scholarly journals Eutectic Phenomenon of LiNH2-KH Composite in MH-NH3 Hydrogen Storage System

Molecules ◽  
2019 ◽  
Vol 24 (7) ◽  
pp. 1348 ◽  
Author(s):  
Kiyotaka Goshome ◽  
Ankur Jain ◽  
Hiroki Miyaoka ◽  
Hikaru Yamamoto ◽  
Yoshitsugu Kojima ◽  
...  
Keyword(s):  
Melting Point ◽  
Storage System ◽  
Atomic Mobility ◽  
Melting Points ◽  
Lithium Amide ◽  
Hydrogen Storage System ◽  
Lower Melting Point ◽  
Hydrogenation Temperature ◽  
The Individual ◽  
Potassium Hydride

Hydrogenation of a lithium-potassium (double-cation) amide (LiK(NH2)2), which is generated as a product by ammonolysis of litium hydride and potassium hydride (LiH-KH) composite, is investigated in details. As a result, lithium amide (LiNH2) and KH are generated after hydrogenation at 160 °C as an intermediate. It is noteworthy that the mixture of LiH and KNH2 has a much lower melting point than that of the individual melting points of LiNH2 and KH, which is recognized as a eutectic phenomenon. The hydrogenation temperature of LiNH2 in the mixture is found to be significantly lower than that of LiNH2 itself. This improvement of reactivity must be due to kinetic modification, induced by the enhanced atomic mobility due to the eutectic interaction.

scholarly journals Initiation of solid explosives by impact and friction: the influence of grit

1949 ◽  
Vol 198 (1054) ◽  
pp. 337-349 ◽  
Keyword(s):  
Melting Point ◽  
Hot Spots ◽  
Hot Spot ◽  
Threshold Value ◽  
Maximum Temperature ◽  
Melting Points ◽  
Solid Explosives ◽  
Lower Melting Point ◽  
Determining Factor ◽  
Spot Temperature

This paper describes an experimental study of the initiation of solid explosives, and in particular the effect of artificially introducing transient hot spots of known maximum temperature. This was done by adding small foreign particles (or grit) of known melting-point. The minimum transient hot-spot temperature for the initiation of a number of secondary and primary explosives has been determined in this way. It is shown that the melting-point of the grit is the determining factor , and all the grits which sensitize these explosives to initiation either by friction or impact have melting-points above a threshold value which lies between 400 and 550 ° C. Grit particles of lower melting-point do not sensitize the explosives. The same explosives initiated by the adiabatic compression of air required, for initiation, minimum transient temperatures of the same order as the threshold melting-point values. The results provide strong evidence that the initiation of solids as well as of liquids by friction and impact is thermal in origin and is due to the formation of localized hot spots. There is evidence that in the case of the majority of secondary explosives which melt at comparatively low temperatures, intergranular friction is not able to cause explosion and the hot spots must be formed in some other way. With the primary explosives which explode at temperatures below their melting-points, hot spots formed by intergranular friction can be important.

Phase and Morphological Transformation of Preformed AZ91D Magnesium Alloys in Remelting

2005 ◽  
Vol 475-479 ◽  
pp. 473-476
Author(s):  
Ming-Xu Xia ◽  
Hong-xing Zheng ◽  
Sen Yuan ◽  
Jian Guo Li
Keyword(s):  
Melting Point ◽  
Magnesium Alloys ◽  
Semisolid State ◽  
Melting Points ◽  
Morphological Transformation ◽  
Lower Melting ◽  
Partial Remelting ◽  
Final Microstructure ◽  
Lower Melting Point ◽  
Two Stages

The phase and morphological transformation during the remelting process was investigated by isothermal soaking and rapidly quenching of preformed AZ91D magnesium alloys in semisolid state. It was revealed that the morphological transformation of preformed alloys is crucial to obtain homogenously fine spheroidal grains and affect the final forming ability. The transformation is divided into two stages, local remelting of the whole experiment and partial remelting of the respective grains, which behave as liquid bands and liquid cells structures, respectively. In the partial melting, the lower melting point phase, β-Mg17Al12, diffused to the grains boundary and center of the grains and separated to Al2Mg and Mg. The Al2Mg and Mg phases with lower melting points melt into cells structures. The final microstructure of the remelting experiments is composed of cells structures, spheroidal grains and liquid phase.

Tiefschmelzende nematische Eutektika / Low Melting Nematic Eutectics

1971 ◽  
Vol 26 (2) ◽  
pp. 87-91 ◽  
Author(s):  
Ralf Steinsträsser ◽  
Ludwig Pohl
Keyword(s):  
Melting Point ◽  
Binary Mixtures ◽  
Eutectic Composition ◽  
Melting Points ◽  
Lower Melting ◽  
Clearing Point ◽  
The Individual

Binary mixtures of homologous nematic N- (p-alkyloxybenzylidene) -p′-acyloxyanilines always show the same eutectic composition of 2 moles of lower melting and 1 mole of higher melting component. The melting point of such eutectics is more depressed with respect to the melting point of the individual components than their clearing point. This results in a marked broadening of the nematic range towards lower temperatures. It is therefore possible to obtain nematic liquid crystaline systems with melting points below 0 °C and mesophases of up to 120 °C.

The effects of environmental factors on fatty acid composition and the assessment of marbling in beef cattle: a review

2004 ◽  
Vol 44 (7) ◽  
pp. 663 ◽  
Author(s):  
R. K. Tume
Keyword(s):  
Fatty Acids ◽  
Melting Point ◽  
Visual Assessment ◽  
Phase Changes ◽  
Major Influence ◽  
Fatty Tissue ◽  
Melting Points ◽  
Diverse Range ◽  
Visual Appearance ◽  
The Individual

Marbling refers to the appearance of white flecks of fatty tissue between muscle fibre bundles. The whiteness and opacity of the fat is important for visual assessment of marbling and depends on the crystallisation of the triacylglycerols within the fat cells. In the living animal, fat is in a liquid state. With chilling, the triacylglycerols undergo phase changes (solidify) and become opaque. The temperature at which this occurs is largely dependent upon the melting points of the individual fatty acids. Marbling fat can comprise a diverse range of fatty acids and each has an individual melting point (e.g. palmitoleic melts at 0°C; stearic melts at 70°C). The visual appearance of marbling will thus depend on the melting points of the constituent fatty acids at chiller temperature. The high melting point stearic acid can vary significantly in content across groups of cattle and has a major influence on the physical properties and visual appearance of marbling fat. The effects of nutrition, seasonal and climatic variation are reviewed and linked to marbling appearance and fat hardness.

Separation and Characterization of Standard Propoxyphene Diastereomers and Their Determination in Pharmaceutical and Illicit Preparations

1981 ◽  
Vol 64 (4) ◽  
pp. 875-883
Author(s):  
Shiv K Soni ◽  
Daniel Van Gelder
Keyword(s):  
High Pressure ◽  
Optical Isomers ◽  
Gold Chloride ◽  
Melting Points ◽  
Eutectic Melting ◽  
Racemic Mixtures ◽  
The Individual ◽  
Isomeric Mixtures ◽  
Asymmetric Carbon

Abstract Due to the existence of 2 asymmetric carbon atoms in: the propoxyphene molecule, there are 4 diastereomers: alpha dextro, alpha levo, beta dextro, and beta levo. Only α-d-propoxyphene is included under the federal Controlled Substances Act. Baseline separations of propoxyphene from various incipients (aspirin, caffeine, phenacetin, and acetaminophen) present in pharmaceutical and illicit preparations, and between the alpha and beta diastereomers, were achieved by high pressure liquid chromatography. The column eluant was collected and propoxyphene was extracted. The optical isomers were differentiated and characterized by melting points and by chemical microcrystalline tests. Using hot stage thermomicroscopy, the eutectic melting points of binary isomeric mixtures of propoxyphene bases and salts were found to be depressed about 10° and 15-30°C, respectively, below the individual isomer melting points. The characteristic microcrystals formed with the alpha racemic mixtures by using a glycerin-aqueous gold chloride reagent were not produced by the beta racemic mixtures.

Preparation, Structure and Thermolysis Characteristics of Ammonia Borane

2016 ◽  
Vol 680 ◽  
pp. 529-533
Author(s):  
Jian Li Ma ◽  
Hai Yan Cao ◽  
Xiao Xia Zhang ◽  
Dong Chen
Keyword(s):  
Boric Acid ◽  
Storage System ◽  
Ammonia Borane ◽  
Mass Ratio ◽  
Hydrogen Storage System ◽  
Ammonia Complex ◽  
Ft Ir ◽  
Ammonia Source ◽  
Boron Source ◽  
Amino Complex

Ammonia borane (NH3BH3, AB) is an excellent source of hydrogen(19.6 wt %) for fuel cell applications. In this paper, pure ammonia borane is successfully prepared by using amino complex for ammonia complex Ag(NH3)2Cl as new ammonia source, and sodium borohydride (NaBH4) as boron source. The composition and constitution of the products are measured by XRD and FT-IR. The thermolysis of ammonia borane is significant for its practical application. Boric acid plays a role in improving ammonia borane hydrogen performance. The effects of different mass ratio of boric acid and ammonia borane on dehydrogenation are tested by XRD, TG/DTA and TPD-MS. The results show that boric acid can decrease the first level dehydrogenation temperature of ammonia borane decrease to about 85°C (working temperature of PEMFC). What’s more, the onset temperature of AB’s thermolysis can decrease to about 60°C when the mass ratio of ammonia borane and boric acid is equal to 3:1. This makes ammonia borane be more suitable for the application in on-board hydrogen storage system.

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