Electrodeposition and corrosion resistance of Ni-W-B coatings

A ternary nickel-base alloy Ni-W-B has been developed for surface corrosion and wear resistance to replace chromium plating, which uses environmentally hazardous solutions. The deposition conditions used an alkaline bath and insoluble anodes. The as-deposited alloy typically contains 40 wt % W and 1 wt % B and has an amorphous or partially amorphous structure. These deposits compare favorably with hexavalent chromium deposits in throwing power, color uniformity, and reflectivity. The corrosion resistance of Ni-W-B alloy was compared with hexavalent chromium and electroless nickel deposits in a variety of acids, including hydrochloric, sulfuric, fluoroboric, and phosphoric. In all cases, best results were obtained with the Ni-W-B deposits.     

Electrodeposition of bismuth from a trilon B-sulfosalicylate bath

Bismuth electrodeposition from baths containing bismuth nitrate, trilon B (disodium ethylenediaminetetraacetate Na₂H₂Edta), and sulfosalicylic acid H₃SSA was studied with various ratios of the bath components. Adding H₃SSA to the bath made the deposit become semibright and its current efficiency enhance. Original Russian Text ? T.P. Petrova, K.V. Zelenetskaya, I.F. Rakhmatullina, M.S. Shapnik, 2006, published in Zashchita Metallov, 2006, Vol. 42, No. 4, pp. 393–398.     

Electrodeposition of copper-zinc from an alkaline bath based on EDTA

The electrodeposition of copper-zinc on 1010 steel from a non-cyanide alkaline electrolyte based on EDTA (ethylenediaminetetraacetic acid, disodium salt) — alkaline with various proportions of copper and zinc ions, was investigated. The complexation of copper and zinc by EDTA stabilized the solution. The deposition potential and the composition of the Cu-Zn bath were shown to influence the composition, morphology and phase composition of the Cu-Zn deposits. Scanning electron microscopy analysis showed that the best conditions to obtain smooth Cu-Zn deposits were at − 1.45 V, with Cu70-Zn30 and Cu50-Zn50 baths, and at − 1.60 V, with Cu30-Zn70. Besides being smoother than others, these deposits were golden in colour. Energy-dispersive X-ray spectroscopy analysis showed that a Zn content above 60 wt.% in the Cu-Zn deposits was achieved from the last bath, at − 1.45 V. X-ray diffractograms of the Cu-Zn deposits produced at -1.45 V, from Cu70-Zn30, Cu50-Zn50 and Cu30-Zn70 baths, indicated the occurrence of phases Cu_0.61Zn_0.39 and Cu, CuZn, Cu₅Zn₈ and Cu, CuZn, Cu₅Zn₈, CuO, Cu_0.61Zn_0.39, respectively. For the Cu30-Zn70 bath at − 1.60 V, Cu, CuZn, Cu₅Zn₈, and CuO phases were observed.     

Electrodeposition of NiFe/Cu multilayers from a single bath

NiFe/Cu multilayers were deposited from a single bath in the potentiostatic mode using two different solutions. In solution A, the ionic concentration ratios were Fe²⁺: Ni²⁺: Cu²⁺ 9: 60: 10 and in solution B they were 1: 103: 1. To characterize the layers, scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and atomic force microscopy (AFM) were used. SEM results revealed the layered structure of the deposits for relatively thick bilayers. While HRTEM provided direct evidence for the composition modulation across successive layers in the NiFe/Cu nanometer-multilayered structure prepared from solution B. Therefore, the layers prepared from solution B seemed to be more appropriate for giant magnetoresistance (GMR) applications. The effect of stirring during the electrodeposition process of the multilayers was also investigated.     

Electrodeposition of chromium from trivalent chromium urea bath containing sulfate and chloride

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The mechanical properties of in-situ composites

Because in-situ composites offer such a wide selection of reinforcement types, size, and volume fractions, understanding the mechanisms controlling mechanical properties will allow more intelligent decisions to be made when tailoring a composite system for a specific application. This article provides an overview of the mechanical properties of discontinuously reinforced metal-ceramic and intermetallic-ceramic composites produced by in-situ techniques. Systems for which the mechanisms controlling mechanical properties are known are emphasized. Editor’s Note: A hypertext-enhanced version of this article can be found at http://www.tms.org/pubs/journals/JOM/9708/Aikin-9708.html. Robert M. Aikin, Jr., earned his Ph.D. in metallurgical engineering at Michigan, Technological University in 1987. He is currently an associate professor at Case Western Reserve University. Dr. Aikin is also a member of TMS.     

Microstructure and mechanical properties of SiC-nanowire-augmented tungsten composites

The effect of an addition of SiC nanowire on the microstructure and mechanical properties of tungsten-based composites is investigated in this study. SiC-nanowire-augmented tungsten composites were prepared by a spray-drying process and an in situ spark plasma sintering process. Three distinctive reaction phases, tungsten, tungsten carbide (W₂C) and rod-type tungsten silicide (W₅Si₃) were formed during the sintering process. The flexural strength was significantly increased from 706 MPa to 924 MPa in tungsten composites augmented with SiC nanowires, as was the formation of W₂C and W₅Si₃ phases. The rod-type W₅Si₃ bears significant stress by both sharing a portion of the load and providing a bridging mechanism. Furthermore, a high ablation resistance at an elevated temperature was observed for tungsten composites augmented with SiC nanowires.     

Electrodeposition and characterization of zinc-cobalt alloy from chloride bath; influence of coumarin as additive

Zinc-cobalt alloys were electrodeposited from chloride bath under continuous current and in the presence and absence of coumarin. The deposit morphology was analyzed using Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) was used to determine the preferred crystallographic orientations of the deposits. Zinc-cobalt alloys was without texture in the absence of coumarin whereas, the preferred crystallographic orientations was (103) at 65% in the presence of coumarin. The presence of coumarin yields deposits with a finer grain size. The alloy composition was examined using the Energy Dispersive X-ray Fluorescence Spectroscopy (EDXRF). The percentage of cobalt in the alloy decreases from 1.04 wt.% to 0.69 wt.% in the presence of coumarin. Voltammetric studies show that coumarin affects the reduction of zinc but it was without effect on cobalt reduction. That explains the decrease of cobalt percentage in the alloy in the presence of coumarin.     

Microstructure and mechanical properties of Al-Fe-V-Si/SiCp composites

The characteristics of microstructures and mechanical properties of the multi-layer spray deposited SiCp/A1-6.SFe-0.6V-1.3Si, SiCp/A1-8.SFe-1.3V-1.7Si and SiCp/Al-10Fe-1.3V-2Si composite sheets obtained by rolling after extruding were investigated. The evolution of the grain and phases of these composites during processing were examined, and the influence of the microstructures on the mechanical properties was analyzed. The experimental results show that the ultimate tensile strengths σb of the three kinds of composite sheets are 420, 535, 470 MPa respectively at room temperature, and 232, 285, 300 MPa at 315℃ and 148, 180, 200 MPa at 400 ℃. The excellent mechanical properties can be attributed to the high solid solubility, fine grain size, Al12（Fe,V）3Si precipitation particles and the SiC particles. And the composition of the matrix alloy has an obvious effect on the mechanical properties of the as-rolled sheets.     

HA/UHMWPE复合材料的微观组织及力学性能

采用机械球磨法对羟基磷灰石(HA)/超高分子量聚乙烯(UHMWPE)粉末进行混合处理,通过热压将混合粉末制成复合材料.通过X射线衍射、SEM观察及力学性能测试对混合粉末及复合材料进行微观组织和力学性能的分析.结果表明:球磨使HA颗粒得到了细化,而UHMWPE有粗化的趋势,同时HA/UHMWPE混合粉末组织更加均匀.球磨后HA没有发生分解,也没有新的物质产生.复合材料断面形貌呈网状结构,球磨时间越长,这种网状组织越均匀.随着球磨时间的增加,HA/UHMWPE复合材料的拉伸强度、冲击强度呈上升趋势.经球磨时间40 h后的复合材料具有较好的综合力学性能,同时又具有较理想的微观组织.     

Electrochemical studies of Zn-Ni alloy coatings from non-cyanide alkaline bath containing tartrate as complexing agent

The Zn-Ni alloys have been electro-deposited from a non-cyanide alkaline bath containing tartrate as a complexing agent for Ni²⁺ ions. A water soluble polymer is used as a brightener. It was prepared by the reaction of epiclorohydrin with hexamethylenetetramine and mercaptobenzimidazol. Its effect on co-deposition process was examined. It was found that adding brightener in plating bath has a great effect on the cyclic voltammogram and galvanostatic measurements during the electrodeposition. Under the examined conditions, the electrodeposition of the alloys was of anomalous type. X-ray diffraction measurements revealed that the alloys consisted δ-phase (Ni₃Zn₂₂). The composition and morphology of the deposits were also studied by using scanning electron microscopy (SEM) and energy dispersive analysis X-ray (EDAX), respectively. The effect of optimum plating bath conditions on the corrosion resistance is studied by Tafel polarization.     

Fabrication and mechanical properties of FeAl/TiC composites

1　INTRODUCTIONOver the past few decades, considerable inves tigations have been carried out to identify alterna tive binders for cermets in order to improve theirmechanical properties and also to overcome certainshortcomings, such as high cost and density, lowoxidation and corrosion resistance, and environ mental toxicity[1, 2]. Iron aluminides are of particu lar interest due to their low cost and density, highspecific strength, environmental friendliness andexcellent oxidati…     

Microstructure and mechanical properties of iron-containing titanium metal-metal composites

Titanium-based metal-metal composites show promises in many applications. In this work, iron-containing titanium-based composites were fabricated by using powder metallurgy method and rotary swaging process. Titanium-based composites with steel addition were sintered at temperature below TiFe eutectic temperature. Increase of the steel addition to 23% resulted in formation of TiFe intermetallic and density decrease in the composites. Further, the as-sintered composites present relatively good workability so hot rotary swaging of the as-sintered composites can be conducted. Steel particles were diffused into the Ti matrix and the composite transformed to a discontinuous β-Ti fiber-reinforced structure. As a result, mechanical properties (in axial direction) of the swaged composites were significantly improved. The tensile strength and elongation reached 1360 MPa and 9.3%, respectively.     

Process and properties of electroless Ni-W-B amorphous electrical resistance film

The process and properties of electroless plating Ni-W-B alloy have been studied. The results show that the deposits containing W and B are obtained, and the deposition rate of the bath is increased with increase of W content when a certain amount of sodium tungstate solution is added in the Ni-B bath. The Ni-W-B alloy is amorphous as deposition and its resistivity increases directly with the increase of W content in the coating, but decreases gradually with increasing the deposit thickness. XRD and SEM show that the distributions of W and B in the Ni-W-B alloy film are very uniform and dispersed without any segregation.     

Electrodeposition of cerium oxide films and composites

Nanostructured CeO₂ films were prepared by cathodic electrolytic deposition (ELD) and electrophoretic deposition (EPD). Benzoic acid has been utilized for the dispersion and charging of CeO₂ nanoparticles for EPD. The kinetics of ELD and EPD was investigated. Electrodeposition method has been developed for the deposition of poly(2-vinylpyridine) (PVP) films. The thickness of the films was varied in the range of 0.1-3 μm. The deposition mechanism was based on the pH increase in the cathodic reactions, electrophoresis of the protonated PVP macromolecules, neutralization of their charge and film formation at the cathode surface. The deposition yield was studied by the quartz crystal microbalance method. Two electrochemical strategies were developed for the fabrication of composite PVP-CeO₂ films, which were based on the electrodeposition of PVP and ELD or EPD of CeO₂. The composite films were studied by electron microscopy, X-ray diffraction, thermogravimetric and differential thermal analysis. The CeO₂ content in the composite films was varied by the variation of bath composition. The deposition methods allowed the fabrication of crack-free PVP-CeO₂ films, which provided corrosion protection of stainless steel substrates in aqueous NaCl solutions.     

Microstructural and mechanical properties of cBN-Si composites prepared from the high pressure infiltration method

The grain size dependence of the mechanical properties of cBN-Si composites prepared using the high pressure infiltration method has been investigated. Indentation testing indicates that cBN-Si composites have hardness values of 38–43 GPa, which increase with increasing grain size and are harder than traditional polycrystalline cBN composites (PcBNs). Thermostability analyses display that cBN-Si composites with a grain size of > 9 μm also possess a higher temperature of oxidation, compared to traditional PcBNs, and the thermostability increases with increasing cBN grain size. Fracture toughness tests show that almost no cracks appear on the polished cBN-Si samples when the loading forces are increased to 294 N and the fracture toughness is better than for commercial samples. Scanning electron microscopy illustrates that deformations and close pores occurred easily between coarse BN grains, leading to denser cBN-Si compacts with better mechanical performances.     

Chemically deposited Ni-W-B coatings: Composition, structure, and properties

The effect of temperature and solution components of the chemical catalytic reduction on the composition of Ni-W-B alloy coatings is studied. The x-ray photoelectron spectroscopy in combination with the layer-by-layer profile analysis is used to determine the chemical state of elements and the composition of surface and bulk layers of the coatings containing 28 and 1.8 wt % (10 and 12 at. %) tungsten and boron, respectively. The surface of such coatings is shown to contain up to 90 and 80 at. % reduced nickel and boron, respectively. The deposits have amorphous structure. The effect of thermal treatment conditions on the structure and microhardness of the coatings is investigated. The coatings with a tungsten content of 10 at. % are shown to be nonmagnetic.Translated from Zashchita Metallov, Vol. 41, No. 1, 2005, pp. 61–68.Original Russian Text Copyright © 2005 by Drovosekov, Ivanov, Krutskikh, Lubnin, Polukarov.Presented at the 4th Session of All-Russian Conference on Corrosion and Electrochemistry (Ya.M. Kolotyrkin memorial), November 2003.     

石墨烯强化CuCr25合金的制备与性能

采用高压低温SPS烧结的新工艺制备了高硬度高电导率的CuCr25/石墨烯复合材料。X射线衍射(XRD)和拉曼分析(Raman)揭示石墨烯在新合金的制备过程中并未变性亦无新相产生,利用扫描电镜(SEM)以及能谱仪(EDS)进行形貌分析显示石墨烯在新合金中分散均匀。性能测试结果显示,在600℃,300 MPa条件下经SPS烧结后制得的CuCr25/石墨烯合金,与对比试验中采用相同工艺制得的未添加石墨烯的CuCr25合金相比,硬度提高了11.3%,电导率下降了4.2%;而与传统工艺制备的CuCr25合金相比,其电导率和硬度则分别提高了35%和48%,表明成分和工艺的改进对性能的提高均有贡献。     

非晶颗粒增强纯铝基复合材料的组织与性能

采用机械合金化制备了Al70Ni17Ti13非晶粉末,在450℃下采用无压烧结-热压工艺烧结制备了铝基复合材料,研究了不同含量的非晶粉末的加入对纯铝基复合材料显微组织及力学性能的影响。结果表明:复合材料的硬度随着增强体含量的增加逐渐增加,但其抗拉强度随着增强体含量的增加呈现出先上升后下降的趋势。复合材料的显微硬度由纯铝的46 HV0.01提高到195.3 HV0.01,效果显著。当非晶粉末颗粒体积分数为10%时,抗拉强度达到最大值为196.6 MPa,相比纯铝抗拉强度性能提升了113%。当非晶粉末颗粒体积分数为15%时,复合材料的耐蚀性能最佳。