Recent Studies of the Action of Inorganic Inhibitors

CORROSION ◽  
1962 ◽  
Vol 18 (9) ◽  
pp. 316t-322t ◽  
Author(s):  
G. H. CARTLEDGE
Keyword(s):  
Solid Phase ◽  
Experimental Studies ◽  
Anodic Process ◽  
Radioactive Tracers ◽  
Semiconductor Physics ◽  
Oxidation Reduction ◽  
Adsorption Of Gases ◽  
Electrostatic Polarization ◽  
Solute Species ◽  
Kinetics Of

Abstract The goal in recent studies of the action of inhibitors has been to apply some of the concepts and experimental techniques that have been fruitful in problems of electrode kinetics, heterogeneous catalysis and, to some extent, semiconductor physics. The purpose has been to determine fundamentally the manner in which an inhibitor of corrosion acts. In order to disclose the nature of the corrosion process to be inhibited, some of the recent work on the anodic process is discussed. The importance of adsorption and of semiconducting surfaces in the kinetics of electrode reactions is illustrated. The principal theories of inhibitor action are outlined and discussed in the light of recent experimental studies, in which radioactive tracers have had a prominent role. In considering the physical-chemical basis for the specificity of solute species as inhibitors, it is shown that such species may interact with a solid phase through a variety of mechanisms. These include oxidation-reduction processes, adsorption and ion-exchange, and electrostatic polarization. The effects of these interactions are shown to correlate with phenomena observed in the adsorption of gases on metals and in certain surface properties of semiconductors. The conclusion reached is that a comprehensive consideration of all such types of interaction is necessary for an understanding of the action of inhibitors. 5.8.3, 5.8.4, 3.2.2

Specifics of Cementation Processes for Metals Removal

1991 ◽  
Vol 24 (7) ◽  
pp. 235-246 ◽  
Author(s):  
B. M. Khudenko ◽  
J. P. Gould
Keyword(s):  
Experimental Studies ◽  
Reduction Reactions ◽  
Antagonistic Effects ◽  
Species Effects ◽  
Oxidation Reduction ◽  
Metals Removal ◽  
Kinetics Of

Specific features of cementation processes observed in numerous experimental studies are explained on the basis of a recently developed theory. This theory considers the kinetics of the oxidation reduction reactions and the possibility of either migrational or diffusional transport of the noble species. In particular, synergistic and antagonistic effects in simultaneous reductions of noble species, effects associated with anionic promoters, and effects of atmosphere are considered in the present paper.

scholarly journals KINETICS OF RHEOLOGICAL CHARACTERISTICS OF FOAM CONCRETE MIXTURE

2021 ◽  
pp. 110-118
Author(s):  
V. Martynov ◽  
◽  
O. Martynova ◽  
V. Elkin ◽  
S. Makarova ◽  
...  
Keyword(s):  
Structural Strength ◽  
Solid Phase ◽  
Chemical Activation ◽  
Experimental Studies ◽  
Concrete Mixture ◽  
Rheological Characteristics ◽  
Foam Concrete ◽  
Plastic Strength ◽  
Kinetics Of ◽  
Cellular Concrete

Abstract. The results of experimental studies are presented, the purpose of which was to study the influence of variable formulation and technological factors on the rheological characteristics of the foam concrete mixture, in particular, the structural strength. This is preceded by an analysis of the process of structure formation of cellular concrete. As a result, it is shown that the properties of cellular concrete are determined by the nature of the distribution of the solid component. The structure of the solid phase is formed at the earliest stages of the formation of cellular products and depends on the rheological characteristics of the mortar and cellular mixture. In the technology of cellular concrete, it is important to synchronize the processes of pore formation and the growth of plastic (structural) strength, which is also associated with a change in the rheological properties of the mixture. Using the methods of mathematical statistics, the influence of the content of the filler in the mixture with cement, the content of the complex additive, and the effect of mechanical chemical activation on the kinetics of the plastic strength of the foam concrete mixture were studied. The kinetic dependences of the plastic strength of the foam concrete mixture in the range of 6 ... 24 hours from the moment of manufacture have been constructed. Each of the 15 curves is maximized by a 3rd-degree polynomial. Based on the obtained dependences, they are differentiated between the first and second derivatives. As a result, the equations of the speed and intensity (acceleration) of the plastic strength of the foam concrete mixture were obtained. According to the results of the previous experiment, carried out according to a three-factor plan, a 4-factor plan was synthesized, in which the aging period of the foam concrete mixture was taken as the fourth factor. The calculated theoretical values of the characteristics of the structural strength of the foam concrete mixture were entered into the matrix. As a result, mathematical models of plastic strength, speed, and intensity of plastic strength of the foam concrete mixture were calculated and the influence of variable factors studied on the isosurfaces of these properties was visualized. The analysis of these dependencies made it possible to determine the characteristic recipe and technological conditions for obtaining a foam concrete mixture with the required values of plastic strength.

scholarly journals Study of the kinetics of carboxymethyl cellulose synthesis in a screw reactor

2021 ◽  
Vol 6 (3(62)) ◽  
pp. 15-20
Author(s):  
Kateryna Konovalenko ◽  
Yurii Beznosyk ◽  
Liudmyla Bugaieva
Keyword(s):  
Carboxymethyl Cellulose ◽  
Solid Phase ◽  
Homogeneous Model ◽  
Experimental Studies ◽  
Heterogeneous Reactions ◽  
Process Conditions ◽  
Cellulose Synthesis ◽  
Important Indicator ◽  
Screw Reactor ◽  
Kinetics Of

The object of research is the reactor for the synthesis of carboxymethyl cellulose. An important indicator of the quality of sodium carboxymethyl cellulose, which determines the field of its application, is the degree of polymerization. However, obtaining a product with a specific parameter under industrial conditions is associated with a number of difficulties. Therefore, important research tasks are the development of a mathematical model of the kinetics of carboxymethyl cellulose synthesis, experimental studies to determine the rate constants of synthesis reactions, modeling of a screw reactor for the synthesis of carboxymethyl cellulose, and computer studies. When studying the kinetics of reactions of carboxymethyl cellulose, one of the possible approaches was to use a quasi-homogeneous model, which is widely used in modeling processes on a catalyst grain. This approach is used to describe and analyze individual stages; however, a number of difficulties arise in heterogeneous reactions of cellulose. In the course of these reactions, the properties of the solid phase change and the processes, respectively, are unsteady in time. The reaction does not take place on the surface of hard particles, but in the entire volume of the fibers. The concentration and reactivity of cellulose hydroxides, water, and products formed during the reaction remain approximately constant; therefore, the use of a quasi-homogeneous model is quite acceptable and does not cause additional mathematical difficulties. As a result of these experiments, according to the obtained integral curves, the method of least squares was used to find the constants. To determine the values of the kinetic constants, an experiment was carried out in an integral isothermal reactor. During the experiments, the degree of substitution of carboxymethyl cellulose and the concentration of free alkali were measured. As a result of numerous implementations of the search task, the values of the constants and activation energies were obtained. This kinetic modeling approach can be used in the synthesis of other cellulose ethers. The rate constant of the synthesis reaction depends on the process conditions. Using the proposed approach to describing the interaction of cellulose with a reagent, the reaction mixture considered as a quasi-homogeneous system can be described using a single-phase flow model.

scholarly journals Mechanochemical Activation Effect on Technogenic Iron Oxide Reduction Kinetics

Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 320
Author(s):  
Oleg Sheshukov ◽  
Mikhail Mikheenkov ◽  
Larisa Vedmid ◽  
Denis Egiazaryan
Keyword(s):  
Iron Oxide ◽  
Reaction Kinetics ◽  
Iron Oxides ◽  
Mechanochemical Activation ◽  
Solid Phase ◽  
Experimental Studies ◽  
High Rate ◽  
Oxide Reduction ◽  
Iron Oxide Reduction ◽  
Kinetics Of

Understanding the reaction kinetics of iron oxide reduction by carbon is a key task of the theory of metallurgical processes. One of the understudied features of the reaction kinetics of iron oxide solid-phase reduction by carbon is the discrepancy between the reacting substances’ small contact area and the process’s high rate. A convincing theoretical and experimental explanation of this effect has not yet been obtained. The data obtained earlier show that an increase in the scale of the briquetting pressure from 0 to 300 MPa increases the degree of its metallization during heating two-fold, and the metallization temperature decreases by more than 40 °C. Therefore, it was assumed that these effects during heating are a consequence of the mechanochemical activation (MCA) of iron oxides in the scale during its pressing. This paper presents the results of experimental studies on the influence of two types of scale MCA (grinding and pressing) on iron oxide reduction. The study of the MCA effect on the reaction kinetics of scale iron oxide reduction by carbon is a promising way to assess the criteria for scale phase composition changes under external factors. The presented results indicate a decrease in the amount of trivalent iron oxide (Fe2O3) after the MCA and an increase in the amount of one-and-a-half oxide (Fe3O4) and bivalent iron oxide (FeO). The obtained experimental data show that the initial stage of iron oxide reduction, consisting in the transition from higher iron oxides to lower ones, is possible at room temperature without carbon presence.

scholarly journals A Study of the Impact of Graphite on the Kinetics of SPS in Nano- and Submicron WC-10%Co Powder Compositions

Ceramics ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 331-363
Author(s):  
Eugeniy Lantcev ◽  
Aleksey Nokhrin ◽  
Nataliya Malekhonova ◽  
Maksim Boldin ◽  
Vladimir Chuvil'deev ◽  
...  
Keyword(s):  
Activation Energy ◽  
Solid Phase ◽  
Continuous Heating ◽  
Diffusion Creep ◽  
Hard Alloys ◽  
Fine Grained ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
The Impact ◽  
Kinetics Of

This study investigates the impact of carbon on the kinetics of the spark plasma sintering (SPS) of nano- and submicron powders WC-10wt.%Co. Carbon, in the form of graphite, was introduced into powders by mixing. The activation energy of solid-phase sintering was determined for the conditions of isothermal and continuous heating. It has been demonstrated that increasing the carbon content leads to a decrease in the fraction of η-phase particles and a shift of the shrinkage curve towards lower heating temperatures. It has been established that increasing the graphite content in nano- and submicron powders has no significant effect on the SPS activation energy for “mid-range” heating temperatures, QS(I). The value of QS(I) is close to the activation energy of grain-boundary diffusion in cobalt. It has been demonstrated that increasing the content of graphite leads to a significant decrease in the SPS activation energy, QS(II), for “higher-range” heating temperatures due to lower concentration of tungsten atoms in cobalt-based γ-phase. It has been established that the sintering kinetics of fine-grained WC-Co hard alloys is limited by the intensity of diffusion creep of cobalt (Coble creep).

Effect of maturity of Napier grass (Pennisetum purpureum) hay on intake, digestibility, and rumen dynamics when given to zebu bulls

2000 ◽  
Vol 2000 ◽  
pp. 144-144
Author(s):  
A.J. Ayala-Burgos ◽  
F.D.DeB. Hovell ◽  
R.M. Godoy ◽  
Hamana S. Saidén ◽  
R. López ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Solid Phase ◽  
Napier Grass ◽  
Pennisetum Purpureum ◽  
Ad Libitum ◽  
The Tropics ◽  
Kinetics Of

Cattle in the tropics mostly depend on pastures. During dry periods the forage available is usually mature, constraining both intake and digestion. These constraints need to be understood, for intake and digestibility define productivity. Intake depends on the rumen space made available by fermentation and outflow. Markers such as PEG (liquid phase), and chromium mordanted fibre (solid phase) can be used to measure rumen volume and outflow, but have limitations. The objective of this experiment was to measure intake, digestibility, and rumen kinetics of cattle fed ad libitum forages with very different degradation characteristics, and also to compare rumen volumes measured with markers with those obtained by manual emptying.

Kinetics of arsenic-enhanced solid phase epitaxy in silicon

2004 ◽  
Vol 95 (8) ◽  
pp. 4427-4431 ◽  
Author(s):  
B. C. Johnson ◽  
J. C. McCallum
Keyword(s):  
Solid Phase ◽  
Solid Phase Epitaxy ◽  
Kinetics Of
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