Powder stacking

The range of processing techniques that can be employed to produce FGMs is also broad [1]. Vapor-phase methods e.g., CVD, CVI, and PVD methods), liquid-phase methods e.g., electrodeposition, sol-gel, plasma spraying and molten metal infiltration methods), and a variety of solid-phase methods based on powder metallurgy are available. The solid-state methods include powder stacking techniques, powder infiltration techniques, slurry techniques e.g., sedimentation... 

Drums of Bleaching Powder stacked at a depot in England, August 1945. 

Fig. 7. Fabrication process for MLC capacitors. Steps are (a) powder (b) slurry preparation (c) tape preparation (d) electroding (e) stacking (f) lamination (g) dicing (h) burnout and firing and (i) termination and lead attachment.

Powder X-ray diffraction and SAXS were employed here to explore the microstructure of hard carbon samples with high capacities. Powder X-ray diffraction measurements were made on all the samples listed in Table 4. We concentrate here on sample BrlOOO, shown in Fig. 27. A weak and broad (002) Bragg peak (near 22°) is observed. Well formed (100) (at about 43.3°) and (110) (near 80°) peaks are also seen. The sample is predominantly made up of graphene sheets with a lateral extension of about 20-30A (referring to Table 2, applying the Scherrer equation to the (100) peaks). These layers are not stacked in a parallel fashion, and therefore, there must be small pores or voids between them. We used SAXS to probe these pores. 

Leave space for possible hose runs for a fire in any stack and provide dry powder extinguishers around the area. 

If a series of sieves is stacked in order of increasing mesh size, when a known amount of powder to be analyzed is placed on the topmost sieve and agitated, the powder will then be classi-... 

A typical testing procedure involves several steps. First, the selected number and size of sieves are stacked upon one another, with the largest openings (inversely related to mesh per inch) being at the top of the stack, and beneath that a pan to collect the particles finer than the smallest sieve. The known amount of powder to be analyzed is then placed on the top sieve and the set is vibrated in a mechanical device for a predetermined time period. The results are obtained by weighing the amount of material retained on each sieve and on the collecting pan. The suction method uses one sieve at a time and examines the amount retained on the screen. In both methods the data are expressed as frequency or cumulative frequency plots, respectively. 

Zeolite structures sometimes remain unsolved for a long time, because of either their complexity, the minute size of the crystallites or the presence of defects or impurities. One extreme example of stacking disorder is provided by zeolite beta [1,2], Different stacking sequences give rise to two polymorphs (A and B) in zeolite beta that always coexist in very small domains in the same crystal. Not only do the small domains make the peaks in the powder X-ray diffraction pattern broad and thereby exacerbate the reflection overlap problem, but the presence of stacking faults also gives rise to other features in the diffraction pattern that further complicate structure solution. 

Fig. 2 Mechanically oriented bilayer samples as a membrane model for ssNMR. (a) Illustration of the hydrated lipid bilayers with MAPs embedded, the glass supports, and the insulating wrapping, (b) A real sample consists of 15 stacked glass slides, (c) Schematic solid-state 19F-NMR lineshapes from an oriented CF3-labelled peptide (red), and the corresponding powder lineshape from a non-oriented sample (grey), (d) Illustration of typical orientational defects in real samples - the sources of powder contribution in the spectra...

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