Papers by Keyword: Composite Electrodeposition

Abstract: The concept and the primary preparation method of functional gradient materials are described in this paper. Functional gradient material is prepared as a tool electrode by electrochemical method and its performance is further tested in the micro electrical discharge machining (micro-EDM) experiments. Compared with the homogeneous material electrode, the functional gradient material electrode can effectively inhibit the wearing of the tool electrode and improve the distribution trend of current density during the micro-EDM process. The results disclose the prospects for functional gradient material to be used as tool electrode in the micro-EDM process.

Abstract: Zinc-nickel-SiO2 electrodeposits have been produced from an acid sulphate bath. Thecodeposition behavior of SiO2 and the homogeneity of platings were examined. The presence ofSiO2 nanoparticles in the plating bath appears to change the alloy deposition behavior. Rate ofnickel deposition was considerably decreased with SiO2 nanoparticles in the bath. The homogeneityof platings between zinc and nickel were improved by adding the SiO2 nanoparticles in the bath. Atan early stage of electrodeposition, it seems that the SiO2 nanoparticle acts as a nucleus of theprecipitation. The SiO2 nanoparticle has not uniformly dispersed in a plating film, but distributedonly in the SiO2 rich layer with about 50 nm in thickness formed beneath the surface. In addition,this SiO2 rich layer can improve the anticorrosive performance. Therefore, the zincic use can besuppressed, because film thickness can be more thinned, compared with zinc and zinc-nickel alloyelectroplating.

Abstract: Composite electrodeposition is one of the most important metallic material surface finishing technology and metal-based composite material preparation technology. Electric field and flow field are the two main influence factors during electrodeposition process of composite coatings. In this paper, numerical simulation of flow-field of zinc-silica composite electrolyte is finished by FLUENT software and the actual flow state is recorded by Particle Image Velocimetry (PIV). The research work is also focused on influence of current and stirring intensity on flow character of electrolyte. The electrolyte composition and plating conditions are: ZnCl₂ 80 g/L, KCl 220 g/L, H₃BO₃ 25 g/L, brightening agent 0.5 g/L, pH value of electrolyte 5.5, temperature 25°C, mass concentration of SiO₂ particles in electrolyte 1 g/L. The average particle size of SiO₂ particle is 11.07 μm. The stirring intensity is controlled between 0 and 3000 rpm, and current is controlled between 0 and 0.5 A. The results show that influence degree of stirring on flow field is much greater than current, and the numerical simulation of flow field finished by FLUENT software is approximately similar to the actual flow charactor recorded by PIV.

Abstract: The electrode(Ni-MWNTs) containing nickel(Ni) and multi-walled carbon nanotubes (MWNTs) was prepared by composite electrodeposit. Electrochemical hydrogen storage of the electrode was studied. The result showed a high electrochemical discharging capacity of up to 1361.1mA·h·g-1, which corresponds to a hydrogen storage capacity of 4.77Wt%(weight percent). Test of cyclic lifespan showed MWNTs had certain cyclic lifespan. Cyclic voltammetry tests showed that MWNTs can store hydrogen in chemical form.

Abstract: Formation of a protective scale such as chromia or alumina is a prerequisite for an excellent oxidation performance of high-temperature materials. Based on this principle, a novel concept of designing chromia- or alumina-forming nanocomposites by means of nanocomposite electrodeposition of Ni with Cr or/and Al nanoparticles were proposed. A brief review on the high temperature oxidation performance of such novel electrodeposited nanocomposites like Ni-Cr, Ni-Al and Ni-Cr-Al is presented.