Electrochemical behavior of organic and inorganic zinc-rich coatings in 3.5% NaCl solution

1　INTRODUCTIONZinc richcoatings (ZRP)havebeenusedformanyyearsinordertoprotectsteeleffectivelyinag gressiveatmospheres ,mainlyinmarineandindustrialenvironments,againstcorrosion .ItiscommonlyacceptedthattwofundamentalprotectionmechanismsoperateinZRP[13] :1)thegalvanicprotectionstage ,whichrequires goodelectricalcontactamongthezincparticlesthemselvesaswellasbetweenthemandthesteelsubstrate ;2 )thebarrier likebehaviorstage ,whichisreinforcedbytheamountandnatureofzinccorrosionproductslead ing…     

富锌漆研究进展

综述了70年来富锌漆的研究与应用的若干进展。对富锌漆的分类、防蚀机理、耐久性、性能特点以及存在的问题和补救措施等，进行了比较全面的评价．简单介绍了用于富锌漆的锌粉的分类和性能特点，此外，还介绍了有关富锌涂层电化学研究的一些进展．     

硅烷偶联剂处理对富锌涂层行为的影响

采用测量涂层的腐蚀电位和电化学阻抗谱(EIS)等方法研究了硅烷偶联剂处理(钢铁表面的硅烷偶联剂预处理和富锌漆中掺入硅烷偶联剂)对富锌涂层在3.5mass%NaCl溶液中腐蚀行为的影响.结果表明,两种硅烷处理方式均明显延长了富锌涂层的阴极保护期.钢铁表面硅烷处理减弱了无机富锌涂层的阴极保护作用.     

Effects of surface modification on electrochemical performance of MnO2

The MnO2 samples coated with Ca（OH）2 were prepared by a liquid-phase surface treatment method. The physical properties of the samples were examined by SEM, EDAX and chemical analysis, and their electrochemical performances were investigated by means of galvanostatic charge-discharge, cyclic voltammetry and electrochemical impedance spectroscopy （EIS）. The SEM results show that the samples coated with Ca（OH）2 display a porous surface structure. The electrochemical experiments indicate that the surface modification decreases the polarization of MnO2 electrodes and improves their discharge potentials and discharge capacities.     

Corrosion protection of cold-rolled steel by zinc-rich epoxy paint coatings loaded with nano-size alumina supported polypyrrole

High porosity and intense galvanic function related low electrolytic barrier profile and fast delamination of zinc-rich paints (ZRPs) are addressed by the utilisation of intimately structured, highly dispersed, polypyrrole (PPy) deposited alumina particles (PDAPs) embedded zinc-rich hybrid paints. The more globular but less-packed structure type PPy-contained water-solvent-prepared PDAPs-composited hybrids comprising spherical zinc pigment at 70 wt.%, provided moderate galvanic function with enhanced electrolytic barrier properties. In addition, the less globular structured but well-packed PPy-comprised aqueous ethanol-solvent-prepared PDAPs-composited hybrid coatings indicated highly efficient suppressed galvanic function and improved barrier properties, realising solid performance improvement over conventional ZRPs in immersion and salt-spray chamber tests. Furthermore, the application of highly dispersed PDAPs at a content of 3.2 wt.% while PPy incorporated into zinc-rich hybrids at 0.16 wt.% is proposed to result in emerging additional functionalities increasing long-term anticorrosive performance of ZRPs by inhibiting sacrificial and self-corrosion of zinc and scavenging oxidative radicals thereby hindering oxidative degradation of the organic binder.     

基体表面粗糙度对镀硬铬层零件镜面抛光的影响

机械电解镜面抛磨镀硬铬层轴类零件时，通常从电、液参数以及工件、工具转速等着手，优选出最佳参数。但从实验中发现，零件基体表面粗糙度对抛光效果有着非常重要的影响，甚至决定抛光的成败。通过大量的对比试验和观察发现：零件基体表面粗糙度越小，抛光效果越好；反之，则差。     

Influence of the Pigment Shape on the Electrochemical Behaviors of Zinc—Rich Paint Coatings in 3.5% NaCl Solution

针对粘合剂种类、Zn粒形状和涂层厚度的协同作用,采用电化学阻抗谱(EIS)研究了富Zn涂层在3．5％NaCl溶液中的电化学行为．富Zn涂层的EIS谱有两个时间常数,其中,锌的电子转移反应发生在低频段,而高频段则体现聚合物和Zn表面氧化层的介电性质．根据等效电路及其元件参数解释了钢铁／富Zn涂层／盐水体系的EIS测量结果．实验结果表明,鳞片锌消耗速度太快以至于鳞片富Zn涂层在相对较短的时间内就失去了阴极保护作用,随后形成了稍微致密的屏蔽阻挡层。     

涂料中含铬量对烧结式富锌涂层性能的影响

以片状锌粉和铝粉为原材料 ,研究了涂料中铬酐含量对烧结式富锌涂层性能的影响。结果表明 :涂料中的铬酐含量决定涂层中金属粉的粘结情况 ,铬酐含量过高 ,涂层局部爆皮 ;铬酐含量过低 ,涂层粉化。在得到粘结性好的涂层范围内 ,铬含量越高 ,涂层耐蚀性越好。     

Investigation on the effect of various surface preparations on corrosion performance of powder coated steel by EIS

Powder coating systems have been considered for different purposes since they have many advantages in use. The performance of the different powder coating systems needs to be examined by various methods. In this paper, a polyester powder coating was applied on various pretreated mild steel panels. Electrochemical Impedance Spectroscopy (EIS) measurements were used to study the durability of the coating on pretreated mild steels upon immersion in 3.5% w/w NaCl solution at ambient temperature for 7 and 50 days. Various elements of the equivalent circuit are proposed for the different metal/coating systems. The lowest coating and double layer capacitances were measured for acid pickled followed by phosphating pretreated steel panel while the coating and charge transfer resistance were the highest for this system. It revealed an improvement of coating durability on the substrate by phosphating pretreatment. This can be attributed to decreasing ingress of water, dissolved oxygen and ions into the coating.     

高速铣削表面粗糙度的研究

通过在HSM－700型高速铣床上的正交铣削试验，联系平时实际的生产加工情况，分析高速铣削的切削加工参数对零件表面粗糙度的影响。通过分析不同铣削参数下的零件表面粗糙度和切屑变形，为高速加工切削参数的选择和表面质量的控制提供依据。     

Effect of substrate surface roughness on the adherence of NiCrAlY thermal spray coatings

The adherence of plasma sprayed NiCrAlY bond coats can be improved by an appropriate substrate surface finish. The interface fracture energy for crack propagation along the coating/substrate interface has been measured for different surface roughness by means of a specially designed four-point bending test. An increase of the interface fracture energy of about 15% was observed for a three times higher surface roughness. In addition, four-point bending tests with the coating on the side face of bending specimens were performed to analyze the fracture and spalling behavior of the coatings both under large tensile and compressive substrate deformations.     

Ga和Bi对Al-Zn-Sn牺牲阳极电化学性能的影响(英文)

通过光学显微镜(OM)、扫描电镜(SEM)、能谱分析(EDAX)和电化学性能测试等方法,研究了Ga和Bi对Al-7Zn-0.1Sn(质量分数,%)牺牲阳极微观组织和电化学性能的影响。Al-Zn-Sn合金加入Ga和Bi元素后,合金组织由粗大枝晶转变为等轴晶,仅剩下少量枝晶。Al-7Zn-0.1Sn-0.015Ga-0.1Bi合金具有高的电流效率(97%)和均匀的腐蚀形貌,表明添加适量的Ga和Bi元素能有效改善Al-Zn-Sn合金的组织和电化学性能。     

NiCrAlY涂层的表面状态对高温氧化行为的影响

将原始喷涂态和表面抛光的NiCrAlY涂层在1050℃恒温氧化300h，利用XRD、SEM，EDS方法，测定涂层的氧化物及其相转变，分析表面氧化膜的生长破坏行为，结果表明：两种涂层在1050℃保温，在150h以内均能生成α-Al2O3氧化膜，150h后，抛光态涂层保护性氧化膜被破坏，抗氧化能力下降，喷涂态涂层表面粗糙，连续Al2O3保护膜的形成较晚，氧化早期氧化膜中存在微裂纹，可释放应力，有利于氧化膜与涂层的结合。氧化动力学曲线符合抛物线规律，氧化至300h，表面氧化膜只有少量微裂纹，无剥落，说明喷涂涂层的长期恒温抗氧化能力比抛光态涂层强。     

Influence of surface roughness of PVD coatings on tribological performance in sliding contacts

The influence of surface roughness on the tribological performance, i.e. friction, wear and material pick-up tendency, of two different commercial PVD coatings, TiN and WC/C, in sliding contact with ball bearing steel has been evaluated using two different types of sliding wear laboratory tests. Post-test characterisation using SEM/EDS, AES, ToF-SIMS and XPS was used to evaluate the prevailing friction and wear. The results show that the surface roughness of the coating is of importance in order to control the initial material pick-up tendency and thus the friction characteristics in a sliding contact. Once initiated, the material pick-up tendency will increase, generating a tribofilm at the sliding interface. For steel-TiN sliding couples a FeO-based tribofilm is generated on the two surfaces and FeO/FeO becomes the sliding interface (interfilm sliding) resulting in a high friction coefficient. For steel-WC/C sliding couples the WC/C displays a pronounced running-in behaviour which generates a WO₃-based tribofilm on the steel surface while a carbon rich surface layer is formed on the WC/C surface, i.e. WO₃/C becomes the sliding interface (interface sliding) resulting in a low friction coefficient.     

Influence of surface roughness on the flattening of powder particles during thermal spraying

The time evolution of the splat thickness, radius, and rate characteristics in the process of flattening of droplets during thermal spraying is investigated taking into account the surface roughness, splat solidification, and mass loss of the droplet liquid phase. Analytical formulas describing the final values of the splat thickness, radius, and rate characteristics are found. Results agree well with the experimental data. They can be used to predict the splat flattening parameters.     

Visual comparators of propeller surface roughness

Visualization has played an effective role in supporting many engineering applications. In this paper, standard reference surfaces taken from actual propellers were measured using a surface profiling system. The measurement data were then preprocessed and exported to a graphics workstation. For each sample surface, points were selected and input into a geometric modeling and interrogation system, PRAXITELES. These points were then approximated by a non-uniform rational B-spline (NURBS) which is the standard format for representing surfaces in modem geometric modeling systems. The surfaces were visualized and can be used as standard visual comparators to assess the roughness of measured manufactured and in-service propeller surfaces.     

激光低速切割对热影响区宽度和表面粗糙度的影响

设计AISI 316L不锈钢激光低速切割实验,研究在较低切割速度条件下,切割表面热影响区宽度和表面粗糙度的变化规律,提出适用于生产制造的激光切割工艺参数。研究发现:切割速度对表面粗糙度、热影响区宽度和表面宏观缺陷有显著影响;随着切割速度的降低,热影响区宽度随之增加;如果对切割表面的表面质量要求不高,且不再对切割表面进行再加工,建议采用最大切割速度;如果对表面质量要求高于对热影响区宽度的要求,则建议采用低于最大切割速度的切割速度。     

多道富锌基涂层在NaCl溶液中的电化学行为研究

多道富锌基涂层的电化学行为研究表明,涂层中的Zn粉未表现出明显的阴极保护作用,即使在富锌涂层上覆盖几个微米厚的环氧清漆涂层, Zn的阴极保护作用也会变得非常微弱. Zn粉对钢铁的保护作用在于Zn粉腐蚀产物对涂层的“自修复能力”.在环氧清漆覆盖条件下,无机富锌涂层中Zn粉的反应活性比有机富锌涂层中Zn粉的高,即Zn粉的反应速度更快.     

金刚石砂轮磨削铁氧体的表面粗糙度与形貌分析

本文研究了树脂结合剂金刚石砂轮磨削铁氧体材料时,磨削深度、工件进给速度对磨削表面粗糙度和材料去除方式的影响规律,以此探索提高铁氧体磨削表面质量的有效途径。采用单因素法设计试验方案对铁氧体进行磨削,测量表面粗糙度数据并对其进行方差分析,对铁氧体磨削表面形貌进行观察。结果表明：随着磨削深度、工件进给速度的增加,表面粗糙度值升高,同时表面塑性痕迹减少,脆性断裂痕迹增加,且磨削深度对表面粗糙度的影响要比工件进给速度的更显著,因此,制定磨削工艺时,考虑到粗磨为了提高效率,降低表面损伤,优化得到磨削工艺为磨削深度5μm,工件进给速度10 m/min;精磨为了获得较低的表面粗糙度,采用磨削深度5μm、工件进给速度为5 m/min,可以提高磨削表面延展性。