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通过对不同电解液成分和浓度的选取,制备氧化和着色兼容的微弧氧化膜。不同种类的电解液所得到的微弧氧化膜层颜色也不同,同种体系中的主要成分浓度的不同是影响微弧氧化膜颜色和生成速率的原因之一。 相似文献
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微弧氧化是近几年发展起来的一项材料表面改性技术,用微弧氧化技术处理铸铝材料在其表面可以形成几十至上百微米的陶瓷氧化层。经X射线衍射分析该氧化层具有α相和γ相Al2O3结构,使表面硬度提高到800—1000HV,大大改善了铸铝表面的耐磨、耐蚀、耐压绝缘和抗高温冲击特性,在发动机活塞和电熨斗中得到了很好的应用。 相似文献
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Wenbin Xue Qian Jin Qingzhen Zhu Ming Hua Yueyu Ma 《Journal of Alloys and Compounds》2009,482(1-2):208-212
The corrosion-resistant ceramic coatings up to 80 μm thick were fabricated on SiCP/AZ31 magnesium matrix composite by microarc oxidation (MAO) technique in Na3PO4 + KOH + NaF solution. The microstructure, composition and phase constituent of ceramic coatings were analyzed by SEM and XRD, and the electrochemical corrosion behaviour of coatings was evaluated by the electrochemical polarization method. The thicker coating is compact and displays a good adhesion to the composite substrate. The ceramic coatings consist of MgO, Mg2SiO4, MgF2, Mg3(PO4)2, furthermore, a few residual SiC phases were also found in the coatings by means of SEM observation and EDX analysis. Most of SiC reinforced particles in the oxidized composite substrate have transformed into the oxides under microarc discharge sintering, but a few residual SiC reinforcements in the MAO coatings have not disrupted the continuity of coatings. So the corrosion resistance of the SiCP/AZ31 composite is greatly improved by MAO surface treatment, however, the corrosion resistance of coated composite also depends on the coating thickness. 相似文献
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The influence of substrate on the microstructure and phase composition of surface layers synthesised by microarc oxidation (MAO) on aluminium and its alloys 2214-T6 and 7050-T74 is studied using scanning (SEM) and transmission electron microscopy (TEM) as well as cross-sectional X-ray diffraction. MAO layers are composed of three layers and are mainly made of gamma-Al2O3 and alpha-Al2O3 phases. The proportion of each phase depends on the substrate. The external porous layer is mainly composed of the gamma-Al2O3 phase. The internal dense layer can present two aspects according to the percentage of the alpha-Al2O3 phase. The so-called granular aspect indicates a high proportion of “dendrite” defect which results from discharge formation and implies a high percentage of the alpha-Al2O3 phase. The so-called columnar aspect indicates a high proportion of “small channels” associated with a very weak percentage in the alpha-Al2O3 phase. In the latter, it is believed that a Zn alloying element can inhibit the growth of alpha-Al2O3. During the MAO process, discharges likely occur in the vicinity of the MAO layer/substrate interface, probably in the spherical porosities that result from oxygen generated in the thin layer localised at the interface. 相似文献
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以纳米BaTiO3、纳米TiO2、乙二醇、甘油和三乙醇胺分别作为添加剂,在0.5 mol/L Ba(OH)2基础溶液中,采用微弧氧化在钛板表面原位生长铁电薄膜,利用XRD、SEM、EDS和HP4284型电容探测仪等对薄膜的物相构成、厚度、表面粗糙度、元素分布及介电性能进行表征。结果表明,所得薄膜的物相组成均主要是四方相BaTiO3,添加剂的加入对物相无影响。甘油可显著改善薄膜的表面形貌,降低表面粗糙度值,所得薄膜介电性能优越,100 Hz条件下其介电常数和介质损耗值分别为200.7和0.055。纳米TiO2和乙二醇也可降低薄膜表面粗糙度且使薄膜生长速度升高,但两者对薄膜介电性能的优化不及甘油。故欲获得表面形貌良好、生长速度较快且介电性能优越的BaTiO3铁电薄膜,可选择甘油作为添加剂。 相似文献
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L. Rama Krishna 《Wear》2006,261(10):1095-1101
Microarc oxidation (MAO), a novel coating technique capable of depositing dense, hard ceramic composite coatings on aluminium and its alloys, has the potential to replace conventional hazardous anodizing techniques. However, the emergence of such a scenario depends strongly on the properties and performance of MAO coatings in comparison to hard-anodized coatings. In order to facilitate such a comparative investigation, a 6061 T6 aluminium alloy was employed as the substrate and the coatings were deposited through microarc oxidation (MAO) and hard anodizing techniques. The tribological performance of the coatings was evaluated using dry-sand abrasive wheel tests at different normal loads and solid-particle erosion wear tests at different particle velocities and impact angles by employing silica as erodent. The hard-anodized coatings reduced the abrasive wear rate of 6061 Al alloy by a factor of 2, while the MAO coatings reduced the wear rate by a factor of 12-30. Under erosion conditions, the overall wear rate of MAO coatings is identical to that of bare alloy, whereas the hard-anodized coatings exhibit 10 times higher erosion rate. 相似文献
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Corrosion-resistant films were fabricated by the microarc oxidation technique on the LC4 zinc-containing aluminum alloy in silicate electrolyte. The electrochemical corrosion behaviors of LC4 alloy, with and without films, were evaluated using potentiodynamic polarization curves. Galvanic currents and galvanic potentials of bare and coated alloys coupled with copper were measured using the zero-resistance technique. Scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX) was used to analyze the microstructure of films and the corrosion morphology before and after corrosion testing. After microarc discharge treatment, the corrosion potential was increased and the corrosion current was significantly reduced. For a thin film sample, the galvanic current is similar to that of the bare alloy. However, a thick film can protect the LC4 alloy against galvanic corrosion. 相似文献
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NaOH体系中添加石墨对铝合金微弧氧化层生长及磨损性能的影响 总被引:3,自引:0,他引:3
在NaOH溶液中添加石墨粉末后对LY12铝合金进行了微弧氧化处理。分析了石墨相的含量对微弧氧化陶瓷层生长过程的影响和微弧氧化陶瓷层的相组成,在自制的磨损试验机上测定了陶瓷层和对摩件的耐磨损性能。结果表明,石墨相的引入大大降低了陶瓷层以及对摩件的磨损失重。 相似文献