微弧氧化工艺及封孔处理对镁合金耐蚀性能的影响

为寻求在低成本下获得高性能镁合金防护膜的方法,采用直流低压微弧氧化工艺,在硅酸盐体系中添加抑弧剂抑弧以获得均匀的膜层,并对随后获得的微弧氧化陶瓷膜进行封闭处理.通过形貌分析及腐蚀析氢的方法研究了膜层的耐蚀性能及腐蚀特征,结果表明:在低电流密度下适当延长微弧氧化时间,可获得更为致密的陶瓷膜层,抗腐蚀性能更好.碳酸盐封孔处理可使膜层的致密层变厚,并进一步强化膜层的致密度;能保证基体完全不受腐蚀的时间显著延长,并在较长时间内使膜层的抗腐蚀性能明显提高.     

2ED300C17-S在大功率微弧氧化电源中的应用

微弧氧化电源是实现微弧氧化工艺的关键因素之一,IGBT的驱动系统是该电源的核心。传统的大功率驱动模块无法满足设备的要求。介绍了该电源的结构以及技术指标,分析了2ED300017--S的特点,设计了基于2ED300C17-S的驱动电路,并进行了调试,结果表明了2ED300C17-S的高可靠性。     

大功率镁合金微弧氧化电源中一种实用的IGBT过流保护方法

大功率微孤氧化电源是实现微孤氧化工艺的关键设备。针对IGBT驱动过流保护问题,提出了一种适用的IGBT过流保护方法,并详细的分析了大功率微弧氧化电源中产生的过流现象及其识别、IGBT过流保护的工作原理,并且进行了验证。     

Characteristic, cell response and apatite-induction ability of microarc oxidized TiO2-based coating containing P on Ti6Al4V before and after chemical-treatment and dehydration

The structure, cell response and induction capability for apatite formation of the microarc oxidized (MAO) coating before and after chemical-treatment and subsequent dehydration at 400 °C were investigated. The surfaces of the chemically treated MAO (C-MAO) coatings before and after dehydration showed ribbon-like amorphous phase mainly containing Na, Ti and O elements with network morphology. Subsequent dehydration has no pronounced effect on the surface roughness, wetting ability, surface constituents and chemical state of Ti, Na and O of the C-MAO coating. The outer layers of the C-MAO coating before and after dehydration showed Na, Ti and O elements with uniform distributions along the surface depth. Chemical-treatment improves the apatite-forming ability of the MAO coating; however, subsequent dehydration greatly lowers that of the C-MAO coating, since it changed the ability of C-MAO coating to release Na⁺ ions, which is unfavorable for the formation of Ti-OH groups. The apatite formed on the two coatings contained HPO₄²⁻ and CO₃²⁻ ions. In addition, the dehydration of the C-MAO coating seemed to be unsuitable for the cell proliferation on its surface.     

Effects of the electric conditions of AC-type microarc oxidation and hydrothermal treatment solution on the characteristics of hydroxyapatite formed on titanium

This study examined the effects of the conditions for AC-type microarc oxidation (MAO) and the type of hydrothermal treatment solution on the characteristics of hydroxyapatite(HAp)-containing oxide films deposited on commercially pure titanium (CP-Ti). The MAO treatments were carried out in an electrolyte containing 0.2 M calcium acetate monohydrate and 0.02 M β-glycerophosphoric acid disodium salt pentahydrate (β-GP) using AC-type rectangular electric pulses at different voltages and frequencies. HAp formation on the surface of the MAO-treated group was induced by a hydrothermal treatment in either an alkaline solution to form HT-treated groups or a 0.002 M β-GP solution (pH = 11.0) to produce HTP-treated groups. A mixed crystalline structure consisting of anatase TiO₂, rutile TiO₂ and CaTiO₃ was observed on the MAO-treated groups treated with a low frequency and voltage. When the AC frequency was increased, anatase TiO₂ became the dominant crystalline structure and there was an even distribution of pores. HAp particles were formed more densely on the HTP-treated groups than on the HT-treated groups. Among the HTP groups, the groups fabricated at higher frequencies contained more evenly distributed and crystallized HAp crystallites.     

Effect of voltage on microstructure and corrosion resistance of microarc oxidation coatings on CP-Ti

The surface modification of commercially pure titanium (CP-Ti) by microarc oxidation (MAO) under different voltages was investigated using 1%H₃PO₄ solution as an electrolyte. The microstructure, phase composition and elemental distribution of ceramic coatings were investigated using scanning electron microscopy (SEM) and X-ray diffraction. The corrosion behaviour of the coating was also examined by potentiodynamic polarisation testing in a 3·5 wt-%NaCl solution. Micropore oxide films were formed on all the sample groups by MAO. The thickness and micropore size of the MAO coating increased with the increasing voltage. Energy dispersive X-ray spectroscopy results indicate that Ti, O and P became incorporated into the MAO coatings. At a low voltage of 250 V, the MAO coatings were composed of amorphous, P₂O₅, TiP₂O₇ and titania phases (rutile and anatase). Variation of treatment voltages increased the ceramic coatings from an amorphous structure to a phase structure, and the P₂O₅ phase disappeared. The corrosion potential Φ_corr of the MAO sample shifted towards nobler directions, and the corrosion density I_corr fell significantly compared with that of the bare CP-Ti. Corrosion testing showed that the sizes of the micropore of the MAO samples obviously decrease, and the MAO surface becomes smooth.     

添加剂对镁铝合金微弧氧化作用的研究

通过对电解液特性测试和微弧氧化膜成分、结构和性能的试验,研究多元醇基的E11和E12添加剂加入铝酸盐和钼酸盐混合电解液体系后镁铝合金微弧氧化膜的性能及其微弧氧化工艺。结果表明镁铝合金在NaAlO2 NaMoO4 E11 E12复合电解液体系中微弧氧化电流为3~5A、电解液温度不超过35℃、溶液电阻率3.5Ω.m;镁铝合金微弧氧化膜主要由MgO、MgAl2O4和Al12Mg17组成,其腐蚀速率比基体降低2个数量级以上,加入添加剂后的微弧氧化膜较不加添加剂的更加均匀、致密。     

镁合金微弧氧化膜的SiO2溶胶封孔处理研究

以正硅酸乙酯为原料,乙醇为溶剂,盐酸为催化剂制备了SiO2溶胶封孔剂.该封孔剂的傅立叶红外光谱(FTIR)中含有Si-O-Si键的伸缩振动吸收峰,证明了SiO2微粒存在,而且干凝胶的Si-O-Si键的伸缩振动吸收峰强度不随热处理温度的变化而变化,表明封孔剂有良好的高温稳定性.SiO2溶胶封孔剂可浸入镁合金微弧氧化膜的微孔,形成有效封孔.封孔处理可使镁合金微弧氧化试样的腐蚀速率由106 mg/(m2·h)降至32 mg/(m2·h),而且封孔处理还可显著提高镁合金微弧氧化试样在410 ℃下的抗氧化性能,对镁合金基体有很好的保护作用.     

微弧氧化-水热合成法在二氧化钛膜上制备羟基磷灰石涂层

利用微弧氧化技术在钛片和钛合金表面得到二氧化钛薄膜，在高压釜中利用水热合成反应在二氧化钛薄膜上生成羟基磷灰石涂层，制备出晶粒较完整的羟基磷灰石纳米棒。借助X射线衍射、扫描电镜对样品的组分、形貌进行了分析。     

The Overcoat Oil Lubrication of Microarc Oxidation Coating on Al Alloy by Liquid Plasma Technique

Ceramic coatings were deposited on 2Al2 alloy with a 100 kW micro-arc oxidation equipment consisting of a potential adjustable ac power supply and alkali electrolyte. The structure of the micro-arc oxidiation coatings was examined using scanning electron microscopy and transmission electron microscopy. The tribological properties of the coatings sliding against steel under the drop and adsorption lubrication of liquid paraffin were evaluated with a Timken tester. The lower friction coefficient of 0.14 and longer wear life of 2450 m of overcoat were observed for the polished micro-arc oxidation coating of 180μm thick at a sliding speed 2. 50 m/s and load 1500 N. This is because the coating has an interlayer of suitable porosity and thickness, which helps to improve the deposition of lubricants and endure the higher load. In other words, the oil is able to adsorb in the porous holes of the overcoat and provided the lubrication of micro reservoir during friction, and the compact and relatively hard interlayer of oxidation coating is able to support heavy load and prevent the oil lubricating film from damage.