Effect of the electrolyte composition on In and Ag–In alloy electrodeposition from cyanide electrolytes

A procedure for preparation of clear and stable indium cyanide electrolytes, containing indium salt, d(+)-Glucose and KCN is proposed. NMR investigations revealed that the formation of a complicated indium complex in which the products of the disintegration of d(+)-Glucose in the KCN-solution are closely situated to the indium ion ensures the clearness of the electrolyte. The effect of nitrate, chloride and sulphate ions on the electrochemical processes of indium and silver–indium alloy electrodeposition is studied by cyclic voltammetry. During alloy electrodeposition under galvanostatic conditions unique spatio–temporal structures are observed on the cathodic surface.     

Measuring of heat capacity

A simply device was developed and tested. It is designed to measure the heat capacity of square plates with size ～30 × 30 mm, at room temperature. This device consumes permanent electric power. The heat losses to the surroundings are taken into account. A mathematical model, of this heat capacity meter, is described in the paper. The heat capacity of a sample is calculated as a difference between measured heat capacity (of heater and sample) and heat capacity of the heater only. The optimal size of a test body, and reference one, is so as the contact surface of the heater.     

Effect of brighteners on hydrogen evolution during zinc electroplating from zincate electrolytes

Hydrogen evolution during zinc electrodeposition on a steel substrate from zincate electrolytes containing different additives was studied using various experimental techniques.The hydrogen evolution reaction is limited by the electron transfer step. Hydrogen evolution is most intensive during the first seconds from the beginning of electrodeposition due to the lower overpotential of hydrogen on steel as compared with that on zinc. The evolved hydrogen is dissipated in three ways. Most is dissipated to the atmosphere via gas bubbles at a constant rate. Some is dispersed in the electrolyte some diffuses into the steel substrate, predominantly at the commencement of deposition. The additives affect both the total amount of evolved hydrogen and its distribution. The highest amount of hydrogen is evolved in the presence of the anisaldehyde bisulphite containing composite additive. The highest amount of hydrogen included in the substrate and remaining in the electrolyte corresponds to the use of the Na–N-benzylnicotinate containing additive. In this case blistering is observed.     

Pulsed laser deposition of Mn-Zn ferrite thin films

Mn-Zn ferrite thin films were deposited on sapphire substrates by pulsed laser deposition from sintered Mn_{1 – x}Zn _x Fe₂O₄ ceramic targets. A full stoichiometric transfer from targets to substrates was achieved. Magnetic inplane measurements in two perpendicular directions were carried out and the macromagnetic properties of films were determined. The hysteresis loops obtained are rectangular and the values of the coercive force, the saturation, and the remanent magnetization are comparable to the same parameters of the bulk Mn-Zn ferrite. The films were characterized using a vibrating sample magnetometer (VSM), a scanning electron microscope (SEM) and by X-ray photoelectron spectroscopy (XPS).     

Creep-rupture strength prediction of an epoxy composite under tension

It is known that the durability of materials is related to the conditions under which they are exploited, including the loading that they undergo. The material “durability-constant load” relation is known as Creep-Rupture Strength (CRS). It takes a long time to determine CRS experimentally, and it proves to be expensive. In this paper we check a method for predicting CRS under tension that employs data from short term tests. The results for loading under tension are compared with results for the same material subjected to bending. An erratum to this article can be found at     

Effect of electrolysis conditions on the deposition of silver–bismuth alloys

The electrochemical deposition and dissolution of silver, bismuth and silver–bismuth alloy from a cyanide–tartrate electrolyte were studied by means of cyclic voltammetry. The influence of the electrolyte composition on the electrochemical reactions is discussed. The deposition potentials of the two metals could be maintained close to each other by means of appropriate complex forming agents, leading to their codeposition. Silver deposition is the predominant reaction in the electrolyte studied and the bismuth content in the coating increases with increased current density. The dissolution potentials of the two metals are quite distinct; they differ by more than 0.5 V. In the presence of a free complex forming agent, both the deposition and the dissolution potentials of silver can be shifted in the negative direction. Depending on the type and amount of the complex forming agent, they can become more negative than the deposition and dissolution potentials of bismuth. Predominant deposition of bismuth is realized in this case and the codeposition of silver is enhanced at higher current densities. By varying the amount of the complex forming agent, silver–bismuth coatings of any desired composition can be obtained.