteristics, showing that tensile yielding stress is approximately 300 MPa at 1650 °C and superior thermal stability at 1700 °C in an air atmosphere. The present material shows strong selective emission bands at wavelength 1.5 μm due to Er3+ ion. The emission bands of this material are nearly coincident with the sensitive region of GaSb PV cell, therefore, the Al2O3/EAG eutectic ceramic can be regarded as one of the promising emitter materials in TPV systems. 相似文献