电镀法制备Ni-W合金镀层的耐盐雾腐蚀性能

利用电镀法在N80钢表面制备了Ni-W合金镀层,用SEM、EDS分析了镀层表面与界面形貌以及化学元素的分布,通过XRD测试了镀层物相的组成。在5% NaCl溶液中测试了镀层盐雾腐蚀能力,分析了Ni-W镀层抗盐雾腐蚀机理。试验结果表明,镀层厚度约40m,主相为Ni-W,Ni和W以金属形式存在于镀层中;经过高温热处理后,镀层与基体发生了化学元素扩散现象,形成冶金结合;盐雾腐蚀后镀层表面腐蚀物为Fe的氧化物和氯化物,基体无腐蚀现象发生。     

Q235钢复合涂层腐蚀行为及微观组织研究

为探析舰船常用防护涂层的失效机制,制备了涂有环氧富锌底漆、环氧云铁中间漆和丙烯酸聚氨酯面漆的Q235钢板涂层试样,在盐雾下腐蚀1400h,用扫描电镜和能谱仪对涂层和基体金属表面的微观形貌、界面结构变化,表面缺陷,元素组成进行了研究.试验结果表明：盐雾腐蚀试验后,Q235钢表面涂层厚度增加,试样表面预制划痕处出现腐蚀,腐蚀产物呈片状,微观结构疏松,但涂层与基体在腐蚀后附着良好,涂层有良好的层间附着力,中间层和面层的防渗透性能保持在良好状态.     

X70管线钢热浸渗铝处理后盐雾腐蚀行为

利用热浸渗技术对X70管线钢表面进行了渗铝处理,通过SEM和EDS观察了X70管线钢渗铝处理前后表面微观形貌和化学元素的变化,采用XRD分析了其盐雾腐蚀前后表面物相,研究了渗铝处理对X70管线钢盐雾腐蚀的影响。试验结果表明,盐雾腐蚀后未处理试样表面点蚀较为严重,热浸渗铝处理后试样表层形成一层致密的Al2O3层,有效地阻止了腐蚀性介质Cl-离子和基体活性铁的接触;热浸渗铝后X70管线钢渗铝层组织有多种析出物,其表层黑色物质为FeAl,有效地抑制了表面点蚀的发生;未处理试样表面含铁量高,产生活性铁原子,是盐雾腐蚀发生点蚀主要因素。     

Effect of Salt Spray Corrosion on Tribological Properties of HVOF Sprayed NiCr-Cr_3C_2 Coating with Intermediate Layer

The objective of the present work was to determine the influence of the neutral salt spray corrosion on the wear resistance of HVOF sprayed NiCr-Cr_3C_2 coating with intermediate layer. Ni-Zn-Al_2O_3 coatings as interlayers were prepared by low pressure cold spray(LPCS) between NiCr-Cr_3C_2 cermet coatings to form a sandwich structure to enhance the corrosion resistance properties. The tribological properties were examined using the UMT-3 fricition and wear tester by line-contact reciprocating sliding under dry and salt spray one week corrosion. The morphology, element distribution, and phase compositions of the coating and worn sufaces were analyzed by using scanning electron microscopy, energy dispersive spectrometry, and X-ray diffraction respectively. The corrosion behavior of the coating was studied by the open-circuit potential, the electrochemical impedance spectroscopy, potentiodynamic polarization, and salt spray corrosion methods. It is found that the sandwich structured coating has better corrosion resistance than the single layer coating. The results show that under dry wear conditions, the wear mechanism is abrasive and adhesive wear, whereas under salt spray corrosion conditions it becomes corrosion wear. The friction coefficient of the sandwich structured coating after salt spray corrosion is slightly lower than the dry friction coefficient, but the weight of the wear loss is lower than that under dry condition.     

Effect of salt spray corrosion on tribological properties of HVOF sprayed NiCr-Cr<Subscript>3</Subscript>C<Subscript>2</Subscript> coating with intermediate layer

The objective of the present work was to determine the influence of the neutral salt spray corrosion on the wear resistance of HVOF sprayed NiCr-Cr₃C₂ coating with intermediate layer. Ni-Zn-Al₂O₃ coatings as interlayers were prepared by low pressure cold spray (LPCS) between NiCr-Cr₃C₂ cermet coatings to form a sandwich structure to enhance the corrosion resistance properties. The tribological properties were examined using the UMT-3 fricition and wear tester by line-contact reciprocating sliding under dry and salt spray one week corrosion. The morphology, element distribution, and phase compositions of the coating and worn sufaces were analyzed by using scanning electron microscopy, energy dispersive spectrometry, and X-ray diffraction respectively. The corrosion behavior of the coating was studied by the open-circuit potential, the electrochemical impedance spectroscopy, potentiodynamic polarization, and salt spray corrosion methods. It is found that the sandwich structured coating has better corrosion resistance than the single layer coating. The results show that under dry wear conditions, the wear mechanism is abrasive and adhesive wear, whereas under salt spray corrosion conditions it becomes corrosion wear. The friction coefficient of the sandwich structured coating after salt spray corrosion is slightly lower than the dry friction coefficient, but the weight of the wear loss is lower than that under dry condition.     

Effects of laser heat treatment on salt spray corrosion of 1Cr5Mo heat resistant steel welding joints

The surface of 1Cr5 Mo heat-resistant steel welding joint was processed with CO2 laser, and the corrosion behaviors before and after laser heat treatment(LHT) were investigated in the salt spray corrosion environments. The microstructures, phases, residual stresses and retained austenite content of 1Cr5 Mo steel welding joint before and after LHT were analyzed with optical microscope and X-ray diffraction, respectively. The cracking morphologies and chemical compositions of corrosion products after salt spray corrosion were analyzed with field emission scanning electron microscopy(FESEM) and energy disperse spectroscopy(EDS), respectively, the polarization curves were measured on a PS-268 A type electrochemical workstation, and the mechanism of corrosion resistance by LHT was investigated as well. The results show that the passive film of original sample is destroyed owing to the corrosive media penetrating into the subsurface, resulting in the redox reaction. The content of residual austenite in the surface and the self-corrosion potential are increased by LHT, which is contributed to improving the capability of salt spray corrosion resistance.     

磁控溅射TiCN薄膜对Al-Cu-Mg-Ag合金组织与性能的影响

基于正交试验设计，在铝合金表面磁控溅射沉积TiCN薄膜，采用盐雾腐蚀、电化学腐蚀、硬度测试等探究磁控溅射工艺参数（钛靶功率、碳靶功率、氮氩比）对Al-Cu-Mg-Ag合金硬度与抗腐蚀性能的影响规律，并结合扫描电镜（SEM）、X射线衍射（XRD）等对其机理进行探讨。结果表明：磁控溅射工艺参数对合金的膜层硬度、盐雾最大腐蚀深度、腐蚀电流密度、膜基结合力的影响顺序分别为：氮氩比>C靶功率>Ti靶功率；C靶功率>氮氩比>Ti靶功率；C靶功率>氮氩比>Ti靶功率；Ti靶功率>C靶功率=氮氩比。C靶功率200 W、Ti靶功率100 W、氮氩比为1：40时，可以获得耐蚀性、硬度和膜基结合力综合性能优良的TiCN膜层。     

Mg-9Gd-3Y镁合金PEO-EPD复合膜层组织结构与耐蚀性研究

为了提高镁合金的耐蚀性,本文利用扫描电镜分析了Mg-9Gd-3Y(GW93)镁稀土合金表面等离子电解氧化陶瓷层、等离子电解氧化-电泳复合膜层和电泳膜层的表面与纵截面形貌组织,利用傅立叶红外光谱仪(FT-IR)分析了电泳膜层有机官能团类型,用电化学测试手段和盐雾试验方法测试了该合金不同处理膜层的耐蚀性,讨论了电泳电压和固体粉料分数对等离子电解氧化-电泳复合膜层厚度、成膜速率和耐蚀性的影响.研究结果表明,随着电压、固体份的升高,等离子电解氧化-电泳复合涂层厚度和成膜速率呈增大趋势,腐蚀速率随着电压升高呈先减小后增大的趋势,随着固体份的增加呈降低趋势.电泳电压为70V,固体份为19%时,在等离子电解氧化膜层上生成陶瓷层与有机化合物层结合紧密的等离子电解氧化-电泳复合膜层,腐蚀电流密度比等离子电解氧化膜层降低两个数量级,自腐蚀电位正移200mV,耐蚀性提高近13倍.     

Corrosion resistance of waterborne epoxy coating pigmented by nano-sized aluminium powder on steel

A novel kind of waterborne epoxy coating pigmented by nano-sized aluminium powders on high strength steel was formulated. Several coatings with different pigment volume content (PVC) were prepared. The coating morphology was observed using scanning electron microscopy (SEM), and the electrochemical properties were investigated by electrochemical impedance spectroscopy (EIS). Immersion test and neutral salt spray test were also conducted to investigate the corrosion resistance of the coating. It is demonstrated that the critical pigment volume content (CPVC) value is between 30% and 40%. The coating with PVC of 30% exhibits good corrosion resistance in 3.5% (mass fraction) NaCl solution.     

Corrosion of carbon steel under epoxy-varnish coating studied by scanning Kelvin probe

The corrosion behavior of partly coated carbon steel was investigated by salt spray test and scanning Kelvin probe (SKP) in order to understand the long-term corrosion behavior of coated carbon steel in marine atmosphere environment. The localized corrosion was accurately characterized by SKP in both coated and uncoated regions. The SKP results showed that Volta potential varied with the test time, and the more the corrosion products, the more positive the potential. The borderline between coated and uncoated regions of partly coated steel shifted towards the coated side with the increasing of test time. The coating disbonding rate could be determined according to the shift of potential borderline measured by SKP. The corrosion mechanism of partly coated steel in NaCl salt spray was discussed according to the potential maps and corrosion morphologies.     

40NiCrMo7钢表面锰系磷化膜的制备及耐蚀性

为了满足紧固件在工业中的实际应用,采用不同磷化工艺于40NiCrMo7钢表面制备了锰系磷化膜,并作为紧固件的表面腐蚀防护层.运用扫描电子显微镜、能谱仪、X射线衍射仪、盐雾腐蚀试验机与电化学测试系统对磷化膜的结晶组织、相结构及耐蚀性进行了研究.结果表明,磷化膜的主要相结构为MnHPO_4·2.25H_2O;在工艺Ⅱ条件下,锰系磷化膜组织均匀致密,且覆盖完整;磷化膜的腐蚀速率为0.018 mm/a,同时腐蚀防护率高达97.20%;经240h盐雾腐蚀试验后,磷化膜在工艺Ⅱ条件下的腐蚀面积仅为1%.     

Hot-corrosion mechanism of Ni-Cr coatings at 650°C under different simulated corrosion conditions

The oxidation and lower temperature hot corrosion (LTHC) processes occurring on the surface of Ni-Cr coatings produced by high velocity arc spray (HVAS) were studied. Several different conditions were studied under simulated boiler conditions at 650°C. The protection effect of an Al coating deposited by HVAS onto the Ni-Cr coating was also investigated. Microscope, X-ray diffraction and corrosion rate curves have been used to analyze corrosion mechanisms. The experimental results show that: 1) The oxidation rates are almost superposed in both air (no SO₃) and in simulated coal-fired gas (containing SO₃) as long as no salt was present on the surface. These rate curves show a logarithmic relationship. 2) When the surface is coated with salt (75%K₂SO₃ + 25%Na₂SO₃) the rate curve for LTHC of the Ni-Cr coated surface shows a parabolic shape in the simulated coal-fire flue gas. In air only the oxidation reaction takes place, the second type of LTHC was not seen. And 3) the Al over coating on the Ni-Cr enhances resistance to LTHC because an inter-metallic compound, Al₃Ni₂, forms at the Al/Ni-Cr interface and because of the increase in coating thickness.     

Corrosion mechanism of HVOF silicate glass coating in 5% NaCl solution

On the basis of good anticorrosion capability of silicate glass,silicate glass coating was sprayed by high velocity oxygen fuel (HVOF) and the corrosion mechanism in 5% NaCl solution was studied. Scanning electron microscope (SEM) ,energy dispersive X-ray analysis (EDX) ,X-ray diffraction (XRD) and potentiom- eter were used to study the coating composition and corrosion process. The result shows that silicate glass coating is entirely noncrystallizable. Silicate glass coating has very low incidence of hole with compact structure. Electric double-layer can form at coating/solution interface and corrosive solution performs as a lead connecting the coating surface and substrate after permeating through glass coating. The corrosion mechanism of silicate glass coating is similar to that of glass and the entire corrosion process can be divided into some states. The whole corrosion process happens in glass coating without substrate basically. The fluctuation of the self-corrosion potential about glass coating in corrosion solution can help to research the corrosion process.     

钢铁镀锌层纳米陶瓷转化膜的制备及性能

为了更深入地探讨钢铁镀锌层纳米陶瓷转化膜形成工艺以及对耐蚀性的影响,采用扫描电子显微镜（SEM）观察镀锌层的表面形貌,以及对涂层性能进行测试,结果表明,在镀锌层上形成很完整的纳米陶瓷转化膜;并且在形成纳米转化膜后与涂层具有有良好的结合力与耐腐蚀性能。     

低温烧结活性瓷釉涂层钢筋耐腐蚀性能试验研究

为了研究低温烧结活性瓷釉（LTCRE）涂层的性能和机理,利用差示扫描量热法（DSC）和热重法（TG）对LTCRE涂层的烧结温度进行优化,采用扫描电子显微镜（SEM）、X射线能谱分析（EDS）和X射线衍射（XRD）分析涂层微观结构和腐蚀过程,通过中性盐雾试验和氙灯老化试验研究LTCRE涂层钢筋的耐腐蚀性能. LTCRE涂层的优化烧结温度为500~540 °C,涂层具有结构致密、孔隙率低的特点,LTCRE涂层钢筋在腐蚀后的质量变化为普通钢筋的1.6%,800 h盐雾腐蚀后人为缺陷孔的剥离半径为0.26 mm,在氙灯照射下耐老化时长超过500 h. 结果表明,LTCRE涂层作为无机陶瓷涂层,具有比环氧树脂涂层更优异的耐老化性能,具备长期稳定的耐腐蚀能力. 涂层密实少孔的结构和烧结时良好的化学反应使得LTCRE涂层钢筋能够有效阻止外界腐蚀物质渗入与蔓延,即使在缺陷孔发生腐蚀后也能够阻止腐蚀加剧,起到涂层自愈合的效果.     

Hot-corrosion mechanism of Ni-Cr coatings at 650 ℃ under different simulated corrosion conditions

The oxidation and lower temperature hot corrosion (LTHC) processes occurring on the surface of Ni-Cr coatings pro-duced by high velocity arc spray (HVAS) were studied. Several different conditions were studied under simulated boiler conditions at 650 ℃. The protection effect of an A1 coating deposited by HVAS onto the Ni-Cr coating was also investigated. Microscope,X-ray diffraction and corrosion rate curves have been used to analyze corrosion mechanisms. The experimental results show that: 1)The oxidation rates are almost superposed in both air (no SO3) and in simulated coal-fired gas (containing SO<,3>) as long as no salt was present on the surface. These rate curves show a logarithmic relationship. 2) When the surface is coated with salt (75%K2SO3 25%Na2SO3) the rate curve for LTHC of the Ni-Cr coated surface shows a parabolic shape in the simulated coal-fire flue gas. In air only the oxidation reaction takes place, the second type of LTHC was not seen. And 3) the AI over coating on the Ni-Cr enhances resistance to LTHC because an inter-metallic compound, Al<,3>Ni<,2>, forms at the Al/Ni-Cr interface and because of the increase in coating thickness.     

防锈油对QPQ渗层抗腐蚀性能的影响

针对机械产品在腐蚀环境,尤其是特殊腐蚀条件下易腐蚀的问题,研究表面粗糙度Ra 0.2的非调质态45钢经过QPQ处理并结合使用防锈油后的抗腐蚀性能。利用中性盐雾加速腐蚀,通过光学显微镜、X线衍射仪观察分析,结果表明:QPQ处理后抗腐蚀性增强,主要原因是渗层中形成氧化膜和化合物层;防锈油提高了产品的耐腐蚀能力,主要原因是防锈油中油溶性缓蚀剂作用。经过QPQ处理和防锈油结合使用的试样的耐蚀性得到极大提高,最长抗盐雾腐蚀时间可达432 h,在工业防腐蚀中有很大的应用范围。       

铝合金支撑MFI型分子筛膜的合成及耐蚀性能研究

2024型铝合金被广泛应用在航天航空工业,但其耐蚀性差.为改善这一缺点,用原位水热合成法在2024型铝合金表面合成MFI型分子筛膜.采用SEM/EDS对分子筛膜的表面形貌和元素组成进行表征;研究晶化时间对分子筛膜致密性的影响;研究该分子筛膜在中性NaCl、pH=1.0的NaCl-HCl和pH=13.0的NaCl-NaOH介质中的耐蚀性能.结果表明：晶化16 h在合金表面形成的分子筛膜均匀且致密,耐蚀性最好,腐蚀电流密度为0.241 A/cm2,远小于裸铝合金的腐蚀电流密度57.140 mA/cm2,确定为最佳晶化时间;3种介质比较,在碱性和中性NaCl介质中耐蚀性好,尤其在pH =13.0的NaCl-NaOH溶液中耐蚀性最佳,并且在该介质中分子筛膜能提供对铝合金的长期防护.探讨分子筛膜对铝合金的防护机制.由此得出结论,MFI型纯硅分子筛膜耐蚀性很好,对提高2024型铝合金的耐蚀性具有很好的实用价值.     

Corrosion behaviors of zinc and Zn-Ni alloy compositionally modulated multilayer coatings

Zinc and Zn-Ni alloy compositionally modulated multilayer （CMM） coatings were electrodeposited from dual baths. The coated samples were evaluated in terms of surface appearance, surface and cross-sectional morphologies, as well as corrosion resistance. The results obtained from the salt spray test show that the zinc and Zn-Ni alloy CMM coatings are more corrosion-resistant than the monolithic coatings of zinc or Zn-Ni alloy alone with a similar thickness. The corrosion potential measurement and anodic polarisation tests were undertaken to examine the probable corrosion mechanisms of zinc and Zn-Ni alloy CMM coatings. Analysis on the micrographic features of zinc and Zn-Ni alloy CMM coatings after the corrosion test explains the probable reasons why the Zn-Ni/Zn CMM coatings have a better protective performance. Surface morphologies and compositional analysis of the remaining coating material of Zn-Ni alloy deposit after the corrosion test confirms the dezincification mechanism of the Zn-Ni alloy deposit during the corrosion process.     

Microstructure and corrosion resistance of modified AZ31 magnesium alloy using microarc oxidation combined with electrophoresis process

A top electrophoresis coating was deposited on the surface microarc oxidation (MAO) modified ceramic coating on AZ31 magnesium alloy. Microstructure and corrosion resistance of this composite coating were studied by SEM, electrochemical potentiodynamic polarization, and acid corrosion test. The results showed that the composite coating with a top electrophoresis coating on the surface of ceramic coating exhibited a better corrosion resistance compared with the coating formed by chemical conversion film combined with electrophoresis process. Corrosive ions could permeate into the substrate with corrosion time, and the composite coating was firstly destroyed around the scratch. The formation of composite coating with a higher adhesive force due to the porosity of the ceramic coating contributed to the improved corrosion resistance property.