394 research outputs found
Mould walls inclination and dendritic morphology of CMSX-4 blades airfoils
The airfoils of single-crystalline turbine blades were studied. The blades made of industrial CMSX-4 superalloy
were obtained by the Bridgman technique. Five different withdrawal rates (1–5 mm/min) were used. Series of
as-cast samples were prepared by cutting the airfoils at different distances from the blade root. The metallographic
sections, prepared for each cutting planes, were subjected to scanning electron microscopy observations and Laue
diffraction studies. Macrostructure images of whole area of airfoil cross-sections were obtained by stitching several
obtained SEM images. Morphology of dendrites in different area of cross-sections were analysed. The crystal
orientation of each sample were determined by analysis of Laue pattern. It was found that the morphology of
dendrites changes in the area, where the dendrite growth is limited by inclined mould walls
Characterization of casting defects in the single crystal turbine blade airfoil
In the paper turbine blades made from single crystal CMSX-4 superalloy were investigated by X-ray diffraction
methods (topography,
-scan mapping) complemented by scanning electron microscopy observations. By the X-ray
diffraction topography method several misorientation defects were visualized as well as dendrites arrangement.
It was discussed that tip of the airfoil and thin walled area of the turbine blades located near the trailing edge can
accumulate more growth defects than other airfoil part, due to the complex shape of the mould
Crystal perfection studies of single crystal superalloy turbine blades by X-Ray diffraction methods
In the paper the crystal structure of single crystal CMSX-4 blade casts, applied in high pressure turbine of
aircraft engines was analyzed. The longitudinal section of blade, cast at withdrawal rate of 3 mm/min was used
as a sample. During the conducted research, following X-ray diffraction methods were applied: EFG
-scan,
Auleytner X-ray topography and analysis of diffraction reflex profile (“rocking curve”). The authors determined
crystal orientation in entire blade casts on the basis of set criterion concerning values of angle — deviation of
[001] direction from the direction of cast withdrawal. Conclusions concerning the crystal structure quality of the
blade were drawn based on results from three different research methods. Local changes in crystal orientation on
the surface of blade cast, also areas with significant structure defect degree and the presence of internal stresses
were characterized
Dendrite growth in selector-root area of single crystal CMSX-4 turbine blades
The single crystal turbine blades made of CMSX-4 nickel-based superalloy were studied. The turbine blades
were obtained by the Bridgman technique with withdrawal rate of 5 mm/min. The samples, cut-off from root part
of blades and containing the fragment of the selector, were studied. The effect of selector geometry on the dendrites
growth and defects formation in the selector-root area of the blade were analyzed. The Laue diffraction, scanning
electron microscopy, and X-ray diffraction topography were applied. It was found that, during crystallization of the
selector, the dendrite cores, after reaching the surface of mould, may bend, if the angle between dendrite cores and
the mould surface was equal to 12 . When the angle was equal to 24 the growth of dendrites has been stopped.
It can be stated that the defects, which appeared in the selector were inherited by the root part
Analysis of CMSX-4 single-crystalline turbine blades root by electron and X-Ray diffraction methods
The root of single-crystalline turbine blade made of CMSX-4 superalloy were studied. The studied blade was produced by the Bridgman technique in industrial ALD furnace at withdrawal rate of 3 mm/min. The samples for investigations were cut from the blade root parallel to the withdrawal direction. Metallographic sections of longitudinal samples planes were prepared for further investigations. The samples were analysed using scanning electron microscopy and the Laue diffraction studies. The crystal orientations in macro-scale were determined by analysis of the Laue pattern and local crystal orientations were studied by electron backscattered diffraction technique. Morphology of dendrites were examined by analysis of scanning electron microscopy macro-images. Study of subgrain structure was performed by X-ray diffraction topography. The sharp parallel contrast bands, visible on the X-ray topograms, were related with dendrite cores, arranged with the same direction. Additionally, the low angle boundaries were formed in certain samples, visible on the topograms as contrast shifts. Step changes of local crystal orientation in certain areas were observed on the electron backscattered diffraction maps. The electron backscattered diffraction crystal orientation maps were related to the misorientation visualized in topograms
The LRL electron and proton spectrometer on NASA's Orbiting Geophysical Observatory 5/E/ /instrumentation and calibration/
Systems analysis of electron and proton spectrometer on OGO-
Preparation and characterization of novel polymer-based gel electrolyte for dye-sensitized solar cells based on poly(vinylidene fluoride-cohexafluoropropylene) and poly(acrylonitrile-cobutadiene) or poly(dimethylsiloxane) bis(3-aminopropyl) copolymers
Polymer gel electrolytes based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and poly(acrylonitrile-co-butadiene) (PAB) or poly(dimethylsiloxane) bis(3-aminopropyl)-terminated (PDES-bAP) copolymers were prepared and investigated in dye-sensitized solar cells (DSSCs). Selected optical and electrochemical properties of all compositions with various ratio from 9:1 to 6:4 were investigated towards DSSC applications. The highest value of power conversion efficiency equal to 5.07% was found for DSSCs containing a PVDF-HPF:PAB (9:1) gel electrolyte. Compositions of electrolytes were additionally tested by electrochemical impedance spectroscopy. The influence of the ratio and type of polymers used as an additive to PVDF-HPF on absorption wavelengths, energy gap, and Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) levels were investigated. Individual components of DSSCs, such as the TiO2 layer and platinum nanoparticles, were imaged by scanning electron microscope. Finally, a DSSC module with six electrically separated solar cells with a 7 × 80 mm2 active area was constructed based on gel electrolytes and tested. © 2020 by the authors
Hidden evidence of non-exponential nuclear decay
The framework to describe natural phenomena at their basics being quantum
mechanics, there exist a large number of common global phenomena occurring in
different branches of natural sciences. One such global phenomenon is
spontaneous quantum decay. However, its long time behaviour is experimentally
poorly known. Here we show, that by combining two genuine quantum mechanical
results, it is possible to infer on this large time behaviour, directly from
data. Specifically, we find evidence for non-exponential behaviour of alpha
decay of 8Be at large times from experiments.Comment: 12 pages LaTex, 3 figure
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