Thermal Decomposition of Spherically Granulated Malachite: Physico-Geometrical Constraints and Overall Kinetics

2021 ◽  
Author(s):  
Yuta Aoki ◽  
Yui Yamamoto ◽  
N. Koga
Keyword(s):  
Thermal Decomposition ◽  
Granular Form ◽  
Geometrical Constraints ◽  
Overall Kinetics ◽  
Kinetic Features

The thermal decomposition of spherically granulated malachite particles was investigated to unveil the specific kinetic features of the reaction in sample in granular form toward the improvement of the thermal...

The thermal decomposition of methylene chloride

1959 ◽  
Vol 250 (1261) ◽  
pp. 180-196 ◽  
Keyword(s):  
Thermal Decomposition ◽  
Hydrogen Chloride ◽  
Methylene Chloride ◽  
Flow System ◽  
Vessel Diameter ◽  
Chlorine Atoms ◽  
System A ◽  
Pressure Time ◽  
A Chain ◽  
Kinetic Features

The thermal decomposition of methylene chloride has been studied in the temperature range 500 to 650 °C by both the static technique of pressure-time measurement and the use of a flow system in conjunction with gas chromatographic analysis. The reaction, which leads principally to carbon and hydrogen chloride is characterized by a slow acceleration, the rate of which decreases with the vessel diameter. In vessels of diameter less than 5 mm the reaction is almost completely inhibited. The reaction rate is increased by the addition of inert gas, nitric oxide and, particularly, by dichlorethylene. Using the flow system a number of chlorinated hydrocarbons were detected as minor products of the reaction and their rate of formation relative to the major products was followed in detail. By identifying some of these as radical recombination products and one, dichlorethylene, as a degenerate branching agent, a delayed branching mechanism has been deduced which explains most of the kinetic features of the reaction as well as the formation of the observed minor products. This involves the production of the intermediate, dichlor­ethylene, in a chain carried by chlorine atoms and dichlormethyl radicals, and the conversion of this to carbon and hydrogen chloride by a coupled chain also involving chlorine atoms. The average primary chain length has been estimated as fifteen by measurement of the rate of formation of the supposed recombination products, but this figure is uncertain since the termination products appear to be destroyed in turn by chlorine atoms generated in the main chain.

The thermal decomposition of aromatic compounds - II. Dichlorobenzenes

1954 ◽  
Vol 224 (1159) ◽  
pp. 544-551 ◽  
Keyword(s):  
Thermal Decomposition ◽  
Thermal Stabilities ◽  
Carbonaceous Deposit ◽  
Chain Processes ◽  
Composition And Structure ◽  
Gaseous Decomposition Product ◽  
Molecular Reaction ◽  
Complete Exclusion ◽  
The Stability ◽  
Kinetic Features

A kinetic study of the thermal decomposition of the dichlorobenzenes shows that the three isomers behave similarly. The compounds differ strikingly from chlorobenzene, inasmuch as the rate of decomposition is not reduced by nitric oxide or ammonia. Other kinetic features suggest that the reaction is unimolecular, and that chain processes do not occur to an appreciable extent. The main gaseous decomposition product is hydrogen chloride, and nearly all the combined chlorine can be accounted for as this product. Very small amounts of gaseous hydrogen are also found, but the balance of the combined hydrogen remains in the carbon deposited on the walls of the reaction vessel; this carbonaceous deposit is of similar composition and structure to that formed from chlorobenzene. Comparison of the thermal stabilities of benzene, chlorobenzene and the dichlorobenzenes shows that the stability is dependent on the extent of substitution of the aromatic ring but is little influenced by the relative positions of the substituents. The increased rate of decomposition caused by a second chlorine atom is evidently due to its ability to facilitate a molecular reaction, which apparently operates to the complete exclusion of chain processes.

The pyrolysis of monosilane

1966 ◽  
Vol 293 (1435) ◽  
pp. 543-561 ◽  
Keyword(s):  
Thermal Decomposition ◽  
Kinetic Study ◽  
Pressure Range ◽  
Initial Pressure ◽  
Product Formation ◽  
Reaction Vessel ◽  
Silicon Hydride ◽  
Temperature Range ◽  
Gaseous Products ◽  
Kinetic Features

A detailed analytical and kinetic study of the thermal decomposition of monosilane in the temperature range 375 to 430 °C and the initial pressure range 35 to 230 mmHg has been conducted. The gaseous products in the very early stages of the reaction are hydrogen, disilane and trisilane. In addition, later in the reaction a solid silicon hydride is formed, its composition varying as the reaction progresses. The kinetic features of product formation during the first 3 % of decomposition have been studied in detail, while those relating to higher extents of decomposition have been investigated less fully. The reaction is accelerated by the addition of certain foreign gases, but is unaffected by packing of the reaction vessel. A tentative mechanism involving the species silene, SiH 2 , is proposed.

scholarly journals Revealing the effect of water vapor pressure on the kinetics of thermal decomposition of magnesium hydroxide

2020 ◽  
Vol 22 (24) ◽  
pp. 13637-13649 ◽  
Author(s):  
Satoki Kodani ◽  
Shun Iwasaki ◽  
Loïc Favergeon ◽  
Nobuyoshi Koga
Keyword(s):  
Thermal Decomposition ◽  
Water Vapor ◽  
Vapor Pressure ◽  
Magnesium Hydroxide ◽  
Water Vapor Pressure ◽  
Kinetics Of Thermal Decomposition ◽  
Effect Of Water ◽  
Kinetics Of ◽  
Kinetic Features

Kinetic features of the thermal decomposition of Mg(OH)2 are revealed under different heating and water vapor pressure conditions.

Plastic Deformation in Microtomed Sections

1971 ◽  
Vol 29 ◽  
pp. 458-459
Author(s):  
J. Temple Black
Keyword(s):  
Plastic Deformation ◽  
Plastic Strain ◽  
Applied Stress ◽  
Elastic Strain ◽  
High Strain ◽  
Tool Material ◽  
Cutting Edge ◽  
Material Structure ◽  
Geometrical Constraints

The output of the ultramicrotomy process with its high strain levels is dependent upon the input, ie., the nature of the material being machined. Apart from the geometrical constraints offered by the rake and clearance faces of the tool, each material is free to deform in whatever manner necessary to satisfy its material structure and interatomic constraints. Noncrystalline materials appear to survive the process undamaged when observed in the TEM. As has been demonstrated however microtomed plastics do in fact suffer damage to the top and bottom surfaces of the section regardless of the sharpness of the cutting edge or the tool material. The energy required to seperate the section from the block is not easily propogated through the section because the material is amorphous in nature and has no preferred crystalline planes upon which defects can move large distances to relieve the applied stress. Thus, the cutting stresses are supported elastically in the internal or bulk and plastically in the surfaces. The elastic strain can be recovered while the plastic strain is not reversible and will remain in the section after cutting is complete.

Applications of Photoelectron Microscopy

1976 ◽  
Vol 34 ◽  
pp. 506-507
Author(s):  
William J. Baxter
Keyword(s):  
Electron Microscopy ◽  
Thermal Decomposition ◽  
Chemical Composition ◽  
Ultraviolet Radiation ◽  
Thin Layer ◽  
Edge Effects ◽  
Electron Optics ◽  
Surface Layers ◽  
Crystalline Orientation ◽  
Fluorescent Screen

In this form of electron microscopy, photoelectrons emitted from a metal by ultraviolet radiation are accelerated and imaged onto a fluorescent screen by conventional electron optics. image contrast is determined by spatial variations in the intensity of the photoemission. The dominant source of contrast is due to changes in the photoelectric work function, between surfaces of different crystalline orientation, or different chemical composition. Topographical variations produce a relatively weak contrast due to shadowing and edge effects.Since the photoelectrons originate from the surface layers (e.g. ∼5-10 nm for metals), photoelectron microscopy is surface sensitive. Thus to see the microstructure of a metal the thin layer (∼3 nm) of surface oxide must be removed, either by ion bombardment or by thermal decomposition in the vacuum of the microscope.

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