Clean Grain Boundary Found in C14/Body-Center-Cubic Multi-Phase Metal Hydride Alloys
The grain boundaries of three Laves phase-related body-center-cubic (bcc) solid-solution, metal hydride (MH) alloys with different phase abundances were closely examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and more importantly, electron backscatter diffraction (EBSD) techniques. By using EBSD, we were able to identify the alignment of the crystallographic orientations of the three major phases in the alloys (C14, bcc, and B2 structures). This finding confirms the presence of crystallographically sharp interfaces between neighboring phases, which is a basic assumption for synergetic effects in a multi-phase MH system.
Effects of Vanadium/Nickel Contents in Laves Phase-Related Body-Centered-Cubic Solid Solution Metal Hydride Alloys
Structural, gaseous phase hydrogen storage, and electrochemical properties of a series of annealed (900 °C for 12 h) Laves phase-related body-centered-cubic (BCC) solid solution metal hydride (MH) alloys with vanadium/nickel (V/Ni) contents ranging from 44/18.5 to 28/34.5 were studied. As the average Ni-content increases, C14 phase evolves into the C15 phase and a new σ-VNi phase emerges; lattice constants in BCC, C14, and TiNi phase all decrease; the main plateau pressure increases; both gaseous phase and electrochemical hydrogen storage capacities decrease; the pressure-concentration-temperature (PCT) absorption/desorption hysteresis decreases; both high-rate dischargeability (HRD) and bulk hydrogen diffusivity increase and then decrease; and the surface reaction current decreases. There is a capacity-rate tradeoff with the change in V/Ni content. Alloys with relatively lower Ni-content show higher capacities but inferior high-rate performance compared to commercially available AB5 MH alloy. Increasing the Ni-content in this BCC-based multi-phase alloy can improve the high-rate capability over AB5 alloy but with lower discharge capacities. The inferior surface reaction current in these alloys, compared to AB5, may be due to the smaller surface area, not the total volume, of the Ni clusters embedded in the surface oxide layer of the activated alloys.
Application of Automatic Tracking Correlation Filtering in Motored Spindle Dynamic Balancing
According to the information characteristics of the dynamic imbalance signal and the definition of correlation function,the principles and algorithm of relevant filter with automatic tracking is given.In labview development system,based on the principles of relevant filter with automatic tracking,the graphics programming of extracting the dynamic imbalance signal is developed.With this programming,the vibration signal including different frequency harmonic signals and noise is processed by simulation and on-site experiment.The results show that: through relevant filter with automatic tracking,the dynamic imbalance signal under different rotating speed can be extracted accurately,and it can meet the requirement of motored spindle dynamic balancing measurement.