Platinum Metals Rev., 1996, 40, (1), 36
Hydrogen Treatment of Materials
Palladium Studies Reported at a Donetsk Conference
PALLADIUM STUDIES REPORTED AT A DONETSK CONFERENCE
Technological interest in the results of interactions of hydrogen with metals and with various other materials has been concerned with both destructive and advantageous structural alterations. This has been demonstrated by the contributions presented at the series of conferences held over recent years in Wyoming, U.S.A., organised by A. W. Thompson, N. R. Moody and I. M. Bernstein.
The programme of studies pursued by Professor V. I. Goltsov and his colleagues in Donetsk, Ukraine, has tended to concentrate on the advantageous consequences resulting from the interaction of hydrogen with various materials. Thus at the recent conference on Hydrogen Treatment of Materials, held from 20th to 22nd September, 1995, at the State Technical University in Donetsk, Professor Goltsov, in a keynote introductory address, highlighted the advantages of hydrogen treatment. In many instances this can provide competitive alternatives to straightforward mechanical treatment or to other means of processing materials.
Considering the rather specific subject matter of this conference, there was an encouraging attendance of approximately 100 participants, including representatives from France, Spain, Poland, China, Japan, South Korea, United Kingdom and United States of America, together with representation from ten of the Confederation of Independent States, with most contributors being from Ukraine and Russia.
In the historically-centred review by Professor Goltsov, mention was made of various areas where advantageous results occurring after hydrogen treatments had either been initiated or further developed. These included improvements achieved in some well investigated topics, such as in specific cases of structural damage and distortion, embrittlement and even softening of metals and alloys.
Another previously quite well investigated research area, included to emphasis its advantageous significance, concerned macroscopic fracturing and powdering together with subsequent reformulation. This topic was introduced with particular emphasis on the treatment of titanium, titanium alloys and analogous materials. However it was also discussed in terms of the beneficial incorporation of hydrogen treatments during the processing of intermetallic and electronic materials. These may have relevance to the solution of problems associated with hydrogen storage and energy generation, such as hydrogen batteries and shape memory devices. Improvements in kinetic parameters, including those of diffusion processes, order-disorder transformations and the formation of specifically selected products, resulting from hydrogen treatment were also discussed.
Further Studies with Palladium and Palladium Alloys
Contributions dealing with studies on palladium and palladium alloys were still focused largely upon their use as hydrogen purification membranes and in particular chemical processes where their specific catalytic advantages are utilised. In both of these areas the technological research had two objectives: improving the composition of membrane materials used for various combinations of experimental conditions, and avoiding the development of irreversible lattice dimensional and dislocation structural network damage, resulting from the α ↔ β-phase hydride transitions.
The possibility of unwanted dimensional changes taking place within membranes during sequences of hydrogen absorption and desorption was again addressed. R. V. Kotelva and colleagues from the Technical University in Donetsk described changes in the shape of a palladium plate and discussed experimental procedures in some detail. A further report from Donetsk, presented by T A. Ryumishina and colleagues, concerned the evolution of stresses during hydrogen diffusion processes in palladium. Associated problems of kinetic and morphological peculiarities occurring during hydride phase transformations were reported by Yu. A. Artemenko and co-workers of Donetsk, while allied measurements of changes in the mechanical properties of the palladium/hydrogen system were presented by A. P. Kusin and colleagues, also from the same university.
Further quantitative and theoretical consequences of the effects of hydrogen expansion were discussed. The modelling of hydrogen-induced non-elastic deformations was reported by V. N. Madudin and co-workers, Chelyabinsk, Russia. A paper by Young-sui Cho, University of Kangwon, South Korea, considered the kinetics of hydrogen absorption - determined from measurements of changes in the electrical resistivity of thin palladium films.
The importance of stress/strain gradient behaviour to bulk lattice hydrogen dimision processes, as shown by Gorsky and Diffusion Elastic Effect related phenomena, was reported in a paper by R. V. Bucur, Uppsala, Sweden, K. Kandasamy, Jaffna, Sri Lanka, Y. Sakamoto, Nagasaki, Japan, together with X. Q. Tong and F. A. Lewis, Belfast, Northern Ireland, with particular ref-erence to apparent changing trends in the hydrogen diffusion coefficient, DH, with the initial values of the hydrogen content.
Lastly, results of hydrogen isotope structure analyses by powder X-ray diffraction, for compositions approximating to PdH0.6 PdD0.5 and PdT0.66 were reported by T. A. Beiter and J. S. Cantrell, of Miami University, Oxford, Ohio.
A number of the papers presented at this Donetsk conference will be published in a special issue of the International Journalof Hydrogen Energy.