Aerothermochemistry of Metal Erosion by Hot Reactive Gases

1978 ◽  
Vol 100 (3) ◽  
pp. 531-536 ◽  
Author(s):  
A. Gany ◽  
L. H. Caveny ◽  
M. Summerfield
Keyword(s):  
Surface Reactions ◽  
Experimental Studies ◽  
Heating Surface ◽  
Melting Rate ◽  
Short Exposure ◽  
Convective Heating ◽  
Erosion Rates ◽  
Diffusion Limited ◽  
O2 Concentration ◽  
Reactive Gases

Analytical studies were conducted to investigate the mechanisms of metal erosion produced by short exposures (< 2 ms) to flowing high pressure (∼ 350 MPa), high temperature (∼ 3000 K) reactive gases. Previous experimental studies established that the intense heating during the short exposure produced melting and, when reactive gases were used, oxidation of the surface and enhanced erosion. The reactions were modeled as diffusion-limited, heterogeneous surface reactions which achieved equilibrium at the gas/metal interface. Calculated results for the sequential events of initial heating, surface reactions, and melting explained and correlated the experimental trends for Fe, Al, Ti, and Mo. Rapidly increasing erosion rates with increasing O2 concentration are the result of the surface reactions between the metal and O2. As O2 concentration increases, the heating produced by the surface reaction exceeds the forced convective heating which, in turn, greatly enhances the melting rate.

scholarly journals Editorial for Special Issue “Mineral Surface Reactions at the Nanoscale”

Minerals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 185
Author(s):  
Christine Putnis
Keyword(s):  
Surface Reactions ◽  
Experimental Studies ◽  
Analytical Techniques ◽  
Aqueous Fluid ◽  
Mineral Surfaces ◽  
Special Issue ◽  
Mineral Surface ◽  
Electron Microscopies ◽  
Interface Control ◽  
The Earth

Reactions at mineral surfaces are central to all geochemical processes. As minerals comprise the rocks of the Earth, the processes occurring at the mineral–aqueous fluid interface control the evolution of the rocks and, hence, the structure of the crust of the Earth during such processes at metamorphism, metasomatism, and weathering. In recent years, focus has been concentrated on mineral surface reactions made possible through the development of advanced analytical techniques, such as atomic force microscopy (AFM), advanced electron microscopies (SEM and TEM), phase shift interferometry, confocal Raman spectroscopy, advanced synchrotron-based applications, complemented by molecular simulations, to confirm or predict the results of experimental studies. In particular, the development of analytical methods that allow direct observations of mineral–fluid reactions at the nanoscale have revealed new and significant aspects of the kinetics and mechanisms of reactions taking place in fundamental mineral–fluid systems. These experimental and computational studies have enabled new and exciting possibilities to elucidate the mechanisms that govern mineral–fluid reactions, as well as the kinetics of these processes, and, hence, to enhance our ability to predict potential mineral behavior. In this Special Issue “Mineral Surface Reactions at the Nanoscale”, we present 12 contributions that highlight the role and importance of mineral surfaces in varying fields of research.

Postglacial geomorphic development of the Dinosaur Provincial Park badlands, Alberta

1987 ◽  
Vol 24 (1) ◽  
pp. 135-146 ◽  
Author(s):  
Rorke B. Bryan ◽  
Ian A. Campbell ◽  
Aaron Yair
Keyword(s):  
Red Deer ◽  
Experimental Studies ◽  
Sediment Discharge ◽  
Erosion Rates ◽  
Water And Sediment ◽  
Provincial Park ◽  
Geomorphic Processes ◽  
Aeolian Sands

Experimental studies concerning current geomorphic processes and erosion rates in the badlands of Dinosaur Provincial Park, Alberta, have not explained the unusual extent of badland development or prominent nonstructural near-horizontal surfaces that occur in the park. Two of these surfaces result from spillway development associated with Wisconsin deglaciation, and the extent of badland development is associated with major spillway concentration and exposure of highly erodible Cretaceous strata. A third surface is associated with erosion caused by locally generated runoff. All surfaces are blanketed with aeolian sands and silts deposited around 5500 BP, which profoundly affected the hydrology of the area and water and sediment discharge from the badlands to the Red Deer River. Subsequent stripping of the aeolian cover by streams, along with piping and tunnel erosion, has reexposed vulnerable Cretaceous strata and restored the high erosion rates now observed in these badlands.

scholarly journals Cavitation Erosion in Nonaqueous Liquids

1970 ◽  
Vol 92 (4) ◽  
pp. 807-813 ◽  
Author(s):  
M. S. Plesset
Keyword(s):  
Cavitation Erosion ◽  
Organic Liquid ◽  
Pure Water ◽  
Short Exposure ◽  
Organic Liquids ◽  
Cavitation Damage ◽  
Molecular Ratio ◽  
Erosion Rates ◽  
Damage Rate ◽  
Water Glycerol

Cavitation erosion rates in the organic liquids formamide, ethanol, acetone, and glycerol are compared with the rate in distilled water. As is to be expected, these non-ionizing liquids, which are chemically less reactive with metals than water, show lower damage rates. The cavitation damage rates have also been measured for solutions of these organic liquids in water and all these solutions show a monotonic decrease in going from pure water to the pure organic liquid except glycerol. The water-glycerol solutions go through a minimum damage rate for a solution with molecular ratio of glycerol to water of approximately 1 to 1. Solutions of ethanol in glycerol show a maximum in damage rate for a solution with molecular ratio, glycerol/ethanol, of about 2 to 1. Qualitative differences in the cavitation bubble cloud in the various liquids studied are indicated by short-exposure photographs.

scholarly journals Absorption of pollutants from exhaust gases by low-temperature heating surfaces

2021 ◽  
Vol 323 ◽  
pp. 00018
Author(s):  
Victoria Kornienko ◽  
Mykola Radchenko ◽  
Roman Radchenko ◽  
Marcin Kruzel ◽  
Dmytro Konovalov ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Low Temperature ◽  
Internal Combustion Engines ◽  
Experimental Studies ◽  
Heating Surface ◽  
Dew Point ◽  
Fuel Oil ◽  
Exhaust Gas ◽  
Acid Vapor ◽  
Exhaust Gases

One of the most effective methods aimed to improving the environmental safety is fuel oil combustion in the form of specially prepared water-fuel emulsions. The combustion of water-fuel emulsion in internal combustion engines makes it possible to reduce a rate of low-temperature corrosion at wall temperatures below the dew point temperature of sulfuric acid vapor, to install a condensing lowtemperature heating surface in the exhaust gas boiler that leads to increase the efficiency of boiler. Therefore, it is of great importance to assess the effect of the presence of condensate (water, acid) and pollution on these surfaces on the processes of NOx, SO2 absorption from exhaust gases. Investigations of SO2, NOx and particulate matter emission were carried out on the experimental installation for fuel oil and water-fuel emulsion combustion with different water content. Using condensing heating surface enables to reduce the concentration of NOx and SO2 by 65 %. Experimental studies have shown that condensing heating surface ensures the capture of up to 30 % of particulate matter from the exhaust gas flow.

scholarly journals Capture of Pollutants from Exhaust Gases by Low-Temperature Heating Surfaces

Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 120
Author(s):  
Zongming Yang ◽  
Victoria Kornienko ◽  
Mykola Radchenko ◽  
Andrii Radchenko ◽  
Roman Radchenko ◽  
...  
Keyword(s):  
Low Temperature ◽  
Gas Flow ◽  
Experimental Studies ◽  
Heating Surface ◽  
Exhaust Gas ◽  
Graphic System ◽  
Acid Vapor ◽  
Exhaust Gases ◽  
Heating Surfaces ◽  
Temperature Heating

One of the most effective methods towards improving the environmental safety of combustion engines is the application of specially prepared water-fuel emulsions (WFE). The application of WFE makes it possible to reduce primary sulfur fuel consumption and reveals the possibility of capturing the pollutants from exhaust gases by applying condensing low-temperature heating surfaces (LTHS). In order to realize such a double effect, it is necessary to investigate the pollution processes on condensing LTHS of exhaust gas boilers (EGB), especially the process of low-temperature condensing a sulfuric acid vapor from exhaust gases to investigate the influence of condensing LTHS on the intensity of pollutants captured from the exhaust gases. The aim of this research is to assess the influence of the intensity of pollutants captured from exhaust gases by condensing LTHS in dependence of water content in WFE combustion. Investigations were carried out at a special experimental setup. The processing of the results of the experimental studies was carried out using the computer universal statistical graphic system Statgraphics. Results have shown that in the presence of a condensing heating surface, the degree of capture (purification) of pollutants from the exhaust gas flow is up to 0.5–0.6.

Comparative study of the growth characteristics and electrical properties of atomic-layer-deposited HfO2 films obtained from metal halide and amide precursors

2018 ◽  
Vol 6 (27) ◽  
pp. 7367-7376 ◽  
Author(s):  
Il-Kwon Oh ◽  
Bo-Eun Park ◽  
Seunggi Seo ◽  
Byung Chul Yeo ◽  
Jukka Tanskanen ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Comparative Study ◽  
Film Growth ◽  
Surface Reactions ◽  
Experimental Studies ◽  
Atomic Layer ◽  
Growth Characteristics ◽  
Metal Halide

Theoretical and experimental studies were performed on surface reactions during film growth and electrical properties of HfO2 using two different Hf precursors, HfCl4 and Hf(N(CH3)2)4.

A Kinetic Model for Metalorganic Chemical Vapor Deposition of GaAs from Trimethylgallium and Arsine

1988 ◽  
Vol 131 ◽  
Author(s):  
Triantafillos J. Mountziaris ◽  
Klavs F. Jensen
Keyword(s):  
Chemical Vapor Deposition ◽  
Kinetic Model ◽  
Gas Phase ◽  
Vapor Deposition ◽  
Metalorganic Chemical Vapor Deposition ◽  
Transport Model ◽  
Surface Reactions ◽  
Experimental Studies ◽  
Chemical Vapor ◽  
Metalorganic Chemical

ABSTRACTA kinetic model for metalorganic chemical vapor deposition (MOCVD) of GaAs from trimethylgallium and arsine is presented. The proposed mechanism includes 15 gas-phase species, 17 gas-phase reactions, 9 surface species and 29 surface reactions. The surface reactions take into account different crystallographic orientations of the GaAs substrate. Sensitivity analysis and existing experimental observations have been used to develop the reduced mechanism from the large number of reactions that might in principle occur. Rate constants are estimated by using thermochemical methods and reported experimental data. The kinetic mechanism is combined with a two-dimensional transport model of a hot-wall tubular reactor used in experimental studies. Model predictions of gas-phase composition and GaAs growth rates show good agreement with published experimental studies. In addition, the model predicts reported trends in carbon incorporation.

Permeability limitation in estimation of local brain blood flow with [14C]antipyrine

1975 ◽  
Vol 229 (1) ◽  
pp. 215-221 ◽  
Author(s):  
WW Eckman ◽  
RD Phair ◽  
JD Fenstermacher ◽  
CS Patlak ◽  
C Kennedy ◽  
...  
Keyword(s):  
Blood Flow ◽  
Capillary Permeability ◽  
Experimental Studies ◽  
Local Cerebral Blood Flow ◽  
Indicator Method ◽  
Diffusion Limited ◽  
Theoretical Analyses ◽  
True Values ◽  
Ideal Tracer ◽  
Local Brain

Influence of capillary permeability on local cerebral blood flow (LCBF) estimated by the autoradiograhpic diffusible-indicator method was analyzed by computer simulation. Its influence increases with increasing flow. With normal perfusion rates in gray matter, capillary permeability coefficient x surface area (PS value) must exceed 0.12 cm3-s(-1)-g(-1) for estimated LCBF to attain 95% of true values in all structures. In white matter, with its lower perfusion rates, the PS value must exceed 0.035 cm3-s(-1)-g(-1) for equivalent accuracy. [14C]antipyrine, widely used in the LCBF technique, has a PS value below these values and leads to undersestimation of LCBF. Experimental studies in cats in which LCBF was measured with either [14C]antipyrine or the freely diffusible, radioactive gas, [131I]trifluoroiodomethane, demonstrated consistently lower estimates of LCBF with [14C]antipyrine than with the gas; the deviations in the various cerebral structures approximated those predicted by the theoretical analyses. These results suggest that the uptake of [14C]antipyrine by cerebral tissues is diffusion limited as well as flow limited, and it therefore is not an ideal tracer for the autoradiographic LCBF technique.

scholarly journals Experimental studies of surface reactions among OH radicals that yield H2O and CO2 at 40–60 K

2011 ◽  
Vol 13 (35) ◽  
pp. 15792 ◽  
Author(s):  
Yasuhiro Oba ◽  
Naoki Watanabe ◽  
Akira Kouchi ◽  
Tetsuya Hama ◽  
Valerio Pirronello
Keyword(s):  
Surface Reactions ◽  
Experimental Studies ◽  
Oh Radicals
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