TiO2/Al2O3-Al2O3-TiO2/Al2O3绝缘结构的真空沿面闪络特性

基于变插入层介电常数的多层绝缘结构能改善电场分布、提高真空沿面闪络特性.通过真空热压烧结制备了TiO2/Al2O3-Al2O3-TiO2/Al2O3(A-B-A)3层绝缘结构,A层w(TiO2)为0.5%到20%.测量了该绝缘结构的真空沿面闪络特性,发现闪络特性随w(TiO2)的增加而提高,当w(TiO2)为20%时,其脉冲初次闪络电压较同等厚度的Al2O3陶瓷提高了63%.研究发现:A层的介电常数可由w(TiO2)调控,介电常数的增大能有效降低真空-绝缘子-阴极三结合点处的电场强度;A层表面存在的TiO2颗粒可以减小二次电子发射系数并改善表面电荷分布;TiO2的电导率虽比Al2O3高,但其仍为绝缘体,即使TiO2含量较高时也不会形成贯穿的导电通道.     

CaO-ZrO2-TiO2-Al2O3-B2O3-SiO2玻璃陶瓷的制备及化学稳定性研究

玻璃陶瓷是固化处理中、高放废物和α废物较为理想的候选材料之一。研究了特定条件下制备的CaO-ZrO2-TiO2-Al2O3-B2O3-SiO2体系玻璃陶瓷在水淬和空气中自然冷却的两种冷却制度对其结晶行为和显微结构的影响,用粉末浸泡实验方法测试了其化学稳定性。结果表明:自然冷却形成的玻璃陶瓷晶相主要是ZrSiO4和ZrTiO4;在25～70℃范围内,温度对玻璃陶瓷浸出率无明显影响,90℃下浸出率比25℃,40℃,70℃的浸出率高一个数量级;7 d元素总的归一化浸出为1.87 g/m2。     

等离子喷涂纳米和微米Al_2O_3-TiO_2涂层摩擦磨损性能研究

采用大气等离子喷涂的方法制备了纳米和微米Al2O3-TiO2涂层,其中w(TiO2)=13%.分析了涂层组织形貌特征和结合强度等性能,研究了两种涂层在不同载荷下的摩擦磨损性能.结果表明,纳米Al2O3-TiO2涂层是由未熔或半熔纳米颗粒区域与完全熔融粒子铺展区域共同构成的,孔隙率低,显微硬度、结合强度均高于层状结构的微米涂层,且纳米涂层磨损量明显小于微米涂层.高载荷下磨屑均匀细化、圆整,形成微滚珠效应,纳米涂层稳态摩擦系数随载荷增大而下降,而微米涂层摩擦系数随载荷变化不明显.     

纳米Fe2O3-Al2O3复合材料的制备

采用溶胶-凝胶表面包覆法制备了纳米Fe₂O₃-Al₂ O₃复合材料, 利用X射线衍射和透射电镜对样品的物相、 粒度和形貌进行了研 究. 结果表明, α-Fe₂O₃掺杂降低了Al₂O₃相变温度, 在900 ℃可以得到稳定的α-Al₂O₃相.     

Growth characteristics of directionally solidified Al2O3/YAG/ZrO2 ternary hypereutectic in situ composites under ultra-high temperature gradient

Oxide eutectic ceramic in situ composites have attracted significant interest in the application of high-temperature structural materials because of their excellent high-temperature strength,oxidation and creep resistance,as well as outstanding microstructural stability.The directionally solidified ternary Al2O3/YAG/ZrO2 hypereutectic in situ composite was successfully prepared by a laser zone remelting method,aiming to investigate the growth characteristic under ultra-high temperature gradient.The microstructures and phase composition of the as-solidified hypereutectic were characterized by using scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),and X-ray diffraction(XRD).The results show that the composite presents a typical hypereutectic lamellar microstructure consisting of fine Al2O3 and YAG phases,and the enriched ZrO2 phases with smaller sizes are randomly distributed at the Al2O3/YAG interface and in Al2O3 phases.Laser power and scanning rate strongly affect the sample quality and microstructure characteristic.Additionally,coarse colony microstructures were also observed,and their formation and the effect of temperature gradient on the microstructure were discussed.     

Yb2O3、Al2O3、TiO2对Yb-TZP材料性能的影响

用超细ZrO     

Effect of Fe2O3 on the size and components of spinel crystals in the CaO-SiO2-MgO-Al2O3-Cr2O3 system

size of spinel crystals in the CaO-SiO₂-MgO-Al₂O₃-Cr₂O₃ system was investigated using lab experiments carried out in a carbon tube furnace. Scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) and X-ray diffraction (XRD) were used to analyze the microstructure, components, and the mineral phases of synthetic slags. FactSage 7.1 was used to calculate the crystallization process of the molten slag. The results showed that the addition of Fe₂O₃ promoted the precipitation of spinel crystals and inhibited the formation of dicalcium silicate. The size of spinel crystals increased from 2.74 to 8.10 μm and the contents of chromium and iron in the spinel varied as the Fe₂O₃ addition was increased from 0 to 20wt%. Fe₂O₃ thermodynamically provided the spinel-forming components to enhance the formation of FeCr₂O₄, MgFe₂O₄, and Fe₃O₄. The addition of Fe₂O₃ increased the fraction of liquid phase in a certain temperature range and promoted diffusion by decreasing the slag's viscosity. Therefore, Fe₂O₃ is beneficial to the growth of spinel crystals in stainless steel slag.     

纳米Al2O3颗粒对Cu-Al2O3性能的影响

采用溶胶-凝胶法制备纳米Al₂O₃颗粒,通过粉末冶金法制备氧化铝铜（Cu-Al₂O₃）。采用X射线光电子能谱仪、扫描电子显微镜、洛氏硬度仪和涡流计分别测试了Cu-Al₂O₃的结合能、微观组织、硬度和导电率。结果表明：随Al₂O₃颗粒含量的增加,Cu-Al₂O₃的硬度先升高后降低,当Al₂O₃颗粒的质量分数达到0.084%时,Cu-Al₂O₃的硬度达到最大值75.73（HRB）。Cu-Al₂O₃的导电率随着Al₂O₃颗粒含量的增加逐渐下降。Al₂O₃颗粒的质量分数为0.084%时为最佳值,Cu-Al₂O₃的硬度达到最大值,导电率达到69.1% IACS。     

H4SiW12O40/ZrO2-Al2O3催化合成环己酮乙二醇缩酮

采用浸渍法制备了H4SiW12O40/ZrO2-Al2O3催化剂,并通过FT-IR、XRD对其进行了表征。探讨了该催化剂对合成环己酮乙二醇缩酮的催化活性,研究了不同因素对产品收率的影响。在n（乙二醇）∶n（环己酮）=1.4∶1,催化剂用量为反应物总质量的1.5%,反应时间75 min的条件下,环己酮乙二醇缩酮的收率为87.5%.     

Fe2O3转变为Fe3O4粉末的微波碳热还原

以活性炭为还原剂及以氩气为保护气,采用微波碳热还原的方法,将弱磁性的Fe2O3还原成强磁性的Fe3O4,并研究焙烧温度、保温时间以及SiO2粉末的加入对其还原焙烧成分及磁化效果的影响规律.结果表明:在配碳量一定的条件下,焙烧温度是微波碳热还原的关键因素,随着温度的升高,还原产物中Fe3O4的含量发生有规律的变化;650℃、保温5 min的条件下经微波还原后生成了纯Fe3O4粉末,其磁化率和还原度分别达到理论值2.33和11.11%;含SiO2的Fe2O3粉末在750℃以上进行微波还原,会生成大量的硅酸亚铁和氧化亚铁,导致Fe3O4含量降低,恶化还原焙烧指标,所以微波磁化焙烧的最佳温度应在570~650℃.     

原位合成CNTs/Cu-Al2O3复合材料的性能研究

对Al的质量分数分别为0.20%,0.35%,0.60%的Cu-Al合金粉末进行内氧化,得到Cu-Al₂O₃粉末。采用化学气相沉积法在Cu-Al₂O₃粉末表面原位生长碳纳米管(carbon nano tubes, CNTs),采用放电等离子烧结工艺成功制备了CNTs/Cu-Al₂O₃复合材料。采用扫描电子显微镜和透射电子显微镜观察了CNTs/Cu-Al₂O₃复合粉末、复合材料断口的形貌。采用显微硬度计、微拉伸试验机、摩擦磨损试验机分别对纯Cu及复合材料的维氏硬度、抗拉强度、摩擦因数进行测试。采用电化学工作站测试复合材料在3.5%NaCl (质量分数)水溶液中的耐腐蚀性能。结果表明,随着Al的质量分数的增加,粉末表面合成的CNTs的数量也增多。Al的质量分数为0.35%时,CNTs/Cu-Al₂O₃复合材料的综合性能最佳,与纯Cu相比,复合材料的抗拉强度和腐蚀电势分别提高了86.4%和43.2%,分别为315 MPa和-0.268 V,摩擦因数降低了53.3%,仅为0.28。     

Al2O3-SiO2∶Ln3+发光陶瓷的合成及发光行为

采用溶胶-凝胶法合成出了Al     

H3 PW12 O40/ZrO2-WO3催化合成己酸正丁酯

采用浸渍法制备了H3 PW12 O40/ZrO2-WO3催化剂,并通过FT-IR、XRD对其进行了表征.探讨了该催化剂对合成己酸正丁酯的催化活性,研究了不同因素对产品收率的影响.在n(正丁醇)∶n(己酸)=1.5∶1,催化剂用量为反应物总质量的1.0%,带水剂环己烷4mL,反应时间75min的条件下,己酸正丁酯的收率为84.1%.     

TiO2微粉对Al2O3-MgO-Cr2O3浇注料性能的影响

马克思的市民社会决定国家理论的形成,经历了一个思想交锋、自我批判、绵延提升直至最终导出唯物史观之创建的逻辑进程。马克思立足于《莱茵报》时期的感性经历,先后运用哲学、历史学和政治经济学的方法和知识对黑格尔理性国家观进行系统的理论清算,纠正了黑格尔的市民社会与国家关系的“历史错位”,首次确立了“社会本体论”原则。市民社会决定国家理论的形成是标志着唯物史观开始诞生的第一命题。分析马克思市民社会决定国家理论的发展脉络和演进逻辑,有利于澄清马克思市民社会理论与唯物史观的内在关联,科学评价市民社会理论在历史唯物主义中的历史地位。     

SO4^2--La2O3-TiO2固体超强酸催化水杨酸的酯化反应

首次以SO42--La2O3-TiO2为非均相催化剂,以水杨酸为原料,合成了水杨酸甲酯和乙酰水杨酸。考察了影响反应的条件,获得优化实验条件:n水杨酸:n甲醇为1:12,催化剂用量40 g/mol酸,反应5 h时,水杨酸甲酯的收率可达86%;n水杨酸:n乙酸酐为1:4,催化剂用量6 g/mol酸时,乙酰水杨酸的收率可达87%,同时催化剂回收再生容易,重复使用4次催化活性无明显降低,是一种环境友好的催化剂。     

XPS Study of CeO2/Al2O3 film

The redox capacity of CeO₂/Al₂O₃ thin film which was prepared by sol-gel method has been investigated by X-ray Photoelectron Spectrascopy (XPS). The results showed that the thin film was easier to be reduced and re-oxidized than pure CeO₂ powder. The key role played by oxygen vacancies which were created from the interaction between CeO₂ and Al,O, was also discussed.     

Oxidation behavior of in-situ Al2O3/TiAl composites at 900°C in static air

In-situ Al₂O₃/TiAl composites were successfully synthesized from the starting powders of Ti, Al, TiO₂ and Nb₂O₅. The oxidation behavior of the composites at 900°C in static air was investigated. The results indicate that the composite samples present a much lower oxidation mass gain. Under long-time intensive oxidation exposure, the formed oxide scale is multi-layer. The formation of the outer TiO₂ layer is fine and dense, the internal Al₂O₃ scale has good adhesiveness with the outer TiO₂ scale, and the TiO₂+Al₂O₃ mixed layer forming the protective oxide scale is favorable for the improvement of oxidation resistance. It is believed that the incorporation of Al₂O₃ particulates into the metal matrix decreases the coefficient of thermal expansion of the substrate, and forms a local three-dimensional network structure that can hold the oxide scale. The formation of the oxide scale with finer particle size, stronger adherence, less micro-defects and slower growth rate can contribute to the improvement of oxidation resistance. Nb element plays an important role in reducing the internal oxidation action of the materials, restraining the growth of TiO₂ crystals and promoting the stable formation of the Al₂O₃-riched layer, which is beneficial to improve the oxidation properties.     

烧结助剂Cr2O3、Mn2O3的添加对ZTM陶瓷常温性能的影响

通过对试样的断裂强度、断裂韧性、相对密度、气孔率、玻璃相含量以及显微结构的研究,探讨了Cr     

CaO-Al2O3-P2O5玻璃的结构与相变

FT-IP分析表明,50CaO