1,721,314 research outputs found
Electrodeposition of Ni-P alloy coatings: a review
No full textNi[sbnd]P coatings are extensively employed in engineering, owing to their mechanical and tribological properties which confer protection against corrosion and wear. Classically, such deposits can have a thickness of <500 μm, although there is a trend to thinner coatings to achieve faster deposition and lower costs. Depending on their composition and structure, as-plated deposits demonstrate good mechanical, tribological and electrochemical features, catalytic activity but also beneficial magnetic characteristics. Following thermal treatment, the hardness of Ni[sbnd]P metal deposits can approach or exceed that of hard Cr coatings. This paper provides a general survey of research on the electrodeposition of Ni[sbnd]P binary alloy coatings. Proposed phosphorus incorporation mechanisms, Ni[sbnd]P alloy microstructure before and after thermal treatment. Mechanical, tribological, corrosion, catalytic and magnetic properties are considered, as are the key process variables influencing the phosphorus content of deposits and the roles of the major electrolytic bath constituents. The merits of employing pulse plating and fabrication of newer (layered and functionally graded)structures are concisely explored. Interaction of four aspects: substrate state, electrolyte composition, process conditions and deposit properties is seen to be important during electrodeposition of Ni[sbnd]P alloys; areas deserving further study are identified.</p
Electrodeposition of Ni-P composite coatings: a review
No full textNi-P coatings produced by electrodeposition have important mechanical, tribological and electrochemical properties. They can also exhibit catalytic activity and beneficial magnetic behaviour. With subsequent thermal treatment, the hardness of such Ni-P coatings can approach or exceed that of hard Cr coatings. Electrochemical codeposition of homogeneously dispersed second phase particles within the Ni-P matrix can enhance deposit properties and meet the challenging demands on modern engineering coatings. A general overview of research work on the electrodeposition of Ni-P composite coatings containing included ceramic or polymeric particles is provided. Advances in research into Ni-P composite layers reinforced by SiC, B4C, WC, Al2O3, SiO2, TiO2, CeO2, MWCNT, MoS2, WS2, TiN, hexagonal BN, PTFE and their combinations are considered. Major models proposed for the codeposition of particles, the influence of bath hydrodynamics and control of operational parameters are illustrated by examples. Important trends are highlighted and opportunities for future R & D are summarised
Data for Electrodeposition of platinum on titanium felt in a rectangular channel flow cell
No full textHighly porous platinised titanium substrates are attractive electrode materials for industrial electrochemical processing and electrochemical energy storage. The electrodeposition of platinum on titanium felt was carried out in a divided, rectangular channel flow cell from an alkaline bath without additives. The morphology and spatial distribution of the platinum deposits in the porous material were analysed using SEM and EDS microscopy in addition to X-ray computed tomography (CT). The electroplated surface area was estimated from the charge transfer current ratio for Ce(IV) reduction and related to a theoretical electrosorbed hydrogen monolayer surface area. The platinised titanium felt showed a significant enhancement of active surface area in comparison to conventional electrode materials. Although platinum was present throughout the porous electrode, CT revealed heterogeneous deposits accumulating in regions near the membrane (during electrodeposition), as a result of the potential distribution in the felt material and flowing electrolyte. Uniform platinum coatings are possible on thin titanium felt under 200 µm thick, by either potentiostatic or galvanostatic electrodeposition.
Data for the paper Arenas Martinez, Luis, Ponce De Leon Albarran, Carlos, Boardman, Richard and Walsh, Frank (2016) Electrodeposition of platinum on titanium felt in a rectangular channel flow cell. Journal of The Electrochemical Society, 164, (2), D1-D10. (doi:10.1149/2.0651702jes)</span
The continued development of multilayered and compositionally modulated electrodeposits
No full textTraditionally, electroplating has involved the continuous deposition of a single layer of metal at constant current. However, electrodeposition of alternate layers can offer benefits such as reduced wear, improved corrosion resistance and higher tensile strength. The alternate layers can involve different morphology or thickness of metal, different metals or the alloy composition of layers with and without included particles. In the case of a single bath, electrocrystallisation is continuous but layers can be tailored to have different chemical composition, phase composition, morphology and microstructure. The composition of layers can also be systematically modified in a gradient fashion. The thickness of each metal layer can vary from >20 μm down to ≈1 nm; in the case of nanometre thick layers, up to 500 layers of 1 nm thick individual layers might be involved. Compact multilayer deposition from a single bath is often achieved by applying a potential waveform in the laboratory or pulsed current in industry. While multilayer electrodeposition is going through a phase of rediscovery, growth and diversification, the field can be traced back to a patent involving Cu–Ni multilayers, in 1905. Progress in multi-layered electrodeposition has made use of contemporary trends in electroplating research, including self-assembled layers, nanowire arrays and the use of deep eutectic solvents for electrolytes. The developing uses of multilayer deposits are seen to span industries as diverse as wear and corrosion resistant coatings, tool bits and heavy engineering. Speciality uses include electronic, optical and magnetic materials as well as catalytic electrode surfaces for electrochemical technology. Recommendations are made for topics which deserve further R & D.</p
Dataset for Current distribution in a rectangular flow channel manufactured by 3D-printing
No full textThe characterization and improvement of a rectangular channel electrolyte flow compartment used in an iron-air flow battery was carried out by using an arrangement of copper electrodes to measure the current density distribution employing the limiting current technique. The present work addresses the hydrodynamics and mass transport distribution in the compartment and their improvement by an improved electrolyte compartment that results in a more uniform current distribution. The current distribution was evaluated as the ratio between the local and the averaged limiting current densities during the reduction of copper ions over a range of mean linear flow velocity across the electrode surface (2-30 cm s-1).
The initial compartment, showed larger differences between the minimum and maximum currents than the electrolyte compartment that resulted as part of the design process and showed a higher pressure drop at a given mean linear flow velocity.
This data supports the publication:
Figueredo Rodriguez, Horacio, Mckerracher, Rachel, Ponce De Leon Albarran, Carlos and Walsh, Frank (2016) Current distribution in a rectangular flow channel manufactured by 3D-printing. AIChE Journal , 1-35. (doi:10.1002/aic.15454).</span
Composite, multilayer and three-dimensional substrate supported tin-based electrodeposits from methanesulphonic acid
No full textTin and tin–alloy deposits enjoy many applications in the electronics, tribology and engineering industries with potential applications as electrodes for lithium batteries and as electrocatalyst coatings. Methanesulphonic acid (MSA) has become a favoured electrolyte due to its environmental benefits and ability to offer a vehicle for many metal alloy, conductive polymer and composite coatings. A number of emergent uses require less common compositions or structures of alloy, polymer or composite deposits. This paper concisely provides diverse examples of modern tin-containing deposits from aqueous MSA, including Sn–Cu alloys having a very wide composition together with a wide range of colours (golden-yellow–dark-brown) and surface finishes, a Sn–Cu composite deposit containing ceramic, protonated titanium oxide nanotubes for batteries, a tin–copper–bismuth ternary alloy and tin deposits supported on an inert reticulated vitreous carbon or carbon felt substrate to provide a porous, three-dimensional tin surface for electrocatalysis and batteries. The importance of controlled current distribution and electrode/electrolyte movement is illustrated by the use of the rotating disc electrode, rotating cylinder electrode and rotating cylinder Hull cell
Electrodeposited Co-P alloy and composite coatings: A review of progress towards replacement of conventional hard chromium deposits
No full textHard chromium coatings have attracted much attention due to their strong tribological and corrosion performance. There is a global need to replace such coatings in industrial applications owing to technical problems, environmental concerns and legislation. Co-P electrodeposits are a promising alternative to hard chromium in a variety of engineering applications due to their appreciable microhardness and high corrosion resistance. Attractive magnetic, tribomechanical and electrical properties are evident together with excellent thermal stability. Environmentally acceptable process conditions may be used which allow controlled deposition on diverse workpieces across a wide scale. This review provides an overview of the influence of operational parameters, including type of current control, electrolyte composition, pH, current density and electrolyte agitation on the physicochemical and mechanical characteristics of the deposits. The incorporation of ceramic particles into Co-P electrodeposits to produce tailored composite coatings is also considered. An insight is given into the development of next generation alloy and composite deposits to replace hard chromium deposits from acidic Cr(VI) baths. Diverse applications for Co-P electrodeposits are considered and topics deserving further R & D are highlighted
Effective particle dispersion via high-shear mixing of the electrolyte for electroplating a nickel-molybdenum disulphide composite
No full textThe hydrophobic nature of molybdenum disulphide (MoS2) particles is a major challenge for electrodepositing uniform Ni- MoS2 composite coatings due to particle agglomerates present in the aqueous nickel plating bath. In this study, high-shear mixing was shown for the first time as a facile and effective way to achieve a narrow particle-size distribution and stable particle dispersions in the electrolyte, which were characterised by measuring particle-size distributions via dynamic light scattering. The influence of shear mixing duration and speed on particle dispersion in the electrolyte was investigated. The resulting Ni-MoS2 composite coating had a compact structure, showing a lower coefficient of friction and enhanced wear resistance in unlubricated wear tests. In comparison, magnetic stirring was less effective in breaking down particle agglomerates in the bath, which led to a porous and fragile deposit with poor tribological properties
Alternative tribological coatings to electrodeposited hard chromium: a critical review
No full textThe traditional importance of hard chromium electroplating in surface engineering is recognised and the key features of this well-established technology are summarised. Despite the high hardness, corrosion protection and wear resistance of chromium electrodeposits, a number of alternative coating compositions and application techniques have been developed for specific applications in tribology. Environmental challenges associated with hard chromium electroplating are highlighted and the need to develop and evaluate alternative coatings is stressed. Key examples of the alternative coatings are described, including their method of application, microstructure and tribological performance in controlled service environments. Research needs requiring rapid development are highlighted. A summary is given of the most competitive coatings and those having the potential to match the performance of hard chromium in selected applications are identified
Kinetics of alkali metal ion exchange into nanotubular and nanofibrous titanates
No full textThe kinetics of intercalation of Li+, Na+, K+ and Cs+ cations between the layers of titanate nanotubes and nanofibres have been studied in an aqueous suspension of nanotubes at 25ºC. The rate of intercalation was found to be similar for different cations and depended on the length of the nanotubes. The decrease in nanotube length resulted in a higher rate of ion-exchange, indicating that the transport of cations in titanate nanotubes occurred probably along their length. In contrast, the transport of cations in titanate nanofibres probably dominated in the direction perpendicular to length. Correlations between the rate of intercalation and the crystal structure modification following intercalation have been established for nanotubular and nanofibrous titanates
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