Application of hydrogen embrittlement in the preparation of powders of fourth, fifth group elements, their alloys and determination of hydrogen in these matrixes

The hydride-dehydride (HDH) process is the one that has been available for many years as a means of producing powders of elements like zirconium, titanium, niobium and tantalum, but still it requires a good understanding of the process, controlling of operation and careful handling for full industrial utilization. The advantages of HDH process are its flexibility for the variety of feed stock materials, production of high purity extremely fine powders with favorable cost consequences, etc.. The determination of hydrogen in these powders plays an equally important role in their application. In general, the critical steps involved in the HDH process for these elements/alloys involve surface preparation, pyro-vacuum treatment, control flow of hydrogen, crushing of the brittle hydrided material and dehydrization under in high temperature and vacuum. At Special Materials Plant (SMP) of Nuclear Fuel Complex, hydriding and dehydriding parameters were examined from the standpoint of required input and in attaining required particle size while maintaining purity. Systematic studies were carried out for industrial scale production of powders/ granules of zirconium, titanium, niobium, tantalum, ZrNb master alloy (50-50), ZrNi (70-30) alloy etc. These studies were carried out for the purpose of optimization of process parameters and the sequence of operations in obtaining high quality powders. Tonnage quantity of these metals and alloys which have been produced are used in-house as well as sold to other industries. The paper discusses the advantages and disadvantages of HDH powder and in safe handling of these pyrophoric powders. Standardization of analytical parameters for determination of hydrogen in these matrices by in IGP-TC method using LECO analyzer is also discussed. (author)