铝合金局部厚膜硬质阳极化工艺

针对有些零件在硫酸或铬酸阳极化后需进行局部厚膜硬质阳极化,提出了以硫酸或铬酸阳极氧化膜经醋酸镍封闭和重铬酸钾封闭后用作局部厚膜硬质阳极氧化保护膜的工艺方法。介绍了其工艺流程,讨论了2种工艺中电压的限制。结果表明,以经醋酸镍和重铬酸钾封闭后的硫酸或铬酸阳极氧化膜作局部厚膜硬质阳极氧化的保护膜,则硬质阳极化时电压分别限制在39 V和42 V。2种工艺得到的硬质阳极氧化膜厚可达到60μm,而且硬质阳极氧化后硫酸或铬酸阳极氧化膜层能通过336 h的盐雾试验。因此,经醋酸镍和重铬酸钾双重封闭后的硫酸或铬酸阳极氧化膜可以取代传统的蜡封或涂漆工艺,用作局部厚膜硬质阳极氧化的保护膜。     

建筑铝材表面处理及其性能研究

选用建筑铝材6063-T6作为基体,分别采用硬质阳极氧化和草酸阳极氧化进行表面处理.比较了未处理及处理后试样的微观形貌、物相、显微硬度、耐磨性能和耐蚀性能,结果表明:硬质阳极氧化和草酸阳极氧化处理后铝材的微观形貌和表面粗糙度与未处理铝材相比有所不同,硬质氧化膜与草酸氧化膜相比较为平整致密.未处理铝材的表面成分以Al元素为主,主要物相为Al相,处理后铝材的表面成分以Al和O元素为主,主要物相为Al相、α-Al2O3相和γ-Al2O3相.硬质阳极氧化和草酸阳极氧化处理后铝材的显微硬度较未处理铝材分别提高了约274 HV、191 HV,摩擦系数明显减小,耐蚀性能有较大程度提高.硬质阳极氧化是提高建筑铝材表面性能的有效措施,在提高建筑铝材的耐蚀性能方面,草酸阳极氧化替代硬质阳极氧化具有可行性.     

AC7A铝合金表面硬质氧化膜制备及性能研究

阳极氧化是提高铝镁合金表面硬度的一种有效方法。在AC7A铝合金表面制备硬质阳极氧化膜,研究了阳极氧化时间、电流密度、工作液温度以及阳极氧化溶液中硫酸浓度等工艺参数对氧化膜显微硬度及耐蚀性的影响,并对工艺参数进行了优化。结果表明,优化后的工艺参数θ为-6℃,氧化t为50 min,Ja为1~6 A/dm~2,240 g/L硫酸,硬质阳极氧化膜硬度可达480 HV,有效强化了轮胎模具花纹块配合表面的硬度,提高了其使用寿命,可以达到工件硬质阳极氧化膜硬度的要求,且氧化膜颜色深而均匀。最佳工艺参数下制备的氧化膜在240 h盐雾试验中,耐中性盐雾腐蚀性能明显提高。     

温度对2A12铝合金硬质阳极氧化膜性能的影响

为提高2A12铝合金硬质阳极氧化膜均匀性、膜厚、硬度、耐蚀性等性能,采用数字式涂层测厚仪、显微硬度计、电化学工作站和扫描电镜,分别对2A12硬质阳极氧化膜厚度、硬度、耐蚀性及微观形貌和能谱进行检测观察,分析了温度对2A12铝合金硬质阳极氧化膜性能的影响。研究结果表明,当温度为-8℃,硬质阳极氧化膜的均匀性、厚度、硬度、耐蚀性等性能最佳。     

硫酸-有机酸混合酸体系中铝合金硬质氧化膜的研究

在硫酸溶液中添加乳酸、磺基水杨酸构成硫酸-有机酸阳极氧化体系,并用该混合酸体系对2024-T3铝合金进行硬质阳极氧化处理。研究了电流密度及氧化时间对氧化膜性能的影响。混合酸体系能够有效提高硬质阳极氧化的操作温度,使得该工艺可以在室温下进行,大大降低了能耗。采用该工艺制备的硬质阳极氧化膜的厚度为10μm左右,硬度可达3 500~4 000 MPa。     

电压对铝锂合金硬质阳极氧化膜性能的影响

选用2099铝锂合金作为基体进行硬质阳极氧化，并研究电压对硬质阳极氧化膜形貌特征、成分、厚度、硬度、耐磨和耐腐蚀性能的影响。结果表明：随着电压从50 V提高到90 V，硬质阳极氧化膜的结构趋于致密，然后变得疏松，表面粗糙度先降低后增加，厚度先增加后降低，导致硬度、耐磨与耐腐蚀性能表现出明显的差异，但硬质阳极氧化膜的元素组成未变。电压为70 V制备的硬质阳极氧化膜表面结构致密，厚度达到27.3μm，具有高硬度(457.4HV)、良好的耐磨和耐腐蚀性能，平均摩擦系数和腐蚀电流密度仅为0.49和2.02×10^-6 A/cm²，对铝锂合金的防护效率达到95.1%。由于电压提高逐步形成较致密的硬质阳极氧化膜并促使膜层增厚，承载能力、抵抗局部塑性变形能力、阻碍腐蚀介质渗透和抵抗腐蚀能力增强，因此硬质阳极氧化膜的性能明显提高。     

脉冲技术在铝合金硬质阳极氧化中的应用

阐述了铝合金硬质阳极氧化的工艺条件，特点及应用现状，提出将脉冲技术应用于铝合金硬质阳极氧化。比较了脉冲硬质阳极氧化膜与普通硬擀阳极氧化膜的各项性能。脉冲硬质阳极氧化膜在硬度、耐蚀性、柔韧性、抗电击穿性和膜厚均匀性等方面都优于普通硬质氧化膜。此外，从理论上探讨了脉冲硬质阳极氧化膜的生长过程。     

预存氧化膜覆盖下铝在草酸中的阳极氧化行为

先采用硫酸溶液,通过硬质阳极氧化法在铝上获得一层预氧化膜,然后在草酸中继续阳极氧化.研究了在预存氧化膜覆盖下进行铝后续阳极氧化的规律.结果表明,预氧化膜不仅令高电场强度条件下铝在草酸中进行硬质阳极氧化更容易,还拓宽了后续阳极氧化的电压窗口,使后续草酸阳极氧化膜层的生长更均一、有序.     

2A12铝合金硬质阳极氧化工艺研究

采用正交试验分析了2A12铝合金硬质阳极氧化的工艺参数,研究了电流密度、硬质阳极氧化时间及硫酸浓度对膜层显微硬度及厚度的影响规律。结果表明,电流密度对硬质阳极氧化膜厚度影响相对较大,硫酸质量浓度对硬质阳极氧化膜的显微硬度的影响显著。最佳的氧化工艺参数为:电流密度3.0 A/dm~2,氧化时间t为70 min,硫酸质量浓度240 g/L。该工艺参数下得到的硬质氧化膜平均硬度可达352 HV,膜层厚度δ可达60μm,膜层致密,厚度均匀,综合性能优异。     

国际硬质阳极氧化学会即将成立

硬质阳极氧化技术的发展已有40年左右的历史,近年来,在新技术、尖端的高技术中应用日广。在这样的情况下,今年十月初,国际硬质阳极氧化学会将于美国科罗拉多州丹佛市成立。该学会的宗旨是:1、促进会员的共同利益,推动硬质阳极氧化工业的进步与发展;2、收集技术资料,准备其他宣传材料,制订教育规划,从而促进硬质阳极氧化     

铝硬质氧化液中C_2O_4~（2－）、Cl~－和Fe~（2＋）离子浓度的快速测定

根据酸性介质中Ｃ２Ｏ４２－，Ｃｌ－和Ｆｅ２＋离子在铂电极上的电化学氧化特性，用ＤＺ—１Ｂ型电镀添加剂测定仪快速测定铝及铝合金硬质氧化液中这些离子的浓度。操作简便、快速，可在生产车间应用。     

铝合金硬质阳极氧化工艺研究

通过大量的工艺试验,确定了能够同时满足三种铝合金硬质阳极氧化的溶液配方、工艺流程和工艺参数.实验结果表明,通过选择适当的工艺参数,能够在铝合金表面形成均匀、致密、高耐磨、高耐蚀性的硬质阳极氧化层.     

铝及其合金材料表面处理研究进展

较系统地评述了近年来铝及其合金材料在表面处理方面取得的研究进展。阳极氧化方面主要介绍了硬质阳极氧化和复合阳极氧化等方面的研究成果;表面转化膜方面主要介绍了稀土转化膜以及无机非金属转化膜等在该方面取得的最新研究成果;文中还较详细地介绍了微弧氧化技术以及电化学陶瓷成膜技术在铝及其合金材料表面强化处理方面的研究进展。     

阳极氧化挂具的设计与应用

草酸阳极氧化、硬质阳极氧化处理工艺电流密度大、电压高、产热量大,必须采用压缩空气不断搅拌槽液,由此可能导致工件与挂具接触不良,引起工件烧伤和报废。设计和制作了专用挂具,保证挂具与导电杆连接牢固,挂具将工件夹紧,又便于拆卸,     

Destruction of coating material during spark anodizing of titanium

An investigation has been carried out, using a sequential anodizing procedure, of the loss of coating species to the electrolyte during spark anodizing of titanium. Anodic coatings were formed galvanostatically in alkaline silicate electrolyte and then further thickened by re-anodizing in alkaline phosphate electrolyte. In addition to examination of coating compositions and morphologies following different times of anodizing in each electrolyte, solution analyses for silicon and titanium were carried out subsequent to anodizing in the phosphate electrolyte. Significant amounts of both elements were detected, indicative of destruction of the coating at sites of dielectric breakdown in the phosphate electrolyte. The lost coating material is replaced by formation of phosphorus-rich material at the breakdown sites, as evident from elemental mapping of coatings.     

Fabrication of diameter-modulated and ultrathin porous nanowires in anodic aluminum oxide templates

Anodic aluminum oxide (AAO) membranes with modulated pore diameter were synthesized by pulse anodization in 0.3 M sulfuric acid at 1 °C. For AAO growth, a typical combination of alternating mild anodizing (MA) and hard anodizing (HA) pulses with applied potential pulses of 25 V and 35 V was applied. The control of the duration of HA pulses will provide an interesting way to tune the shape of pores and the structure of AAO channels. It was found that a non-uniform length of HA segments in cross section of AAO is usually observed when the HA pulse duration is shorter than 1.2 s. The pulse anodization performed with longer HA pulses leads to the formation of AAO templates with periodically modulated pore diameter and nearly uniform length of segments. Various diameter-modulated metallic nanowires (Au, Ag, Ni and Ag–Au) were fabricated by electrodeposition in the pores of anodic alumina membranes. A typical average nanowire diameter was about 30 nm and 48 nm for MA and HA nanowire segments, respectively. After a successful dealloying silver from Ag–Au nanowires, porous ultrathin Au nanowires were obtained.     

Temperature influence on well-ordered nanopore structures grown by anodization of aluminium in sulphuric acid

The nanostructure dimensions and regularity of the hexagonal arrangement of nanopores formed by self-organized anodization of aluminium in a 20 wt.% sulphuric acid was investigated at various cell potentials and temperatures. The quantitative analyses of defects and Fourier transforms (FFT) performed from SEM images showed that regularity of nanopores arrangement can be improved by increasing anodizing potential, independently of the anodizing temperature. The best result in controlled anodization of aluminium can be obtained at 25 V and the temperature of 1 °C. The pore size and interpore distance distribution diagrams constructed for 1000 independent measurements showed that increasing uniformity of pore diameter and interpore distance is directly responsible for improvement of the regularity of hexagonal arrangement of nanopores observed with increasing anodizing potential at temperatures of −8 or 1 °C. At 25 V and independently of the anodizing temperature, the reduced number of generated defects is predominant factor improving regularity of the nanopore arrangement. The temperature influence on the lattice data, porosity of the nanostructure and real current density at the bottom of nanopores have been demonstrated.     

Fabrication of highly ordered pore array in anodic aluminum oxide

Highly ordered pore array in anodic aluminum oxide was fabricated by anodizing pure aluminum. The order of a pore array was affected by anodizing voltage, electrolyte temperature, and first anodizing time. A regular pore array with mean diameter of 24 nm and interpore distance of 109 nm could be formed by two-step anodization at 40 V., oxalic acid concentration of 0.3 M and electrolyte temperature of 15 ‡C. The measured interpore distance showed linearity with anodizing voltage. The diameter of pores was adjusted by pore widening treatment in a 5 wt% phosphoric acid solution at 30 ‡C after two step anodization. The mechanism of self-arrangement of pores could be explained by the repulsive interaction between the pore walls.     

纳米有序多孔阳极氧化铝制备方法的研究进展

多孔阳极氧化铝(PAA)模板以六角形元胞紧密排列,孔径大小可调,且化学稳定性好,近年来在催化、传感、过滤和仿生等领域受到了越来越多的关注。PAA模板的制备一直以来都是研究的热点,因为模板的结构和性质直接影响其应用的效果。本文在简要介绍了自组织有序多孔阳极氧化铝的特点及影响因素的基础上,较为全面地综述了制备自组织PAA模板不同方法的研究进展,包括温和阳极氧化法、强烈阳极氧化法、脉冲式阳极氧化法和周期性阳极氧化法。具体分析了不同阳极氧化方法的特点以及各自得到的氧化铝模板不同的特点和应用范围,说明了氧化电压、氧化温度和电解液种类在制备PAA模板时对其孔洞尺寸的重要作用,最后对阳极氧化铝膜的发展前景进行了展望。     

Embedded space charge in porous alumina films formed in phosphoric acid

The embedded charge in the barrier layers of porous alumina, formed potentiostatically in phosphoric acid was studied as a function of anodizing voltage (30-57 V) and bath temperature (18 and 21 °C). For that, the polarization measurements of as-grown and annealed alumina/Al samples were conducted in the same anodizing bath by anodic potential sweep at a scan rate of 2.6 V/min. The plane capacitor model was used for the assessment of the charge density in the barrier layers of as-grown porous alumina. For the barrier layers of films formed at 18 °C this value equals to 0.747 μC cm⁻² and does not depend on the anodizing voltage. Increase in electrolyte temperature rises the embedded charge density. Polarization measurements carried out in this paper clearly present that the barriers of phosphoric acid films grown at the anodizing voltages lower than 39 V contain a layer of virtual cathode while at higher voltages this layer disappers. The obtained results allow speaking about promising opportunities of potentiodynamic polarization measurements of alumina films in the same anodizing solution before and after annealing for the studies of charges embedded within the alumina barriers and for the regularities of ion transport.