Papers by Keyword: Electrolytic Deposition

Abstract: A technique for applying a protective and hardening coating on steel 18G2S by electrodeposition from ionic melts has been developed. Melt in the triple eutectic point of salts NaF - 30%, NaCl - 16.6% and AlF3 - 53.4% is used as an electrolyte. During electrolysis, a graphite crucible was used as an anode, samples of reinforcing steel (18G2S) cleaned of corrosion and other contaminants were used as a cathode. The temperature of the ionic melt during electrolysis was 1120 ± 5K. In the process of electrolysis, the value of the electric current and voltage were controlled, the change in the mass of the deposited aluminium over a given time was measured. The current output during the deposition of aluminium was kept in the range of 89 ... 96 %. During electrolysis, aluminium diffuses into the surface layers of steel and with iron form solid solutions, intermetallic compounds and eutectics. At the same time, crystals of the FeAl₃ compound (59.18% Al) appear in the structure. A further aluminium content decrease in the depth of the surface layer entails the appearance of chemical compounds of the following compositions: Fe₂Al₇, Fe₂Al₅, FeAl₂ , FeAl. The elasticity limit and ultimate tensile strength of aluminium-coated samples compared to uncoated samples increased by 7.9% and 7.8% respectively. Electrochemical oxidation of samples with aluminium coating of reinforcing steel in sulfuric acid electrolyte was carried out. The oxidation rates for aluminium are set within (7.1... 8.3) 10^-6 g / (s mm2) and iron (7.6 10.4) 10^-6 g / (s mm2). Experimental assessment of samples oxidation rate under conditions of sulfuric acid electrolyte was carried out at an electric current value of 11 to 18 A.

Abstract: Sn nano particle coatings on MCMB powder, as anodes of lithium ion battery are carried out in SnSO₄ solutions by using cathodic electrochemical synthesis and subsequently dried at 100°C. The electro-deposition reaction was follow: Sn²⁺ + H2O ↔ SnOH⁺_aq + H⁺; SnOH⁺_aq ↔ SnOH+aqs + e-; SnOH+ads + e- → SnOH; SnOH + H+ + e- → Sn + H₂O. The Sn-coated MCMB specimens are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV), and charge/discharge tests. The nano-sized Sn particles coated on MCMB powder are obtained in 0.2M SnSO₄ solutions and desoition current 0.5A. An important parameter in electrode preparation is the adhesion of the coating to the current collector, which greatly affects the cyclability of the electrode. Therefore, the relationship between adhesion strength and cycle performance was investigate in this study. Charge/discharge cycle tests elucidated that Sn-coated MCMB showed higher capacity than MCMB. Compared with MCMB, the second discharge capacity of Sn–coated MCMB increased about 28.8%. After 50 cycles, the reversible capacity was about 339.6 mAhg-1. The capacity retention ratio C25/C2 was about 80.87%. It was shown good cycle life due to the nano-particles effects retarded to Sn aggregation.

Abstract: Calcium phosphates films were deposited onto pipes and stents of nitinol alloys by an electrolytic deposition (ELD) method. Monocalcium phosphate (Ca (H₂PO₄)₂·H₂O) solutions were used as the electrolyte, and electric depositions were carried out at the constant cathode current of 1.59 mA/cm² at 65°C for 60 min. From the deposition on nitinol pipes, deposition rates were changed in 15 minutes and the precipitates were identified to be octacalcium phosphate (Ca₈H₂(PO₄)₆·5H₂O) and dicalcium phosphate anhydrous (CaHPO₄). The electrolytic depositions on the nitinol alloys were useful for the formation of calcium phosphates films on the complex shape of stents.

Abstract: The deposition of alumina (nano-powder, <80nm) and zirconia doped with yttria laminar composite coatings on Ni3Al coatings were investigated via a complex method of Sol-Gel, electrolytic deposition (ELD) and electrophoretic deposition (EPD). The average particle sizes of alumina and zirconia are 80nm and 20nm respectively. The relation of deposition parameters (deposition voltage, dwell time) and deposition rate was discussed based on the experiment results of alumina, zirconia single and laminated coatings deposition. The post thermal treatments were performed in attempt to acquire a dense multilayer composite ceramic coating. The uniform duplex or laminar coatings could be achieved via this complex method. The surface and cross-sectional morphologies of two layers and ten layers alumina/ zirconia composite ceramic coating after sintering showed that the laminar structure thickness could be tailored by controlling the deposition voltage and dwell time. The sintering mechanism of nano-sized alumina and zirconia was also discussed.

Abstract: This paper presents a method to fabricate textile structural electrodes from material preparation to electrode structure design and testing. Silver/Silver Chloride (Ag/AgCl) was assumed to be the best electrode material system for acquisition of biopotential signals. A AgCl coating has been grown on silver (Ag) coated multilament yarn to form Ag/AgCl combination using constant voltage electrolytic deposition in 0.9% wt sodium chloride bath. The AgCl thickness could be controlled by varying processing time (t) and voltage (V). Surface morphology of the treated fibres were studied by scanning electron microscopy (SEM) which revealed that AgCl grain size became bigger and denser as increased processing time and voltage. The impedance of the treated fibre was analyzed by electrochemical impedance spectroscopy (EIS) analysis from 0.1H z to 1000H z which shown that impedance also increased with processing time and voltage. The prepared Ag/AgCl multilament yarn was fabricated into wearable electrode using embroidery technique. ECG testing confirmed that the electrodes made from treated fibre can acquire high quality signal.

Abstract: Nobel metal particles with nanometer size have attracted keen interest because of, for example, their high catalytic activity to be applied for industrial applications. In this study, nano-sized gold particles were deposited onto a graphite carbon plate by two approaches: 1) electrophoresis of colloidal gold nanoparticles, 2) electrolysis of chlorauric acid. For former case, commercially-available gold nanoparticle and anionic mercapto ligand-stabilized gold nanoparticles, synthesized by citric acid reduction of chlorauric acid, were used. Size and morphology of the gold particles deposited were characterized by scanning electron microscopy. Electrolytic deposition resulted in larger gold particles around tens to hundreds nm in size. Electrophoretic deposition accomplished particle sizes smaller than 15 nm, which basically reflected the size of colloidal gold particles used.