烧结钕铁硼磁体表面Zn-Co合金镀层制备工艺与耐蚀性能

采用氯化物镀液体系在钕铁硼磁体表面制备Zn-Co合金镀层,优化了Zn-Co合金镀层制备过程中的电镀工艺参数(镀液pH值、镀液温度、电流密度以及添加剂浓度),通过中性盐雾试验(NSS)、扫描电子显微镜(SEM)和动电位极化曲线,系统研究了Zn-Co合金镀层的显微组织及耐蚀性能。结果表明:烧结钕铁硼电镀Zn-Co合金镀层的最佳电镀工艺参数为:添加剂浓度为15 mL/L,pH值为4,电镀温度为25℃,电流密度为1 A/dm~2。在最佳工艺条件下制备的Zn-Co合金镀层经钝化后其耐中性盐雾时间可达120 h。合金镀层结构致密,有效填补了钕铁硼磁体的固有缺陷,为后期钝化形成致密钝化膜提供了材料基底基础。钝化后的Zn-Co合金镀层表面平整光亮,动电位极化曲线测试表明,相比Zn镀层,钝化后的Zn-Co合金镀层的自腐蚀电流密度下降了一个数量级,表明Zn-Co合金镀层钝化后具有更加优异的耐腐蚀性能。     

氯化物电镀Zn—P合金的研究

研究了Ｚｎ－Ｐ合金电镀液组成及工艺条件对镀层含磷量的影响，在最佳工艺参数条件下，可得到磷的质量分数为０．１％左右的Ｚｎ－Ｐ合金镀层。对镀液、镀层性能进行了测试，实验证明经银白色钝化后的Ｚｎ－Ｐ合金镀层的耐蚀性能是纯锌镀层的２倍以上。     

化学镀Ni-Co-Cu-P非晶镀层及其耐蚀性能

采用化学镀工艺在45钢表面制备Ni-Co-Cu-P四元合金镀层,通过EDX、XRD、SEM、盐雾试验、Tafel曲线等测试方法研究镀层的成分、晶型结构和耐蚀性能。结果表明:Ni-Co-Cu-P镀层为非晶结构,其中Ni、Co、Cu的含量分别为32.66%、47.19%和15.28%(质量分数)。镀层表面均匀分布着直径240~500 nm的球状团簇,一些团簇内部存在纳米级孔隙。镀层经156 h盐雾后出现明显红色锈点,192 h后完全失效。镀层的耐蚀性能明显优于45钢基体和Ni-Co-P镀层。在1.0%H_2SO_4溶液中,镀层的自腐蚀电位和腐蚀电流密度分别为–0.26 V和19.17μA·cm-2,随着电位的升高表面出现大量微裂纹。而在3.5%NaCl(质量分数)溶液中,镀层表现出活化-钝化-过钝化的腐蚀行为,表面钝化膜逐渐被Cl~-穿透而形成针孔。     

不锈钢表面Cr-Pd合金电沉积及镀层在强还原性介质中的耐蚀性

通过选择络合剂、缓冲剂及采用方波脉冲电流和优化电镀工艺, 在酸性镀液中实现了Cr-Pd共镀, 并在不锈钢表面制备出均匀致密且与基体结合良好的Cr-Pd合金镀层. 通过改变镀液中铬盐和钯盐的相对含量, 可以大范围改变镀层成分. Cr-Pd合金镀层可显著提高不锈钢在高温还原性腐蚀介质中的耐蚀性, 在沸腾的20%(质量分数)H₂SO₄溶液中, Cr-Pd合金镀层使316L不锈钢的腐蚀速率降低了4个数量级以上. 镀层中的Cr和Pd对致钝具有协同促进作用, 当镀层中含有2.5%Pd(质量分数)时即具有明显的促进钝化效果, 含33.3%Pd镀层对不锈钢的保护效果与纯Pd镀层相当.     

三价铬硫酸盐体系电镀Fe-Ni-Cr合金镀层的耐蚀性研究

采用三价铬硫酸盐体系在普通碳素钢基体上电镀Fe-Ni-Cr合金镀层,通过浸泡失重法研究不同工艺条件下制备的镀层在3.5% NaCl溶液中的耐蚀性能,并用电化学分析方法研究了镀层试样的耐蚀机理.结果表明,最佳电镀Fe-Ni-Cr合金工艺为:主盐浓度FeS04·7H2O 15 g/L、NiSO4·6H2O 8 g/L、Cr...     

不同活化工艺对电解镍始极片结合力及性能的影响

目的为了提高电解镍始极片与基体的结合力,增加镀层耐蚀性能,改善镀层质量。方法通过采用不同的活化工艺对基体进行表面处理后制备镀层,采用划格法测试镀层与基体的结合力,用场发射电子扫描显微镜观察镀层与基体的截面形貌,用X射线衍射仪(XRD)分析镀层的相组成、应力以及镀层晶粒尺寸大小,用电化学工作站研究镀层的耐蚀性能。结果基体经过活化工艺处理后,镀层与基体结合均匀、致密、完整,大幅提高了镀层与基体的结合力,改善了镀层质量,镀层内应力由287.2 MPa降低到220.0 MPa,并且活化工艺不会给镀层引入其他杂质元素以及改变晶粒尺寸大小。电化学性能测试后发现,经过活化工艺后的镀层耐蚀性能增大,自腐蚀电位由-0.5481 V升高到-0.3980 V;自腐蚀电流密度由9.941μA/cm~2降低到2.927μA/cm~2。结论钛基体经过活化处理后,生成一层薄的活化膜,这层活化膜通过提高钛基体的表面活性,改变钛基体表面状态,来提高金属电沉积层与钛基体的结合强度,同时镀层的综合性能也得到了改善。     

脉冲电镀Ni-W-P镀层及其耐蚀性（英文）

采用脉冲电镀法在Cu基体上制备Ni-W-P合金镀层,并通过单因素方法探讨电解液pH(1~3)、温度(40~80°C)、平均电流密度(1~7 A/dm~2)及脉冲频率(200~1000 Hz)对沉积速度、镀层结构及耐蚀性能的影响。采用扫描电子显微镜、X射线衍射和X射线能谱仪对镀层表面微观形貌、结构及元素组成进行分析。在3.5%NaCl(质量分数)溶液及土壤溶液中采用动电位极化曲线及电化学阻抗谱对镀层的耐蚀性能进行研究。结果表明:脉冲电镀Ni-W-P镀层具有良好的耐蚀性能,且脉冲电镀参数对镀层结构及耐蚀性能具有十分重要的影响。最优脉冲电镀Ni-W-P镀层参数如下:pH 2.0、温度60°C、平均电流密度4 A/dm~2、脉冲频率600 Hz。在最优脉冲电沉积参数条件下制备的Ni-W-P合金镀层具有优良的耐腐蚀性能(276.8 k?),其表面致密,无任何明显缺陷。     

合金元素对Ti-5Ta合金耐硝酸腐蚀性能的影响

研究了Cr、V、Mo、Al等元素对Ti-Ta系合金在6mol/L沸腾硝酸中腐蚀行为的影响规律。通过扫描电子显微镜（SEM）和电化学工作站等分析方法对不同成分合金的腐蚀速率、钝化膜形貌、极化曲线等进行分析。结果表明,单独添加Cr、V、Mo元素对Ti-Ta合金的耐蚀性能影响较小,而添加Al元素会大幅降低合金耐蚀性能;Ti-Ta-Cr合金的腐蚀速率最低,钝化膜致密度最高,稳定性最佳;Ti-Ta-Al合金在腐蚀过程中很难形成致密且稳定的钝化膜。对于Ti-Ta系多元合金,复合添加Cr、V元素有助于获得致密的钝化膜,添加Mo元素会降低钝化膜致密度和稳定性,Al元素添加量为1%（质量分数）时对合金钝化行为的影响不大。提高氧浓度会恶化Ti-Ta-X三元合金在沸腾硝酸中的耐蚀性能。     

镁合金表面化学镀Ni-P合金稳定剂优选试验研究

在合理选择化学镀Ni-P合金配方和工艺条件的基础上,采用对比实验研究了硫脲、Pb(AC)2、KIO3、KI、Bi(NO3)2几种稳定剂及其复合对镁合金化学镀Ni-P合金镀液及镀层性能的影响。研究发现:适合NiSO4体系镁合金化学镀的稳定剂为KI KIO3,采用复合稳定剂的镀液稳定性及镀层性能明显优于单一稳定剂,在优化的稳定剂及相应的工艺条件下,镀液的稳定性好,镀速高,镀层均匀、致密,孔隙率低,耐蚀性能优良。     

化学镀Ni-Co-Cu-P非晶镀层及其耐蚀性能研究

采用化学镀工艺在45钢表面制备Ni-Co-Cu-P四元合金镀层,通过EDX、XRD、SEM、盐雾试验、Tafel曲线等测试方法研究镀层的成分、晶型结构和耐蚀性能。结果表明：Ni-Co-Cu-P镀层为非晶结构,其中Ni、Co、Cu的含量分别为32.66 wt.%、47.19 wt.%和15.28 wt.%。镀层表面均匀分布着直径约240 ~ 500 nm的球状团簇,一些团簇内部存在纳米级孔隙。镀层经156 h盐雾后出现明显红色锈点,192 h后完全失效。镀层的耐蚀性能明显优于45钢基体和Ni-Co-P镀层。在1.0 wt.% H2SO4溶液中,镀层的自腐蚀电位和腐蚀电流密度分别为-0.26 V和19.17 μA?cm-2,随着电位的升高表面出现大量微裂纹。而在3.5 wt.% NaCl溶液中,镀层表现出活化-钝化-过钝化的腐蚀行为,表面钝化膜逐渐被Clˉ穿透而形成针孔。     

Zn-Fe合金镀层耐蚀性研究

通过改变工艺条件,可以从碱性溶液中获得含 Fe0.4～0.8%的 Zn-Fe合金镀层。试验表明这种镀层的耐蚀性是普通镀锌层的2倍。含 Fe 量不同的镀层其耐蚀性也不同。含 Fe 在0.4～0.8%的镀层在5%NaCl 溶液中在稳定电位条件下处于钝化区,而且镀层的极化电阻比较大,是镀锌层的2倍以上,而镀锌层在同样溶液中处于活化溶解区,有很大的溶解电流,而且极化电阻较小。腐蚀后形貌观察也表明 Zn-Fe 合金镀层与镀锌层的特征不同,呈花球状形貌。正是由于上述差异决定了 Zn-Fe 合金镀层的耐蚀性是优良的。     

碱性溶液锌铁合金电沉积研究

在碱性锌酸盐溶液中电沉积获取 Fe0.4—0.8%的锌铁耐蚀合金镀层。探讨了镀液成分对合金含 Fe 量的影响,含 Fe0.4～0.8%的 Zn-Fe 合金镀层的耐蚀性优于普通镀层。讨论认为 Zn-Fe 合金的共沉积为异常共沉积。     

稀土铈对锌-铁合金镀层耐蚀性的影响

研究了铈盐对电沉积锌-铁合金镀层耐蚀性的影响,通过失重法、浸泡实验、电化学腐蚀参数的测量,得出在镀液中添加一定量的铈盐能显著改善镀层的耐蚀性能.扫描电镜测定镀层表面形貌的结果表明,定量铈盐参与下,可获得更加致密的镀层,这正是提高镀层耐蚀性的原因.     

Corrosion protection of sintered NdFeB magnets by CAPVD Ti2N coating

Sintered NdFeB magnets have poor corrosion resistance and are readily susceptible to corrosion under different environmental conditions. Cathodic arc physical vapour deposited (CAPVD) titanium nitride coating for sintered NdFeB permanent magnets has been investigated in this paper. Tafel extrapolation was employed to study the corrosion behaviour in 3.5% NaCl solution at ambient temperature. The adhesive strength of the coating was estimated with the help of the scratch test. The surface chemistry and coating morphologies were studied with scanning electron microscope (SEM). X-Ray diffraction (XRD) was used for qualitative phase analyses of coatings and substrate. The properties of CAPVD titanium nitride coating were compared with electrodeposited multilayer nickel–copper–nickel coating. It was figured out that the CAPVD titanium nitride coating had better adhesion strength and shifted the free corrosion potential (FCP) of the system towards positive potential, providing protection to the NdFeB substrate. However, the corrosion rate of CAPVD titanium nitride coating was more than the electrodeposited multilayer nickel–copper–nickel coating. The magnetic properties remained comparable.     

Electroplated super-hydrophobic Zn-Fe coating for corrosion protection on magnesium alloy

A superhydrophobic Zn-Fe alloy coating was prepared on the surface of a reactive magnesium alloy using a simple, low-cost, eco-friendly method. Firstly, the Zn-Fe coating was obtained in a neutral glycerol Zn-Fe plating solution, which is green, compositionally stable, and non-corrosive to the equipment. And then the superhydrophobic surface with a flower-like microstructure was obtained by grafting myristic acid onto the Zn-Fe coating via a chelation reaction. The water contact angle was >150° and the rolling angle was 3°-4°. The corrosion rate of the two groups of superhydrophobic magnesium alloy samples with electrodeposition time of 30 and 50 min, respectively, was reduced by about 87% compared to that of the bare magnesium alloy. The prepared superhydrophobic coatings exhibit high performance in self-cleaning, abrasion resistance, and corrosion resistance.     

等离子喷涂制备Co基TiC金属陶瓷涂层的微观形貌及耐高温腐蚀性能

采用等离子喷涂技术在GH586合金表面制备了一层Co基TiC金属陶瓷涂层。研究了TiC含量对Co基TiC金属陶瓷涂层显微组织及耐高温腐蚀性能的影响。结果表明:TiC陶瓷颗粒与Co基粉体有良好的润湿性,呈现相互包裹的结构,涂层结合紧密无缺陷;TiC的加入,提高了Co基TiC金属陶瓷涂层的耐磨性,但当TiC含量过高时,团聚现象严重,导致涂层的耐高温腐蚀性能降低;TiC质量分数为10%时,TiC颗粒在涂层中分布较为均匀,此时涂层的耐高温腐蚀性能和耐磨性都较优。     

铁基锌镀层的腐蚀电化学研究

为寻找耐蚀性好的镀层材料及确定稀土对镀层的影响,通过弱极化区极化曲线测定和Tafel曲线测定2种电化学测试方法对Zn/Fe、Zn-Fe/Fe、Zn-Fe-Re/Fe在5%NaCl溶液中的腐蚀行为进行了测试和分析,并将腐蚀测试结果进行了比较,由比较结果可知,3种镀层的耐蚀性排序为:Zn-Fe-Re/Fe>Zn-Fe/Fe>Zn/Fe.稀土元素的存在使得镀层更加均匀、致密,镀层表面更加平整,腐蚀产物可以很好地保护基底,从而增大了耐蚀能力.     

Optimization of deposition conditions for development of high corrosion resistant Zn-Fe multilayer coatings

Composition modulated multilayer alloy (CMMA) coating of Zn-Fe was developed galvanostatically on mild steel through single bath technique (SBT), using thiamine hydrochloride as additive. Electrodeposits with different coating matrices were developed, using square current pulses. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods were used to assess the corrosion performance of the coatings. The cyclic cathode current densities (CCCDs) and number of layers were optimized, for highest corrosion resistance. Experimental results showed that CMMA Zn-Fe coating, developed at 2.0-4.0 A/dm², having 300 layers is ∼30 times higher corrosion resistant than corresponding monolithic alloy of same thickness. The corrosion resistance increased with number of layers up to a certain number of layers; and then decreased. The better corrosion resistance was attributed to the dielectric barrier at the interface, evidenced by dielectric spectroscopy. The formation of multilayer and corrosion mechanism was analyzed using scanning electron microscopy (SEM).     

Electrodeposited nickel/alumina composite coating on NdFeB permanent magnets

NdFeB magnets are highly susceptible to corrosion in various environments. A nickel/alumina composite coating for NdFeB magnets was investigated in this paper. The microstructures of electrodeposited nickel coating and nickel/alumina composite coating were determined by scanning electron microscope (SEM). The corrosion behavior of nickel coating and nickel/alumina composite coating in 3.5 wt% sodium chloride solution was studied by polarization curves and electrochemical impedance spectroscopy (EIS). The results show that the nickel coating and nickel/alumina composite coating can both provide adequate protection to the NdFeB substrate. Furthermore, the free corrosion potential of nickel/alumina composite coating is more positive and the passivation region is more obvious compared with nickel coating, and the capacitance loop diameter of nickel/alumina composite coating is significantly larger than that of nickel coating. With the increase in immersion time, a flat of passivation film is formed on the surface of nickel/alumina composite coating, resulting in excellent corrosion resistance after 288 h immersion in 3.5% sodium chloride solution according to EIS testing.     

Zn－Fe合金电镀的应用与发展

综述了各种Ｚｎ－Ｆｅ合金电镀工艺的特点及研究应用现状，重点对比研究了各种络合体系的碱性锌酸盐Ｚｎ－Ｆｅ合金电镀工艺．结果表明，含铁量≤０．８％的Ｚｎ－Ｆｅ合金镀层，可以直接经铬酸盐钝化处理而大幅度提高膜层的耐蚀性能．