非晶态镍—钨—磷合金电沉积层的组织结构及耐蚀性

非晶态镍－钨－磷合金镀层由于具有优良的耐蚀性而被广泛用作材料的防护处理。采用扫描电子显微技术、Ｘ射线衍射分析及腐蚀介质浸泡试验研究了镍－钨－磷合金电镀层的组织结构,成分及耐蚀性。试验发现,所得合金镀层呈非晶态。进行热处理,当温度达３００℃以上时,镀层开始由非晶态向晶态转化;当加热至４００℃以上,镀层已完全转变为晶态结构,腐蚀试验发现,镍－钨－磷合金镀层在８５％Ｈ３ＰＯ４、１０％Ｈ２ＳＯ４、２０％Ｈ     

钨对化学镀Ni-W-P合金镀层结构及性能的影响

通过不同的化学镀工艺配方,获得了4种不同钨含量的化学镀Ni-W-P三元合金镀层.研究了钨含量对镀层结构、硬度及在5%H2SO4溶液中耐蚀性的影响规律.研究发现,化学镀Ni-W-P三元合金镀层的结构受镀层中钨含量的影响较大,非晶态Ni-W-P三元合金镀层所需磷含量较非晶态Ni-P二元镀层所需磷含量要低,并且钨含量越高,所需磷含量越少;镀层硬度随镀层结构从非晶态→混晶态→纳米晶态转变而增加;镀层的耐蚀性随镀层中钨含量增加而变好,且非晶态镀层较混晶态和纳米晶态镀层更易形成钝化区.     

NdFeB永磁体化学镀Ni-Cu-P合金的研究

在NdFeB永磁体表面化学镀Ni-Cu-P合金镀层,研究了镀液配方对镀层性能的影响。结果表明:镀层表面形貌呈致密的胞状结构,Ni,Cu,P元素分布均匀;随着镀层中Cu和P的质量分数的变化,镀层结构分别由晶态、混晶态和非晶态组成;晶态镀层的硬度最高、结合力最好,非晶态镀层的耐蚀性最好。     

化学镀Ni-P与Ni-Mo-P合金镀层的耐蚀性能

研究了镀层结构(非晶态、晶态)以及Mo、P含量对化学镀Ni-P和Ni-Mo-P合金镀层在0.5MH2SO4溶液中的耐蚀性能的影响。结果表明:在相同合金镀层下,非晶态镀层具有较晶态镀层更好的耐蚀性能;镀层中Mo、P等元素的含量对镀层的耐蚀性能有着较大影响,其中P(非晶化元素)的影响最大。     

代铬镀层--Ni-W、Ni-W-B非晶态合金镀层性能研究

通过在浓硝酸、ω=5％NaCl溶液c=1mol/L H2SO4溶液中的浸渍试验,研究了不同基体上的Ni-W非晶态合金镀层的耐蚀性;通过测定在ω=5％ NaCl溶液及c=1mol／1．的HNO3溶液、H2SO4溶液、HCl溶液中的阳极极化曲线,研究了Ni-W非晶态合金镀层薄膜本身的耐蚀性;采用线性极化方法对Ni—W—B非晶态合金镀层在u=5％ Na—Cl溶液、c=1mol／L H2SO4溶液及HNO3溶液中的腐蚀速度进行了测定,并测定了以上2种非晶态合金镀层的硬度与耐磨性.结果表明．非晶态的Ni—W、Ni-W-B镀层比晶态镀层的耐腐蚀性能要好．而Ni—W—B非晶态合金镀层比Ni—W非晶态合金镀层的耐蚀性能又明显提高;经热处理后,Ni—W—B非晶态镀层的硬度值明显高于Ni—W非晶态镀层,耐磨性能都提高了1倍以上Ni—W、Ni—W—B非晶态镀层极有望成为一种比较好的代铬镀层。     

高磷非晶态镍磷合金镀层的研究

化学镀镍磷合金镀层由于其非晶态结构而具有优异的性能。本文通过使用一种亲型的添加剂，获得了磷含量为10％－40％的高磷非晶态合金镀 镀层。实验结构表明：（1）镀层中磷含量随着添加剂含量的增加而提高；（2）高磷合金镀层当磷含量控制在10％－15％时，在酸性介质中具有优异的耐蚀性能；（3）镀层中磷含量高，屏蔽性能好。     

机械结构钢表面三种化学镀层的性能比较

在40Cr钢表面分别制备了化学镀Ni-P合金镀层、化学镀Ni-Co-P合金镀层和化学镀Ni-P/SiC复合镀层。观察了三种化学镀层的形貌和微观结构,并测试了三种化学镀层的显微硬度、磨损量和摩擦因数。结果表明:三种化学镀层的表面质量整体较好,都呈胞状形貌;当衍射角2θ为45°左右时,三种化学镀层的XRD谱图中都出现了明显的漫散射峰,三种化学镀层都为非晶态结构;三种化学镀层中,化学镀Ni-Co-P合金镀层的显微硬度最高,耐磨性最好。     

Ni-W镀层的非晶化机制

用电沉积法制备Ni－W非晶态镀层。随着镀层中钨含量的增加，Ni－W合金镀层结构由晶态向非晶态转变。x射线光电子能谱分析结果表明，Ni－W非晶态镀层中Ni、W均以零价态形式存在，没有形成金属间化合物。     

柠檬酸对Ni-P合金化学镀沉积速度和镀层性能的影响

研究了柠檬酸浓度对乙酸盐缓冲体系Ni-P合金化学镀沉积速度、镀层含磷量及其耐蚀性与结构的影响，并对镀层在镀态下和经热处理后的耐蚀性与结构进行了比较。结果表明，随柠檬酸浓度的增加，沉积速度先增加后l牵低，而镀层中磷含量则先降低后增加；镀态时高磷合金为非晶态结构且具有较好的耐蚀性，中磷合金则为非晶 微晶结构，耐蚀性较低，而所有镀层经350℃热处理1h后，结构都转变为晶态，且耐蚀性明显提高。     

Ni-Co-P/SiC纳米复合粉体化学镀机理及其电磁性能

以SiC为原材料,以KNaC4H4O6为络合剂、(C2H3O2)2Pb为稳定剂,用化学镀方法,在Ph 9～10,65℃条件下,将纳米SiC表面处理制得Ni-Co-P/SiC纳米复合粉体.用X射线衍射及能谱分析了镀层的组成并提出了其化学镀机理.用波导法测定了Ni-Co-P/SiC复合粉体的电磁参数,用振动样品磁强计测试了样品的磁性能.结果表明:Ni-Co-P/SiC颗粒表面的Ni-Co-P镀层由非晶态Ni-Co-P及微晶态α-Co,500℃热处理后该表面镀层转化为晶态的Ni3P,Ni和β-Co.当Ni2 与Co2 的摩尔比为0.88,H2PO2-与(Ni2 Co2 )的摩尔比为0.95时,镀液有足够的还原能力和良好的稳定性,Ni-Co-P镀层有较高矫顽力和较好的电磁参数,此时SiC颗粒表面Ni和Co的质量分数分别为9.4%和11.5%.     

Microstructure and corrosion behavior of electroless Ni�CP coatings on 6061 aluminum alloys

The microstructure and corrosion behavior of electroless Ni–P alloy plating on 6061 aluminum alloys substrate in an alkaline plating bath with sodium hypophosphite as reducing agent were investigated. The effects of bath temperature on the plating rate, compositions, and microstructure of the electroless Ni–P deposits were studied. The results showed that the deposition rate and the P content of the electroless Ni–P deposits increased with the rise of the bath temperature. Scanning electron microscopy (SEM) of the deposits showed nodular structure for binary deposits. X-ray diffraction patterns of all the deposits revealed a single and broad peak which indicated the amorphous structure of the deposits. Corrosion resistance of the Ni–P coatings was evaluated by potentiodynamic polarization. The results indicated that electroless Ni–P plating could obviously improve the corrosion resistance of 6061 aluminum alloy.     

The anodic polarization behavior of amorphous PdTiP alloys in NaCl solutions

The corrosion resistance and electrocatalytic activity for chlorine evolution of amorphous PdTiPalloys in NaCl solutions was investigated. Particular attention was given to the difference between amorphous and crystalline states and the effect of titanium addition. The corrosion rate of the amorphous alloys in the potential region for gas evolution was significantly lower than that of palladium over wide ranges of polarization potential and pH of solutions. This fact was attributed to the formation of a uniform passive film on the amorphous alloys and to the stabilization of passivity by the addition of titanium. The catalytic activity of the amorphous alloys for gas evolution was lower than that of palladium and decreased with an increase in titanium conten-t. The oxygen overvoltage of amorphous PdTiP alloys is considerably higher similarly to that of palladium     

Electrochemical characterization of Ni–P and Ni–Co–P amorphous alloy deposits obtained by electrodeposition

Ni–P and Ni–Co–P amorphous alloy deposits were obtained by electrodeposition at 80 °C on carbon steel substrates. The influence of the electrolyte Co²⁺ concentration and of applied current density was investigated. The corrosion behaviour of amorphous and crystalline deposits was evaluated by polarization curves and electrochemical impedance spectroscopy in NaCl 0.1 M solution at room temperature. Impedances were measured for samples under total immersion (free potential against time) and for polarized samples in predefined regions of the polarization curves. It was found that the alloy deposit composition is highly affected by the composition of the electrolyte but displays no significant dependence on applied current density. The results showed that the presence of Co on Ni–P amorphous alloys improves the deposit performance in the studied corrosive medium. It was also verified that the amorphous structure provides higher corrosion resistance to both Ni–P and Ni–Co–P alloys.     

镁合金化学镀镍工艺的研究

采用硫酸镍为主盐、次磷酸钠为还原剂,并在镀液中加入氟化物和稳定剂,研究了镁合金的化学镀镍工艺.运用正交试验分析了镀液中各主要组分对镀速及耐蚀性等影响,优选化学镀最佳工艺.该工艺沉积速率快,镀层耐蚀性优异.运用X-射线衍射方法对镀层的组织结构进行了分析,结果表明,镁合金化学镀镍层由非晶态的镍及部分微晶的镍组成.     

Microstructural characterization and corrosion resistance of Ni–Zn–P alloys electrolessly deposited from a sulphate bath

Electroless Ni–Zn–P alloy coatings were obtained on an iron substrate from a sulfate bath at various pH values. The effects of changes in bath pH on alloy composition, morphology, microstructure and corrosion resistance were studied. Scanning electron microscopy was performed to observe the morphological change of the deposits with bath pH. Coating crystallinity was investigated by grazing incidence asymmetric Bragg X-ray diffraction and transmission electron microscopy. A transition from an amorphous to polycrystalline structure was observed on increasing the bath alkalinity, and thus decreasing the phosphorus content of the alloys. A single crystalline phase corresponding to face-centred-cubic nickel was identified in the alloys obtained from a strong alkaline solution. An increase in zinc percentage up to 23% in the deposits does not change the f.c.c. nickel crystalline structure. Corrosion potential and polarization resistance measurements indicated that the corrosion resistance of electroless Ni–Zn–P alloys depends strongly on the microstructure and chemical composition. The deposits obtained at pH 9.0–9.5 and with 11.4–12.5% zinc and 11.8–11.2% phosphorous exhibited the best corrosion resistance.     

Electroplating of antimony and antimony-tin alloys

The electroplating of antimony from KSb(OH)₆ and antimony-tin alloys from mixtures of KSb(OH)₆ and Na₂Sn(OH)₆ onto steel substrates has been investigated under variable plating conditions. The influence of added tartaric acid, current density and temperature on cathodic potentials, cathodic current efficiencies, appearance of the deposits and chemical composition of the alloys has been studied. X-ray diffraction analysis has showed that amorphous or hexagonal antimony deposits are produced from solutions free from or containing tartaric acid. The alloy deposit (56% antimony) was produced in rhombohedral crystal structure. Fine-grained, highly adherent and dark-greyish deposits of antimony and antimony-tin alloys were plated in most cases.     

Electrolytic oxygen evolution on Ni-Co-P alloys

Electrolytically obtained Ni–Co–P alloys exhibit amorphous structure. On heating these alloys to 773 K crystalline nickel and cobalt phosphide phases, and also nickel crystallites, are formed. After cathode-anode polarization of the amorphous and crystalline Ni–Co–P alloys in 5m KOH for 18 h, oxygen-cobalt compounds together with crystalline or amorphous nickel phosphides appear on the electrode surface. The evolution of oxygen from 5m KOH was studied on Ni–Co–P alloys prepared in this way. The Tafel parameters were determined and it was ascertained that the values of directional coefficients of the Tafel lines are comparable with those obtained for spinel NiCo₂O₄ oxides, while calculated values of the exchange currents for the oxygen evolution reaction are dependent on the chemical composition of the alloy. The rate of electrolytic oxygen evolution is virtually identical for amorphous and crystalline Ni–Co–P alloys of the same chemical composition. The highest rate of oxygen evolution was found for the alloy containing 15–20% Ni, 66–73% Co and 12–14% P.     

磷质量分数对镁合金化学镀镍层结构及性能的影响

采用直接化学镀的方法在AZ91D镁合金上化学镀镍,通过改变镀液pH获得不同磷质量分数的镀层,研究了磷质量分数对镀层结构、硬度、耐磨性和耐蚀性的影响。结果表明:随着磷质量分数的降低,镀层结构由非晶态向晶态转变;镀层硬度比AZ91D镁合金基体提高了5～6倍;磷质量分数为2.4%的低磷镀层,具有很好的耐蚀耐磨性能。     

The electrodeposition of Mn and Zn-Mn alloys from the room-temperature tri-1-butylmethylammonium bis((trifluoromethane)sulfonyl)imide ionic liquid

Zinc, manganese and zinc-manganese alloys were electrodeposited from the hydrophobic room-temperature ionic liquid, tri-1-butylmethylammonium bis((trifluoromethane)sulfonyl)imide. Zn(II) and Mn(II) species needed to produce these alloys were introduced into the ionic liquid by the anodic dissolution of the respective metallic electrodes. The diffusion coefficients of the dissolved Zn(II) and Mn(II) species are not constant, but decrease with the increasing concentrations of these ions, suggesting the formation of aggregated species at higher concentrations. Coatings containing Zn, Mn or Zn-Mn can be obtained by controlled-potential electrolysis. The current efficiencies of Mn electrodeposition in this ionic liquid approach 100%, which is a high improvement comparing to the results obtained in aqueous solution (20-70%). The Mn/Zn ratio of these alloys depended almost completely on Mn(II)/Zn(II) concentration ratio in the ionic liquid. The Zn-Mn alloy deposits obtained in this study were compact, adherent, and exhibited an amorphous structure. The surface morphology of these deposits depended on the Mn/Zn ratio. The addition of Mn up to about 50 a/o improves the corrosion resistance of Zn. However, the addition of Mn beyond this amount decreases the corrosion resistance of the Zn-Mn alloy.