Influence of Temperature and Exposure Time upon Calcareous Deposits

Kunjapur, M. M.; Hartt, William H.; Smith, Sinclair

doi:10.5006/1.3583848

Cited by 48 publications

(20 citation statements)

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“…The layers (region 1 in Figure 8) are clearly Mg-rich with the lighter contrast areas (region 2 in Figure 8) and Ca-rich with the fine layer at the metal surface a combination containing both Ca and Mg. The coating consists of a fine layer of a mixture of Ca and Mg, followed by a predominantly brucite coating; this is contrary to others findings of the two layer structure of a fine brucite layer followed by CaCO3 [7,14,16,17,[19][20][21]. Figure 9.…”

Section: Compositioncontrasting

confidence: 53%

“…The most widely adopted is the inhibiting effect of Mg 2+ ions on the nucleation and growth of calcite and the nucleation of aragonite and once the formation of the brucite layer depletes the zone of Mg 2+ ions the calcite and aragonite can nucleate and grow [16,18]. Other explanations involve a change in the electrostatic properties of the brucite layer [10,11,17].…”

Section: Introductionmentioning

confidence: 99%

“…Leeds and Cottis [22] found that a CaCO3 only deposit occurred at a potential of −0.7 V (SCE) and Barchiche et al [19] suggested an aragonite deposit would be formed at a potential −0.9 ≤ E ≤ −1.1 V (SCE), a combination of aragonite and brucite at −1.2 V (SCE) with brucite the only phase forming at a potential more negative than −1.3 V (SCE) in the 10-30 °C range with rotating electrodes. The transition from a Mg(OH)2 to CaCO3 composition is still not fully understood and several explanations of the mechanism have been proposed [10,11,[16][17][18]. The most widely adopted is the inhibiting effect of Mg 2+ ions on the nucleation and growth of calcite and the nucleation of aragonite and once the formation of the brucite layer depletes the zone of Mg 2+ ions the calcite and aragonite can nucleate and grow [16,18].…”

Section: Introductionmentioning

confidence: 99%

“…In previous studies it has been established that the deposit has a two layer structure made up of a fine layer of Mg-rich brucite followed by a Ca-rich polymorph [7,14,[16][17][18][19][20][21]. Leeds and Cottis [22] found that a CaCO3 only deposit occurred at a potential of −0.7 V (SCE) and Barchiche et al [19] suggested an aragonite deposit would be formed at a potential −0.9 ≤ E ≤ −1.1 V (SCE), a combination of aragonite and brucite at −1.2 V (SCE) with brucite the only phase forming at a potential more negative than −1.3 V (SCE) in the 10-30 °C range with rotating electrodes.…”

Section: Introductionmentioning

confidence: 99%

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Natural Deposit Coatings on Steel during Cathodic Protection and Hydrogen Ingress

Smith

Paul

2015

Coatings

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Abstract:The calcareous coating formed during cathodic protection (CP) in seawater is known to reduce the current demand by hindering the transport of species required to support the cathodic reactions and, thereby, improve the economic performance of CP systems. There is, however, uncertainty as to whether the coating reduces hydrogen uptake or indeed enhances it. To ascertain this, two sets of samples were polarized at −1.1 V (standard calomel electrode, SCE) in 3.5% w/v NaCl and synthetic seawater (ASTM D1141) at 20 °C and the diffusible hydrogen content measured over a period of 530 h. Under such conditions reports suggest a deposit with two distinct layers, comprising an initial brucite layer followed by an aragonite layer. Contrary to other findings, a fine initial layer containing Ca and Mg followed by a brucite layer was deposited with a few specks of Ca-containing zones in synthetic seawater. The hydrogen uptake was found to occur within the initial 100 h of exposure in synthetic seawater whilst it continued without the benefit of a deposit coating, i.e., in 3.5 wt % NaCl solution.

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Section: Compositioncontrasting

confidence: 53%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Natural Deposit Coatings on Steel during Cathodic Protection and Hydrogen Ingress

Smith

Paul

2015

Coatings

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“…In the system, the effect of flow-rate and time on the polarization curve can be taken into account for defining the boundary conditions. Key words : boundary element method (BEM), 2D, 3D, axi-symmetry, potential, current density, catholic protection, galvanic corrosion, polarization curve, seawater, pump (2-1, Honfujisawa 4 chome, Fujisawa, 251 Japan) (11-1, Haneda Asahi-cho, Ohta-ku, Tokyo, 144 Japan) (12-1, O-okayama 2-chome, Meguro-ku, Tokyo, 152 Japan) (Manuscript received December 27, 1996 ; in final form February 24,1997) …”

Section: Dep Of Mechanical and Environmentalmentioning

confidence: 99%

Development of BEM Analysis System for Corrosion Protection Design

Miyasaka

Takayama

Amaya

et al. 1997

CORROSION ENGINEERING

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In order to make a practical application of boundary element method (BEM) to quantative predictions of catholic protection and macro-cell corrosion, a BEM analysis system based on the programs for 2D, 3D and axi-symmetric regions was developed. The system consists of a polarization curve database and programs to perform element discretization, input file set up, BE analysis and graphic display of input and output data. Even an engineer with no knowledge of corrosion will be able to easily operate this system and perform effective analyses for optional 3 D regions. The usefulness of the system is demonstrated by an application example for the cathodic protection design of a seawater pump. In the system, the effect of flow-rate and time on the polarization curve can be taken into account for defining the boundary conditions.

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Mechanistic Insights into Electrodeposition in Seawater at Variable Electrochemical Potentials

Devi,

Wagner,

Lopez

et al. 2023

Advanced Sustainable Systems

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The classical approach to manufacturing cement and concrete involves considerable and energy‐intensive exploitation of minerals from the environment, calling for alternative and sustainable methods to obtain such resources. Electrodeposition resulting from local pH changes near an oxygen or water reduction electrode can be used to grow valuable minerals in seawater for use in the cement and concrete industries, with the potential to use clean electricity without relying on the mining of resources. Limited knowledge is available about the electrochemical reaction networks that yield mineral precipitates via electrodeposition in seawater, hindering a complete assessment of the promise of such an approach to serving the construction industry. This work presents an investigation of the electrodeposition in seawater as a function of the applied potential. The work identifies multiple electrochemical potential regimes that yield distinct polymorphs, quantities, and production rates of calcium and magnesium‐based minerals due to the varying rates of oxygen reduction and water‐splitting reactions. The quality of the produced minerals is comparable to that of traditionally mined aggregates in terms of morphology and composition, supporting that seawater represents a vast source of raw materials for use in the construction industry upon an enhancement in the efficiency of hydroxide‐producing reactions and the reactor design.

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Influence of Temperature and Exposure Time upon Calcareous Deposits

Cited by 48 publications

References 0 publications

Natural Deposit Coatings on Steel during Cathodic Protection and Hydrogen Ingress

Natural Deposit Coatings on Steel during Cathodic Protection and Hydrogen Ingress

Development of BEM Analysis System for Corrosion Protection Design

Mechanistic Insights into Electrodeposition in Seawater at Variable Electrochemical Potentials

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