铝及铝合金硬质阳极氧化新工艺的研究

论述研制铝及铝合金在40℃下的硬质阳极氧化的新工艺。槽液的主要成分是硫酸、草酸、酒石酸和三乙醇胺,铝及铝合金经阳极氧化处理后,氧化膜硬度高、外观光亮、抗腐蚀性强。该工艺在提高铝硬质阳极氧化槽液温度、增加膜的硬度和节能等方面都县有很大的实用价值。     

铝及铝合金阳极氧化工艺问题

在铝和铝合金阳极氧化过程中常遇到一些问题 ,现选较为典型的与大家共同探讨。1　工件经阳极化并染色后表面有绑扎印痕问题按阳极化工艺要求 ,阳极化件的传导电流应用夹具 ,夹于工件的非装饰面的隐蔽部位 ,只有这样做才能达到安全、保险和避免产生绑扎印痕等质量问题 ,而上述质量问题显然是采取铝丝绑扎来代替夹具而引起的 ,其中的原因和影响有以下几个方面 :(1 )用作绑扎的铝丝都较细 ,由于截面积不足而影响电流的正常畅通引起发热并常因此而烧断 ,甚至工件掉入槽中 ,终止了阳极氧化过程的继续 ,从而带来一系列的麻烦 ;(2 )采用绑扎方法没…     

铝及铝合金阳极氧化前处理经验谈

众所周知,前处理是电镀工艺中的关键工序,对铝及铝合金阳极氧化工艺也不例外。铝及铝合金阳极氧化的前处理包括除油、腐蚀、出光、粗化、打砂等。下面结合实例谈谈我们在生产中解决的一些相关的问题。l 铝合全出光后发花 某厂来的一批铝合金小零件,牌号不详,经化学除油→化学腐蚀→出光后发花,具体表现为:有的零件色白,有的零件色黑,有的零件黑白交错。使用的出光液是1:1（体积比）的硝酸     

铝及铝合金铬酸阳极氧化工艺实践

介绍了锌及锌合金铬酸阳极氧化的电解液组成及工艺过程。讨论了工艺中各种因素包括铬酸浓度、工作条件、杂质离子对氧化膜的影响,给出了膜层抗蚀性能的检测方法及标准。     

铝及铝合金阳极氧化膜中温封闭工艺

研究铝及铝合金阳极氧化膜和电解着色膜的中温封闭工艺,对影响膜层封闭质量的各成分含量及工艺参数进行了试验。使用含有可水解镍盐和NF-2络合剂的中温封闭液可获得满意的封闭质量。     

改进铝和铝合金阳极氧化的工艺

对铝和铝合金零件表面硫酸阳极氧化的生产实践证实,在原硫酸槽液中同时添加适量的草酸、乳酸、丙三醇和硫酸镍后,扩大了工艺温度范围,提高了生产效率,也能保证膜层质量。     

铝阳极氧化膜冷封闭工艺的研究

介绍了铝阳极氧化膜冷封闭剂Hy-1的化学组成、工艺、参数的确定及工艺条件,对封孔性能进行对比试验,并对封闭机理进行了讨论。     

泡沫铝阳极氧化工艺研究

介绍了泡沫铝阳极氧化工艺,通过试验对比分析了KD-SY酸蚀工艺和碱蚀工艺的差异,探讨了泡沫铝阳极氧化过程中,硫酸浓度、电流密度、温度、Al3+浓度、杂质元素对阳极氧化膜的影响.     

阳极氧化处理对钛表面粗糙度和亲水性的影响

本文通过阳极氧化处理技术在钛表面制备出具有不同粗糙度和亲水性的纳米表面。采用扫描电镜观察表面特征,原子力显微镜检测表面粗糙度,接触角仪测量亲水性。实验结果表明,表面形貌随着氧化电压和时间的改变有较大变化。在优化的电解液和氧化条件下,可以在钛表面制备规则排列的纳米管阵列。粗糙度随着氧化时间的延长而增大,在几十到几百纳米之间变化,而氧化电压对粗糙度的影响不大。表面亲水性随着氧化时间的延长先增加,再降低。钛表面结构形貌、粗糙度与亲水性的变化可用阳极氧化过程中表面发生的反应进行解释。     

Crystallization of anodic titania on titanium and its alloys

Crystallization of amorphous anodic films grown at constant current density on sputtering-deposited titanium, and Ti-Si and Ti-Al alloys, in ammonium pentaborate electrolyte, has been examined directly by transmission electron microscopy. In the case of titanium, anatase develops at relatively low voltage in the inner film region, formed by inward migration of oxygen species. In contrast, the outer film region, formed at the film/electrolyte interface, is composed of amorphous oxide only. Oxide crystals are particularly found near the plane, separating the two regions, which is located at a depth of 35-38% of the film thickness. Oxide zones, of size ∼ 1 nm, with a relatively ordered structure, developed at the metal/film interface, are considered to lead to transformation of the inner region structure. The incorporation into the film of either aluminium or silicon species suppresses the formation of crystalline oxide to much increased voltages. However, eventually nanocrystals form at ∼40% of the film thickness, probably originating from pre-cursor nuclei in the air-formed on the as-deposited alloy.     

Effect of anodic oxidation on fatigue performance of 7075-T6 alloy

Effect of anodic oxidation on fatigue performance of 7075-T6 alloy for pre-corroded and non-corroded specimens has been investigated by conducting a series of rotary bending fatigue tests at 95 Hz. The anodized specimens with different coating thickness (6, 12 and 23 μm) were exposed to 3.5 wt.% NaCl solution for 6, 48, 96 and 240 h. The results indicate that oxidation has a tendency to decrease the fatigue performance. Fatigue strength was reduced with increasing coating thickness; approximately 40% reduction for a 23 μm thick coating was obtained. It was observed that oxidation mitigated pitting corrosion. Superior corrosion resistance was obtained for the thickest coating layer. Fatigue tests with pre-corroded specimens showed that fatigue life of coated specimens was significantly affected by pre-corrosion, except for the specimen with the thickest coating layer. When the pre-corroded bare and coated specimens were compared, the coating improved the fatigue performance in high cycle fatigue (> 10⁵) only and it degraded the fatigue performance in low cycle regime.     

铸造铝合金圆锭温度场实验研究和数值模拟

通过设备测定了半连续铸造Φ100mm铝合金圆锭温度分布,以此为基础,通过反算法得到直接冷却半连续铸造铝合金水冷段换热系数与铸锭表面温度的关系。计算表明,随着铸锭表面温度的降低．换热系数逐渐增大;在温度由400℃降至130℃的过程中,换热系数急剧增大,温度在130℃左右时达到最大,其最值大约为23000W/(m~2·K);当温度继续降低时,铸锭表面换热系数又迅速减小。并用三维有限元对铸造过程的凝固规律进行了数值模拟,模拟值和实验值基本吻合。     

Anodic oxidation of Ta/Fe alloys

The behaviour of iron during anodizing of sputter-deposited Ta/Fe alloys in ammonium pentaborate electrolyte has been examined by transmission electron microscopy, Rutherford backscattering spectroscopy, glow discharge optical emission spectroscopy and X-ray photoelectron spectroscopy. Anodic films on Ta/1.5 at.% Fe, Ta/3 at.% Fe and Ta/7 at.% Fe alloys are amorphous and featureless and develop at high current efficiency with respective formation ratios of 1.67, 1.60 and 1.55 nm V⁻¹. Anodic oxidation of the alloys proceeds without significant enrichment of iron in the alloy in the vicinity of the alloy/film interface and without oxygen generation during film growth, unlike the behaviour of Al/Fe alloys containing similar concentrations of iron. The higher migration rate of iron species relative to that of tantalum ions leads to the formation of an outer iron-rich layer at the film surface.     

Influence of the microstructure of the aluminum substrate on the regularity of the nanopore arrangement in an alumina layer formed by anodic oxidation

We investigated the microstructure of aluminum sheets with different purities (Al 99.999%, Al 99.95%, Al 99.5% and AlMg1) before and after different treatments (polishing and annealing) by X-ray diffraction (phase analysis and pole figures) and high-resolution scanning electron microscopy. In a two-step anodisation process within sulfuric acid a nanoporous alumina layer (with mean diameters of 25 nm and mean distances of 30 nm) was formed on the aluminum sheets. We found that the regularity of the nanopore arrangement correlates with the fraction of aluminum grains with (100) orientation in the aluminum substrate. A correlation with the grain boundary and dislocation densities within the aluminum could not be determined.     

Kinetic peculiarities of anodic dissolution of copper and its gold alloys accompanied by the formation of insoluble Cu(I) products

The kinetics of anodic dissolution of Cu and Cu-Au alloys (0.1-30 at.% Au) in aqueous chloride-containing universal buffer mixture (pH 1.25-11.90) in the potential range of insoluble Cu(I) products formation has been examined using the technique of multicyclic voltammetry and chronoamperometry of stationary and rotating electrodes. After the formation of anodic film, mass transport controls the dissolution; the phase where the transport is localised depends on the nature of the film, pH of the solution and the alloy composition. The initial stage of CuCl formation on Cu and low-concentration Cu-Au alloys is controlled by 2D-nucleation.     

The effect of water vapor on the oxidation behavior of Ni-Pt-Al coatings and alloys

Turbines fired with hydrogen or syngas from coal gasification will have significantly higher water vapor contents in the combustion gas than natural gas fired turbines. The effect of increased water vapor on alumina-forming coatings and model alloys was investigated at 1100 °C in furnace cyclic testing. Increasing the water vapor content from 10% to 50 vol.% increased the amount of scale spallation on undoped alumina-forming alloys. Compared to dry O₂, increased spallation was observed for β and γ/γ' phase coatings on the substrates of alloys 142 and N5. In all cases, the addition of water vapor appeared to reduce the formation of alumina whiskers and ridges at the scale-gas interface, but did not significantly change the alumina growth rate. The addition of water vapor may have a detrimental effect on the selective oxidation of Al in γ/γ' alloys and coatings.     

A study on the self-sealing process of anodic films on aluminum by EIS

The electrochemical behaviors of anodized aluminum in neutral NaCl and Na₂SO₄ solutions were studied using electrochemical impedance spectroscopy (EIS). The results reveal that there is a self-sealing process for unsealed anodic film in neutral NaCl and Na₂SO₄ solutions. The resistance of the porous layer (R_p) and the capacitance of the barrier layer (CPE_b) increase and the capacitance of the porous layer (CPE_p) decreases with immersion time in the initial stage. Corrosion resistance provided by the anodic film is improved by the self-sealing process of the porous layer. However, chloride ions have an opposite effect. The improving effect of the self-sealing process on film resistance is decreased with the increase of chloride concentration of the solution.     

铝质材料的摩擦学表面改性

铝质材料阳极氧化膜系均匀、规则的微观多孔质结构，利用物理、化学或电化学的方法在其中沉积或原位合成润滑性物质，在保持阳极氧化膜质硬、耐磨特性的基础上，使其具有一定的白润滑性，是近十多年来铝质材料表面改性研究的热点领域之一，本文对该研究的基本原理和国内外发展概况进行了概述，并重点介绍了我们在这一方面研究中的一些最新进展和结果，分别介绍了三种新型体系的自润滑改性阳极氧化铝材料．