Preparation and characterization of Ni-Cu-P/CNTs quaternary electroless composite coating

Ni-Cu-P/carbon nanotubes (CNTs) quaternary composite coatings were successfully obtained on low carbon steel matrix by electroless plating. The effects of CNTs concentration in the bath on the microstructure of the composite coatings, CNTs content in the composite coatings and the hardness of composite coatings before and after heat treatment at 400 °C have been studied. In addition, the corrosion resistance of Ni-Cu-P/CNTs composite coatings was evaluated by anodic polarization curves in 3.5 wt.% NaCl solution at room temperature. It was noted that the CNTs concentration remarkably influenced the surface morphology of the coatings. With increasing CNTs concentration, both the CNTs content in the composite coatings and the hardness of composite coatings increased at first and then decreased. And the composite coatings after heat treatment provided higher hardness than the as-deposited coatings. The corrosion resistance of Ni-Cu-P/CNTs composite coatings is excellent compared with that of Ni-Cu-P coatings.     

NdFeB磁性基材化学镀Ni-Cu-P初期形核过程及机赦

为了弄清NdFeB磁性材料表面化学镀Ni-Cu-P合金初期形核过程及机制,研究了不同时间化学镀Ni-Cu-P合金层初期形核过程、形貌和组织结构特征。结果表明：初期沉积过程具有明显的择优倾向和不均匀性：Ni和Cu原子并非以单个原子的形式沉积于基体表面,而是还原后在固．液界面处形成原子团在基体表面高能量区域优先沉积形核,然...     

Ni-Cu-P化学镀层的腐蚀行为

为了进一步提高Ni-P镀层的耐蚀性能,在Ni-P化学镀液中加入硫酸铜制备了Ni-Cu-P三元合金化学镀层,测试了镀层的沉积速度,采用扫描电镜(SEM)观察了镀层的表面形貌,测试了镀层在5.0%H2SO4,5.0%NaOH及3.5%NaCl溶液中的动电位极化曲线,并与Ni-P化学镀层进行了比较。结果表明:Ni-Cu-P镀层表面的胞状物比Ni-P镀层的更加细小,镀层致密性更好;Ni-Cu-P镀层在3种介质中均表现出更好的耐均匀腐蚀性和抗点蚀性能,主要是因为Ni-Cu-P镀层的非晶态结构减少了镀层缺陷数量,从而减少了腐蚀发生的敏感位置和腐蚀微电池的数量,同时更加细小的晶粒也使Ni-Cu-P镀层比Ni-P镀层更容易钝化和维持钝态,另外Ni-Cu-P镀层更为致密也减少了腐蚀介质渗入基体的通道。     

Cu对铝基化学镀Ni-Cu-P镀层耐蚀性能的影响

采用直接镀工艺,在铝基体上获得了化学镀N-P、Ni-Cu-P各种结构镀层.用X射线衍射分析了镀层结构;用SEM观察了各种结构镀层的表面形貌;测定了各种结构镀层的镀速和结合力;利用线性极化和阳极极化曲线分析了各种结构镀层的耐蚀性能.结果表明,利用直接化学镀工艺可以在铝基上获得结合力良好的镀层;通过控制络合剂的用量可以得到不同结构和不同铜含量的Ni-Cu-P镀层;当镀层达到一定厚度后,Cu元素可以显著提高镀层的耐蚀性能.     

脉冲电镀铁中平均电流密度对镀层的影响

应用现代脉冲电镀技术,分别在钢和铜基体上电镀铁层,以期获得性能优良的镀层.研究了平均电流密度对铁镀层的沉积速度、外貌、显微硬度和显微结构的影响.结果显示:随着平均电流密度的增加,铁镀层外貌先变好后变差;脉冲电沉积速度加快,以16 A/dm2的沉积效率最高;不同条件下的镀层显微硬度呈近似的"正态分布"关系;铁镀层的显微结构为立方晶型,有明显的择优取向.     

Ni-Cu-P化学镀层的制备及其耐烟气冷凝液的腐蚀性能

为了解决冷凝式燃气利用设备的腐蚀问题,采用化学镀工艺在紫铜基体上沉积Ni-Cu-P层.利用扫描电镜(SEM)、电子能谱(EDX)、电子探针(EPMA)分析镀层的形貌和成分,利用极化曲线和交流阻抗谱考察了紫铜基材及其Ni-Cu-P镀层在15℃和60℃煤气烟气冷凝液中的耐腐蚀性能.结果表明:Ni-Cu-P化学镀层表面均匀平...     

Morphological and structural characterisation of electrodeposited Zn–Mn alloys from acidic chloride bath

Zn–Mn coatings were electrodeposited on steel substrate from an acidic chloride bath containing a commercial additive used in zinc plating. The effects of deposition parameters such as stirring, applied current density or potential and temperature on the coating composition, microstructure and crystallography were investigated. It was found that this additive permits to obtain dense, compact and thick Zn–Mn coatings. The morphology is quite particular, displaying hexagonal pyramids whatever the manganese content of the coating. This morphology is associated with the main phase found in the coatings that is the HCP -Zn–Mn. The manganese content reaches a maximum value of 20 wt.% corresponding to a monophasic coating. Stirring of the solution has no influence on the composition of the coatings but induces essentially an improvement of the surface appearance as brightness increases and roughness decreases. The increase of the temperature also leads to an enhancement of the surface appearance but induces a decrease of the manganese content.     

物理气相沉积TiN复合涂层研究进展

物理气相沉积 (PVD) Ti N涂层已获广泛应用。为克服单一 Ti N涂层的缺陷及进一步改善 Ti N涂层的性能 ,近年来致力于复合涂层的研究。本文综述了 Ti N+ Ti、Ti N+化学镀 Ni-P、Ti N+氮化等复合涂层的工艺、组织和性能之间的关系 ,并探讨了过渡层的作用。     

Compositional and structural control in bone regenerative coatings

The development of a low-temperature method of producing bioactive coatings for medical implants has been shown to bypass the problems associated with high temperature processing routes, in particular the appearance of amorphous phases and non-stoichiometric hydroxyapatite (HA), and delamination of the coating from the substrate. An electric field/aqueous solution technique for producing adherent, crack-free calcium phosphate coatings on titanium and stainless steel substrates is described. The characteristics of the coating are a function of electrode spacing, supersaturation, temperature and current and voltage conditions. Scanning electron microscopy (SEM) characterized the surface morphology of the coatings, which were shown to be HA. The possibility of producing a coating of carbonate-substituted HA having the same chemical composition as bone apatite, and forming at physiological temperatures, has also been demonstrated. The size of the microstructure decreased and the morphology changed as the carbonate ion concentration in the calcium and phosphate ion solution increased. © 1999 Kluwer Academic Publishers     

Coatings with graded-reflectance profile: conventional and unconventional characteristics

The main feature of graded optical coatings is a spatial reflectance profile that displays a maximum value at the coating center and goes toward a minimum along the radius according to a predefined law. A number of other requirements for using graded coatings in the laser field have been added to this basic property during the course of time. After a survey of the conventional properties of graded coatings, these additional characteristics are described, and their influence on the coating design and performance is examined.     

Optical coatings for deuterium fluoride chemical laser systems

The high-power laser system has brought an interesting challenge to the development of optical coatings. A wide variety of coating specifications that are often contradictory have to be fulfilled. The choices of deposition process as well as coating materials are critical to coating loss, damage threshold, long-term stability, and other optical properties. A number of optical coatings being newly applied to deuterium fluoride laser systems are presented. The 3.8-mum laser reflection coatings with high damage threshold, multichromatic beam splitters, antireflection coatings with widely separated dual-wavelength bands, and 0.55-14-mum wide-band reflective coatings have been developed on substrates such as Si, Mo, fused silica, chemical vapor deposition ZnSe. Superior results have been obtained with ion-assisted deposition and electron-beam evaporation. Approaches to coating design and practical aspects of coating development are also discussed.     

An investigation into the mechanical and tribological properties of plasma electrolytic oxidation and hard-anodized coatings on 6082 aluminum alloy

A ceramic coating on AA6082 aluminum alloy prepared by plasma electrolytic oxidation (PEO) has been studied and compared against a sulphuric acid hard-anodized coating on the same alloy. Surface morphology and microstructures of the coatings have been examined by scanning electron microscopy. X-ray diffraction is used to determine the phase composition of the coatings. The adhesion strength of the coatings has been evaluated using a scratch test method. The coating's mechanical properties such elastic modulus and hardness data have been generated using a dynamic ultra-microhardness tester. Sliding wear tests with different loading rates are performed on the coatings in order to assess their wear resistance. Test results show that the PEO treated samples exhibit significantly better mechanical properties compared to hard anodized samples. The elastic modulus and hardness of the PEO coating are 2-3 times greater than of the hard anodized coating and subsequently, an improved wear resistance of the PEO coating has been achieved. The mechanical properties of the coatings and their relations to their tribological performance are discussed.     

AZ91D镁合金Ni-Cu-P/纳米TiO_2化学镀层的抗菌性能

为了探究化学复合镀Ni-P层的抗菌性能,对AZ91D镁合金进行了Ni-Cu-P/纳米TiO2化学复合镀,制备出了具有光催化性能及优异抗菌性能的镀层.利用扫描电镜和x射线衍射技术对镀层进行了分析,并对镀层进行了紫外光照射.结果表明:TiO2粉末与复合镀层使甲基橙的脱色率均为12.5%;镀液中TiO2含量为4 g/L时抗菌性能达99.70%,其余含量时抗菌率均达到95.00%以上.     

Improved Langmuir probe surface coatings for the Cassini satellite

A Langmuir probe will be used on the space research satellite Cassini in order to monitor electron density fluctuations in space plasmas surrounding Saturn. In order to obtain well-defined Langmuir probe characteristics a surface with uniform work function Φ must be used. A graphite coating has been used on earlier earth-bound satellite probes, but for the Cassini satellite to Saturn a hard, wear-resistant coating must be used. In this contribution we report on investigations of titanium nitride (TiN) coatings for this purpose. TiN coatings have been prepared by high temperature nitriding in pure nitrogen gas and by reactive magnetron sputtering on plane titanium and titanium alloy substrates. The resulting coatings have been analysed with laterally resolved, relative Φ measurements, and the tribological properties of the coatings have been investigated by solid particle erosion and scratch testing. In the tests, the graphite coating DAG 213 used on earlier satellite probes was used as a reference material. The results show that the TiN coatings are superior to the graphite coating with regard to both photoelectric properties and solid particle impact resistance. The sputtered coatings exhibit the lowest lateral work function variation, but the nitrided coatings have superior erosion resistance. The results demonstrate that TiN coatings are suitable for space plasma probes.     

铝合金3种前处理方式的电泳漆膜耐腐蚀性能探讨

为了选择汽车车身用铝合金合适的涂装工艺,介绍了5182、6016铝合金板材经3种不同前处理方式的工艺要求和皮膜质量控制。采用SEM、XRD等手段比较了2种铝合金板材分别经3种前处理方式的皮膜膜重、外观形貌等特征,并对高泳透力阴极电泳面漆的防腐蚀配套性能进行了研究。结果表明:3种前处理皮膜均符合涂装技术要求,对应的电泳漆膜的力学性能符合技术要求,为选择铝合金涂装工艺及其耐蚀性能提供了参考。     

新型聚苯硫醚复合涂层的制备和性能研究

用浸涂法制备了G/MoS2/Ekonol/PES/PPS多元复合涂层,以涂层结合强度为评价标准,采用混料回归实验优化设计了G/MoS2/Ekonol/PES/PPS复合涂层的涂料配方,用拉开法测定复合涂层的结合强度,并对结合表面进行了观察和分析,研究了涂料组成、涂层制备工艺参数和涂层厚度对涂层结合强度的影响。结果表明,用浸涂法能制得力学性能优良的G/MoS2/Ekonol/PES/PPS复合涂层;采用典型配方Ekonol:PES:PPS:G/MoS2:助剂=25:20:45:8:2(质量比)能够得到较大的结合强度。     

In vitro testing of plasma-sprayed hydroxyapatite coatings

Hydroxyapatite-coated coupons were tested in various physiological media. Immersion in Ringer's solution showed that heat-treated coatings displayed a weight gain but the assprayed coatings underwent a weight loss. Dissolution of the coating was measured by weighing the specimen before and after ageing. Immersion of hydroxyapatite coatings showed the appearance of small spheres that were identified by X-ray diffraction as hydroxyapatite. Changes in coating morphology were detected and the coating degradation mechanisms are discussed. This paper thus looks at the morphology, composition, crystallinity and dissolution of hydroxyapatite coatings aged in Ringer's solution.     

锌-铁系蓝色磷化工艺参数对膜外观及耐蚀性能的影响

为了提高磷化膜的装饰效果,替代钢铁室温发蓝工艺,开发了一种能在室温下获得蓝色磷化膜的磷化工艺。用目测法和硫酸铜点滴试验研究了溶液pH值、温度、磷化时间等因素对磷化膜外观和耐蚀性的影响;用电化学法考察了蓝色磷化膜在3.5%NaCl溶液中的电化学行为,分别采用扫描电镜(SEM)和能谱仪(EDS)观察分析了蓝色磷化膜的微观形貌和组成成分。结果表明:在pH值2.5～3.0,温度23～31℃,时间15min条件下所获蓝色磷化膜有较好的耐蚀性,其耐硫酸铜点滴时间56s;能使Q235钢基体自腐蚀电位提高0.3V,并且使基体由阳极活性溶解态转变成钝化态。     

热浸镀锌合金镀层的研究进展

热浸镀锌液中添加合金元素,将对镀层厚度、显微组织、耐蚀性和外观质量等产生重要的影响.重点介绍了含有镍、镬、钛、锰、铋的5种合金镀层技术,探讨了这几种合金元素对热浸镀层组织、性能的影响,并展望了其前景.     

Hardness and indentation-induced damage of SiC-coated graphite

The hardness and indentation damage of chemical vapour-deposited SiC coating/graphite substrate composites have been studied. Experimental results indicate that hardness is a non-linear function of coating thickness, and is not significantly affected by the changes in the magnitude of the residual stresses in SiC coating. The size of indentation lateral crack, observed using optical microscopy, varies with coating thickness. Acoustic emission spectra show that thinner coatings suffer more extensive fracture as compared with thicker coatings.