Electrochemical hydriding of magnesium alloys in alkaline solutions is proposed as a method of storing hydrogen in a solid phase. In this article, we present a new approach to hydrogen storage for ...mobile applications. Rapidly solidified ribbons of Mg–14Ni alloy were prepared by melt spinning. Subsequently, they were exposed to electrochemical hydriding at 90
°C/120
min in various alkaline electrolytes. It was found that hydrogen reached up to 1.4 wt.%. Higher hydrogen concentrations might be achieved by proper adjustment of hydriding conditions.
Molybdenum disulphide (MOS2) might be a useful addition in the production of composite self-lubricating high-speed steel parts, which are used in different anti-wear applications. MoS2 might also has ...a favourable influence on the synthesis of sintered high-speed steels (HSSs) improving the compressibility of the metal powder mixture during its cold compaction, as well as acting as a sinterability enhancer of powder compacts during their sintering. In view of this, the compressibility and the sinterability of M3/2 and M35 types of HSS powder mixtures with MoS2 additions were investigated. In this article, the influence of MoS2 additions on the densification during cold compaction and vacuum sintering of selected HSSs is presented. It has been established that the MoS2 promotes a consolidation of HSS powders during automatic die compaction, as well as final densification during sintering. Sintering of HSS-MoS2 powder mixtures proceeds by the combination of a reactive and supersolidus liquid-phase sintering process. The added MoS2 reacts with the steel matrix, enhancing densification. Fine dispersion of complex sulfides (Cr, V, Fe)S is formed, which improves the machinability and tribological properties of sintered steel.
We produced amorphous Fe-Si-B soft-magnetic powder using water atomisation. During annealing the powder particles developed a nanocrystalline structure, and annealing at over 700 deg C led to the ...formation of ferrite and boride phases. Here we present a high-magnification electron backscatter diffraction (EBSD) mapping analysis of the powder particles, in combination with a field-emission-gun scanning electron microscopy (FEGSEM) analysis. Some of the problems associated with the preparation of the powder particles for the EBSD analysis as well as the drift problems occurring during the EBSD mapping are reported.
Laboratory cast alloys with 2–27% of δ ferrite were aged for up to 17,520
h in the temperature range 290–350
°C. Tensile and Charpy tests were performed at 22 and 290
°C on specimens aged for ...different times, and the microhardnesses of both constituents of the microstructure were determined for the alloy with 27% of δ ferrite. The effects of the content of δ ferrite, the ageing and testing temperature, and the ageing time on mechanical properties and notch toughness are presented and discussed.
Surfacing with single- or multilayer hard coatings represents a modern trend in the prolongation of tool lifetime. The tools for metal powder compaction were vacuum heat treated, pulsed plasma ion ...nitrided and coated with TiN or CrN by PVD. Industrial tests of tools, during normal production, showed that, after the same hard coating process, the lifetime of some tools was prolonged by at least twice, but some tools failed very quickly. Research showed that the main reason for early tool wear or failure was improper diameter of the tools after coating.
A commercial metal powder mixture was used for the laser sintering experiments. Different substrates in the form of simple blocks and complex testing tool-inserts for pressure die casting of Al-based ...alloy were prepared at different process conditions and post-surface treatments. Additional improvement of surface quality was obtained with the hard coating. In the present article, the basic principles of laser sintering are presented. Morphological and microstructure properties of metal powders and sintered products are also discussed. The results show that relatively porous and heterogeneous microstructures are obtained during laser sintering in the presence of the liquid phase. However, improved properties of the laser-sintered products can be obtained by careful selection and control of powder properties, optimization of direct metal laser sintering conditions, and by the hard coating of the sintered product.
