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101.
Al2O3薄膜的应用近年受到很大的关注,它在过滤和分离等领域内具有极大的应用前景,但就其本身而言,仍存在一些不足之处。本文用Sol-Gel法制备了掺杂ZrO2、SiO2的改性Al2O3薄膜,并通过SEM、XRD等方法进行了表征。实验表明,掺杂后能提高Al2O3薄膜的化学稳定性和延缓烧结过程中的相变,使薄膜的性能得到提高。 相似文献
102.
Formation of thaumasite in synthetic cement mineral slurries 总被引:4,自引:0,他引:4
In order to investigate the effect of alite polymorphism on the susceptibility of cements to thaumasite formation, slurries were prepared from magnesium sulphate solution and mixtures of calcium carbonate with synthetic cement preparations plus additions of 0%, 1% or 2% w/w alumina. Two synthetic cement preparations were used; a co-prepared mixture of monoclinic alite (C54S16AM) with β-C2S (designated A) and a 99% pure, primarily triclinic C3S (designated B). The slurries were prepared after the manner of Gaze [Cement Concrete Res. 27(2) (1997) 259] and maintained in a state of continual agitation at 5 °C for 100 days. After this period, the slurries were dried and characterised using X-ray diffraction. In slurries made with A, both ettringite and thaumasite (or a solid solution thereof) were detected, the apparent ratio of the former to the latter increasing with alumina addition. No gypsum was detected. In slurries made with B, the only sulphate phase detected was gypsum.
This interesting observation leads to a number of avenues for discussion;
- • that alumina must be present in sufficient quantities within the clinker or gel structure, rather than as an addition, to initiate TF;
- • that TF is only initiated by C2S, not C3S;
- • that TF cannot be initiated by triclinic C3S.
103.
SiC(w)/TZP+mullite陶瓷复合材料界面和组成设计与力学性能 总被引:1,自引:1,他引:1
本文从理论上分析了SiC(w)TZP+mullite(p)复合材料界面残余热应力及其在基质内的分布规律。提出在SiC(w)表面涂复Al2O3和在PZT中加入mullite(p)联合作用来降低晶须/基质界面残余热应力的界面设计方案,导出SiC(w)和mullite(p)协同补强PZT的匹配条件。制备了SiC(w)/TZP+mullite(p)复合材料并了SiC(w)表面涂层Al2O3厚度和SiC(w 相似文献
104.
Oxide ceramics for use as electrical insulators in future fusion devices, will be exposed to ionization and displacement damage (neutrons, gammas, ion bombardment). Enhanced oxygen loss due to ion bombardment increases surface electrical conductivity, and at the same time the surface emits light due to ion beam induced luminescence (IBIL). Results for 3 types of α-alumina and sapphire measuring electrical surface conductivity and IBIL as a function of dose at different temperatures between 20 and 200 °C, show a clear correlation between luminescence and surface electrical degradation. This indicates the potential to remotely monitor insulating material degradation not only in ITER and beyond, but also in the more immediate in-reactor experiments required for materials testing. Partial reduction of degradation by heating in air suggests the possibility for in situ recovery of the insulating properties. 相似文献
105.
Al2O3多孔陶瓷的制备和性能研究 总被引:2,自引:0,他引:2
采用乙基纤维素为成孔剂制备了Al2O3多孔陶瓷,探讨了工艺参数对其性能的影响。研究结果表明,造孔剂含量、球磨时间及烧结温度均对多孔陶瓷的气孔率和抗折强度有影响。烧结温度的升高使得气孔率降低,但变化不明显,抗折强度明显提高。随造孔剂含量的升高,使得气孔率逐渐上升,超过20%后变化趋于平稳。随着球磨时间的增加,试样呈现气孔率下降和抗折强度升高的趋势。以烧结温度为1580℃,造孔剂含量20%;球磨时间为2.5h的条件下,可获得高显气孔率、抗折强度较高的舢203多孔陶瓷。 相似文献
106.
107.
Xiang Qiu Naeem ul Haq Tariq Lu Qi Jun-Rong Tang Xin-Yu Cui Hao Du Ji-Qiang Wang Tian-Ying Xiong 《金属学报(英文版)》2019,32(12):1449
In this study,alumina/A380 composite coatings were fabricated by cold spray.The influence of alumina particulates' morphology(spherical and irregular) and content on the deposition behavior of the coatings(including surface roughness,surface residual stress,cross-sectional microstructure and microhardness) was investigated.Results revealed that the spherical alumina mainly shows micro-tamping effect during deposition,which result in remarkable low surface roughness and porosity of the coatings.In addition,very low deposition efficiency and good interfacial bonding between the coating and the substrate were achieved.For irregular alumina particles,the embedding of ceramic particulates in the coating was dominant during deposition process,resulting in high retention in the final deposit.However,it showed limited influence on porosity,surface roughness and interfacial bonding of the deposit.The coatings containing irregular alumina particulates exhibited much higher microhardness than those containing spherical alumina due to the higher load-bearing capacity of deposited alumina. 相似文献
108.
《Journal of the European Ceramic Society》2017,37(15):5023-5034
This work revisits the proposed mechanisms presented in the literature for CA6 formation in Al2O3-MgO and Al2O3-MgAl2O4 castables bonded with calcium aluminate cement. New experimental tests, thermodynamic simulations and re-evaluation of the chemical composition and microstructural aspects observed for samples fired in the temperature range of 1150 °C to 1500 °C were carried out. Based on these data, a new interpretation of the CA6 generation process, as well as the features which influence the location and morphology of this phase were proposed. CA6 formation via solid and liquid states are suggested to take place in all evaluated compositions, where the former (solid-state) is the main reaction predicted for the silica-free refractories (AM0MS and AS0MS), whereas the liquid-state one prevails in the AM1MS and AS1MS materials. The CA6 crystal morphology should be affected by these different reaction mechanisms. According to the experimental results, it was also discussed the role of the calcium hexaluminate features in the overall corrosion behavior of the designed refractories when they were placed in contact with molten slag at high temperatures. Such aspects have not been previously reported in published papers related to this subject. 相似文献
109.
M. P. Borque A. Lpez-Agudo E. Olguín M. Vrinat L. Cedeo J. Ramírez 《Applied Catalysis A: General》1999,180(1-2):53-61
The effect of the TiO2–Al2O3 mixed oxide support composition on the hydrodesulfurization (HDS) of gasoil and the simultaneous HDS and hydrodenitrogenation (HDN) of gasoil+pyridine was studied over two series of CoMo and NiMo catalysts. The intrinsic activities for gasoil HDS and pyridine HDN were significantly increased by increasing the amount of TiO2 into the support, and particularly over rich- and pure-TiO2-based catalysts. It is suggested that the increase in activity be due to an improvement in reducing and sulfiding of molybdena over TiO2. The inhibiting effect of pyridine on gasoil HDS was found to be similar for all the catalysts, i.e., was independent of the support composition. The ranking of the catalysts for the gasoil HDS test differed from that obtained for the thiophene test at different hydrogen pressures. In the case of gasoil HDS, the activity increases with TiO2 content and large differences are observed between the catalysts supported on pure Al2O3 and pure TiO2. In contrast, in the case of the thiophene test, the pure Al2O3-based catalyst appeared relatively more active than the catalysts supported on mixed oxides. Also, in the thiophene test the difference in intrinsic activity between the pure Al2O3-based catalyst appeared relatively more active than the catalysts supported on mixed oxides. Also in the thiophene test, the difference in intrinsic activity between the pure Al2O3- and pure TiO2-based catalysts is relatively small and dependent on the H2 pressure used. Such differences in activity trend among the gasoil and the thiophene tests are due to a different sensitivity of the catalysts (by different support or promoter) to the experimental conditions used. The results of the effect of the H2 partial pressure on the thiophene HDS, and on the effect of H2S concentration on gasoil HDS demonstrate the importance of these parameters, in addition to the nature of the reactant, to perform an adequate catalyst ranking. 相似文献
110.
按板状刚玉(2.361~0.043mm)91.5%,Al粉(<0.044mm)5%,B4C和炭黑(<0.044mm)3.5%,外加4.5%的热塑性酚醛树脂作为结合剂,制成铝碳材料,分别在氮气气氛和埋炭气氛中经800℃、1000℃、1200℃、1450℃保温5h热处理后,测定试样的常温性能、高温抗折强度(1400℃)和抗水化性能,并用XRD和SEM分析试样的物相组成和显微结构。试验结果表明:随热处理温度的升高,铝碳材料的高温抗折强度逐渐下降;在相同温度条件下,这两种保护气氛处理后试样的高温抗折强度水平相当;在800~1000℃的温度段处理时,埋炭保护处理材料的水化程度大,损伤材料结构,明显降低材料的强度。在相同温度条件下,氮气保护处理试样的抗水化性能优于埋炭保护处理试样。 相似文献