Electroplating of thin films of magnetic FeNi alloys

Electroplating of thin films of FeNi alloys from an acidic sulphate bath containing thioglycollic acid (TGA) and mercaptoethanol (MET) has been studied under different plating conditions. The composition of the alloy is altered with the plating variables. The cathodic current efficiency (CCE) is found to depend on current density, temperature and pH of the medium. The cathodic potential drifted towards less noble direction with increase of current density, temperature and concentration of the addition agent. TGA is a more effective addition agent than MET. The deposited alloy with higher nickel content is smooth and bright with small grain size and uniform solid solution. Electroplating conditions were optimised to get 20:80 Fe:Ni magnetic alloys with the required magnetic property. © 1984

Study of the role of sodium hypophosphite in electroless nickel bath solution

Cyclic voltametric investigations have been made to understand the electrochemical behaviour of sodium hypophosphite in electroless plating bath solution. The possible reaction steps at the anode and cathode have been identified. An ECE type of mechanism appears to be operative in the overall reaction during electroless plating. Both organic and inorganic species in the bath solution influence the voltammetric pattern of the hypophosphite. Temperature enhances the peak currents and changes the reaction mechanism. The oxidation potentials of the reaction steps vary with temperature and also the presence of organic components in the bath solution

Substituted tertiary arsine and phosphines as interfacial adsorption inhibitors for corrosion of zinc in perchloric acid

The effect of triphenylarsine, triphenylphosphine and tri-p-tolylphosphine on the corrosion of zinc in HClO4 at 30° C was studied. A significant decrease in the corrosion rate of zinc is obtained by the addition of these compounds. The corrosion rate is a function of the temperature, pH of the medium and the concentration of the inhibitors. The percentage protection calculated from weight loss and polarization methods are in good agreement. The apparent free energies of adsorption of inhibitors for different possible modes of adsorption are evaluated. The experimental data obtained are in agreement with the corrosion inhibition of zinc by interfacial adsorption of inhibitors. © 1980 Chapman and Hall Ltd

Kinetics of oxidation of benzyl alcohol by sodium N-​chloro-​p-​toluenesulfonamide

The kinetics of oxidn. of p-​RC6H4CH2OH (R = H, MeO, Me, Cl, NO2) by chloramine-​T were studied. The reaction is 1st order in alc. and in oxidant. The fractional order in H+ and Cl-​ suggests complex formation between RNCl-​ and HCl. In higher acidic chloride soln. the rate of reaction is proportional to the concns. of both H+ and Cl-​. The obsd. solvent isotope effect is 1.43 at 30°. The reaction const. (ρ) is -​1.66; thermodn. parameters are evaluated. Probable mechanisms are suggested

The effect of microstructure on the corrosion behaviour of electroless Ni-P alloys in acidic media

The structure and surface morphology of Ni-P alloys obtained by electroless plating has been analysed by X-ray diffraction and microscopic techniques respectively. The bath composition has been found to affect the microstructure of the alloy. The corrosion behaviour of these alloys in acidic media: 1 N H2SO4, 1 N HCl and 5 NaCl (pH 5) was investigated using electrochemical techniques. The corrosion characteristics varied with the degree of crystallinity, the composition of the alloy and the presence of inclusions in the alloy

Role of the thiocyanate ion in the corrosion inhibition of zinc in perchloric acid by n-decylamine

The effect of KSCN on the corrosion of electropolished zinc in 0.1 M HClO4 and 0.1 M HClO4 solution containing different concentrations of n-decylamine (nDA) has been investigated using weight loss and polarization methods. The inhibitor efficiency of nDA increased markedly in the presence of KSCN. pH and temperature affected the corrosion inhibition of zinc by nDA in acidic KSCN solution. The weight loss and polarization measurements gave consistent results. nDA in acidic KSCN solution acted mainly as a cathodic inhibitor, but with a smaller degree of anodic control. The increase in the inhibitor efficiency of nDA in the presence of KSCN is discussed from the viewpoint of the co-adsorption of nDA in cationic form and thiocyanate ions. © 1979

Low-cost black Cu-Ni alloy coatings for solar selective applications

The development of the Cu-Ni alloy coating as a selective surface for solar energy use is reported. The coatings were deposited by electrodeposition using Hull cell. Effects of electrolyte concentration and operating parameters on the appearance and optical properties of the coating were studied. Deposition parameters were optimized to achieve high solar absorptance alpha α=0.94 and low emittance epsilon ε=0.08. The elemental composition and morphology were evaluated by SEM and energy dispersive X-ray diffraction analysis (EDAX). The coating may be promising for solar collector panels used in domestic water heaters. © 2007 Elsevier B.V. All rights reserved

Role of chloride ions in relation to copper corrosion and inhibition

Corrosion rates of copper single crystal faces are determined in stirred 0·1N sulphuric acid with various chloride ion concentrations. A mechanism is proposed to explain the variation of corrosion rate with Cl− ion concentration. Up to 7·5 × 10−3M Cl− ions, the stabilities of the crystal faces are in the order (111)>(100)>(110) but this order is changed to (110)>(100)>(111) in presence of 10−2M Cl− ions. The corrosion potentials of the crystal faces are less noble at all concentrations of Cl− ions and Cl− ion acts as a cathodic inhibitor. There is no significant orientation effect on the kinetics of dissolution of copper

Assay of sulfur compounds with 1-​chlorobenzotriazole

A simple but accurate potentiometric method for the estn. of certain sulfur contg. org. compds. has been developed, based on their oxidn. with 1-​chlorobenzotriazole. A back-​titrn. procedure can also be used. The nature of oxidn. in different media is discussed and the oxidn. products have been identified

Role of ethylamines on the electrochemical behavior of Fe-​Ni alloy films

Cyclic voltammetric expts. were carried out on platinum in acidic soln. (pH 3) contg. ferrous sulfate, nickel sulfate and ethylamines (EtNH2, Et2NH, Et3N)​. Spectral UV absorption studies indicate the complexation of both Fe2+ and Ni2+ ions with ethylamines. The results under transient polarization conditions indicate the redn. of Fe2+ ions through the intermediate species FeOH+, with second electron transfer as a slow step. The higher charge transfer rate of FeOH+ over NiOH+ redn. causes the anomalous codeposition of Fe-​Ni alloy film. Among the ethylamines, Et3N considerably assists the alloy deposition process. A gradual variation in free energy of alloy formation with Fe2+:Ni2+ (mol:mol) in the bath suggests the formation of an alloy intermediate phase rich in iron. Stripping voltammetric curves indicate the preferential dissoln. of iron from iron rich alloy intermediate phase. X-​ray diffraction studies further confirm the phase to be b.c.c. Fe-​Ni alloy. The extent of corrosion of the Fe-​Ni alloy film in the presence of ethylamines is in the following order: Et3N > Et2NH > EtNH2