Thermal Analysis of the Exothermic Reaction between Galvanic Porous Silicon and Sodium Perchlorate

2010 ◽  
Vol 2 (11) ◽  
pp. 2998-3003 ◽  
Author(s):  
Collin R. Becker ◽  
Luke J. Currano ◽  
Wayne A. Churaman ◽  
Conrad R. Stoldt
Keyword(s):  
Thermal Analysis ◽  
Porous Silicon ◽  
Exothermic Reaction ◽  
Sodium Perchlorate

ON THE MECHANISMS OF POROUS SILICON COMBUSTION IN OXYGEN AND AIR ATMOSPHERE WHEN SODIUM PERCHLORATE IS INCORPORATED IN PORES

2020 ◽  
Author(s):  
V. N. MIRONOV ◽  
◽  
O. G. PENYAZKOV ◽  
P. N. KRIVOSHEYEV ◽  
I. A. IVANOV ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Porous Layer ◽  
Sodium Perchlorate ◽  
Spark Ignition ◽  
Joule Heat ◽  
Air Atmosphere ◽  
Breakdown Region ◽  
Ignition And Combustion ◽  
Heating Up

The processes of pSi ignition and combustion in oxygen are described. When spark ignition in the porous layer releases the Joule heat, it leads to a significant heating-up of the breakdown region.

Exploring the Length Scale Limits of Porous Silicon Combustion

2015 ◽  
Vol 1758 ◽  
Author(s):  
Nicholas W. Piekiel ◽  
Christopher J. Morris ◽  
Wayne A. Churaman ◽  
David M. Lunking
Keyword(s):  
Porous Silicon ◽  
Crystalline Silicon ◽  
Energetic Material ◽  
Sodium Perchlorate ◽  
Flame Speed ◽  
Small Scale ◽  
Length Scale ◽  
Sem Images ◽  
Thermal Insulator ◽  
On Chip

ABSTRACTThe present study explores the burning of microscale porous silicon channels with sodium perchlorate. These on-chip porous silicon energetics were embedded in crystalline silicon, and therefore surrounded on three sides by an efficient thermal conductor. For slow burning systems, this presents complications as heat loss to the crystalline silicon substrate can result in inconsistent burning or flame extinction. We investigated <100 μm wide porous silicon strips, sparsely filled with sodium perchlorate (NaClO4), to probe the limits of on-chip combustion. Four different etch times were attempted to decrease the dimensions of the porous silicon strips. The smallest size achieved was 12 x 64 µm, and despite the small dimensions, demonstrated the same flame speed as the larger porous silicon strips of 6-7 m/s. We predict that unreacted porous silicon acts as a thermal insulator to aid combustion for slow burning porous silicon channels, and SEM images provide evidence to support this. We also investigated the small scale combustion of a rapidly burning sample (∼1200 m/s). Despite the rapid flame speed, the propagation followed a designed, winding flame path. The use of these small scale porous silicon samples could significantly reduce the energetic material footprint for future microscale applications.

Identification of Elastomers in Tire Sections by Total Thermal Analysis. III. White Sidewall Compounds of Neoprene Rubber Blends

1975 ◽  
Vol 48 (4) ◽  
pp. 640-652 ◽  
Author(s):  
A. K. Sircar ◽  
T. G. Lamond
Keyword(s):  
Thermal Analysis ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Exothermic Reaction ◽  
Crosslinking Reaction ◽  
Rubber Blends ◽  
Tg And Dtg ◽  
Dsc Curves ◽  
Residual Weight

Abstract DSC curves of sulfur-cured CR differ from peroxide-cured vulcanizates in the shape of the exotherm and the peak temperatures. The exothermic reaction, attributed to dehydrochlorination and subsequent crosslinking, is accelerated by sulfur. TG and DTG curves support this contention. In blends with NR, BR, or SBR, the second polymer intervenes in the crosslinking reaction, resulting in a lower residual weight for the CR network. White sidewall compounds of NR/CR or NR/CR/CSM can be identified by their DSC peaks in nitrogen, glass transition temperature, and DTG peaks. DSC and thermogravimetric curves supplement each other in the identification of these elastomers.

A DTA Study on HVOF Thermally Sprayed WC–M Coatings

2007 ◽  
Vol 566 ◽  
pp. 155-160
Author(s):  
M. Heydarzadeh Sohi ◽  
Shahin Khameneh Asl ◽  
Kazuyuki Hokamoto ◽  
M. Rezvani
Keyword(s):  
Heat Treatment ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
High Temperature ◽  
Amorphous Phase ◽  
Exothermic Reaction ◽  
Intermetallic Phase ◽  
Chemical Compositions ◽  
Crystalline Phases ◽  
Sprayed Coatings

Five types of tungsten carbide based powders with different chemical compositions (WC-12Co, WC-17Co, WC-10Ni, WC-10Co-4Cr and WC- 20Cr-7Ni) were deposited onto ST37 mild steel substrate using high velocity oxy fuel (HVOF) spray technique. The feedstock powders and sprayed coatings were studied by using X-ray diffraction (XRD), and differential thermal analyzing (DTA). The results were shown during HVOF thermal spraying, WC-M powders become partially melted before being sprayed on the surface of the substrate with supersonic speed. In these types of coatings, the crystallographic structures are normally non equilibrium, because the cooling rates of the deposited splats are very high due to the cold substrate acting as a thermal sink. These partially melted powders are then rapidly solidified to an amorphous phase. XRD analysis showed that the amorphous phase was existed in all of the as sprayed coatings. The amorphous phase in WC-12Co, WC-17Co and WC-10Ni coatings was transformed to crystalline phases by heat treatment at high temperature. Heat treatment of these coatings at high temperature also resulted in partially dissolution of WC particles and formation of new crystalline phases. In cobalt base coatings, the new phases were eta carbide phases like Co6W6C and Co3W3C but in WC-10Ni coating a NiW intermetallic phase was formed. Heat treatment of WC-10Co-4Cr and WC-20Cr-7Ni coatings did not change the amorphous phases in these coatings. Differential thermal analysis of cobalt containing coatings revealed an exothermic reaction at approximately 880°C. This exothermic reaction may be related to the transformation of the amorphous phase to eta phases. On the contrary, DTA analysis of feedstock powders of these coatings showed an endothermic reaction at approximately 1000°C. DTA analyses of nickel containing cermets also showed similar results. Differential thermal analysis of chromium containing cermets did not show any noticeable exothermic or endothermic reactions.

Differential thermal analysis of porous silicon

2009 ◽  
Vol 82 (11) ◽  
pp. 1928-1933
Author(s):  
A. A. Nechitaylov ◽  
N. V. Glebova
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Porous Silicon

Studies of the Hard Rubber Reaction. I. Heat of Reaction

1963 ◽  
Vol 36 (4) ◽  
pp. 1059-1070 ◽  
Author(s):  
M. L. Bhaumik ◽  
D. Banerjee ◽  
Anil K. Sircar
Keyword(s):  
Thermal Analysis ◽  
Hydrogen Sulfide ◽  
Differential Thermal Analysis ◽  
Exothermic Reaction ◽  
Heat Evolution ◽  
Linear Increase ◽  
Heat Of Reaction ◽  
Dehydrogenation Reaction ◽  
Rate Of Reaction

Abstract A method for the determination of the heat of the hard-rubber reaction by the application of differential thermal analysis is reported. The heat of reaction was determined with stocks containing different rubber/sulfur ratios and also with a 68/32 stock, preheated to contain different amounts of combined sulfur. Heat evolution is observed first with samples containing about 7 per cent sulfur and therefrom the amount of heat evolved shows a nearly linear increase up to 30 per cent sulfur. With increasing combined sulfur in the 68/32 stock, the quantity of exothermic heat gradually diminishes; so also does the temperature of initiation, i.e., the temperature at which heat evolution appears to begin. Initiation of the exothermic reaction appears to be a function of composition and temperature of the mass. An increase in the rate of reaction was observed when the composition reached 0.5 g-atom of sulfur per isoprene unit. An endothermic dehydrogenation reaction is observed at the end of the hard-rubber reaction. This, however, does not affect the determination of exothermic heat, because there is similar dehydrogenation taking place in the reference material (ebonite) which almost balances this heat loss. The final product has a lower sulfur content due to loss of sulfur as hydrogen sulfide.

scholarly journals Thermal analysis of physical and chemical changes occuring during regeneration of activated carbon

2017 ◽  
Vol 21 (2) ◽  
pp. 1067-1081 ◽  
Author(s):  
Dejan Radic ◽  
Miroslav Stanojevic ◽  
Marko Obradovic ◽  
Aleksandar Jovovic
Keyword(s):  
Thermal Analysis ◽  
Activated Carbon ◽  
High Temperature ◽  
Thermogravimetric Analysis ◽  
Exothermic Reaction ◽  
Drinking Water Treatment ◽  
Mass Change ◽  
Intense Mass ◽  
Loss Of Mass ◽  
Physical And Chemical

High-temperature thermal process is a commercial way of regeneration of spent granular activated carbon. The paper presents results of thermal analysis conducted in order to examine high-temperature regeneration of spent activated carbon, produced from coconut shells, previously used in drinking water treatment. Results of performed thermogravimetric analysis, derivative thermogravimetric analysis, and differential thermal analysis, enabled a number of hypotheses to be made about different phases of activated carbon regeneration, values of characteristic parameters during particular process phases, as well as catalytic impact of inorganic materials on development of regeneration process. Samples of activated carbon were heated up to 1000?C in thermogravimetric analyser while maintaining adequate oxidizing or reducing conditions. Based on diagrams of thermal analysis for samples of spent activated carbon, temperature intervals of the first intense mass change phase (180-215?C), maximum of exothermic processes (400-450?C), beginning of the second intense mass change phase (635-700?C), and maximum endothermic processes (800-815?C) were deter-mined. Analysing and comparing the diagrams of thermal analysis for new, previously regenerated and spent activated carbon, hypothesis about physical and chemical transformations of organic and inorganic adsorbate in spent activated carbon are given. Transformation of an organic adsorbate in the pores of activated carbon, results in loss of mass and an exothermic reaction with oxygen in the vapour phase. The reactions of inorganic adsorbate also result the loss of mass of activated carbon during its heating and endothermic reactions of their degradation at high temperatures.

FAST COMBUSTION MODES OF COMPOSITES "MOUND OF POROUS SILICON FRAGMENTS-SODIUM PERCHLORATE MONOHYDRATE" IN THE ATMOSPHERE

2020 ◽  
Author(s):  
V. N. MIRONOV ◽  
◽  
O. G. PENYAZKOV ◽  
E. S. GOLOMAKO ◽  
S. O. SHUMLYAEV ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Energetic Material ◽  
Sodium Perchlorate ◽  
Nanostructured Silicon ◽  
Combustion Modes ◽  
Potential Use

Numerous studies have demonstrated the potential use of porous silicon (pSi) as an energetic material. However, there are a number of dificulties in such an application of nanostructured silicon. Here are two of the most serious dificulties.

FAST COMBUSTION MODES OF COMPOSITES “MOUND OF POROUS SILICON FRAGMENTS - SODIUM PERCHLORATE MONOHYDRATE” IN THE ATMOSPHERE

2021 ◽  
Vol 14 (2) ◽  
pp. 83-91
Author(s):  
V.N. MIRONOV ◽  
◽  
O.G. PENYAZKOV ◽  
E.S. GOLOMAKO ◽  
S.O. SHUMLYAEV ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Porous Layer ◽  
Sodium Perchlorate ◽  
High Energy ◽  
Combustion Dynamics ◽  
Porous Layers ◽  
Combustion Modes ◽  
Series Of Experiments ◽  
Induction Times ◽  
Energy Processes

One of the criteria for the development of high-energy processes is the large specific surface area of the solid component of composites. Therefore, the maximum preservation of its nanostructured skeleton when separating the porous layer from the monocrystal substrate is relevant. Based on the analysis of the quality of the porous layer under various methods and modes of its formation, two methods were selected that provide simple and effective separation of the porous structure from the monocrystal. For composites based on mounds of porous silicon (pSi) fragments (MPSF), three series of experiments were carried out with fragments of porous layers of different age (formed within the previously established time limits before composites creation) with registration of combustion dynamics, temperatures and combustion spectra, as well as intensity of disturbances in the atmosphere forming during combustion of MPSF-composites. Four combustion modes of MPSF-composites were established: smoldering, frontal, aerosol, and frontal-aerosol. The ignition induction times were determined: from 1 to 50 ^s, pressure pulses in the atmosphere at a distance of 260 mm from the ignition site - up to 1.6 bar (with a mass of composites up to 0.4 g). Combustion velocities ofMPSF-composites and their dependences onthe coefficient of stoichiometry and humidity of sodium perchlorate monohydrate are established.

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