Allin Sidney Pratt

Electrodeposition of aluminium and aluminium/platinum alloys from AlCl3/benzyltrimethylammonium chloride room temperature ionic liquids

This paper shows that aluminium and aluminium/platinum alloys can be deposited from room temperature ionic liquids formed from an adduct of aluminium trichloride with benzyltrimethyl ammonium chloride. The advantages of this ionic liquid over the majority of those previously investigated is that it is less water sensitive, easier to purify and form and significantly more cost effective. Voltammetry and chronoamperometry were used to investigate the deposition and stripping of aluminium on Pt, Al and Fe electrodes. Hull cell tests were performed to obtain the optimum deposition conditions and bulk electrolysis showed that uniform, adherent, crack-free aluminium deposits could be obtained from such ionic liquids. Co-electrodeposition of Al with Pt was also studied and the nucleation mechanism was found to change significantly when Pt complexes were added to the ionic solution. The platinum ligands were found to change the solubility of the complex, but had little effect on the morphology of the deposited film.

The improvement of the hydrogenation properties of nickel-metal hydride battery alloy by surface modification with platinum group metals (PGMs)

Abstract Because of their higher power densities, low memory effects and more environmentally friendly constituents, Nickel Metal Hydride (NiMH) batteries have become a strong competitor to NiCad batteries. The use of multicomponent alloys has been found to improve cell lifetimes, while further improvements to the cell performance are obtained by surface coating or ‘microencapsulation’ techniques with various metals or metal oxides. In the present work, a technique of coating hydride powders with one or more Platinum Group Metals (PGMs) has been developed, which enables the alloy to be charged/discharged rapidly with hydrogen with the additional advantage of being extremely resistant to deactivation. The hydrogenation kinetics of the uncoated and PGM doped alloys were assessed by gravimetric analysis, with periodic exposure to the atmosphere in an attempt to deactivate the powders. It was observed that, in the solid–gas studies, the Ru and Pd/Ru coated alloys were readily charged/discharged with hydrogen, even after long periods in air. Thus, the use of PGMs in this application represents a valuable advance both in the technology of NiMH batteries and of hydrogen storage.

Novel Room Temperature Molten Salts for Aluminium Electrodeposition

SUMMARYThis work describes novel room temperature molten salts which can be used for aluminium electrodeposition. We have characterised the conductivity as a function of the bath composition and shown that the changes in conductivity occur because of an equilibrium between [Al2Cl7] and [AlCl2 The voltammetry of the optimum melt is analysed together with the mechanism of nucleation. Hull cell tests were performed and the morphology of the deposits was analysed using scanning electron microscopy. These room temperature molten salts have a number of advantages over those described in the literature including lower water sensitivity, greater ease of purification and greatly reduced cost. The electrodeposition of adherent, dull aluminium is demonstrated. It is also shown that soluble aluminium anodes can be used. These novel baths form a viable alternative to conventional methods of depositing aluminium.

The Minting of Platinum Roubles

Matthey Technology Centre was approached to examine and characterise four Russian platinum roubles belonging to Johnson Matthey. The coins are: 1828 3 rouble 1830 6 rouble 1834 3 rouble 1835 3 rouble Forged Russian roubles have been identified as being of pure platinum metal, while the genuine coins contain iron impurities of up to 4 wt.% (3, 4). The coins were analysed by four methods: [i] Magnetic, namely permeameter measurements, [ii] Density measurements, see Table I [iii] Scanning electron microscopy (SEM), see Table II, and [iv] X-ray diffraction (XRD), see Table III. In measuring the magnetic characteristics of the coins, a rare earth-transition metal type magnet