Electrodeposition of zinc-nickel alloy from fluoborate baths - as a substitute for electrogalvanising

Use of fluoborate electroytes have been investigated for depositing a suitable composition of zinc-nickel alloy on mild steel for better corrosion protection. In the present investigation, the plating and bath conditions have been optimised so that zinc nickel alloy coating from fluoborate solutions find applications for plating wires as well as other articles advantageously in the place of zinc coatings

Fabrication of Co-Ni alloy nanostructures on copper foam for highly sensitive amperometric sensing of acetaminophen

In this work, electrodeposition of Co-Ni alloy nanostructures was performed on copper foam and directly applied as an electrocatalyst for the electrooxidation of acetaminophen (Paracetamol) and its detection. The surface morphology and the elemental composition were investigated using SEM and EDX analyses respectively. The observed morphology was similar to nano cones that are uniformly grown on the electrode surface. EDX analysis also confirmed the presence of both cobalt and nickel in the electrodeposit. The preferred orientation lies in (002) and (110) planes of cobalt and nickel respectively that confirmed the formation of alloy. Electrooxidation of acetaminophen was carried out using cyclic voltammetric method in 0.1M NaOH solution. On addition of acetaminophen, an apparent anodic oxidation current enhancement was observed with lesser overpotential than cobalt and nickel electrodes which revealed the excellent electrocatalytic activity of the material. Interference studies also revealed the good selectivity for acetaminophen even in the presence of some interfering species. The reproducibility and stability was checked for the proposed Co-Ni alloy modified electrode. The analytical applicability was examined using the commercial paracetamol tablets and the recovery results were also good. The above results revealed that Co-Ni modified electrode on copper foam is a suitable candidate for electrochemical detection of acetaminophen

Droplet Impact on Supercooled Surfaces

Dry ice, traditionally, has found tremendous application in food storage and blast cleaning. In recent years, there has been renewed interest in exploiting the sublimating vapor of dry ice as a liquid repellent for contactless transport thereby reducing drag. This work investigates the impact of a hexadecane drop on a sublimating layer of dry ice at room temperature. The sublimating CO2 layer formed above the dry ice is compressed as the drop approaches the solid surface. Liquids which have lower specific heat capacity and latent heat comparatively can therefore freeze partially before bouncing at certain low Weber numbers. This unravels a hitherto unknown regime as current literature describes bouncing at low Weber numbers which is immediately followed by sticking and freezing at higher Weber for a given class of fluids. We thus examine the impact of a hexadecane drop below its capillary length on dry ice which exhibits this kind of behavior. The applicability of hexadecane as phase change material (PCM) also makes its use attractive in such a study. As the hexadecane drop spreads on this vapor cushion partial freezing ensures the movement of the contact line is arrested and we observe lower maximum drop spread (Dmax) values viz-à-viz impact on Super hydrophobic or Leidenfrost drops which display similar behavior. Furthermore, the drop is acted upon by hydrodynamic instabilities which lead to formation of fingers which give rise to an interesting petal shaped pattern. Our study aims characteristics these various morphological transitions in this regime where there is partial freezing accompanied by bouncing and sticking depending on the impact Weber number. This research thus aims to further our knowledge of drop impact on dry ice with the view of helping us better understand development of liquid repellant coatings and application where drag reductions is important

Role of amino acids on electrodeposition and characterisation of zinc from alkaline zincate solutions

Amino acid-based addition agents have been employed in an alkaline zincate plating electrolyte to modify corrosion resistance, crystal size, surface morphology, and adhesion of deposits. These addition agents such as guanine, histidine and glutamic acid are recommended in zincate solution to improve the corrosion resistance, crystal size and adhesion of the deposits. The XRD pattern obtained for electrodeposited zinc from such baths shows a polycrystalline hexagonal close-packed (hcp) structure. The crystal size was calculated using the Scherrer formula. A uniform and pore-free surface was observed under scanning electron microphotography (SEM) analysis. The corrosion resistance behaviour of the zinc deposits was analysed by potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS). Histidine appears to show most promise in enhancing corrosion resistance and grain refining

ENHANCEMENT OF SOLAR THERMAL STORAGE SYSTEM USING PCM

Abstract This paper summaries the investigation and analysis of thermal energy storage extracted from solar heater and use for domestic purpose. Choosing a suitable phase change materials paraffin wax and sodium acetate try hydrate are used for storing thermal energy in two different insulation tanks. Each tank carries minimum of 15 liters capacity of water. These two different phase change materials are encapsulated in balls and planted in two tanks. Inside the tank phase change materials are receiving hot water from solar panel. This solar energy is stored in encapsulated balls as latent heat energy. Latent heat is absorbed and stored in encapsulated PCM balls. Large quantity of solar energy can be stored in a day time and same heat can be retrieved for later use. PCM are kept in encapsulated balls and planted in the insulation container. Temperature of the water is measured in a definite interval of time. The heat storage system is to be applied to store solar energy and the stored heat is used to domestic hot water supply system and comparison study also taken place between two different encapsulated balls

Synthesis of Co-CeO2 nanoflake arrays and their application to highlysensitive and selective electrochemical sensing of hydrazine

A highly sensitive hydrazine sensor was successfully fabricated based on Co-CeO2 modified nanocomposites by employing a simple, cost effective and versatile electrodeposition technique. The surfacemorphology and the elemental composition were examined from SEM, FESEM and EDAX analysis. The oxidation states of Co and CeO2 nanoparticleswere characterized using XPS. The crystallite structure and the preferred orientationwere analyzed with XRD patterns. FESEMimages showed the hierarchical cobalt nanoflakes morphology inwhich the spherical shaped CeO2 nanoparticleswere embedded over the electrode surface. The electrochemical determination of hydrazine was characterized using cyclic voltammetry and chronoamperometric methods. Interestingly, compared with pure Co, themodified Co-CeO2 electrodeminimizes the overpotential at 0.28 V and largely enhances the oxidation peak current (2.6 mA) for hydrazine electro-oxidation. Amperometric experiments for hydrazine exhibited two linear ranges from0.005mMto 0.1mMand from0.13mMto 0.37mM. In particular the detection limits obtained for the Co-CeO2 modified electrodes were 6 and 12 nm respectively. The extreme sensitivity and selectivity of the proposed senor material could be due to the porous nature of the material. The analytical parameters revealed that Co-CeO2 nanocomposites are the promising electrocatalyst for hydrazine sensin

Electrolytic recovery of silver from low concentrated silver cyanide spent plating solutions

Cyanide silver solution containing 200 to 1000 mg L21 silver ions were used for recovery studies. The nature of the silver deposit was studied using a Hull cell, and the current density range was selected for electrolysis to recover silver. A batch electrochemical reactor, consisting of a planar stainless steel cathode and platinum anode was used and silver was recovered at 0?04 to 0?2 A dm22. The effect of different initial silver concentrations on the electrochemical recovery of the metal was investigated as a function of electrolysis duration at various current densities. The cathode current efficiency and the energy consumption were determined for the solutions for various experimental conditions. Surface morphology and structure of the silver deposit was also studied using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that irrespective of the initial silver concentration, higher current efficiency and lower energy consumption can be achieved at a low current density. For a given current density, the energy consumption to recover silver is lower from relatively concentrated than from dilute solutions

Analysis of Thermal Spray Coating Powder to Enhance Hardness Using Taguchi And ANOVA Technique

Abstract -Researches are being carried out in different parts of the world to enhance the surface properties of materials. Increase in the requirement of quality of surface has increased the usage of thermal spray coating which is a known to be a potential method of improving surface characteristic. This paper deals with the study of detonation gun spray of WC 12% CO ,75% CrC 25% NiCr and Al 2 O 3 powders .Taguchi method was used to optimize the process parameters