无电解镀镍磷非晶态合金的近边结构研究

用ＤＴＡ，ＸＲＤ和ＥＸＡＦＳ方法研究无电解镀镍磷合金层结构，其中含Ｐ１０％（重量百分比）左右的Ｎｉ－Ｐ合金层是非晶态合金固溶体，Ｎｉ，Ｐ之间存在共价键作用，Ｎｉ－Ｎｉ键长０．２５ｎｍ，Ｎｉ－Ｐ键长０．２８ｎｍ经４００℃热处理１后的含Ｐ１０％的Ｎｉ－Ｐ镀层是Ｎｉ３Ｐ晶态与Ｎｉ－Ｐ非晶态的混合物，ＥＸＡＦＳ方法给出了镍磷合金层的结构，键长和配位原子情况，体现出ＥＸＡＦＳ方法在研究金属结构尤其是非晶态金     

混合稀土对Cu—Ni—Si铸态合金组织和电性能的影响

研究了混合稀土对Ｃｕ－Ｎｉ－Ｓｉ三元合金铸态组织和电性能的影响，观察到稀土元素的加入造成合金晶界共晶相的改变以及基体中相中针状η－ＮｉＳｉ的分析，同时稀土元素的加入对合金的电阻率和电阻温度系数产生明显的影响，使得合金的电阻温度系数随稀土加入量的增加呈从递减到递升的变化。     

负载型Ni—B非晶态合金催化剂的表征及催化性能

采用ＩＣＰ,ＸＲＤ,ＤＳＣ,ＳＥＭ和ＴＥＭ等技术对负载型Ｎｉ－Ｂ非晶态合金催化剂进行了表征,研究了这类催化剂对乙烯中微量乙炔的选择加氢性能。结果表明,在负载型非晶态合金催化剂中,Ｎｉ－Ｂ超细微粒的形式分散在载体上,但在不同载体上的分散度不同。通过载体的引入,提高了非晶态合金的热稳定性,阻止了超细Ｎｉ－Ｂ的聚集。负载型非晶态合金催化剂对乙烯中微量乙炔的选择加氢表现出优良的催化性能。     

镍钨磷合金电结晶机理及其镀层结构与显微硬度

应用循环伏安,恒电位阶跃和Ｘ射线衍射（ＸＲＤ）等方法了Ｎｉ－Ｗ－Ｐ合金电沉积特点和镀层结构与显微硬度,结果表明,在以柠檬酸铵为配体的溶液中,Ｎｉ－Ｗ－Ｐ合金 层较Ｎｉ－Ｗ合金有较低的电化学活性,根据电位阶跃的ｉ－ｔ曲线分析表明,在玻碳电极上Ｎｉ－Ｗ－Ｐ合金电结晶过程遵从扩散控制瞬时成核三维成长模式进行,随着过电位的增加,电极表面上晶核数增多,ＸＲＤ试验结果表明,Ｎｉ－Ｗ－Ｐ合金镀层呈现明显的非晶态特征,所获得的Ｎｉ－Ｗ－Ｐ合金电沉层的显微硬度在４５０ｋｇ．ｍｍ＾－２左右。     

轻稀土氧化物对非晶态NiB合金催化剂的改性研究

采用脉冲技术以气相苯加氢为探针反应,首次研究了轻稀土元素Ｃｅ,Ｐｒ,Ｎｄ对化学还原法制备的非晶态ＮｉＢ合金催化剂遥加氢及抗硫性能的影响。用ＸＲＤ鉴定结构,用ＤＳＣ测定晶化温度;并用吸附ＣＯ,ＴＰＲ,ＴＰＤ等手段表征了轻稀土对非晶态ＮｉＢ合金催化剂表面性质的影响。     

非晶态Ni（Co）—B合金作催化材料的研究

用化学法制备了非晶态合金催化剂Ｎｉ－Ｂ和Ｎｉ－Ｃｏ－Ｂ。ＩＣＰ方法测得其组成分别为Ｎｉ９３Ｂ７和Ｎｉ７２Ｃｏ２０Ｂ８。经ＸＤ、ＤＳＣ及ＴＥＭ鉴定所制合金为非晶态。通过考察氧化处理温度对ＣＯ加氢反应的活性及反应稳定性的影响后发现，ＮｉＢ的活性及稳定 均高于ＮｉＣｏＢ。在高真空程度升温脱附及反应装置上研究了Ｈ２作ＣＯ的反应，认为其反应机理可能为：吸附的ＣＯ解离为表面反应的控制步骤，解离态的Ｃ和原子氧分     

稀土对非晶态NiB合金催化剂性能的影响

研究了Ｅｕ,Ｇｄ,Ｔｂ对化学还原法制备非晶态ＮｉＢ合金催化剂的加氢及抗硫性能的影响。Ｅｕ,Ｇｄ,Ｔｂ的加入可提高ＮｉＢ合金的催化活性和抗硫性。其原因是稀土元素与ＮｉＢ合金间存在的相互作用。ＮｉＢ合金催化剂的活性中心与还原态的镍及镍＝硼－氧物种有关。     

电沉积Ni—Mo—P合金镀层在NaCl溶液中的腐蚀特性

用失重法，阳极率曲线，Ｘ－光电子能谱（ＸＰＳ）以及俄歇电子能谱（ＡＥＳ）研究了电沉积Ｎｉ－Ｍｏ－Ｐ合金镀层在５％ＮａＣｌ溶液中的腐蚀特性，非晶态Ｎｉ－Ｍｏ－Ｐ合金镀层比晶态Ｎｉ－Ｍｏ－Ｐ合金镀层有较低的腐蚀速度阳极极化曲线表明，Ｎｉ－Ｍｏ－Ｐ合金镀层中，镍的摩尔分数国０．７１９～０．８６８时，随镀层中磷含量的增加，腐蚀电位正移，而活化区的峰电流随镀层中钼含量的增加而增加，磷含量的活化区的峰电流以及     

离子交换树脂负载Ni—B无定形合金催化剂的制备与性能

制备了一种新型离子交换树脂负载的Ｎｉ－Ｂ无定形合金催化剂．用３种树脂作为催化剂载体，即弱酸型阳离子树脂Ｄ１５２，强酸型阳离子树脂Ｄ７２及强碱型阴离子树脂Ｄ２６１．用ＸＰＳ、ＴＥＭ和ＩＣＰ等技术对催化剂进行了表征．结果表明，催化剂上镍与带有功能基的载体树脂之间有着很强的相互作用，但其强度与所带的功能基有关．３种催化剂Ｎｉ２ｐ３／２的ＸＰＳ谱图上，ＮｉＢ／Ｄ１５２催化剂的氧化态峰最小，而ＮｉＢ／Ｄ２６１的氧化态峰最大．异丙醇脱氢反应活性实验证实了这一结果．     

化学镀Ni-P合金在CO2溶液中的腐蚀磨损行为

研究了化学镀Ｎｉ－Ｐ合金在ＣＯ２溶液中的腐蚀磨损行为。结果表明,ＣＯ２浓度增大,载荷增加,滑动速度增加,化学镀Ｎｉ－Ｐ合金的腐蚀磨损速率增大、自腐蚀电位负移;ＣＯ２浓度增大,载荷减小,滑动速度降低,化学镀Ｎｉ－Ｐ合金的摩擦系数增大。同样条件下,化学镀Ｎｉ－Ｐ合金比Ｇ１０５钢具有更高的耐腐蚀磨损性。     

化学镀镍磷合金镀层孔隙率的电化学评价

本文通过研究镍磷合金、镍磷合金镀层和碳钢在不同浓度硝酸溶液中的动电位极化曲线 ,选择了能够快速检测镍磷合金镀层孔隙率的硝酸浓度 ,并对不同厚度的镍磷合金镀层试样进行评价 .结果表明 :镍磷合金镀层在 1 0 %硝酸溶液中的动电位极化曲线能准确地反映镀层的孔隙率 ,该硝酸溶液最适合作为应用电化学方法检测镀层孔隙率的检测溶液 ,其变化规律是随着镀层孔隙率的减少 ,镀层的腐蚀电位逐渐正移 .应用常规的孔隙率检测方法只能检测较大的孔隙 .     

非晶态Ni-W-B合金的电沉积及其热处理前后的性能

To strengthen the properties of Ni-W alloy, dimethylamine borane （DMAB） was added to an alloy Ni-W electrolyte solution and a ternary Ni-W-B alloy was electrodeposited. The electrodeposition, crystallographic structure, surface morphology, heat treatment and corrosion resistance, of the alloy were studied by DSC, XRD, SEM and electrochemical techniques. The results showed that the structure of the alloy was greatly affected by the cooperation of boron compound. DSC experiment combined with X-ray diffractometry indicated that the obtained Ni-W-B alloy was still in amorphous structure although W content in the alloy was decreased by the addition of DMAB. After heat treatment at 400 ℃ for 1 h, the microhardness was increased from 612 to 947 kg.mm^-2 that was com- parative to Cr coating. The appearance of the as-plated coating was in f＇me and slice grains and kept almost no change after heat treatment. In w=0.03 NaC1 solution the as-plated coating presented very good corrosion resistance. After the coating was heat-treated its corrosion resistance was enhanced.     

Electrochemical Behavior of Dental Ni‐Cr Wirolloy Coated with Eco‐friendly Films in Artificial Saliva

The electrochemical corrosion behavior of the non‐precious Ni‐Cr Wirolloy, being used in dentistry, was investigated before and after applying of two types of eco‐friendly coatings, polyvinyl silsesquioxane (PVS) and nano‐hydroxyapatite (nHAP) separately in artificial saliva solution at 37 °C for 14 d of immersion. The study aimed to investigate the effectiveness of the introduced coating films in enhancing the corrosion resistance of the alloy, and in decreasing the leaching of the toxic Ni ions from the alloy into the environment. The electrochemical corrosion investigation methods used are; open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. The evaluated results revealed that the electrochemically coated alloy with PVS. prepared at cathodic potential showed higher corrosion resistance and more stable film compared to that prepared by conventional dip‐coating method. At the same time, the nHAP electrochemically coated film provided the best anti‐corrosion properties over all examined time intervals. The obtained results were confirmed via surface analysis, which assured the formation of the prepared coatings on the alloy surface. Chemical analysis of the corrosion product/solutions showed that the effect of electrochemically deposited nHAP and PVS. polymer films in suppression of Ni ions leaching is similar and slightly higher than that of the chemically coated PVS. one; however, all of them are efficient in decreasing the leaching of the risky Ni ions into the solution.     

Effect of Cu in electroless Ni–Cu–P coating on passivation process

Electroless Ni–P and Ni–Cu–P coatings were passivated by chromate conversion treatment respectively. The anticorrosive performances of passivated coatings were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy measurements. The passivated Ni–Cu–P coating exhibited a high corrosion resistance with the i_corr of 0.236 μA/cm,² while the value of passivated Ni–P coating was only 1.030 μA/cm,² indicating the passive film could improve the corrosion resistance of Ni–Cu–P coating to a significant extent. High‐resolution X‐ray photoelectron spectroscopy was used to determine the chemical states of elements detected in the passive film. Compared with passivated Ni–P coating, the passive film on Ni–Cu–P coating exhibited a higher ratio of Cr₂O₃ to Cr(OH)₃ with the value of 72:28, which was the main factor for passivated Ni–Cu–P coating showing excellent corrosion resistance. The effect of Cu in electroless Ni–Cu–P coating on passivation process was discussed by the contrast experiment. Copyright © 2016 John Wiley & Sons, Ltd.     

pH值对AZ31镁合金表面植酸转化膜在模拟体液耐腐蚀性能的影响

采用沉积的方法在镁合金AZ31表面制备植酸转化膜并研究了pH值的影响. 利用极化曲线和电化学阻抗谱方法测定其耐腐蚀性能,用扫描电子显微镜观察转化膜的表面微观结构,用能谱测定转化膜的组成元素. 在理论上通过热力学的方法分析最佳pH值. 植酸转化膜可以提高镁合金AZ31的耐腐蚀性能. 当植酸溶液的pH=5时腐蚀效率达到了89.19%,此时腐蚀电位正移了156 mV,腐蚀电流密度与没有处理的试样相比减小了约一个数量级. 热力学分析表明植酸转化膜的耐腐蚀性能不仅受植酸根离子和镁离子浓度的影响,也与氢气释放的速率有关.     

添加氧化铈对AZ91D镁合金表面富镁涂层的保护作用

通过Machu测试、电化学交流阻抗(EIS)和扫描电子显微镜(SEM)等方法研究了添加氧化铈对AZ91D镁合金表面富镁涂层防护性能的影响.氧化铈添加量较少(0.1%,w)时,对涂层耐蚀性无影响;添加量过多(3%)时,涂层耐蚀性降低;添加氧化铈颗粒为0.5%时,涂层的阻抗增大,涂层电容降低,对AZ91D镁合金基体的保护性能明显提高.尽管添加氧化铈不改变富镁涂层对AZ91D镁合金的保护机制,但可显著延长涂层的服役寿命.氧化铈能够降低纯镁颗粒的电化学反应活性,使镁粉腐蚀速率降低,阴极保护时间延长.添加一定量氧化铈后,也有利于涂层屏蔽性能提高,氧化铈能降低AZ91D镁合金表面阳极腐蚀电流密度,提高镁合金腐蚀电位,从而有利于富镁涂层发挥对镁合金基体的阴极保护作用.     

Mechanical and corrosion behavior of amorphous and crystalline electroless Ni–W–P coatings

Two types of electroless Ni–W–P coatings: nanocrystalline with low P and amorphous with higher P content are investigated. Scanning probe microscopy is applied to study their morphology. Textured nanocrystalline coatings consist of coarse pyramids built of nanometer thick lamellas. The surface morphology of amorphous coatings is much finer and uniform. Nanohardness of all coatings depends on W content. Microhardness is increasing during the heat treatment up to 350 °C due to nickel phosphide precipitation affected by tungsten also. The wear resistance of nanocrystalline Ni–W–P coatings is much higher than that of amorphous in spite of the similar tungsten content in both. Lower corrosion resistance of amorphous Ni–W–P coatings is found by weight loss method during long-term immersion in 5 % NaCl. Electrochemical tests by potentiodynamic polarization curves in two model corrosion media—solutions of 0.5 M H₂SO₄ and 5 % NaCl—are performed. The corrosion of bi-layered Ni–W–P/Ni–P and Ni–W–P/Ni–Cu–P deposits on mild steel is also investigated. The results prove that an electroless Ni–W–P coating on mild steel extremely improves its mechanical and corrosion behavior. It is demonstrated that in addition to deposit’s structure and composition, the distribution and chemical state of alloy ingredients are also responsible for its properties.     

Process aspects of electroless deposition for nickel–zinc–phosphorous alloys

Electroless deposition of Ni–Zn–P thin film was considered as a barrier film on a galvanic Zn or Ni–Zn sacrificial layer in a multicomponent corrosion protective coating on steel. The incorporation of zinc on the chemical composition of electroless Ni–Zn–P coating was studied. The effect of operating conditions such as temperature, pH value and concentration of zinc sulphate was investigated. Some physical characteristics such as morphology, structure, corrosion properties of Ni–Zn–P coatings were assessed in parallel with those of Ni–P. Inclusion of Zn to Ni–P is accompanied by the transformation of the coating structure from amorphous to crystalline. The effect of adding nonionic surfactant to the plating solution on the composition and surface morphologies was also investigated. The results indicate that nonionic surfactant has no effect on the Zn % in the deposit layer, but it affects the surface morphology and improves the corrosion resistance of Ni–Zn–P layers. Copyright © 2005 John Wiley & Sons, Ltd.     

The effect of chloride concentration and pH on pitting corrosion of AA7075 aluminum alloy coated with phenyltrimethoxysilane

The effect of chloride ion concentration and pH of solution on the corrosion behavior of aluminum alloy AA7075 coated with phenyltrimethoxysilane (PTMS) immersed in aqueous solutions of NaCl is reported. Potentiodynamic polarization, linear polarization, open circuit potential, and weight loss measurements were performed. The surface of samples was examined using SEM and optical microscopy. Elemental characterization of the coating by secondary ion mass spectrometry indicates an intermediate layer between coating and aluminum alloy surface. The corrosion behavior of the aluminum alloy AA7075 depends on chloride concentration and pH of solution. In acidic or neutral solutions, general and pitting corrosion occur simultaneously. On the contrary, exposure to alkaline solutions results in general corrosion only. Results further reveal that aluminum alloy AA7075 is susceptible to pitting corrosion in all chloride solutions with concentrations between 0.05 M and 2 M NaCl; an increase in the chloride concentration slightly shifted both the pitting and corrosion potentials to more active values. Linear polarization resistance measurements show a substantially improved corrosion resistance value in case of samples coated with PTMS as compared to uncoated samples in both neutral (pH = 7), acidic (pH = 0.85 and 3), and alkaline chloride solutions (pH = 10 and 12.85). The higher corrosion resistance of the aluminum alloy coated with PTMS can be attributed to the hydrophobic coating which acts as a barrier and prevents chloride ion penetration and subsequent reaction with the aluminum alloy.     

AZ91镁合金表面稀土转化膜的制备及耐蚀性能研究

采用在镁合金表面形成无毒、无污染的稀土铈转化膜的方法解决AZ91镁合金表面的腐蚀问题。确定了最佳成膜工艺参数，讨论了处理液的浓度、成膜温度和成膜时间等因素对转化膜耐蚀性的影响。利用湿热实验、阳极极化曲线的测定等实验方法评价了转化膜对镁合金表面的防护作用。结果表明，在潮湿温热条件下稀土铈转化膜试样仍能保持膜层的完整性并具有较高的覆盖度，腐蚀现象不明显。腐蚀电势升高，出现钝化现象，腐蚀电流密度下降，稀土铈转化膜可以提高AZ91镁合金的耐蚀性能。用扫描电镜观察了膜的微观形貌，稀土铈转化膜是由基膜和附着的细小颗粒组成，最佳工艺形成的铈转化膜无破碎现象，对AZ91镁合金表面的腐蚀过程的发生有明显的抑制作用。