Tin(IV) Oxide Coating of Aluminum Borate Whiskers and Alumina Particles by Chemical Vapor Deposition

Aluminum borate whiskers of 0.5–1.0 μ diameter and alumina particles of 10–20 μ diameter were coated with SnO₂ by the reaction of SnCl₄–H₂O–N₂ gas mixtures in a rotary kiln reactor. Prior to coating, the whiskers were slightly etched to ensure adhesion between the SnO₂ layer and the whisker surface. The whiskers were coated at 100°C for 1 h, and then at 300°C for 2 h. This procedure was effective for covering the entire whisker surface with a uniform SnO₂ layer. Precoating was not necessary for the alumina particles. A compressed disk of the coated whiskers had an electrical conductivity of 30–40 S/m.     

Synthesis and Study of a Polypyrrole–Aluminum Oxide Nanocomposite Film on an Aluminum Surface

Using the method of electrochemical anodization, aluminum oxide porous films are obtained in a sulfuric acid solution. The morphology of the aluminum oxide surface is studied by the method of scanning electron microscopy. The high-quality elemental analysis of the initial and oxidized Al films is performed using the method of electron microprobe analysis. A protective composite polypyrrole-aluminum oxide film is produced on the aluminum surface on top of a porous aluminum oxide film in the galvanostatic oxidation mode by the electrochemical synthesis method. The properties of the polypyrrole–aluminum oxide composite film are studied by the methods of voltammetry, as well as impedance and FTIR spectroscopy.     

氧化铝微细颗粒絮凝沉降研究

用羧甲基纤维素、聚丙烯酰胺、硫酸铝和氯化铁四种絮凝剂进行氧化铝微细颗粒的絮凝沉降研究。试验结果表明：在适宜的参数条件下,四种絮凝剂均可显著提高氧化铝微细颗粒的沉降速度。根据沉降颗粒的形貌探讨了有机絮凝剂和无机絮凝剂的絮凝沉降机理     

纳米铝粉粒径对活性量及氧化层厚度的影响

采用TEM、ESEM及元素分析对25～600 nm的铝粉进行了表征,用FastStone软件对TEM照片进行了处理,提出了纳米铝粉氧化层厚度计算公式,结合实验条件,分析了该公式的合理性与通用性.结果表明,纳米铝粉的氧化层厚度存在一个下限值,当铝粉粒径不小于70 nm时,铝粉的氧化层厚度与粒径呈二项指数增加关系.     

铝合金棱角部位阳极氧化膜形貌分析

对铝合金进行阳极氧化,并进行化学浸泡试验和点滴试验,用电子探针观察棱角部位氧化膜的形貌。结果表明,试样表面部位氧化膜化学浸泡试验180min无氢气泡逸出,点滴试验时间大于30min没有观察到腐蚀迹象,达到了航空工业部标准（HB5055-1993）,耐蚀性能优异。然而,试样的棱、外角和内角观察到氢气泡逸出,该处氧化膜产生破损,导致基体金属遭受腐蚀。电子探针分析发现,铝合金棱角部位氧化膜产生裂纹。其原因是棱角部位氧化膜存在边缘效应,阻止了氧化膜在三维方向连续生长,与表面部位相比,棱角部位氧化膜变薄,导致基体金属棱角部位优先遭受腐蚀。     

铈盐封孔对建筑铝合金阳极氧化膜耐蚀性的影响

选取建筑常用的铝合金6063作基体,阳极氧化后采用铈盐封孔,并研究铈盐封孔工艺参数对封孔后阳极氧化膜腐蚀失重的影响.结果表明:随着双氧水浓度从0 mL/L增加到9 mL/L、硝酸铈浓度从2.5 g/L增加到9.0 g/L、温度从25℃升高到65℃、封孔时间从10 min延长到50 min,封孔后阳极氧化膜的腐蚀失重都呈...     

掺铝氧化锌薄膜的制备及应用研究进展

综述了掺铝氧化锌薄膜的各种制备方法,包括磁控溅射法、脉冲激光法和溶胶凝胶法等;重点分析了掺铝氧化锌(ZAO)薄膜的结构、导电机理及光电性能;最后对薄膜的存在问题和应用情况进行了分析。     

硫酸镧对汽车用铝合金阳极氧化膜性能的影响

在汽车用2024铝合金阳极氧化使用的电解液中添加硫酸镧,并研究了硫酸镧的质量浓度对阳极氧化膜的厚度、膜重、硬度、表面形貌及耐蚀性的影响。结果表明:硫酸镧的催化作用有利于提高氧化速率,减小多孔层的孔径,从而提高阳极氧化膜的硬度及耐蚀性。当硫酸镧的质量浓度为0.8 g/L时,阳极氧化膜具有最高的硬度和最佳的耐蚀性。但当硫酸镧的质量浓度大于0.8 g/L时,稀土的吸附作用会使阳极氧化膜的性能有所降低。     

铝阳极氧化膜采用复合无镍封孔工艺的研究

通过分析锂盐与锆盐两种无镍封孔工艺各自对铝阳极氧化膜封孔所存在的优缺点,提出了一种二步法──复合无镍封孔工艺,即第1步用锂盐对铝阳极氧化膜进行封孔,第2步再用锆盐对相同铝阳极氧化膜进行复合封孔,从而既克服了锆盐和锂盐1步法封孔工艺存在的缺点,又保留了各自的优点,使工艺的适应性得到一定改善,使铝阳极氧化膜综合封闭孔质量及重要性能得到较大提高。     

Conditions of Millisecond Laser Ignition and Thermostability for Ammonium Perchlorate/Aluminum Mixtures

The experimental investigations of laser‐induced ignition and heat action of ammonium perchlorate and aluminum powder mixtures are presented in this paper. A laser pulse with wavelength of 1.06 μm and duration of 3.5 ms was used. Powder mixtures of different dispersion were tested, namely, coarsely dispersed powders and nanopowders with average surface diameters of 80 and 0.25 μm, respectively. The values of ignition thresholds and delays of the mixtures activity in air were measured, and experimental results for different exposure conditions were obtained. The possible reasons of different sensitivity for the given mixtures to laser pulse and heat action are discussed.     

Effect of Initial Oxide Layer on Ignition and Combustion of Boron Powder

Only few data exist for experimental studies on ignition and combustion of boron particles with initial oxide thickness. The oxidation, ignition and combustion characteristics including the onset temperatures, weight gain, apparent activation energy, emission spectra during combustion, and ignition delay time of crystalline boron powders with different initial oxide thickness (x₀) were studied by a laser ignition and thermogravimetric (TG) analyses. Simulations of the kinetics of oxide layer during boron ignition were conducted using a common model. The results indicated that the onset temperature was approximately 775 °C, independent of x₀. The total weight gain decreased with increasing x_0, whereas the weight gain at 775 °C did not change. The apparent activation energy was found to be insensitive to x₀ and had a constant value of about 210 kJ mol⁻¹. The intensity of the emission spectra gradually decreased while the ignition delay time increased with increasing x₀. Numerical simulation showed that the removal rate of oxide layer enhanced with increasing x₀. The experimental results revealed that the oxidation of boron powder was no diffusion‐controlled process at low temperatures. But the diffusion of oxygen could become important to the oxidation reaction at high temperatures     

铝阳极氧化膜的显微结构及其着色Ⅰ着色阳极氧化膜的结构及浸渍和发色电解着色

1 前言 阳极氧化膜的种类很多,从用途分,可分为硬质阳极氧化膜、普通阳极氧化膜和阻挡层阳极氧化膜;从形成的介质来分,有硫酸阳极氧化膜、草酸阳极氧化膜、铬酸阳极氧化膜、磷酸阳极氧化膜、硼酸阳极氧化膜、碱性(NaOH、Na3PO4)阳极氧化膜等.本文重点讨论用于电解着色的普通阳极氧化膜、碱性阳极氧化膜.     

Airborne Deployment of an Instrument for the Real-Time Analysis of Single Aerosol Particles

An instrument is described that provides real-time chemical analysis of the composition of individual aerosol particles. A differentially pumped aerosol inlet transfers particles from the ambient atmosphere into the source region of a time-of-flight mass spectrometer where they impact on a heated surface and the resulting vapors are ionized by electron ionization prior to mass analysis. Labora tory calibration studies demonstrated that the instrument was capable of detecting particles with diameters greater than approximately 0.4mu m. The instrument was operated on the NASA DC-8 research aircraft as part of the 1996 SUbsonic aircraft: Contrail and Cloud Effects Special Study (SUCCESS) mission with the intent of studying the chemical composition of upper tropospheric particles. More than 25,000 aerosol particle mass spectra were recorded during 19 mission flights. Although approximately 120 of those spectra showed clear evidence of sulfate, nitrate, and other inorganic materials, the remaining spectra contained only mass peaks consistent with water. Moreover, particles were detected only while traversing clouds. These results are not consistent with expectations of the size, quantity, or composition of upper tropospheric particles. It is likely, however, that a subisokinetic aircraft sampling inlet resulted in the collection of only very large ice particles. This situation would account for both the observed preponder ance of water-only spectra and the apparent lack of particles outside of clouds. Despite the sampling problem, the instrument was able to chemically speciate aerosols directly sampled from a medium altitude aircraft. These represent the first examples of aerosol particles chemically speciated in real time from an airborne platform.     

Grain-Size Effect on Compressive Creep of Silicon-Carbide-Whisker-Reinforced Aluminum Oxide

The steady-state compressive creep of Al₂O₃ with 10 vol% SiC whiskers having grain sizes of 1.2, 2.3, and 4.0 μm has been measured at 1400°C in argon. The creep rate is related to the free volume within the whisker network, not the nominal grain size. The results are consistent with diffusional-controlled creep with different contributions from grain-boundary sliding. Under low stresses, only Liftshitz sliding is possible and the diffusional process controls deformation, while at stresses over a threshold, Rachinger sliding is the mechanism controlling deformation. The evolution between Liftshitz and Rachinger sliding is marked by a significant increase in the value of the stress exponent.     

葡萄糖对多孔阳极氧化铝模板的影响

选用葡萄糖作为添加剂,高纯铝在10℃,40 V直流电压条件下,利用两步阳极氧化法在0.3 mol/L草酸溶液中加入不同浓度的葡萄糖制备多孔阳极氧化铝模板,并且通过场发射扫描电镜(FESEM)、X射线衍射(XRD)对氧化膜的微观形貌、晶体结构进行表征,从而研究不同浓度的葡萄糖对氧化膜的影响。结果表明:葡萄糖的加入不会改变阳极氧化过程;不同浓度的葡萄糖均能使氧化膜致密,孔径变小,但随着葡萄糖浓度的增加,有序性会遭到破坏,在添加不同葡萄糖浓度时,3 g/L的葡萄糖添加剂会得到孔径更小,一定有序性的氧化铝膜;XRD表明葡萄糖的加入并不会影响氧化铝膜的非晶态结构。     

Effect of Dopants on the Defect Structure of Single-Crystal Aluminum Oxide

Density and lattice parameter changes induced by dopants were studied in Czochralski rubies containing from 0.054 to 0.160 wt% Cr₂O₃, in Czochralski sapphires containing from 0.083 to 0.120 wt% TiO₂, and in verneuil crystals grown from powders containing 250 to 1000 ppm Ca, Mg, Si, and V. Densities were determined within at least ∼0.005% using a hydrostatic weighing technique; lattice parameter shifts were measured within a maximum of 0.25% using a step-scanning goniometer technique. Some crystals which appeared to be clear, transparent, and single-phase contained fine particles of a second phase. It is concluded that Si⁴⁺ and Ti⁴⁺ ions enter solution with the formation of cation vacancies to maintain charge neutrality, that verneuil crystals contain vanadium as V³⁺, that the solid solubility of Ca²⁺ is low (<340 ppm), and that MgO decomposes under verneuil growth conditions, resulting in formation of a second phase.     

Effect of Yttrium and Lanthanum on the Tensile Creep Behavior of Aluminum Oxide

The tensile creep behavior of two rare-earth dopant systems, lanthanum- and yttrium-doped alumina, are compared and contrasted in order to better understand the role of oversized, isovalent cation dopants in determining creep behavior. It was found that, despite some microstructural differences, these systems displayed qualitatively a similar improvement in creep resistance, supporting the hypothesis that creep is strongly influenced by segregation. Differences in primary creep behavior and activation energy for steady-state creep were, however, observed for these systems. Given these results, it is expected that creep behavior can be further optimized by adjusting the dopant level and by controlling the microstructure.     

铝阳极氧化多孔膜功能化应用的新趋向

铝阳极氧化形成的具有独特结构的多孔膜的功能化，近年来正逐渐引起人们的重视，在用于研制诸如分离膜及分离催化膜，光学元件，磁化膜材料，选择性吸收膜等功能材料方面，已显示出良好的应用前景。铝阳极氧化多孔膜的功能化为研制新型功能材料开辟了又一新途径。