In this work, Co-P coatings were deposited from a chloride-based bath by direct current (DC), pulse current (PC) and pulse reverse current (PRC) methods, respectively. The effects of current modes on the microstructure, composition, microhardness, wear resistance and corrosion resistance of the Co-P coatings were explored. Results showed that the P content in the Co-P coatings increased and the surface roughness decreased in the sequence of DC, PC and PRC methods. The coatings with low P content deposited by DC and PC methods are crystalline with fcc and hcp structures, respectively, while the coating with high P content deposited by the PRC method is amorphous. Comparing to DC and PC methods, the PRC method can evidently improve the microhardness, wear resistance and corrosion resistance of Co-P coatings. The excellent wear and corrosion resistance of the Co-P coatings deposited by the PRC method could be attributed to its high P content, smooth surface and amorphous structure.

目的研究离子液体中Ni 2+ 浓度对Al-Ni合金镀层结构和成分的影响,同时考察电流密度对镀层表面形貌和织构的影响。方法采用脉冲电流法,在含有不同浓度氯化镍的无水三氯化铝/盐酸三甲胺离子液体中,于不同电流密度下电沉积制备Al-Ni合金镀层。利用扫描电子显微镜、X射线衍射技术和能谱分析仪探究离子液体中Ni 2+ 的浓度对Al-Ni合金镀层结构和成分的影响,考察电流密度对镀层表面形貌和织构的影响。结果随着离子液体中Ni 2+ 浓度的增加,镀层中镍的含量增多,表面胞状颗粒逐渐变小,表面趋于均匀,当Ni 2+ 的浓度为0.2 mol/L时,形成铝镍金属间化合物。另外,随着电流密度的增加,镀层表面形貌由针状晶体变为棒状颗粒,并且颗粒逐渐增大。结论离子液体中Ni 2+ 的浓度和电流密度对Al-Ni合金镀层表面形貌、结构和成分有一定的影响。当溶液中Ni 2+ 的浓度为0.2 mol/L、电流密度为6 m A/cm~2时,电沉积4 h可制备得到厚度为10μm、由3μm大小晶粒组成、含有铝镍金属间化合物的合金镀层。

We have investigated the electropolishing (EP) of aluminum (Al) and its alloys in an ionic liquid composed of anhydrous aluminum chloride and trimethylamine hydrochloride. The EP mechanism of Al was investigated by linear sweep voltammetry. The optimum conditions for EP of Al and Al alloys including the ionic liquid components, current density and polishing time were systematically explored. Moreover, the microstructure and chemical compositions of Al before and after EP were measured by SEM, AFM, XPS and XRD, respectively. Compared to EP in strong acid solution, EP of Al in this ionic liquid can achieve the equivalent polishing effect with less mass loss. Importantly, the polishing ability of this ionic liquid remains stable even after EP for 50 cycles. The corrosion resistance of electropolished Al is drastically enhanced due to the formation of the compact passive layer on the mirror-like bright surface.

The research status of the principle of TiO2 self cleaning coating, the classifications of the coating and prepared methods was discussed. The application of TiO2 self cleaning coating in different fields was introduced. The future development direction of TiO2 self cleaning coating was put forward.

Thermal control ceramic coatings on Mg–Li alloys have been successfully prepared in silicate electrolyte system by plasma electrolytic oxidation (PEO) method. The PEO coatings are mainly composed of crystallized Mg 2 SiO 4 and MgO, which have typical porous structure with some bulges on the surface; OES analysis shows that the plasma temperature, which is influenced by the technique parameters, determines the formation of the coatings with different crystalline phases and morphologies, combined with “quick cooling effect” by the electrolyte; and the electron concentration is constant, which is related to the electric spark breakdown, determined by the nature of the coating and the interface of coating/electrolyte. Technique parameters influence the coating thickness, roughness and surface morphology, but do not change the coating composition in the specific PEO regime, and therefore the absorptance ( α S ) and emissivity ( ε ) of the coatings can be adjusted by the technique parameters through changing thickness and roughness in a certain degree. The coating prepared at 10 A/dm 2 , 50 Hz, 30 min and 14 g/L Na 2 SiO 3 has the minimum value of α S (0.35) and the maximum value of ε (0.82), with the balance temperature of 320 K.

用微弧氧化工艺在钛合金表面制备陶瓷膜层,研究了不同无机盐添加剂对膜层热控性能的影响,确定了钴盐、镍盐和铁盐多种无机盐复合微弧氧化工艺.研究了钨酸钠浓度和微弧氧化时间对膜层厚度、粗糙度、结构及热控性能的影响.在钛合金表面制备了太阳吸收率为0.93、发射率0.88的微弧氧化膜层.

采用中频非平衡反应磁控溅射法在单晶硅P（111）和不锈钢（304SS）基材上制备CrN和CrSiN薄膜;利用球-盘式摩擦磨损试验机（CSM）考察2种薄膜在不同介质（空气、去离子水、质量分数3.5%NaCl溶液）中和WC/Co球对摩的摩擦学性能。结果表明:大气环境下,CrN与CrSiN薄膜的磨损机制主要是磨粒磨损;水润滑下,CrN薄膜主要因机械抛光作用,CrSiN薄膜主要因摩擦化学反应,使得摩擦因数减小;在3.5%NaCl溶液中CrN薄膜易被腐蚀,由于NaCl颗粒析出以及涂层接触区域的腐蚀和磨损产物,作为第三体的润滑作用,导致摩擦磨损发生明显变化,而CrSiN薄膜不易被腐蚀,主要因摩擦化学反应,使得摩擦磨损性能发生显著变化。

Ceramic coatings with high emission and low absorptance were prepared on Ti6Al4V alloy by plasma electrolytic oxidation (PEO) in zirconate electrolyte. The effects of current density and working frequency on the structure and thermal control properties of the coatings were investigated. The phase composition, microstructure, thickness and roughness of coatings were examined by XRD, SEM, EDS, thickness measurement gauge and roughness measuring instrument, respectively. Thermal control properties of the coatings were studied with a UV–VIS–NIR spectrophotometer and an infrared reflectometer. The results show that the coatings are porous and composed of a large amount of KZr2(PO4)3, and a little monoclinic ZrO2, tetragonal ZrO2 and ZrP2O7 as well. The thickness of the coatings increases with the increase of the current density or the decrease of the working frequency while the roughness of the coatings increases with the increase of the current density and the working frequency. The increase of current density reduces the absorptance, but improves the emissivity; the increase of working frequency improves the absorptance, but does not change emissivity apparently. The coating prepared at 10 A/dm2, 50 Hz and 50 min, has the lowest solar absorptance (0.34) and the highest infrared emissivity (0.9).

•The hydrophobicity of APTS modified surface decreased quickly under the compact pressure of droplet.•After applying an enough hydraulic pressure, the hydrophobicity could not be restored automatically.•The wettability of APTS modified surface occurs spontaneously in immersion conditions.•The critical pressure of PFO modified surfaces were much smaller than the static energy barrier ΔP.

In order to reduce the effects of solar energy on the instruments and the apparatus in the outer space, two different kinds of ceramic coatings were prepared on Ti6Al4V alloys by plasma electrolytic oxidation (PEO) in zirconate electrolytes. The phase composition, microstructure, thickness, and roughness of coatings were examined by XRD, SEM, EDS, thickness measurement gauge, and roughness measuring instrument, respectively. The infrared emissivity and solar absorbance of the ceramic coatings were studied with the UV–vis–NIR spectrophotometer and infrared reflectometer. The results show that ZrO2 coatings are dense and deep gray–green, and mainly composed of m-ZrO2, t-ZrO2. In addition, a small amount of TiO2, ZrTiO4, and the amorphous compound containing P exists in the coating. The intrinsic solar absorbance and emissivity of ZrO2 coatings are 0.92 and 0.76, respectively. The KZr2(PO4)3 coating is rough, thick, and white with the main crystalline of KZr2(PO4)3. The intrinsic solar absorbance and emissivity of the KZr2(PO4)3 coating are 0.62 and 0.91, respectively. For both coatings, the absorbance decreases while the emissivity increases due to an increase in the real surface area of the coatings by increasing thickness and roughness of the coatings as the PEO time progresses. The porous structure of the KZr2(PO4)3 is proved to be ideal for high emissivity and low absorbance materials with the lowest solar absorbance (0.239), the highest infrared emissivity (0.99), and a corresponding balance temperature of the coating of 276 K.

The galvanic corrosion behavior between carbon fiber composite material and LY12 aluminum alloy was studied in NaCl solution. The results indicate that there was serious galvanic corrosion when the two kinds of materials were coupled in NaCl solution. The galvanic current was evidently affected by environmental temperature, electrolyte concentration and pH of electrolyte. As the coupled time increased, the galvanic current became lower. However, the galvanic current increased in the beginning then reduced lightly; finally it kept an upper levll in the acid and alkaline solutions. The galvanic corrosion current was the least in the neutral solution. The surface of corrosive LY12 aluminum alloy had obvious pit corrosion hole, the region of corrosion became much more flat.

依据相关标准研究了碳纤维复合材料与LY12铝合金的电偶腐蚀行为,结果表明,碳纤维与LY12铝合金在NaCl溶液中接触时会发生较为严重的电偶腐蚀,环境温度、电解液浓度和pH对电偶电流有较大的影响。电偶电流随偶接时间的增加大体上呈下降的趋势,当电解液体系在酸性或碱性条件下,电偶电流先增大后降低,并保持在一个较高的水平;而在中性条件下电偶腐蚀电流相对最小。LY12铝合金电偶腐蚀后,表面有明显的点蚀坑,且腐蚀区域变得较为平整。

It is of great significance for the research of thermal control coatings on Ti alloys due to their wide applications in aerospace and satellites and many other fields. In this work, black thermal control coatings were prepared on Ti–6Al–4V alloy by plasma electrolytic oxidation (PEO) technique. The coatings were characterized by SEM, EDS and XRD, respectively. The thermal control properties (solar absorbance, αS and emissivity, ε) were investigated by ultraviolet–visible-near infrared spectrophotometer instrument and solar absorption reflectometer. Meantime, the thermal shock properties of the coated samples were investigated as well. The results show that the ceramic coatings are black and porous and the elements such as Fe, Co and Ni and W from the electrolyte incorporate into the coating and exist in the form of an amorphous state. The coatings are of high emissivity and high absorbance character, which are influenced by the doping of Na2WO4 and the PEO time. Increasing the concentration of Na2WO4, αS increases firstly and then remains constant while ε increases gradually. Extending PEO time, both αS and ε increase. The annealing treatment reduces the solar absorbance greatly, but does not influence the emissivity apparently, which may be due to the improvement of the crystallization of the coating. When the dosage of Na2WO4 is 7.5g/L and the reaction time is 25min, the best coating is obtained with αS and ε of 0.93 and 0.88, respectively. This work not only provides an effective method to prepare thermal control coating for Ti alloys as the engineering materials, but also expands the application range of PEO technique in the fields of functional coatings.

为了探究碳纤维复合材料与高强钢在相互接触时实际使用的可行性,将T700碳纤维环氧树脂复合材料与30CrMnSiA高强钢置于NaCl溶液中进行电偶腐蚀,研究了温度、NaCl浓度、pH值对二者电偶腐蚀行为的影响.采用电化学法测试了二者在3.5％NaCl溶液中的开位电位,采用扫描电镜观察二者电偶腐蚀前后的形貌.结果表明:碳纤维与高强钢在NaCl溶液中接触时会发生严重的电偶腐蚀；温度、NaCl浓度及pH值对电偶电流有较大的影响；高强钢电偶腐蚀后,表面有一层暗红色的铁锈,腐蚀严重；随着腐蚀的进行,碳纤维环氧复合材料表面树脂由于溶胀作用遭到剥离,碳纤维露出得越来越多,进一步加快了高强钢的腐蚀.

The effects of working frequency on the composition, morphology, and corrosion resistance of ceramic coatings formed on a ZK60 magnesium alloy by plasma electrolytic oxidation were studied in this paper. It is found that the coatings are composed of MgO only. The rise of frequency led to an increase in the number of the channels and a decrease in the discharge channel diameter. The corrosion resistance of the coated samples was improved compared with that of substrate, which became more obvious as the working frequency was increased. This could be due to the more compact structure of the alloy formed at higher frequencies.

Current density is a key factor of plasma electrolytic oxidation process. Its influences on structure, mechanical, and tribological characteristics of ceramic coatings on ZK60 Mg alloy by pulsed bipolar microplasma oxidation in Na(3)PO(4) solution were studied in this paper. Thickness, structure, composition, mechanical property, and tribological characteristics of the coatings were studied by eddy current coating thickness gauge, scanning electron microscope (SEM), X-ray diffraction (XRD), nanoindentation measurements, and ball-on-disk friction testing. The results show that all the coatings prepared under different current densities are composed of MgO phase. The amount of MgO phase, thickness and friction coefficient of the coatings increased with the increasing current density. Among three ceramic coatings produced under three current densities, the coating produced under the current density of 7 A/dm(2) got the highest nanohardness and lowest wear rate with the value of 1.7 GPa and 1.27 x 10(-5) mm(3)/Nm.

TiO2 films prepared by micro-arc oxidation on the surface of TA1 titanium mesh are used as the support of catalytic oxidation.The support is characterized by XRD,SEM,BET and other analytical methods.The performance of the support is researched by studying the crystal structure,surface morphology and specific surface area of TiO2 films.The results show that the support met the requirements of the active component because its porous is more than others,the distribution is more evenly,and the surface area is biggest,when the concentration of the electrolyte H2SO4 is 0.6 mol/L,current density is 14 A/dm2,and the reaction time is 5 minutes.

Microporous titanium dioxide films were prepared by the sol-gel methods on glass substrates, using tetrabutyl titanate as source material. In order to absorb the visible light and increase the photocatalytic activities, different concentrations of neodymium ions (Nd/Ti molar ratio was 0.5%, 0.7%, 0.9%, and 1.1% respectively) were added into the sol. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and atom force microscopy (AFM) were applied to characterize the modified films. A kind of typical textile industry pollutant (Rhodamine B) was used to evaluate the photocatalytic activities of the films under visible light. The results showed that the activities of the films were improved by doping Nd ions into the sol.

Current density is a key factor in plasma electrolytic oxidation (PEO) process. The aim of this paper is to study the effects of cathode current density on the composition, morphology, and corrosion resistance of ceramic coatings on ZK60 magnesium alloy prepared through bi-polar plasma electrolytic oxidation in Na3PO4 solution. The phase composition, morphology, and corrosion resistance were studied by X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Electrochemical Impedance Spectroscopy (EIS) and potentiodynamic polarization in 3.5% NaCl solution. It is found that the as-produced coatings are only composed of MgO. The increase of cathode current density made the coatings less porous and more compact. Analysis of EIS and potentiodynamic polarization technique on the samples shows that the corrosion resistance of the coated samples is better than that of ZK60 magnesium alloy, and that a bigger cathode current density can improve the corrosion resistance of as-prepared coatings.