铝阳极氧化膜摩擦学性能的研究

考察了铝及阳极氧化铝的磨擦学性能研究,在磨擦过程中铝发生严重的塑性变形和粘着磨损,而阳极氧化铝硬度高,抗磨性强,使对偶钢材料损,在阳极氧化铝的微孔填充二烷基二硫代硫代磷酸更多的（ＤＤＰ）纳米硫化铅能够降低磨擦系数,减少阳极氧化铝对偶件的磨损,扩孔和热处理可以在微孔中填充更多的ＤＤＰ修饰纳米硫化铅。     

Tribological properties of solid lubricating film/microarc oxidation coating on Al alloys

A process for preparation of solid lubricating films on micro-arc oxidation（MAO） coating was introduced to provide self-lubricating and wear-resistant multilayer coatings for aluminum alloys. The friction and wear behavior of various burnished and bonded solid lubricating films on the as-deposited and polished micro-arc oxidation coatings sliding against steel and ceramic counterparts was evaluated with a Timken tester and a reciprocating friction and wear tester, respectively. The burnished and bonded solid lubricating films on the polished micro-arc oxidation coatings are superior to the as-deposited ones in terms of the wear resistant behavior, because they lead to strengthened interfacial adhesion between the soft lubricating top-film and the hard polished MAO sub-coating, which helps increase the wear resistance of the solid lubricating film on multilayer coating. Thus the multilayer coatings are potential candidates as self-lubricating and wear-resistant coatings for Al alloy parts in engineering applications.     

Formation of unidirectional nanoporous structures in thickly anodized aluminum oxide layer

A series of anodic aluminum oxide(AAO) was grown on the commercially pure 1050 aluminum sheet by controlling electrolyte temperature (2–15 °C) and an odizing time (0.5–6 h), using a fixed applied current density of 3 A/dm² in diluted sulfuric acid electrolyte. A crack-free thick AAO with the thickness of 105–120 μm and containing unidirectional nano sized pores (average pore diameter of 5–7 nm) is successfully achieved in the specimens anodized for 2 h, irrespective of electrolyte temperature. When anodizing time reaches 6 h, very thick AAO with the thickness of 230–284 μm is grown, and average diameter of unidirectional pores is in the range of 6–24 nm. The higher values in both the AAO thickness and pore diameter are attained for the specimens anodized at higher temperatures of 10–15 °C. A crack is observed to exist in the AAO after anodizing up to 4 h and more. A higher fraction (more than 9%) of the crack is shown in the specimens anodized at higher temperatures of 10–15 °C for 6 h and a considerable amount of giant cracks are contained.     

Intermediate temperature tribological behavior of carbon nanotube reinforced plasma sprayed aluminum oxide coating

Tribological behavior of plasma sprayed carbon nanotube (CNT) reinforced aluminum oxide (Al₂O₃) composite coatings was examined at room temperature, 573 K and 873 K using tungsten carbide (WC) ball-on-disk tribometer. The weight loss due to wear of Al₂O₃ coating was found to be increasing with the temperature while Al₂O₃-CNT coating showed a decreasing trend in the weight loss with the temperature. Relative improvement in the wear resistance of Al₂O₃-CNT coating compared to Al₂O₃ coating was found to be 12% at room temperature which gradually increased to ∼ 56% at 573 K and ∼ 82% at 873 K. Protective layer as a result of tribo-chemical reaction was observed on the wear track of both of the coatings. The improvement in the wear resistance of Al₂O₃-CNT coating was attributed to three phenomena viz. (i) higher hardness at the elevated temperature as compared to Al₂O₃ coating, (ii) larger area coverage by protective film on the wear surface at the elevated temperature and (iii) CNT bridging between splats. The coefficient of friction (COF) of Al₂O₃ coating was nearly constant at room and elevated temperature whereas COF for Al₂O₃-CNT coating decreased at the elevated temperature (873 K).     

铝阳极氧化层的耐化学腐蚀性能(英文)

将铝放入草酸-硫酸溶液中,在其表面形成耐化学腐蚀的阳极氧化层。生成的阳极氧化层的酸性溶解试验在38℃的35mL/L85%H3PO4+20g/LCrO3溶液中按ASTMB680-80标准进行。研究了硫酸浓度为160g/L时,草酸浓度、溶液温度、阳极电流密度对溶解速率和阳极氧化膜生成比R的影响。结果发现,在低温(5℃)和高电流密度(3A/dm2)的条件下,得到耐化学腐蚀性强、致密的氧化层。添加18g/L草酸有利于阳极氧化层的形成。采用扫描电子显微镜(SEM)、原子力显微镜(AFM)和辉光发射光谱(GDOES)来分析阳极氧化层的形貌和组成。     

激光清洗阳极氧化膜对铝合金焊缝性能的影响分析

针对铝合金焊接边阳极氧化膜,采用非接触、高效激光清洗新技术进行清理,并分析激光清理阳极氧化膜层对焊缝组织性能的影响。实验结果表明:采用激光功率100 W、扫描速度10 mm/s,可以实现5μm厚度阳极氧化膜层的完全清理。焊缝成形均匀,焊缝表面泛有金属光泽,焊缝无聚集状气孔、杂质等内部缺陷。经激光清理的铝合金接头抗拉强度为298~303 MPa,拉伸断裂延伸率6.2%~6.5%,激光清理焊缝与机械刮削焊缝的性能范围一致。     

铝阳极氧化膜不同封孔方法的耐腐蚀性能研究

用电化学法、磷-铬酸质量检测法和金相电子显微镜,研究了6种封孔方法对铝阳极氧化膜耐腐蚀性能的影响。结果表明,都在最佳工艺条件下,硬脂酸封孔后的氧化膜是最耐腐蚀的,依次是硫酸镍封孔后的,重铬酸钾封孔后的,沸水封孔后的,醋酸镍封孔后的,耐蚀性能最差的是氟化镍常温冷封孔后的。     

氧化热对铝合金硬质氧化膜的影响(英文)

采用自制的实验装置和硫酸电解液研究阳极氧化热对铝合金2024硬质氧化膜的影响。与氧化热由氧化膜传递到电解液中相比,氧化热由铝基体传递到冷却液中有利于氧化膜的生长,成膜速度、膜厚、致密度和硬度显著提高,并随着冷却液过冷度的增大而增大。氧化膜生长所需的冷却液过冷度与电解液过冷度、铝基体壁厚、氧化膜厚度、气泡覆盖特性参数以及电流密度有关。可通过控制冷却液温度来控制氧化膜的微观结构和性能。     

Reaction behavior between the oxide film of LY12 aluminum alloy and the flux

In this paper, the brazing mechanism of LY12 aluminum alloy at middle range temperature was presented. The CsF-AlF3 non-corrosive flux was utilized to remove the complex oxide film on the surface of LY12 aluminum alloy. The resultsrevealed that the oxide film was removed by the improved CsF-AlF3 flux accompanied with the occurrence of reaction as well as dissolution and the compounds CsF played an important role to remove the oxide film. Actually, the high activity of flux, say,the ability to remove the oxide film, was due to the presence of the compounds, such as NH4F,NH4AlF4 and composite molten salt. The production of HF was the key issue to accelerate the reaction and enhance to eliminate the oxide film by dissolution.It was found that the rare earth element La at small percentage was not enriched at the interface. Moreover, the rare earth fluoride enhanced the dissolution behavior.     

铝表面二次电解白色膜的形成及性能

以低浓度硫酸溶液为主液 ,添加硼酸或磺基水扬酸、乳酸以及丙三醇等具有缓蚀及缓冲作用的物质组成混合电解液 ,在常规硫酸阳极氧化膜上获得均匀不透明白色膜层 ,通过电流密度—时间关系曲线 ,发现形成不透明白色膜特有的“电流回落现象”。性能测试表明 ,二次电解制得的不透明白色氧化膜厚度及耐蚀性与常规硫酸阳极氧化膜相当 ,而硬度较差 ,但仍能满足常规装饰性能要求。     

Investigation of wear behavior of titanium oxide films, produced by anodic oxidation, on commercially pure titanium in vacuum conditions

The wear performances of titanium oxide films, produced by anodic oxidation, in vacuum conditions were investigated. Anodic oxidation treatments were carried out at − 3 and 40 °C temperatures using H₂SO₄(1.5 M)-H₃PO₄(0.3 M) solution and voltage of 200 V. Wear tests were performed at ambient air, pressures of 10^− 3 mbar and 10^− 6 mbar. Anodizing process produced a porous oxide layer on the surface. Although the pore size decreased with increasing process temperature, surface roughness decreased. Hardness results showed that anodic oxidation at lower temperatures produced oxide film with higher hardness. Wear rate of CP-Ti significantly decreased with anodic oxidation treatment in all wear conditions since oxide film acted like a solid lubricant. The best wear resistance was obtained from the hard-anodized samples both in ambient air and vacuum conditions.     

LY12铝合金氧化膜与钎剂的反应机制

采用CsF-AlF3中温无腐蚀钎剂能够去除LY12铝合金表面复杂的氧化膜, 实现LY12铝合金的中温钎焊.研究发现: 改进的CsF-AlF3钎剂是以反应、溶解方式去除氧化膜的; 在去膜过程中, CsF化合物起主要去膜作用, 钎剂的高活性与NH4F、NH4AlF4及复合盐熔体等化合物的存在有关, 它们的存在可提高CsF-AlF3钎剂的去膜能力, 而HF的生成则是诱发和加速反应、提高溶解去膜能力的关键;微量稀土元素镧未在界面出现富集现象,微量的稀土氟化物则起着"助溶"的作用.     

EIS characterisation of Ti anodic oxide porous films formed using modulated potential

Titanium, due to its excellent corrosion resistance, good mechanical properties and biocompatibility has been employed in many fields, such as in biomedical and dental implants. A passive oxide film formed on titanium surface is responsible for its high corrosion resistance. In the present study, oxide films were grown on titanium surface employing an anodising procedure using modulated potential, in a hydrofluoric acid solution. Electrochemical impedance spectroscopy was used to study the electrochemical behaviour of anodised Ti surface in a NaCl solution. The dependence of oxide film characteristics on forming conditions was analysed employing equivalent circuits. Samples were observed by scanning electron microscopy, in Jeol-JSM-5900LV microscope of the LME/LNLS, Campinas. It was observed that final anodising potential has an influence on the porous layer film morphology and that the anodising procedure with the chosen solution produces a double layer porous anodic film.     

Semiconductive properties of titanium anodic oxide films in McIlvaine buffer solution

The semiconductive properties of anodic oxide films grown on titanium surface at different formation potentials: 1.0, 2.0, 3.0 and 4.0 V were investigated by means of electrochemical impedance spectroscopy and cyclic voltammetry in McIlvaine buffers at pH 2, 4 and 5. The passive films show a Mott-Schottky behavior typical for an n-type semiconductor at the studied potential range with a high concentration of donors. On increasing the film formation potential, the flat band potential and the donor density decrease. Further, lower flat band potentials were obtained for higher pH buffer. These experimental results were related to the film thickness and composition. The influence of film thickness on the oxidation reactions taking place at the titanium electrodes covered by oxide film was evaluated.     

Formation and capacitance properties of Ti-Al composite oxide film on aluminum

Al specimens were covered with TiO2 film by sol-gel dip-coating and then anodized in ammonium adipate solution. The structure, composition and capacitance properties of the anodic oxide film were investigated by transmission electron microscopy (TEM), Auger electron spectroscopy (AES), X-ray diffractometry (XRD) and electrochemical impedance spectroscopy (EIS). It was found that an anodic oxide film with a dual-layer structure formed between TiO2 coating and Al substrate. The film consisted of an inner Al2O3 layer and an outer Ti-Al composite oxide layer. The thickness of layers varied with the number of times of sol-gel dip-coating. The capacitance of anodic oxide films formed on coated specimens was at most 80% higher than that without TiO2. In film formation mechanism, it was claimed that the formation of composite oxide film was mainly affected by the structure of micro-pores network in TiO2 coating which had an influence on Al3+ and O2- ions transport during the anodizing.     

退火工艺对低压铝箔氧化膜和比电容的影响

纯度99.988%的铝箔在300,400和500℃分别进行0.5,1和2h真空退火,然后利用电容法,间接测出退火箔的氧化膜厚度.用扫描电子显微镜观察部分退火箔的腐蚀形貌,测出相应的比电容.结果表明,在400℃退火时,铝箔的氧化膜厚度最小,300℃居中,500℃最大.在300℃退火时,随着保温时间的延长,铝箔的氧化膜厚度减小;而在400℃和500℃退火时,氧化膜厚度增大.500℃退火的铝箔,表面微量元素的分布接近于平衡状态,分布较均匀,铝箔表面腐蚀孔坑较细小,蚀坑密度大,比电容较高.而低温退火的箔样,微量元素偏聚在铝箔表面的位错露头附近,使铝箔表面出现大量的腐蚀孔坑,降低了比电容.     

Formation of zinc aluminum mixed metal oxide nanostructures

We report a method for synthesizing zinc aluminum layered double hydroxide (ZnAl:LDH) nanostructures at room temperature. The ZnAl:LDH nanoplates could be converted into zinc aluminum mixed metal oxide (MMO) nanostructures by calcination in air. The crystalline nature and morphology of the MMO nanostructures could be tuned by varying the calcination temperature. At low calcination temperatures (450-650 °C), nanostructures were composed of crystalline ZnO regions and amorphous regions. The crystalline orientations of the ZnO crystal grains were almost identical throughout the nanostructure. At calcination temperatures above 750 °C, ZnAl₂O₄ crystal grains appeared and amorphous regions could not be found in MMO nanostructures. As the calcination temperature increased, the crystal grain size and surface roughness of MMO nanostructures increased. Calcination at 950 °C resulted in the formation of MMO nanoparticles. The optical properties of the MMO nanostructures were probed by UV-vis diffuse reflectance spectroscopy. The spectra varied depending on their dimensions and crystalline natures.     

The aging of the anodic oxide of titanium during potentiostatic condition by ellipsometry

The aging effect of the anodic oxide film on titanium under constant potential oxidation was investigated by 3-parameter (3-P) ellipsometry in 0.1 mol dm⁻³ sulfuric acid solution. The oxide film was initially formed by a potential sweep oxidation, where the film with a low refractive index grew at relatively high rate. From the low value of the refractive index, the oxide film is assumed to be a hydrated structure. After the sweep oxidation to 4.26 V vs. reversible hydrogen electrode, the constant potential oxidation was performed at a potential of 4.26 V to examine the aging effect of the hydrated oxide film by 3-P ellipsometry. It was found that the refractive index of the oxide film increased from 2.39 to 2.59 during the aging of the constant potential oxidation, and the thickness decreased. The increase of the refractive index and the decrease of thickness may be explained by conversion from the hydrated oxide to a dehydrated oxide during the aging.     

A356铝合金微弧氧化膜微动磨损行为的研究

采用微弧氧化（MAO）在A356铝合金表面制备MAO膜,利用球-平面接触在SRV-V微动摩擦磨损机上探究变载荷和位移下微弧氧化对A356微动磨损机理的影响。结果表明：MAO膜由疏松层和致密层构成,其均匀性、致密性和结合力良好。MAO膜的摩擦系数、磨损率均低于A356,MAO膜减摩耐磨性较好。随位移增加MAO膜的摩擦耗散能系数低于A356,MAO膜能提升A356微动磨损过程的稳定性。载荷增加时A356磨损机制为磨粒磨损-粘着磨损,伴随犁削和疲劳剥层; MAO膜磨损机制为磨粒磨损-粘着磨损和疲劳剥落。位移增加时A356磨损机制为粘着磨损和疲劳剥落,伴随微犁削;MAO膜磨损机制为粘着磨损和疲劳剥层-粘着磨损和磨粒磨损。A356的磨痕内聚集Fe、O元素,存在材料转移和氧化磨损;MAO膜磨痕内聚集Fe元素,存在材料转移。