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Molybdate-based conversion coating solutions have been examined as to their suitability as possible replacements for chromate formulations on electrodeposited zinc-nickel alloy coatings. Investigations have concentrated on producing passive surfaces from simple molybdate solutions using immersion or cathodic coating processes. Passivated surfaces have been examined using scanning electron microscopy to elucidate the coating morphology. The corrosion resistance of the treated surfaces has been assessed using simple, rapid electrochemical techniques as well as more long term salt fog immersion. Initial findings indicate molybdate-based treatment solutions improve times to white and red rust of the zinc-nickel surfaces, but as yet are surpassed by a more conventional chromate-based treatment. 相似文献
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目的更好地开展镁合金防腐蚀研究,提高其耐蚀性。方法利用电化学法制备镁合金磷化膜,通过单因素条件实验研究电流密度、温度以及时间对反应过程的影响,得出制备最佳方案。通过X荧光光谱仪(EDX)、X射线衍射仪(XRD)及电化学测试等现代检测技术对镁合金电化学膜微观结构、沉积速率等进行测试,得出制备的转化膜组成成分的定性及半定量分析结果,以此推断镁合金电化学转化膜的生成机理。结果电化学法制备镁合金磷化膜的最佳工艺条件为:电流密度0.5 A/dm2,温度30℃,反应时间5 min。EDX分析结果显示,磷化膜主要成分为Mg、P、Zn,其质量分数分别为11.017%、2.105%、28.534%。结论电化学转化膜的主要化学成分为Mg、P、Zn,还有少量其他成分,如Al、S、Ca、Mn、Ni、Cu。腐蚀机理复杂,不确定性较大。镁合金磷化膜主要由结晶型磷化锌、磷化铝、锌镁金属磷化夹杂物和单质Zn组成,并且还有少量的其他化合物。 相似文献
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以硫酸盐为主盐,研究了工艺参数中温度、电流密度对Fe-Cr-Ni镀层沉积速率和腐蚀性能的影响。采用电化学试验方法研究不同条件下所获得的镀层在NaCl溶液中的腐蚀行为,结果表明,在饱和NaCl溶液中镀层都有钝化性能。60℃下获得的镀层有明显过钝化现象,抗腐蚀性能较差。不同电流密度下的镀层显示了不同的电化学性能。电流密度为5 A/dm2时,处于钝态时,电流随着电位的正移逐渐增大是一个非常缓慢的过程,钝化膜仍然发挥作用。在饱和NaCl溶液中,电流密度为5 A/dm2时所获得的镀层的耐蚀性能较好。 相似文献
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电镀 Cu-W-Ni 合金的热力学分析 总被引:1,自引:1,他引:1
借助25℃下的Cu-H2O,Ni-H2O和W-H2O的E-pH图,说明了电镀Cu,W,Ni的可能性及范围,并重点分析了电镀Cu-W-Ni合金的可能性。Cu-Ni能在Cu-H2O与Ni-H2O系E-pH图叠合形成的共沉积区里析出。因Cu-H2O与W-H2O系的E-pH图叠合时无法形成Cu-W的共沉积区,Cu-W不能在其对应离子的水溶液中析出,但Ni-W能在Ni2+,WO42-水溶液里诱导共沉积。理论和实验证明,在含Cu2+,Ni2+,WO42-的水溶液中能电镀制备Cu-W-Ni合金。 相似文献
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GUO Zhong-cheng XII Rui-dong WANG Ji-kun l.The Centre of New Materials Surface Engineering Research & Development Kunming University of Science Technology Kunming .Yunnan Metallurgy Group Company Kunming P.R.China 《材料热处理学报》2004,25(5)
SO far,the electrodeposition and electrocrystallizationof single metal has not been known very well,and theresearch into the regularity and theory of co-depositionof two or more metals is more difficult.At present,theresearch and application of alloy electrodeposition areconfined to binary alloys and a few of ternary alloys.The co-deposition conditions may be summarized asfollows:first,at least one of the two metals is an alloycan be deposited individually from the aqueoussolution;and then the… 相似文献
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电沉积RE-Ni-W-P-SiC-PTFE非晶态复合材料的组织及结构 总被引:2,自引:1,他引:2
在碳钢表面进行了RE-Ni-W-P-SiC-PTFE(聚四氟乙烯)非晶态复合材料镀层的电沉积试验,研究了镀液的pH值、电流密度和热处理温度等因素对镀层的组织和相结构的影响,确定了电沉积工艺的最佳条件。结果表明,镀态镀层以非晶态的形态存在,随着热处理温度的升高,镀层逐渐向晶态转变,Ni3P相的衍射峰逐渐加强;在低于400℃时,镀层中含有PTFE相,在400%以上时,PTFE相已不存在,同时镀层中出现了W3O、NiO及(FeNi)相;500%时镀层已完全晶化,此时的物相组成与400%相近,只是W3O相被WO2代替。 相似文献
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Züliyet. Adigüzel Mustafa Anik 《Protection of Metals and Physical Chemistry of Surfaces》2018,54(2):316-324
Nickel (Ni)–Tungsten (W) alloys were electrodeposited galvanostatically (at–10 mA cm–2) on copper substrate with 3 different W contents under the controlled hydrodynamic conditions and then the anodic dissolution behaviors of the alloys were observed by potentiodynamic polarization and electrochemical quartz crystal microbalance (EQCM) techniques. While the structure of the electrodeposited Ni–W alloy with low W content (15.90% W) was crystalline, that of the alloy with high W content (50.80% W) was nano-crystalline according to X-ray diffraction patterns. The increase in the W content of the electrodeposited Ni–W alloy resulted decrease at pH 3 and increase at pH 7 and 12.5 in the anodic currents of the alloy. The pH dependent dissolutions caused electrodeposited alloy surface to have W—enrichment at pH 3 and Ni—enrichment at pH 7 and 12.5. These observations indicated that the selective dissolution of Ni or W was the main mechanism in the anodic dissolution of the electrodeposited Ni–W alloys. The EQCM experiments conducted at pH 7 supported the presence of the selective dissolution mechanism that the anodic dissolution potential of W was 0.42 V lower than that of Ni in the electrodeposited Ni–W alloys. 相似文献
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目的 通过研究自然氧化、过氧化氢氧化和130℃氧化处理对电沉积吸液芯润湿性和毛细性能的影响,探究吸液芯毛细性能在空气中衰减的原因。方法 通过电沉积在铜表面制备一层多孔铜吸液芯,分别对吸液芯进行自然氧化、过氧化氢浸泡和130℃烘烤处理,利用接触角测量和毛细上升法分析吸液芯表面的润湿性和毛细性能,通过扫描电镜(SEM)观察吸液芯微观形貌,采用X射线光电子能谱(XPS)和傅里叶红外光谱分析吸液芯表面成分。结果 3种氧化处理后,吸液芯的润湿性与毛细性能有明显差异。自然氧化处理和过氧化氢处理的吸液芯均表现为超亲水,接触角为0°,而130℃烘烤的吸液芯表现为超疏水,接触角高达150.49°。水在过氧化氢处理的吸液芯表面的运行速度比在自然氧化的表面更快。3种不同状态的吸液芯微观形貌都为树枝状结构,没有明显差异。XPS图显示,自然氧化处理的吸液芯表面部分氧化,存在76.4%(质量分数)Cu2O;130℃烘烤的试样表面全部氧化,为60.6%的Cu2O和39.4%的CuO;而过氧化氢浸泡的表面为100%的CuO2。结论 3种氧化处理不会改变... 相似文献
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Zinc-nickel alloys were electrodeposited under galvanostatic conditions from a sulphate based electrolyte. The effect of deposition current density on alloy composition was determined for an electrolyte containing 0.58 mol/l nickel and 0.92 mol/l zinc (as sulphates). At current densities exceeding 0.01 A/dm2, a transition from normal deposition to anomalous co-deposition (ie where the less noble metal deposits preferentially) was observed and alloys rich in zinc were obtained. The transition current density was observed to increase with an increase in electrolyte temperature or a decrease in electrolyte pH.The electrodeposition mechanism for zinc-nickel alloys in the transition regions was studied in detail using potentiodynamic cathodic polarisation techniques. The results were consistent with the suppression of nickel deposition due to the precipitation of zinc hydroxide on the cathode surface. This was supported by pH measurements made in the vicinity of the cathode where a rise in pH was detected as the transition current density was approached and exceeded the critical pH for zinc hydroxide precipitation. 相似文献
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目的 通过研究镉镀层绿色化学转化膜的电化学性能,获得镉镀层最佳绿色化学钝化工艺。方法 采用无氰镀镉工艺,在30CrMnSiA钢表面电镀镉。采用植酸和钼酸钠在镉镀层表面进行绿色钝化处理,构建复合化学转化膜。通过研究钼酸钠浓度、处理时间和植酸浓度对绿色钝化处理镀镉层在质量分数为3.5%的NaCl溶液中电化学性能的影响,获得最佳的镀镉层绿色钝化工艺。结果 在处理时间为10 min、植酸的质量分数为1.0%的条件下,当钼酸钠的质量分数增至3%时,开路电压先从−0.741 9 V增至−0.739 7 V后,再降至−0.761 1 V,电荷转移电阻Rct从2.34 kΩ.cm2增至8.79 kΩ.cm2,腐蚀抑制率从72.9%增至92.8%,自腐蚀电流密度Jcorr从81.47 μA/cm2降至最低值(6.887 2 μA/cm2)。当钼酸钠和植酸的质量分数分别为2.0%和1.0%时,随着处理时间的延长,开路电压从−0.755 9 V增至−0.729 5 V,Rct先增至6.68 kΩ.cm2,然后降至5.28 kΩ.cm2,自腐蚀电流密度从16.26 μA/cm2降至4.527 μA/cm2。当钼酸钠的质量分数为2.0%、处理时间为10 min时,随着植酸浓度的增加,试样的开路电压从−0.739 3 V降至−0.756 1 V,Rct先增至6.68 kΩ.cm2,然后降低,自腐蚀电流密度Jcorr呈现先降至最小值后再增大的趋势。结论 与镉镀层相比,经化学转化膜处理后试样表现为高的开路电压、大的电荷转移电阻和低的自腐蚀电流。得到了耐蚀性好且成本较低的镉镀层表面绿色钝化工艺,钼酸钠和植酸的质量分数分别为2.0%和1.0%,处理时间为10 min。 相似文献
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通过分析传统阴极电泳动力学公式,结合镁合金特点分析及理论研究,对传统公式进行修正。采用AZ31镁合金进行阴极电泳动力学的研究,经试验验证,公式的推算具有合理性和正确性,并最终得出镁合金阴极电泳动力学公式3.6×1011δ2+4.77×105δ=t(δ为厚度;t为时间,且t<3 min),为指导镁合金阴极电泳涂层的制备提供了理论依据。 相似文献
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电沉积Ni-Mo-P合金镀层的组织结构与耐蚀性 总被引:2,自引:0,他引:2
用扫描电镜、透射电镜和失重法研究了电沉积Ni-Mo-P合金镀层的表面形貌、组织结构和耐蚀性能。结果表明,Ni-Mo-P合金的非晶态镀层,经过不同温度热处理后,镀层结构以非晶态→混晶态→结晶态的顺序变化,镀层的硬度和耐蚀性也因此发生了相应的变化。 相似文献
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采用脉冲电沉积方法从Cr3+溶液中制备Fe-Ni-Cr纳米晶合金镀层,利用SEM,EDS和XRD对Fe-Ni-Cr合金镀层的表面形貌、化学组成和晶粒结构进行观察;利用电化学工作站对镀层进行极化曲线测试并与传统的304不锈钢进行对比。结果表明:电沉积镀层为纳米晶,无裂纹,表面光亮,晶粒尺寸大多分布在10~40 nm之间,镀层主要元素成分含量Cr为25.52%,Fe为59.61%,Ni为6.55%,与传统304不锈钢相比, Fe-Ni-Cr纳米晶镀层在5%的H2SO4溶液的自腐蚀电位提高了近30 mV,自腐蚀电流密度降低了近1/8,维钝电流降低了近1/10。因此,Fe-Ni-Cr纳米晶合金镀层表现出更好的耐蚀性。 相似文献