Q235钢热浸镀铝微弧氧化层的生长规律

微弧氧化是在普通阳极氧化技术基础上建立起来的一项高新技术，在Q235钢表面热浸镀铝后再进行微弧氧化获得一陶瓷层。研究了强化时间和电流密度对所得陶瓷层向内、向外生长厚度的影响，同时研究了陶瓷层向内与向外生长之间的关系。结果表明，微弧氧化陶瓷层向内与向外的生长比例受强化时间和电流密度综合控制。     

铝合金微弧氧化陶瓷层生长过程研究

采用硅酸钠溶液体系，制得250μm左右的微弧氧化陶瓷层。研究了溶液电导率以及电流密度对Al合金微弧氧化陶瓷层生长过程和厚度的影响。结果表明，提高溶液电导率能加速陶瓷层的生长，降低陶瓷层粗糙度。提高电流密度能加速陶瓷层的生长速率，但不宜过高，以10A／dm^2左右为佳。采用金相显微镜观察微弧氧化陶瓷层截面发现陶瓷层呈连续结构，较厚的陶瓷层中有少量金属颗粒存在。     

Y(NO_3)_3对6061铝合金微弧氧化陶瓷层的影响

在硅酸盐碱性电解液中加入Y(NO3)3,利用微弧氧化技术在6061铝合金表面制备了陶瓷层,研究了重稀土对陶瓷层厚度、粗糙度、硬度和表面形貌的影响。结果表明,加入到电解液中的Y(NO3)3可以进入铝合金微弧氧化陶瓷层,适量加入Y(NO3)3可降低铝合金微弧氧化陶瓷层的粗糙度、提高微弧氧化陶瓷层的硬度与耐蚀性,增加陶瓷层的厚度,明显改善铝合金微弧氧化陶瓷层的微观形貌,Y(NO3)3的适宜浓度约为0.003 mol/L。     

纯铝及6061铝合金微弧氧化陶瓷层的微观结构和粗糙度

采用X射线衍射仪、扫描电镜、数字图像处理软件和表面粗糙度仪研究了纯铝和6061铝合金两种基体上微弧氧化(MAO)陶瓷层的构相、微观形貌、元素组成、厚度和粗糙度随微弧氧化时间的变化。结果表明,微弧氧化初期所得陶瓷层的主要相为γ-Al_2O_3,微弧氧化后期所得陶瓷层均存在W相、AlPO_4相和SiO_2相。随微弧氧化时间延长,MAO陶瓷层的厚度增大,纯铝表面MAO陶瓷层的生长速率大于6061铝合金表面MAO陶瓷层的生长速率;MAO陶瓷层的粗糙度受其结构和厚度的影响。     

工艺参数对铸造铝-硅合金微弧氧化层特性的影响

用微弧氧化的方法在铸造铝－硅合金基体上获得陶瓷层,分别研究了电流密度及强化时间对陶瓷层厚度,表面粗糙度及硬度的影响,以及强化时间对成膜速度的影响,结果表明,陶瓷层厚度,表面粗糙度都随电流密度及强化时间的增大而增大,膜厚随二者增加有一极限值,硬度随电流密度增加而增加,也有一极限值,成膜速度在较低电流密度时不随时间而变,在较高电流密度时,成膜速度随时间增加而下降,最终趋于零,电流密越高,下降速度越快。     

电流密度对TC4钛合金微弧氧化陶瓷膜性能的影响

采用恒流和梯度电流两种方式对TC4钛合金进行微弧氧化,微弧氧化液组成和工艺参数为:Na2SiO3 16 g/L,(NaPO3)68 g/L,NaF 2 g/L,频率500 Hz,占空比10%。研究了不同电流模式下电压随微弧氧化时间的变化。对比研究了两种电流模式下所得微弧氧化膜的表面形貌、厚度、粗糙度、显微硬度等性能。结果表明,恒流模式下,随电流密度升高,氧化膜层的终止电压、厚度、粗糙度和表面微孔直径增大,显微硬度先增大后减小;与恒流模式膜层相比,梯度电流模式下所得氧化膜层较厚,粗糙度较低,硬度高,表面微孔直径较小。较适宜的恒流电流密度和梯度电流密度分别为10 A/dm2和15–5 A/dm2,而后者所得膜层的综合性能优于前者所得膜层。     

钛合金微弧氧化钙磷生物膜层形成机制研究

为了利用微弧氧化工艺生成钛合金生物钙磷陶瓷涂层,使用微弧氧化电源,在恒电流条件下制备试样。通过电子扫描电镜和电子能谱仪观测不同氧化阶段涂层形貌和元素组成,膜层厚度变化特点,并分析各阶段微弧放电特性,研究了钛合金微弧氧化生成羟基磷灰石(钙磷)医用陶瓷涂层机制。结果表明,各阶段膜层放电特性不同,膜层先向外生长,后向内生长,且所生成膜层元素成分有区别,致使在微弧放电阶段才有钙磷生物成分生成。结论:若想获得高质量钙磷生物膜层,需使微弧氧化达到微弧放电阶段,但应避免进入弧光放电阶段,所得结论可对研究微弧氧化成膜过程起到一定的指导作用。     

一种兼具装饰性和耐蚀性的镁合金红色微弧氧化膜层的制备

[目的]镁合金微弧氧化在装饰性方面的研究报道不多。[方法]采用微弧氧化技术在ZM5镁合金表面制备了红色的微弧氧化陶瓷层,研究了主盐Na₂SiO₃和着色剂CuSO₄的质量浓度,配位剂的种类,以及氧化时间对膜层的影响。[结果]在含有Na₂SiO₃ 20.0g/L、CuSO₄ 0.5g/L、乙二胺四乙酸二钠0.5g/L和NaF 0.5g/L的电解液中,以电流密度3.5A/dm²氧化25min,能够获得厚度约为31.4μm的红色微弧氧化膜。该膜层致密,主要由MgO、Mg₂SiO₄和CuO组成,在铜加速乙酸盐雾试验中出现锈蚀的时间为48h。[结论]ZM5镁合金表面红色微弧氧化膜的耐腐蚀性能比在不加CuSO₄时所得白色微弧氧化膜更好。     

微弧氧化陶瓷膜的性能研究

微弧氧化是一种新兴的金属材料表面陶瓷化处理技术。利用微弧氧化技术在纯铝和LY12铝合金表面制得陶瓷膜，推导出膜层厚度的计算公式，研究了陶瓷膜的硬度、耐蚀性、孔隙率、电绝缘性和热稳定性。结果表明，微弧氧化陶瓷膜层各项性能优异，具有很好的应用前景。     

溶质离子对AZ31B镁合金微弧诱发过程和陶瓷层结构的影响

采用微弧氧化方法在AZ31B镁合金表面制备了陶瓷层。研究了AZ31B镁合金微弧氧化溶液体系中KOH和Na2SiO3浓度对微弧等离子体诱发过程和陶瓷层微观结构的影响,通过涡流测厚仪、扫描电子显微镜和X射线衍射仪分析了陶瓷层的物相组成、微观形貌和厚度随KOH和Na2SiO3浓度的变化规律。研究表明:恒流模式下,KOH溶液在AZ31B镁合金表面诱发微弧时存在1个临界浓度,约为27mmol/L,且随着KOH浓度的增大,对基体和氧化膜的溶解作用加剧,影响微弧等离子体诱发的稳定性。Na2SiO3含量显著影响镁合金表面微弧诱发过程和陶瓷层的微观结构,随着Na2SiO3浓度的增大,陶瓷层生长速率增快,膜层表面由光滑转变为微孔结构,且孔径逐渐增大;Na2SiO3浓度在1.6~6.4mmol/L时陶瓷层中主要以MgO为主,Na2SiO3浓度大于16mmol/L时,Mg2SiO4和非晶相明显增多。     

Study on corrosion resistance and roughness of micro-plasma oxidation ceramic coatings on Ti alloy by EIS technique

Micro-plasma oxidation (MPO) technique has been developed quickly in recent years. The produced ceramic coatings are reported to possess fine properties and promising application prospects in many fields. The aim of this work is to study the corrosion resistance and the roughness of the micro-plasma oxidation ceramic coatings on Ti alloy by electrochemical impedance spectroscopy (EIS) technique. Compound ceramic coatings were prepared on Ti-6Al-4V alloy by pulsed bi-polar micro-plasma oxidation in NaAlO₂ solution. The phase composition and element distribution in the coating were investigated by X-ray diffractometry and electron probe micro-analyzer. EIS of the coatings was measured through CHI604 electrochemical analyzer in 3.5% NaCl solution. The ceramic coating is composed of a large amount of Al₂TiO₅ and a little α-Al₂O₃ and rutile TiO₂. The coating is of double-layer structure with the loose outer layer and the dense inner layer. The thickness of the coatings is reduced when the working frequency or the cathode pulse current density is increased, while the thickness is increased when the frequency or the anode current density is increased. The established “equivalent circuit” of the coatings is consistent with the double-layer structure. The electric charge transfer resistance (R_t) in the equivalent circuit can be used to assess the corrosion resistance of the coatings, which is consistent with the result of the polarizing curves test. And the empirical exponent (n₁) of the constant phase element (Q₁) in the equivalent circuit can be used to assess the surface roughness of the coatings, which is consistent with the surface SEM analysis of the coatings.     

镁合金表面微弧氧化陶瓷膜的形成过程研究进展

归纳了镁合金表面微弧氧化过程中电解液组成及工艺条件对陶瓷膜层表面形貌、截面形貌和相组成等的影响.结合成膜过程中电压及膜层厚度的变化规律,综述了镁合金微弧氧化陶瓷膜的形成机理.     

金属陶瓷涂层耐蚀性影响因素的研究

研究了溶胶制备中所用催化剂种类、基体金属前处理及涂层厚度对金属陶瓷涂层耐蚀性的影响,不含ＣＩ＾－催化剂的溶胶－凝胶配方所得陶瓷涂层的耐蚀性最了,适当的前处理及适宜的涂层厚度有利于提高陶瓷涂层的耐蚀性。     

N80钢表面陶瓷涂层的制备及耐酸蚀性研究

采用热化学反应方法在N80钢基体表面制备了陶瓷涂层。通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)、体视显微镜和划痕仪对涂层的物相结构、组织形貌和膜基界面结合力进行了研究,利用失重法在20%的质量分数盐酸溶液中测试了涂层的耐蚀性能。结果表明:在600℃固化温度下,以SiO2粉体和SiO2、Al2O3、MgO等两类不同骨料制得的陶瓷涂层中,前者无新相生成,涂层与基体界面结合力24 N;后者有新相MgAl2O4生成,且涂层比较致密,涂层与基体界面结合力约40 N。以水玻璃作粘结剂的复合氧化物陶瓷涂层的表面致密度、平整性均优于以磷酸氢铝作粘结剂的涂层。酸腐蚀测试表明,以水玻璃作粘结剂的复合氧化物陶瓷涂层的平均腐蚀速率约为基体的1/2左右。     

铝及其合金等离子微弧氧化技术

等离子微弧氧化是一种新兴的材料表面陶瓷化技术,利用该技术可在铝及其合金表面生成一层耐磨,耐蚀,耐高温以及电绝缘性能优异的陶瓷膜层,介绍了微弧氧化技术的发展及现状,基本原理,陶瓷膜的制备以及膜层结构及性能特点,并展望了其应用前景。     

Investigation of tribological properties of micro-arc oxidation ceramic coating on Mg alloy under dry sliding condition

To enhance wear resistance of Mg alloy, micro-arc oxidation (MAO) ceramic coatings on Mg substrate were prepared in silicate electrolyte under various currents. It was found that the surface roughness and thickness of MAO coating were increased with the increase of current. The dry tribological tests showed that the friction coefficient and wear resistance of thicker coatings (obtained under currents of 3?A and 4?A) were much higher than that of Mg alloy and the thin coating (obtained under current of 2?A), meanwhile the lifetime of the coating obtained under 4?A was longer than the other coatings under higher load. The wear type of thin MAO coating was slight abrasive wear under low load, whereas translated to severe adhesive wear under high load. While the main wear mechanism of thick MAO coating was slight abrasive wear or scratch under the given test condition, which was attributed to the thick intermediate layer improved load support for the soft substrate. The tribological study indicated that the MAO coating obtained under 4?A current had better wear resistance and life time due to its compact microstructure and thickness.     

钯镀层结晶状态及焊锡能力研究

研究了电流密度、镀液温度及镀层厚度对磷青铜上钯镀层的焊锡性与润湿平衡的影响。钯镀层的晶粒尺寸随电流密度的增加或温度的升高而变大,但受膜厚的影响不大。镀态下,不同条件下制得的钯镀层具有良好的沾锡能力。不同活性助焊剂的使用也会影响钯镀层的焊锡性能。对于经蒸汽老化后的钯镀层,采用中等活性的松香助焊剂可获得比采用非活性松香助焊剂更好的焊锡性能。     

Structure and Properties of ZrO2 Ceramic Coatings on AZ91D Mg Alloy by Plasma Electrolytic Oxidation

ZrO₂ ceramic coatings were prepared in situ on an AZ91D Mg alloy by plasma electrolytic oxidation in a K₂ZrF₆ solution. The phase composition and the surface morphology of the coatings were examined with X-ray diffraction and scanning electron microscopy. The thermal shock resistance of the coatings was evaluated by a thermal shock test. The corrosion resistance of the coated samples was examined by the polarizing curve method in a 3.5% NaCl solution. The prepared coating was composed of t -ZrO₂ and a small amount of c -ZrO₂. There were many residual discharging channels on the coating surface. The coated samples showed excellent thermal shock resistance under 500°C, which improved with increasing frequency or decreasing current density or PEO time. Besides, the coating improved the corrosion resistance of AZ91D Mg alloy considerably. In the experiments, the corrosion current density of the coated samples prepared under 1000 Hz was the least, which also decreased with the current density during the PEO process.     

静端导电块旋转镀银工艺及设备的研究

采用旋转电镀银的方法进行静端导电块的电镀,研究了旋转镀时的转速、有无反转设置、施镀电流密度、阳极电力线均布套筒(板)设置对镀层厚度均匀性的影响,并采用对比方法对施镀件在不同条件下,不同直径上的镀层的平均厚度、同一直径上镀层厚度的最大差值以及不同直径上镀层平均厚度的差值进行了比较。结果表明,施镀工作电流密度为0.8 A/dm~2、转速为10 r/min,设置阳极电力线均布套筒(板)时,镀层均匀性好,d为70 mm处与d为40 mm处平均镀层厚度相差仅为0.1μm。该阴极旋转镀装置在自动生产线上已成功实现了应用。