包铝层和氧化时间对2E12铝合金硫酸阳极氧化及膜层性能的影响

对保留表面包铝和去除包铝的2E12-T3铝合金采用硫酸阳极氧化处理工艺,研究了包铝层和氧化时间对铝合金阳极氧化行为及膜层耐蚀性的影响。采用扫描电子显微镜观察氧化膜的表面以及截面形貌,应用动电位扫描极化曲线和电化学阻抗谱对膜层的电化学性能进行分析。结果表明:两种铝合金表面均能形成具有防护性能的阳极氧化膜,膜层随氧化时间延长而增厚。富铜的第二相颗粒会使得不带包铝的2E12铝合金氧化膜具有更多孔洞缺陷,甚至出现微裂纹。保留包铝的2E12铝合金表面氧化膜更厚,孔洞缺陷少,耐蚀性更好。阳极氧化30min和45min的2E12铝合金阳极氧化膜具有较低的腐蚀电流和较高的多孔层阻抗,耐蚀性好。     

固溶处理对2A12铝合金硬质阳极氧化的影响

为了提高铝合金硬质阳极氧化膜的厚度、硬度及耐蚀性,对2A12铝合金分别进行固溶处理、固溶加自然时效处理,之后再进行阳极氧化。采用金相显微镜、显微硬度计和扫描电镜分别对获得的阳极氧化膜的膜厚、硬度、耐蚀性及形貌进行了检测和观察,研究了固溶处理及自然时效对2A12铝合金硬质阳极氧化的影响。结果显示:在2A12铝合金硬质阳极氧化前增加固溶处理工艺使阳极氧化膜的膜厚、硬度和耐蚀性均有不同程度提高,当固溶温度为505℃时,与未固溶相比,在同样的电解质溶液和工艺参数条件下2A12铝合金阳极氧化膜的膜厚、硬度分别从48.61μm、403.8 HV1 N增加到117.73μm、602.7 HV1 N,自腐蚀电位由-1.45 V提高到-0.63 V,自腐蚀电流降低,膜的质量也大幅提高,膜胞规整度及点阵排布的连续性均显著好于未固溶试样;固溶后自然时效对膜层厚度和性能产生影响,自然时效未进行完全时,阳极氧化膜的厚度、硬度及耐蚀性较未固溶的增加,且自然时效时间越短,效果越好。     

硬铝合金硬质阳极氧化中电解液温度对膜层性能的影响

硬铝合金硬质阳极氧化膜性能优异,但常用的硬质阳极氧化方法存在许多不足.采用硫酸和草酸的混合液作为电解液对硬铝合金硬质阳极氧化,研究了电解液温度对硬质阳极氧化膜厚度、硬度、耐蚀性的影响.结果表明:随着电解液温度的增加,硬质阳极氧化膜的厚度、硬度均先增加后减小;电解液温度为15℃时氧化膜的厚度、硬度最大;硬质阳极氧化膜经重...     

硝酸铈封闭对2A12铝合金己二酸-硫酸阳极氧化膜耐蚀性的影响

研究了硝酸铈溶液封闭对2A12铝合金己二酸-硫酸阳极氧化膜耐蚀性的影响,通过盐雾腐蚀实验、电化学动电位极化扫描法和电化学阻抗谱法(EIS)对阳极氧化膜的耐蚀性进行研究,采用场发射扫描电镜(FE-SEM)观察试样封闭前后的表面微观形貌,并与稀铬酸封闭、沸水封闭传统工艺进行比较。结果表明:采用硝酸铈溶液封闭的2A12铝合金阳极氧化膜腐蚀电流减小,阻抗值增大,耐腐蚀性增强。阳极氧化膜表面呈致密的花瓣状,多孔层内及氧化膜表面附着一层致密铈的氧化物或氢氧化物,其耐蚀性优于沸水封闭,与稀铬酸封闭相当。     

Al-Cu-Mg 系变形铝合金厚膜阳极氧化工艺研究

含铜量高的 Al-Cu-Mg 系铝合金很难阳极氧化形成厚膜,原因是铝合金中析出的 S(CuMgAl_2)相及 CuAl_2相在常用硫酸电解液中阳极氧化时比铝溶解更快,引起电流集中,造成局部烧损。作者测量了铜在四种不同硫酸浓度(100g/1,200g/1,300g/1 和400g/1)电解液中的阳极极化曲线,证明了电解液中硫酸浓度增加有利于抑制铜的阳极溶解。作者也测量了铜在上述四种浓度电解液中的阳极击穿电压,确定了 LY-12铝合金(含铜3.8～4.9%)在400g/1硫酸电解液中阳极氧化获得70～80μm 均匀厚膜的工艺规范。本文还研究了 LY-12铝合金热处理状态对阳极氧化工艺的影响。     

金属表面处理日本标准目录(续)

（１）阳极氧化膜ＪＩＳＨ０２０１：１９８７　　铝表面处理术语ＪＩＳＨ８６０１：１９９２铝及铝合金阳极氧化膜ＪＩＳＨ８６０２：１９９２　　铝及铝合金氧化涂装复合膜ＪＩＳＨ８６０３：１９９５铝及铝合金工业用硬质阳极氧化膜ＪＩＳＨ８６８０：１９９３铝及铝合金阳极氧化膜厚度试验方法ＪＩＳＨ８６８１：１９８８铝及铝合金阳极氧化膜耐蚀性试验方法ＪＩＳＨ８６８２：１９９３铝及铝合金阳极氧化膜耐磨性试验方法ＪＩＳＨ８６８３：１９８４　　铝及铝合金阳极氧化膜密封性试验方法ＪＩＳＨ８６８４：１９９７铝及铝合金阳极氧…     

铝合金接触网零部件表面的微弧氧化处理

为探索更适合接触网铝合金零部件的表面处理技术,通过中性盐雾腐蚀、酸性全浸泡腐蚀试验以及极化曲线测量对比分析了铸造铝合金基体、阳极氧化膜层、微弧氧化膜层的耐蚀性。结果表明:处理后的铝合金耐腐蚀性得到了较大的提高,且微弧氧化膜比阳极氧化膜表现出了更加优异的耐腐蚀性能;微弧氧化膜层致密且孔隙率低的显微结构是其表现出好的耐腐蚀性的主要原因。     

铝及铝合金阳极氧化膜的耐腐蚀性能

铝阳极氧化膜在较强的腐蚀环境中,仍可能发生局部腐蚀、降低其使用寿命.为此,采用极化曲线和交流阻抗法研究了铝及其合金在H2SO4溶液中及添加丙三醇(C3H8O3)后所得阳极氧化膜的耐蚀性,以及氧化膜耐蚀性随电流密度的变化趋势.结果显示:氧化膜随电流密度的增加而增厚,氧化膜厚度的增加有助于增加铝片的交流阻抗值,提高膜的耐蚀性;当电流密度为3.3 A/dm2,在150 mL/L H2SO4中添加9 mL/L丙三醇时,常温下得到的氧化膜均匀致密,交流阻抗值较大,具有较好的耐蚀性.该研究可为合理选材及铝阳极氧化工艺选择提供参考.     

温度冲击对不同阳极氧化温度SiC_P/2A12复合材料阳极氧化膜开裂行为的影响

通过己二酸-硫酸工艺制备了SiCP/A1合金(2A12)复合材料阳极氧化膜,研究了不同阳极氧化温度下(15~35℃)制备的SiCP/2A12复合材料阳极氧化膜温度冲击后的开裂行为及耐蚀性能。采用FE-SEM对温度冲击前后SiCP/2A12复合材料阳极氧化膜的微观形貌进行了分析,采用电化学阻抗谱(EIS)研究了冲击前后SiCP/2A12复合材料阳极氧化膜的耐腐蚀性能。结果表明:温度冲击对不同阳极氧化温度制备的SiCP/2A12复合材料阳极氧化膜影响程度不同,随着阳极氧化温度的升高,温度冲击后SiCP/2A12复合材料阳极氧化膜的裂纹密度逐渐增加。阳极氧化温度为25℃时,温度冲击后SiCP/2A12复合材料阳极氧化膜耐蚀性最好。SiCP/2A12复合材料阳极氧化膜的耐温度冲击性能优于2A12铝合金氧化膜。     

复合封孔对铸铝阳极氧化膜耐蚀性的影响

研究了沸水、醋酸镍溶液和稀土盐封孔对铸铝阳极氧化膜耐蚀性的影响.采用能谱仪(EDXA)分析封孔后阳极氧化膜的成份,采用极化曲线研究氧化膜的耐蚀性.结果表明,经过2种稀土盐复合封孔处理的阳极氧化膜比单一稀土盐封孔氧化膜的耐蚀性明显提高;经过醋酸镍封孔处理的氧化膜在中性、酸性和碱性NaCl溶液中也都具有良好的耐蚀性,但经过长时间的浸泡后,其耐蚀性下降较快,而经复合封孔处理的氧化膜经过长时间浸泡后仍保持良好的耐蚀性.     

Das Verhalten von Aluminium-Werkstoffen in der Hausinstallation

The corrosion behaviour of aluminium alloys . The corrosion behaviour of the aluminium alloys AlMgMn, AlMgSi 0,8 and AlZn 1 was investigated at two temperatures in two natural waters with different contents with and without oxygen. These measurements were performed as well separated as in contact with copper, brass, iron and zinc; the electrode potentials and the galvanic currents were measured and registrated. The results of the metallographic investigations concerning pitting corrosion of the aluminium samples and of the measurements under potentiostatic conditions were summarized in especial corrosion diagrams. Out of these the corrosion risks of the aluminium materials can be seen. The investigated aluminium alloys – except AlZn 1 – showed unpolarized a good corrosion resistance. The best of them was AlMgMn. In contact with iron and copper containing alloys aluminium were polarized in anodic direction depending of the different metals and of oxygen content of the water. The limit of the pitting corrosion has been exceeded at times. In the cold waters zinc polarized the aluminium alloys cathodic. References were given for applications of aluminium building parts in the home installation and it was informed about experiences which corresponds with these results.     

Characterization of the protective effect of aluminium surface treatments by d.c. and a.c. measurements

Steady-state and electrochemical impedance spectroscopy measurements have been made on anodic layers on 1050 and 2024T3 aluminium alloys prepared from solutions of phosphoric acid, boric acid and sodium tetraborate, before and after impregnation treatment with zinc. Corrosion characteristics of the anodic layers were dependent on the aluminium substrate and the electrolyte. Aluminium alloy composition was found to be the most important factor for corrosion resistance; alloying elements of 2024T3 alloy (like copper) had a harmful influence on this layer property. Steady-state measurements allowed the oxide layer behaviour to be studied in the anodic range by the determination of an anodic passivity domain. This domain was characterized by a weak aluminium oxidation through the oxide layer. The zinc impregnation treatment had a marked protective effect on each studied anodic layer. This treatment can be used as an alternative to hot sealing in water or chromic acid solution.     

Environmentally assisted cracking of aluminium alloys

A short review of the stress corrosion cracking (SCC) behaviour of aluminium alloys is given. Mechanisms of environmentally assisted cracking are outlined. For aluminium alloys, in which stress corrosion cracks propagate predominantly along grain boundaries, anodic dissolution and hydrogen embrittlement have been proposed. Transgranular stress corrosion cracking occurring at severe loading conditions has found particular interest concerning localised corrosion‐deformation interactions. Accelerated test methods for assessing the SCC behaviour are described, including the slow strain rate testing technique and the breaking load method. Results of recent studies on environmentally assisted cracking of aluminium alloys are summarised. Most of the work published in the last two decades has been on aluminium‐lithium based alloys and improved high strength Al‐Zn‐Mg‐Cu alloys in corrosion resistant retrogressed and re‐aged tempers.     

A filiform corrosion and potentiodynamic polarisation study of some aluminium alloys

The aim of the present investigation is a combined study of filiform corrosion of aluminium alloys by accelerated exposure tests and potentiodynamic polarisation measurements. The accelerated exposure tests are performed on binary Al-Cu, Al-Mg, Al-Si and Al-Zn model alloys, a ternary Al-MgSi alloy and on the two commercial alloys, AA2024-T351 and AA7075-T651, with variations of composition and surface treatments. The surface treatments cover simple degreasing, chromate and cerium based treatments. A trend of a higher filiform corrosion susceptibility with increasing alloying elements concentrations was observed for all model systems. Furthermore, the filiform corrosion susceptibility varies with the solute atom, in particular Cu was found to have a detrimental effect on the filiform corrosion properties. Both chromating and cerating improve the filiform corrosion resistance of the alloys significantly. To explain the trends observed in the exposure tests, polarisation measurements were performed on the untreated Al-Cu and Al-Zn alloys in bulk anolyte and catholyte solutions which are characteristic for the local anodic and cathodic sites in the filaments on the aluminium substrates. From these measurements a filiform corrosion current, defined as the intercept of the anodic and cathodic curves, can be determined. The present set of experiments shows a correlation between the filiform corrosion properties during accelerated exposure tests and the potentiodynamic polarisation measurements for the Al-Cu alloys. When comparing the results for the Al-Cu and Al-Zn binary alloys it can be concluded that the correlation factor differs significantly with the solute atom and the filiform corrosion current proves to be a non-uniquely discriminating parameter for the filiform corrosion susceptibility of the model alloys. The difference in correlation factor for the Al-Cu and Al-Zn alloys is attributed to differences in the electrochemical behaviour of these alloys with local variations in substrate composition. For the Al-Cu and Al-Zn model alloys the filiform corrosion initiation characteristics are related to the passive range and thus implicitly to the ease of pitting of the alloy. A smaller passive range corresponds to a higher filiform site density for both the Al-Cu and Al-Zn alloys.     

Effect of hydrogen in aluminium and aluminium alloys: A review

Susceptibility of aluminium and its alloys towards hydrogen embrittlement has been well established. Still a lot of confusion exists on the question of transport of hydrogen and its possible role in stress corrosion cracking. This paper reviews some of the fundamental properties of hydrogen in aluminium and its alloys and its effect on mechanical properties. The importance of hydrogen embrittlement over anodic dissolution to explain the stress corrosion cracking mechanism of these alloys is also examined in considerable detail. The various experimental findings concerning the link between hydrogen embrittlement and stress corrosion cracking are also discussed.     

颗粒增强铝基复合材料阳极氧化与耐蚀性的研究

基体中加入与铝合金基体电位不同、高体积分数的碳化硅和石墨颗粒增强材料,可能导致材料的耐蚀性降低.采用盐雾腐蚀和硬质阳极氧化方法对4种喷射沉积制备的颗粒增强铝基复合材料和一种喷射沉积锭坯颗粒增强铝基复合材料的腐蚀行为及阳极氧化工艺进行了研究.结果表明,颗粒增强铝基复合材料具有较高的腐蚀率,腐蚀形态均为明显的点蚀;在适当阳极氧化工艺条件下,颗粒增强铝基复合材料表面可以制得优良耐蚀性的硬质阳极氧化膜.     

Oxidation and corrosion behaviour of laser-alloyed mild steel with chromium

The oxidation and corrosion of mild steel coated with chromium powder followed by laser treatment has been investigated. Chromium powder was deposited on mild steel surface using atmospheric plasma spraying. The chromium-coated surface was irradiated separately using a pulsed Nd:YAG laser and a continuous CO₂ laser. The oxidation tests were carried out in air at 700°C and anodic polarization tests in 1N H₂SO₄ solution. There was significant difference in the morphologies of the surface alloys formed using CO₂ laser and Nd:YAG laser. Samples treated with CO₂ laser showed better oxidation resistance whereas the surface alloys formed using Nd:YAG laser showed poor oxidation resistance. Anodic polarization tests carried out on samples laser-treated with CO₂ laser showed improved corrosion resistance.     

硅酸钠浓度对镁合金阳极化的影响

采用电压-时间曲线、全浸腐蚀实验、极化曲线法、X射线衍射法(XRD)、扫描电镜(SEM)、能量色散谱仪(EDS)和X射线光电子能谱法(XPS)等方法研究了AZ91D镁合金在含不同浓度硅酸钠的阳极化溶液中的阳极氧化行为和膜层的成分、结构.结果表明:在本文给定工艺中,AZ91D镁合金的阳极化过程可分为三个阶段:电火花出现之前的致密层生成阶段,少量小电火花出现的多孔层生成阶段,出现较大电火花的多孔膜层稳定生长阶段.阳极氧化过程中,随着阳极氧化溶液Na2SiO3浓度的升高,出现电火花的时间缩短,出现电火花时的电压值降低;阳极化膜的颗粒度变大甚至膜层出现裂纹,膜层厚度基本不变.阳极化膜层中主要含有Mg2 、O2-、Si4 和B3 ,主要相结构为MgO、MgSiO3和Mg3B2O6.硅酸钠浓度对阳极化膜的耐蚀性影响较大,当硅酸钠浓度为120g/L时,膜层耐蚀性能最好.