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。     

30Cr2Ni4MoV合金的抗盐雾腐蚀性能

为了解舰船常用铁基材料30Cr2Ni4MoV的盐雾腐蚀行为和腐蚀机理,对该合金在盐雾腐蚀下不同时间试样的表面和截面形貌以及腐蚀产物的组成、盐雾腐蚀的失重速率和腐蚀速率进行研究.结果表明:30Cr2Ni4MoV腐蚀400 h后,试样表面均布满腐蚀产物,主要腐蚀产物是FeO(OH),腐蚀产物与基体出现了脱离现象;腐蚀由腐蚀坑开始逐渐扩展,腐蚀面趋于基本一致后出现新的腐蚀坑,继续腐蚀;在最初的100h,腐蚀速率变化剧烈.     

7050铝合金盐雾腐蚀疲劳性能的研究

为了研究7050铝合金盐雾腐蚀后的疲劳性能,以不同表面处理和装配方式对7050铝合金进行了盐雾腐蚀试验,测试其疲劳寿命,采用DFR法和统计学中T检验法和F检验法分析处理所得疲劳寿命数据,利用光学显微镜和扫描电镜手段研究了盐雾腐蚀深度、断口形貌等腐蚀特征.研究结果表明:7050铝合金盐雾腐蚀试样的疲劳寿命显著降低,疲劳裂纹在腐蚀点处萌生;不同表面处理状态的7050铝合金与TC18接触时,不涂胶和不涂漆的腐蚀最为严重;7050铝合金阳极化后涂漆和涂胶是保护材料的有效措施.     

离子镀铝的钛合金紧固件的耐蚀性能研究

研究了离子底铝的钛合金紧固件的孔隙率、耐盐雾腐蚀性能和电偶腐蚀性能给出了孔隙率的大小与铝镀层晶粒尺寸和厚度间的关系，铝镀层在两种不同表面状态下的耐盐雾腐蚀性能和电偶腐蚀试验结果。     

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%.     

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.     

热浸镀锌层在中性盐雾试验中的防腐性能研究

采用2种定制的热浸镀锌试件,经5000 h中性盐雾试验后发现镀层防腐性能存在显著差异.采用镀锌层厚度损耗测试法、X射线衍射分析法（XRD）和扫描电镜分析法（SEM）分别测试了镀层的厚度损耗量、盐雾试验前后的晶体物质组成和腐蚀前后的微观形貌.研究表明:2种热浸镀锌试件在盐雾腐蚀过程中的产物和机理相似,而影响其防腐性能的主要因素为热浸镀锌的生产工艺、腐蚀产物的致密程度.     

激光辐照镀铬钢合金化工艺与性能研究

用大功率ＣＯ２激光器对镀铬３０ＣｒＭｎＳｉ钢表面连续搭接式辐照处理，达到了在高含铬量的合金层和镀层与基体界面间获得高含铬量熔渗层两种不同的冶金效果，并实现镀层与基体间冶金结合，对此研究辐照前后耐磨性、阳极极化特性以及盐雾条件下的腐蚀行为。结果表明：激光辐照后耐磨性提高近一倍；激光合金化层耐蚀性明显提高；而熔渗工艺条件的电化学特性与原镀层相当，但原镀层穴蚀和龟裂的倾向得到克服，结合强度得到提高。     

硫脲对Ni-P镀层腐蚀行为的影响

在镀液中添加硫脲,分析了硫脲对Ni-P镀层沉积速度、表面形貌、孔隙率等的影响,并通过极化曲线和交流阻抗测试了硫脲对Ni-P镀层腐蚀性的影响。结果表明,当镀液中添加1 mg/L硫脲时,镀层的沉积速率加快,腐蚀速率增大。这主要是因为镀液添加硫脲后,镀层的孔隙率加大,促进了腐蚀介质渗入到基体表面,增加了腐蚀微电池的数量,形成了大阴极(镀层)-小阳极（基体）腐蚀微电池,使自腐蚀电流密度增大,电荷转移电阻减小。当镀液中添加硫脲质量浓度大于3 mg/L时,镀液被毒化,无法施镀。     

热阴极离子镀技术制备特种硬质薄膜及性能研究

采用热阴极离子镀技术在YG6基体上制备了CrNx薄膜,利用X射线衍射方法、划痕试验、扫描电镜观察对所制备的试样进行了物相、结构分析和性能测试。结果表明：热阴极离子镀技术能够制备出CrNx薄膜;膜一基结合强度好;膜层呈致密的柱状晶;5号试样性能最佳。参考5号试样工艺在模具表面镀CrNx薄膜,将镀层与未镀层的模具做加工试验对比,镀层后能显著提高模具的寿命。     

The surface morphologies and spectroscopy analysis of VC coatings on the substrate of Cr12MoV prepared by TD process after salt spray

The normal temperature corrosion of VC coating on the substrate of Cr12MoV prepared by TD process was tested in 5% NaCl aqueous solution, its surface morphologies and corrosion components after salt spray were observed with SEM and EDS, respectively, and the effects of salt spray on micro-structures of VC coating were analyzed. Moreover, the invalidation mechanism of VC coating after salt spray and its effect on substrate material were discussed. The experimental results shown that the uniformity and integrity of VC coating surface are destroyed by salt spray for 120 h, a large number of the pits are produced on the coating surface, and the coating falls off, which speeds corrosion breakage of its substrate; the oxidated film on its surface becomes rougher, broken and discontinuous, and falls off easily, which reduce the ability of resistance salt spray; the failure modes of VC coating after salt spray are expressed with falling off of oxidated film, stress concentration and pore effect and so on, the corrosion breakage of oxidated film is the corrosion result of deoxidization corrosion from oxygen and HCl produced by NaCl and vapor.     

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.     

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.     

复层牺牲用极的研制及其抗蚀特性

本文研制了一种新型的复层牺牲阳极,其构成是钢表面氮碳共渗形成的ε相层为内层覆以电位较低的化学镀Ni-P合金为外层。金相和SEM电镜分析表明,ε-相层表面经过合适的活化后的化学镀Ni-P合金层不仅结构致密,而且二者界面呈牢固的锯齿状结合。标准盐雾和醋酸浸泡试验证明,由于这种复层充分发挥了二者硬度高,耐蚀抗磨性能好的特点,同时避免了ε相层表面疏松、Ni-P化学镀层存在针孔的缺点,因此其抗蚀性十倍甚至百倍的优于单一的ε相层或Ni-P化学镀层。     

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.     

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.     

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.