二氧化钛对黑色Al2O3陶瓷性能的影响

以超微细a-氧化铝粉为主要原料,添加适量过渡金属氧化物以及不同分量的TiO2粉末,采用传统粉末冶金技术、干压烧结法制备了黑色Al2O3陶瓷。对制备工艺中的原料准备、压制成型、烧结过程进行了讨论,并对其导电性能进行了测试分析。实验结果表明：TiO2是一种良好的添加剂,它不仅可以降低烧成温度,还有利于Al2O3陶瓷黑色的形成,改善其电气性能。     

TiO2 在Al2 O3 -SiO2 系耐火材料中的作用

阐述了TiO2在Al2O3-SiO2系耐火材料,特别是高铝矾土中的分布和存在方式,并通过分析Al2O3-SiO2系耐火原料的煅烧过程和Al2O3-SiO2系制品的使用过程中TiO2、Al2O3和SiO2三者之间的化学反应,介绍了TiO2对Al2O3-SiO2系耐火材料结构和性能的影响。     

TiO2掺杂对Na2CO3/Al2O3吸收剂CO2捕捉性能的影响

钠基固体吸收剂脱除燃煤烟气CO₂技术具有反应温度低、能耗低等优点,日益受到学术界的关注。该技术的主要不足是吸收剂的活性成分碳酸钠与CO₂的反应（碳酸化反应）活性较低。针对这一问题,本文旨在研制一种新型改性钠基固体吸收剂,采用活性氧化铝作为载体、TiO₂作为掺杂剂进行改性,利用热重分析装置、XRD、SEM和氮吸附仪研究钠基固体吸收剂的CO₂捕捉性能。结果表明：掺杂TiO₂后,钠基固体吸收剂与CO₂的反应速率加快,CO₂捕捉量增加;反应前后除TiO₂外无其他含Ti化合物生成;碳酸化反应产物为NaHCO₃和Na₅H₃（CO₃）₄;然而TiO₂掺杂过多会堵塞吸收剂的微观孔道,不利于甚至阻碍碳酸化反应的进行,因此,TiO₂的掺杂量应控制在一定的范围内。     

Effect of Modifiers on the Reactivity of Cr2O3/Al2O3 and Cr2O3/TiO2 Catalysts for the Oxidative Dehydrogenation of Propane

Chromium oxide supported on alumina and titania supports was modified with oxides of sodium, vanadium and molybdenum. The modified and unmodified chromium oxide catalysts were characterized by several techniques. The presence of surface chromium oxide and surface molybdenum and vanadium oxide species was detected in the unmodified and molybdenum and vanadium oxide modified supported chromium oxide catalysts. The reducibility (T_max and H/Cr ratio) of the surface chromium species was not affected for the vanadium and molybdenum oxide modified catalysts; however, the reducibility changed noticeably for sodium modified supported chromium oxide catalysts. Studies of the reactivity of the ODH of propane revealed the effect of modifiers on the reactivity properties of the surface chromium oxide species. The activity and propene selectivity decreased for sodium modified supported chromium oxide catalysts. However, the activity increased for vanadium oxide modified catalysts and was similar for molybdenum oxide modified catalysts irrespective of the support. The propene selectivity was higher for molybdenum oxide modified chromium oxide catalysts. However, the propene selectivity for vanadium oxide modified catalysts depends on the support since it appears that the inherent selectivity of the surface vanadium oxide species is reflected.     

Influence of Bi2O3/TiO2, Sb2O3 and Cr2O3 doping on low-voltage varistor ceramics

The influence of the amount of Bi₂O₃ and TiO₂ additions at a TiO₂/Bi₂O₃ ratio of 1, as well as Sb₂O₃ and/or Cr₂O₃ doping, on the microstructural development and electrical properties of varistor ceramics in the ZnO–Bi₂O₃–TiO₂–Co₃O₄–Mn₂O₃ system was investigated. In samples with a low level of Bi₂O₃ and TiO₂ (0·3 mol%) and therefore small amount of liquid phase, exaggerated growth of the ZnO grains results in high microstructural inhomogeneity. Co-doping with Sb₂O₃ significantly changes the phase composition of TiO₂ doped low-voltage varistor ceramics. The Bi₃Zn₂Sb₃O₁₁ type pyrochlore phase forms at the expense of the γ-Bi₂O₃ and Bi₄Ti₃O₁₂ phases and decreases the amount of liquid phase in the early stages of sintering. Already small amounts of Sb₂O₃ and/or Cr₂O₃ added to a TiO₂ doped low-voltage varistor ceramics limit ZnO grain growth and increase the threshold voltage V_T of the samples.     

Effect of ZnO and TiO2 doping on the sintering behavior of Y2O3 ceramics

Full densification of Y₂O₃ is challenging and requires a very high sintering temperature (above 1700 °C). In this study, the effect of ZnO and TiO₂ dopants on its densification was investigated, showing that both dopants lowered the sintering temperature and improved the process. Moreover, ZnO promoted the grain growth, while TiO₂ inhibited it; hence, the ZnOTiO₂ co-doping and the change in the ZnO/TiO₂ ratio allowed the control of the sintered body microstructure while maintaining high densification. Since Y₂O₃ has a higher plasma erosion resistance than conventional Si-based materials, the plasma dry etching resistance of the sintered Y₂O₃ was also evaluated and found superior due to the improved densification and controlled grain size of the doped samples.     

TiO2加入量对MgO - TiO2-Al2O3系熟料特性的影响

制作MgO含量相同、TiO2含量不同的各种熟料，测定熟料特性，研究TiO2加入量对MgO-TiO2-AlO3，系熟料特性的影响。TiO2含量不同，各种熟料的矿物组成中尖晶石固溶体的成分不同。TiO2和Al2O3共存可提高抗热化性和抗热震性。TiO2能促进烧结的进行。     

Al2O3纤维增强钛酸铝陶瓷

介绍了一种Al2O3纤维增强钛酸铝陶恣复合材料，在一定范围内随着Al2O3纤维含量的增加，复合材料的抗弯强度和断裂韧性均提高，当Al2O3纤维含量达到4.5%(体积分数）时抗弯强度和断裂韧性达到最大值，使钛酸铝基体材料分别提高近120％和75％。     

Preparation of alumina catalyst supports and NiMo/Al2O3 catalysts

Several alumina catalysts were prepared to investigate effects of catalyst preparation variables on pore structure, including sintering time and temperature, acid type, and fiber type and loading. Each catalyst was characterized with a porosimeter and sorptometer in terms of pore size distribution, average pore diameters, pore volumes, densities and surface area. Bimodal NiMo catalysts were effectively prepared without losing surface area by using a combined method of coextrusion and fiber incorporation.     

负载型光催化剂TiO_2/Al_2O_3的制备与研究

以γ Al2O3小球为载体,以钛酸正丁酯的正丁醇溶液为浸涂液,采用浸渍涂覆法制备了TiO2/Al2O3光催化剂,用XRD对催化剂的物相进行了表征,并通过可溶性偶氮染料酸性媒介红B考察其光催化活性。实验表明,当TiO2的负载量为8.79%时,TiO2/Al2O3对酸性媒介红B的脱色率可达到95%以上;酸性媒介红B的光催化氧化符合一级反应动力学。     

Al_2O_3/TiO_2纳米抗菌剂的制备及性能

以TiC l4、A l2(SO4)3为原料,控制n(A l2O3)/n(TiO2)=0.2,采用液相共沉淀法制备了A l2O3/TiO2纳米抗菌剂,并用DSC-TG、XRD、UV-vis等手段研究了A l2O3复合对TiO2抗菌性能的影响。结果表明,复合A l2O3后,TiO2纳米抗菌剂经900℃煅烧后完全是锐钛矿结构;950~1 050℃为良好的混晶结构,其中,经950℃煅烧后,混晶结构中锐钛矿相质量分数约占77%,平均粒径约20 nm,可见光吸收带边红移显著,光吸收阈值由纯TiO2的380 nm红移至430 nm左右,抗菌性能好,在荧光灯下对大肠杆菌和金黄色葡萄球菌的抑菌圈直径达15mm左右。     

Nanoindentation of Al2O3/Al2TiO5 composites: Small-scale mechanical properties of Al2TiO5 as reinforcement phase

The mechanical properties of alumina/aluminum titanate composites (Al₂O₃/Al₂TiO₅) were evaluated and analyzed by nanoindentation. Indentations with different penetration depths were performed, and residual imprints on specimens were located and observed by combining complementary characterization techniques. The mechanical response of composites was found to be determined by grain size of alumina and aluminum titanate, as evaluated from indentations performed at 1500 nm of penetration depth. On the other hand, small indents in individual grains permitted to assess the hardness as well as the elastic modulus of non-cracked particles of Al₂TiO₅ through implementation of different analytical indentation models. The attained values for the local mechanical properties were validated through critical comparison of them with those predicted by the rule of mixtures. Results showed no evidence of microcracking on grains of the reinforcing phase for all the tested composites, before and after low penetration depth indentations. Elastic modulus of Al₂TiO₅ was found to be higher than the values reported on bulk aluminum titanate, presumably because of the absence of microcracking for small grain sizes. The bulk composite mechanical response is finally discussed on the basis of contributions from those of the individual phases.     

Support Effects on Thiophene Hydrodesulfurization over Co-Mo-Ni/Al2O3 and Co-Mo-Ni/TiO2-Al2O3 Catalysts

A carbon-based sulfonated catalyst was prepared by direct sulfonation and carbonization （in moderate conditions：200 ＆#176;C, 12 h） of red liquor solids, a by-product of paper-making process. The prepared sulfonated cata-lyst （SC） had aromatic structure, composed of carbon enriched inner core, and oxygen-containing （SO3H, COOH, OH） groups enriched surface. The SO3H, COOH, OH groups amounted to 0.74 mmol·g^-1, 0.78 mmol·g^-1, 2.18 mmol·g^-1, respectively. The fresh SC showed much higher catalytic activity than that of the traditional solid acid catalysts （strong-acid 732 cation exchange resin, hydrogen type zeolite socony mobile-five （HZSM-5）, sulfated zir-conia） in esterification of oleic acid. SC was deactivated during the reactions, through the mechanisms of leaching of sulfonated species and formation of sulfonate esters. Two regeneration methods were developed, and the catalytic activity can be mostly regenerated by regeneration Method 1 and be fully regenerated by regeneration Method 2, respectively.     

TiO2/Al氮化合成复相TiN-Al2O3

从热力学角度讨论了Al作为还原剂还原氮化TiO2制备复相TiN-Al2O3的可行性.利用综合热分析、X射线衍射仪、扫描电镜及能谱仪分析研究了在1 100～1 500℃TiO2和金属Al粉还原氮化过程中样品的质量变化、相组成和显微结构.结果表明:在1 100℃合成产物中已有少量的AlN和TiN,说明A1的氮化反应以及TiO2和Al的还原氮化反应都已开始.在1200～1 300℃,TiN含量明显增加,AIN含量逐渐减少.在1 350℃,合成产物中只有TiN和Al2O3,说明还原氮化反应完成.继续提高温度,在1400～1 500℃,TiN和刚玉的晶粒长大.     

Effect of TiO2–Al2O3 Sol–Gel Supports on the Superficial Ni and Mo Species in Oxidized and Sulfided NiMo/TiO2–Al2O3 Catalysts: Influence on Dibenzothiophene Hydrodesulfurization

The present work presents a comparative study of NiMo catalysts supported on sol–gel TiO₂–Al₂O₃ mixed oxides with 5 and 95 mol% content of Al₂O₃. The DRX and N₂ physisorption results showed that the sol–gel method allows preparation of TiO₂–Al₂O₃ mixed oxides possessing high superficial area and an amorphous TiO₂ structure. Results of ζ-potential showed that the net surface pH of the supports depends on their structure and composition. According to UV–Vis and Raman spectra obtained from the solids after impregnation, catalysts with high content of Al₂O₃ showed Mo₇O₂₄ ^2? and Mo₈O₂₆ ^4? species displaying Mo–O–Mo stretching vibration modes. On the other hand, catalysts with high content of TiO₂ showed Mo₇O₂₄ ^2? and Mo₈O₂₆ ^4? species with vibration modes corresponding to terminal Mo=O_t bonds. Therefore, it appears that impregnation of catalysts with a pH 9 solution allows a polymerization process of MoO₄ ^2? and [Ni²⁺4O^2?] solution species to Mo₈O₂₆ ^4? and Mo₇O₂₄ ^2? species with a close interaction with [Ni²⁺6O^2?] species. However, these species have low interaction with the support. Thus, composition of the support appears to be more important than net surface pH in order to obtain a better distribution of superficial Mo species. XPS results suggest a higher proportion of “NiMoS” phase on the TiO₂ rich support. The most active catalyst in the dibenzothiophene hydrodesulfurization was NiMo/TiO₂–Al₂O₃ with 5 mol% Al₂O₃. This suggests that Mo₇O₂₄ ^2? and Mo₈O₂₆ ^4? in combination with [Ni²⁺6O^2?] species produce a better Ni/(Ni + Mo) ratio and NiMoS phase.     

Al2O3/TiO2复合膜的结构及光催化性能

利用电沉积方法在铝硫酸阳极氧化膜表面制备了具有光催化活性的T iO2薄膜。分析了A l2O3/T iO2复合膜的结构,观察了薄膜表面形貌及断面构造,并分析了薄膜表面的化学成分,通过紫外光照射下甲基橙溶液的光催化降解反应初步研究了该复合膜的光催化活性。结果表明,未经热处理的A l2O3/T iO2复合膜处于非晶态,550℃热处理3 h后,T iO2转变为锐钛矿结构;沉积在铝氧化膜表面的T iO2薄膜厚度约5μm,呈均匀不连续状态,表面存在大量裂纹,电沉积T iO2过程中基体氧化铝存在着部分溶解;薄膜表面主要由T i、O两种元素构成,同时存在较少量的A l、S、K等元素。该A l2O3/T iO2复合膜可光催化降解甲基橙溶液,具有光催化活性。     

Effect of CeO2 and Al2O3 contents on Ce‐ZrO2/Al2O3 composites

Effect of CeO₂ and Al₂O₃ contents on phase composition, microstructures, and mechanical properties of Ce–ZrO₂/Al₂O₃ composites was studied. The CeO₂ content in CeO₂–ZrO₂ varied from 7 to 16 mol%, and the Al₂O₃ content in Ce‐ZrO₂/Al₂O₃ composites were 7 and 22 wt%. When CeO₂ content was ≤10 mol%, high Al₂O₃ content contributed to hinder the tetragonal‐to‐monoclinic ZrO₂ phase transformation during cooling and decrease the density of microcracks in the composites. Tetragonal ZrO₂ single‐phase was obtained in the composites with ≥12 mol% CeO₂, regardless of the Al₂O₃ content. Hardness, flexural strength, and toughness were dependent on CeO₂ and Al₂O₃ contents which were related to the microcracks, grain size, and phase transformation. The high flexural strength and toughness of the composites with 7wt% Al₂O₃ could be obtained at an optimum CeO₂ content of 12 mol%, whereas those of the composites with 22 wt% Al₂O₃ could be achieved in the wide CeO₂ content range of 8.5‐12 mol%.     

微乳-水热法合成核壳型TiO2/Al2O3纳米粉体

本文采用微乳-水热法一步合成了核壳型TiO2/Al2O3纳米粉体.通过对产物的Zeta电位研究得出制备Ti(OH)4/Al(OH)3核壳前驱体的最佳pH值.并且采用XRD、TEM及SEM等表征方法与普通一步水热法合成的TiO2/Al2O3纳米粉体的晶形晶貌进行比较.结果表明:微乳-水热法能改善颗粒形状和大小,产品的颗粒大小均匀、平均晶粒粒径为13.68 nm.     

Effect of particle size distribution of raw powders on pore size distribution and bending strength of Al2O3 microfiltration membrane supports

To lower the sintering temperature of Al₂O₃ microfiltration membrane support, Al₂O₃ powders with particle size distribution of tri-modal are chosen. The results show that the function of fine Al₂O₃ grains depends on their agglomeration state: if fine Al₂O₃ grains distribute discretely, the bending strength of the support increases along with a slight increase in porosity; however, the aggregated fine grains are harmful to both bending strength and pore size distribution of the support. The bridging of medium Al₂O₃ grains between coarse grains contributes to increase the bending strength, but has less effect on porosity. The addition of medium (and/or fine) Al₂O₃ powder has less effect on the pore size distribution of the support if only coarse Al₂O₃ grain forms the support's framework, which suggests a new way to prepare the support with both high bending strength and high porosity at low temperature.