Comparative Study on Cold Compaction Behavior of TiH2 Powder and HDH-Ti Powder

The compaction mechanism of titanium hydride powder is an important issue because it has a direct impact on density and strength of green compacts and ultimately on the physical and mechanical properties of a final sintered products. In this paper, the characteristics and compaction behavior of titanium hydride and hydrogenation-dehydrogenation titanium powders are comparatively studied and analyzed for better understanding of compaction mechanism of brittle low-strength titanium hydride. The results indicate that the particles of titanium hydride powder are easily crushed under compaction loading at relatively low pressure well below compression strength of bulk titanium hydride, the degree of particle crushed increases with the increase of pressure. The compaction behavior of titanium hydride powder mainly includes the rearrangement and crushing of particles in the early compaction stage, minor plastic deformation, if any, and further rearrangement of particle fragments with filling the pores in the later stage. Such compaction behavior provides relative density of green hydride compacts higher than that for titanium powder of the same size. The relatively coarse titanium hydride powder with wide particle size distribution is easier to fill the pores providing highest green density.

ON THE DEVELOPMENT OF A NOVEL TECHNIQUE FOR HYDRIDING USING ZIRCONIUM HYDRIDE POWDER

Zirconium alloys are of particular interest for applications within the nuclear industry given their low thermal neutron capture cross-section to strength ratios, adequate corrosion resistance, and high temperature stability. However, zirconium alloys are susceptible to hydrogen embrittlement, which limits the service lives of zirconium alloy components in reactor systems. Hydrogen charging, or hydriding, is a technique used to artificially age ex-service or as-received material to predetermined hydrogen concentrations for material testing on representative specimens. This study presents a thermo-mechanical approach to precision hydriding. Discussion on the development and commissioning of a suitable apparatus, called the Thermomechanical Hydrogen Ingression System (THIS), is provided. Hydriding results from commissioning as well as several repeatability tests are reported, which demonstrate the viability of the technique and equipment.