USE OF THE HARING CELL FOR MEASURING ADDITION AGENT CONCENTRATION IN ELECTROLYTIC BATHS

1943 ◽  
Vol 21b (5) ◽  
pp. 81-91 ◽  
Author(s):  
W. Gauvin ◽  
C. A. Winkler
Keyword(s):  
Temperature Change ◽  
Low Temperatures ◽  
Copper Sulphate ◽  
Relative Increase ◽  
Dilute Solutions ◽  
Addition Agent ◽  
Cathode Polarization ◽  
Polarization Measurements ◽  
Current Densities ◽  
Gelatin Concentration

Cathode polarization measurements during electrodeposition from acid copper sulphate solutions were made with a Haring cell, using a method previously developed (4). Measurements made at 2°, 24.8°, and 50.1 °C. show that the polarization decreases as temperature increases, this decrease being larger for a temperature change from 2° to 24.8 °C. than for a change from 24.8 to 50.1 °C. An increase in acidity has little effect on the polarization (except for low acidities) at apparent current densities below 2 amp. per dm.2, while it results in an increase in polarization above that value. The increase in polarization caused by various concentrations of gelatin was studied at −4.2°, 2°, 24.8°, and 50.1 °C. For a given gelatin concentration, the increase in polarization is greater the lower the temperature, while for a given temperature, the relative increase in cathode polarization is greater at smaller gelatin concentration. It is concluded that control of the gelatin or glue concentration of an electrolyte with a Haring cell may be considerably improved by making the measurements at low temperatures and in dilute solutions.

EFFECT OF GELATIN ON THE CHANGES IN INITIAL CATHODE POLARIZATION DURING ELECTRODEPOSITION OF COPPER

1954 ◽  
Vol 32 (6) ◽  
pp. 581-590 ◽  
Author(s):  
B. I. Parsons ◽  
C. A. Winkler
Keyword(s):  
Steady State ◽  
Current Density ◽  
Copper Sulphate ◽  
Chloride Concentration ◽  
High Current ◽  
Concentration Increase ◽  
Addition Agent ◽  
Cathode Polarization ◽  
Current Densities ◽  
Gelatin Concentration

In the absence of addition agent, the cathode polarization during initial electrolysis of copper from a solution of acid copper sulphate rose almost instantaneously from zero to approximately the steady state polarization. When gelatin was present in the electrolyte, the polarization generally increased to a maximum, Pmax, (in time tmax) then decreased to a minimum, Pmin, (in-time tmin) beyond which it increased to the steady state value, Ps. Generally, Pmax increased to a steady value with an increase in the time, T0, the electrode was in contact with the electrolyte before electrolysis was begun. At low, moderate, and high current densities respectively, tmax increased continuously, passed through a maximum, and decreased continuously with T0.The behavior of tmin approximately paralleled that of tmax. The polarization was linear in the logarithm of the current density; tmax and tmin decreased with increase in current density. The polarization values increased and tmax decreased, with increase in gelatin concentration. Increase of temperature had approximately the same effect as decrease in current density. With both chloride and gelatin present, Pmax was practically independent of T0 and chloride concentration, while Pmin and Ps showed minimum values at about 2 mgm./l. chloride.

Specific Heat

1983 ◽  
pp. 47-73
Author(s):  
L. L. Sparks
Keyword(s):  
Solid State ◽  
Specific Heat ◽  
Temperature Change ◽  
Low Temperatures ◽  
Historical Development ◽  
Fundamental Property ◽  
Data Sources ◽  
Unit Mass ◽  
Practical Applications ◽  
Lattice Specific Heat

Abstract Specific heat is a fundamental property that relates the total heat per unit mass added to a system to the resultant temperature change of the system. This chapter begins with the definition and historical development of specific heat. Thermodynamic and solid state relationships are presented which include discussions about lattice specific heat and the effects of magnetic and superconducting transitions. Data sources for practical applications and methods of estimating specific heat for materials are also included. The chapter concludes with a section concerning the measurement of specific heat at low temperatures.

CATHODE SURFACE CHANGES IN THE PRESENCE OF GELATIN DURING ELECTRODEPOSITION OF COPPER

1943 ◽  
Vol 21b (6) ◽  
pp. 125-132 ◽  
Author(s):  
W. Gauvin ◽  
C. A. Winkler
Keyword(s):  
Grain Size ◽  
Current Density ◽  
Copper Sulphate ◽  
Cathode Surface ◽  
Active Area ◽  
Cathode Polarization ◽  
Active Centres ◽  
Main Factor ◽  
Surface Changes

Measurements of the cathode polarization during electrodeposition of copper from acid copper sulphate solutions indicate that introduction of gelatin into the electrolyte decreases the area of the cathode available for deposition, or active area, owing to adsorption of gelatin on the active centres. This decrease in area causes an increase in the true current density, with a resulting increase in cathode polarization, the former being assumed the main factor in causing an increase in the rate of nuclear formation and decrease in grain size.

THE EFFECT OF ADDITION AGENTS ON CATHODE POLARIZATION DURING ELECTRODEPOSITION OF COPPER AT SINGLE CRYSTAL COPPER CATHODES

1955 ◽  
Vol 33 (12) ◽  
pp. 1756-1767
Author(s):  
K. Ekler ◽  
C. A. Winkler
Keyword(s):  
Steady State ◽  
Single Crystal ◽  
Single Crystals ◽  
Linear Relation ◽  
Crystal Orientation ◽  
Chloride Ion ◽  
Addition Agent ◽  
Cathode Polarization ◽  
Single Crystal Copper ◽  
Copper Single Crystals

The polarization–time relations for the initial (Pi), maximum (Pmax), and pseudo-steady-state (Ps) polarizations on copper single crystals in the absence and presence of gelatin and gelatin plus chloride ion were found to depend upon crystal orientation. The Pi and Pmax in the absence of gelatin, the Pi in its presence, and the static potentials were all similarly related to the reticular density. The Pi increased, and the time to maximum polarization (tmax) decreased, with increase of current density; the relations between these quantities showed marked differences for the different crystals. The variation with reticular density of Pi and Pmax in the absence of addition agents and of Pi in its presence probably represents differences in activation overpotential at the various crystal faces. The adsorption of gelatin on different crystal faces was also found to be markedly different. Polarization in the presence of gelatin was decreased by small amounts of chloride ion; a linear relation for all the crystals used was obtained by plotting the increase in polarization caused by gelatin against the decrease caused by 2 mgm./liter chloride ion in the presence of gelatin. In the absence of addition agent, change of acid concentration from 50 to 200 gm./liter had no effect on Pi and addition of chloride ion had no effect on Ps at single crystal cathodes.

REDUCED COLD-HARDINESS OF PEAR PSYLLA (HOMOPTERA: PSYLLIDAE) CAUSED BY EXPOSURE TO EXTERNAL WATER AND SURFACTANTS

1996 ◽  
Vol 128 (5) ◽  
pp. 825-830 ◽  
Author(s):  
David R. Horton ◽  
Tamera M. Lewis ◽  
Lisa G. Neven
Keyword(s):  
Low Temperatures ◽  
Cold Hardiness ◽  
Dilute Solutions ◽  
Subzero Temperatures ◽  
Pear Psylla ◽  
External Water

AbstractOverwintering pear psylla, Cacopsylla pyricola (Foerster), were misted with water or with one of several dilute solutions of water and surfactant, and then exposed to a range of subzero temperatures for 24 h. Misted psylla had significantly greater mortality than unmisted controls. Increases in mortality occurred at temperatures as warm as −6°C, a temperature well within the range of conditions in the field. At extreme low temperatures (−18°C) there was virtually no mortality in the unmisted controls, whereas mortality approached or reached 100% in several of the misted groups. Temperatures necessary to kill 50% of insects estimated for topically treated psylla ranged between −2.6 and −12.7°C for surfactant-treated insects, and below −18°C for water-treated or control insects. The possibility of using surfactants and water for control of overwintering pear psylla is discussed.

scholarly journals Insights from corrosion current measurements on corrosion mechanisms in reinforced concrete and on the evaluation of other corrosion data

2019 ◽  
Vol 289 ◽  
pp. 03008 ◽  
Author(s):  
Ulrich Schneck
Keyword(s):  
Reinforced Concrete ◽  
Linear Polarization ◽  
Polarization Resistance ◽  
Corrosion Behaviour ◽  
Corrosion Current ◽  
Material Loss ◽  
Polarization Measurements ◽  
Tafel Polarization ◽  
Macro Cell ◽  
Current Densities

During the past years Tafel polarization measurements have been implemented into the scope of measurements of CITec corrosion diagnosis projects. This has created a vast database of different and corresponding corrosion parameters, such as chloride and water content in the rebar vicinity, open circuit potential, electrolyte resistance, polarization resistance (from galvanostatic pulse and linear polarization) and corrosion current from Tafel polarization measurements. Although general limitations in using these methods on macro cell systems such as reinforced concrete are known, the comparative assessment of these data has led to a better understanding of the corrosion behaviour and of specific circumstances of the structures which deviated partly from usual expectations. For instance, a low polarization resistance at high chloride content will not result necessarily in a high corrosion current, if the reinforcement in the wider vicinity of the test location is similar active, and cathodic rebar areas are either very distant or retarded by very wet concrete. So the extended range of corrosion testing gives a more precise evaluation of the corrosion situation and permits a tailored repair and maintenance concept to be found. It has also been found that the Stern-Geary equation which is often used to calculate corrosion current densities and material loss of the reinforcement from linear polarization (LPR) measurements, doesn’t seem very feasible if used on reinforced concrete structures, as there appears to be a dominant influence of macro cell corrosion over the corrosion model of a homogenous mixed electrode (for which the Stern-Geary equation applies), and the true corrosion current densities may be either larger or (very often) much smaller than those calculated from Stern-Geary. This is not a new observation, and the findings will be discussed for several project cases.

Heat Capacity of Dilute Solutions of LiquidHe3INHe4at Low Temperatures

1966 ◽  
Vol 16 (7) ◽  
pp. 263-264 ◽  
Author(s):  
A. C. Anderson ◽  
W. R. Roach ◽  
R. E. Sarwinski ◽  
J. C. Wheatley
Keyword(s):  
Heat Capacity ◽  
Low Temperatures ◽  
Dilute Solutions

The response of plants to temperature change

1990 ◽  
Vol 115 (1) ◽  
pp. 1-5 ◽  
Author(s):  
C. J. Pollock
Keyword(s):  
Temperature Change ◽  
Plant Species ◽  
High Temperatures ◽  
Low Temperatures ◽  
Considerable Effect ◽  
Economic Importance ◽  
Form And Function ◽  
Sense And Respond ◽  
And Performance ◽  
And Function

In general, the form and function of living plants reflect a requirement to maximize their interaction with the environment in order to harvest more effectively the energy and materials they require (Corner 1964). Thus, fluctuations in the aerial environment exert a considerable effect upon the physiology of the plant and lead to initiation of a range of responses. Changes in temperature are known to exert a pronounced effect on the growth of plants, and hence upon their productivity (Ong & Baker 1985). Most temperate species spend the majority of their life at mean temperatures below the optimum for their growth, and there are marked genetic differences between plant species in their ability to tolerate nonoptimal temperatures (Pollock & Eagles 1988). This review summarizes some of the ways in which plants are known to sense and respond to temperature change and discusses the potential for improving growth and performance at nonoptimal temperatures. Discussion concentrates upon temperate grasses and cereals because of their suitability as experimental material and because of their economic importance. Consequently, this review is largely concerned with responses to low temperatures, but some responses of tropical cereals to high temperatures are also described.

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