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.
A high strength low alloyed (HSLA) V-Nb steel was heat treated to martensite and lower bainite with different grain size, reheated for 3 seconds at 750 degree C and air cooled. Charpy notch tests ...were performed from-100 degree C to 60 degree C and the hardness assessed at room temperature. For as delivered steel and lower bainite, the upper shelf toughness was above 200 J and the transition temperature low, while, for martensite the upper shelf toughness threshold was aproximateky at 0 degree C. After reheating, notch toughness was decreased moderatly for martensite and strongly for lower bainite. Independently on grain size, lower bainite was more propensive than martensite to embritlement after short reheating in the ( alpha + gamma ) range. For martensite, the change of notch toughness was not related to change of hardness, as by lower hardness lower, also toughness was lower.
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.
