Corrosion Inhibition of Carbon Steel by Lithium Molybdate in Concentrated LiBr Solutions at Elevated Temperatures

Itoh, Masahiko; Midorikawa, Heihachiro; Izumiya, Masakiyo; Aizawa, Michihiko; Tanno, Kazuo

doi:10.3323/jcorr1974.39.6_298

Cited by 11 publications

(6 citation statements)

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“…Test solutions as described below were prepared by dissolving reagent grade chemicals of LiBr•H 2 O, LiOH•H 2 O and Li 2 MoO 4 into deionized water at about 333 K 1,4) (hereafter, % represents mass%);…”

Section: Methodsmentioning

confidence: 99%

“…Tanno et al 4) reported that the surface of the carbon steel after immersion for 720 ks was covered with a film and corrosion was suppressed. On the other hand, the present research measured the polarization curves of the specimen after immersion in the solution for a short time of 0.3 ks.…”

Section: Effect Of Temperature On Cathodic Current Densitymentioning

confidence: 99%

“…For example, Tanno et al 1,2) evaluated corrosion weight loss for carbon steel specimens in LiBr solutions containing LiOH and some oxoates such as molybdate, chromate, nitrate and tungstate as corrosion inhibitors. On the other hand, some attempts have been conducted to evaluate a corrosion rate of the carbon steel in the LiBr solution, and most of them 3,4) have investigated it in terms of corrosion weight loss of the steel after immersion in the LiBr solution for the period longer than 180 ks (= 50 h). This conventional corrosion evaluation method can reveal the practical behavior of the corrosion, but insufficiently discuss the mechanism of the corrosion because of the lack of electrochemical information such as contribution of anodic and cathodic processes.…”

Section: Introductionmentioning

confidence: 99%

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Polarization Curves of Carbon Steel in Concentrated LiBr Solutions Containing LiOH and Li2MoO4 at Different Temperatures after Short Immersion

et al. 2021

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We have tried to measure polarization curves of SS400 carbon steel in concentrated LiBr solutions over 393 K, and investigated the influence of temperature as well as concentrations of LiOH and Li 2 MoO 4 on its corrosion behavior. Test solutions were 65 mass% (mass% is replaced by % hereafter) LiBr solutions containing 0 to 0.2% LiOH and 0 to 0.03% Li 2 MoO 4 . Test temperatures were 393 and 438 K. The test solutions were deaerated. The specimen was immersed in the test solution for a short time of 0.3 ks and was subjected to measurement of polarization curve in the same solution. As a result, the followings were obtained: The anodic current density in 65% LiBr solution without LiOH increased monotonically with a rise in a potential, and the relation was maintained regardless of Li 2 MoO 4 addition and temperature change. In 65% LiBr solutions with LiOH up to 0.2% at 393 and 438 K, the anodic polarization curves showed active dissolution and passivation. When 0.05% LiOH was added to the 65% LiBr solution, the corrosion potential negatively shifted, and the potential was maintained regardless of more addition of LiOH. As a LiOH concentration increased, a pitting potential was raised. The polarization curves at 393 and 438 K showed almost no change regardless of addition of 0.03% Li 2 MoO 4 , meaning that Li 2 MoO 4 had almost no effect on corrosion inhibition to the specimen for the short immersion. The corrosion rate at 393 K was approximately 0.3 A•m ¹2 regardless of the addition of LiOH nor Li 2 MoO 4 . Whereas, the corrosion rate at 438 K slightly decreased with increasing LiOH concentration, regardless of the addition of Li 2 MoO 4 . Cathodic current density in the solution with 0.2% LiOH and 0.03% Li 2 MoO 4 increased with a rise in a temperature on the basis of Arrhenius relation. It is thought that insufficient effect of LiOH and Li 2 MoO 4 on corrosion inhibition was observed because of a short immersion time of 0.3 ks before measurement of polarization curves.

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Section: Methodsmentioning

confidence: 99%

Section: Effect Of Temperature On Cathodic Current Densitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Polarization Curves of Carbon Steel in Concentrated LiBr Solutions Containing LiOH and Li2MoO4 at Different Temperatures after Short Immersion

et al. 2021

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“…Molybdate induces passivation of steel in an alkaline LiBr solution but does not cause pitting as chromate 8) 10) and nitrate 2), 8) do. It was revealed that molybdenum oxide layer is formed on the outer side of the surface film on steel as a result of reduction of molybdate 5) . Yashiro et al 7) reported film formation kinetics on carbon steel in the concentrated LiBr solutions containing LiOH and Li 2 MoO 4 .…”

mentioning

confidence: 99%

“…2), it took about 40 h for the Fe electrode to rise in potential. The concentration of molybdate of the order of 10 3 mol/kg is regarded as acceptable for steady running of commercial adsorption refrigerators 5) . However, the initial passivation process does not seem fast enough at this concentration because the evolution of hydrogen could deteriorate the performance of the refrigerator.…”

mentioning

confidence: 99%

Passivation Behavior of Iron in Concentrated LiBr Solutions Containing Molybdate and Nitrate at Elevated Temperature

Yashiro

Kawata

Itoh

et al. 2006

ZAKAEP

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Absorption refrigeration systems use highly concentrated LiBr solutions (up to about 65 mass ) as an absorbent of coolant (water) 1) . The maximum temperature of the absorbent in a modern double stage generating machine is over 433 K. Carbon steel, the main structural material could be attacked severely unless adequate inhibitors are not added into the absorbent 2), 3) . Among the inhibitors proposed so far, molybdate is regarded as the most preferable because of its high inhibition efficiency and low environmental hazard 4) 7) . Molybdate induces passivation of steel in an alkaline LiBr solution but does not cause pitting as chromate 8) 10) and nitrate 2), 8) do. It was revealed that molybdenum oxide layer is formed on the outer side of the surface film on steel as a result of reduction of molybdate 5) . Yashiro et al. 7) reported film formation kinetics on carbon steel in the concentrated LiBr solutions containing LiOH and Li 2 MoO 4 . The thickness of the oxide layer increased in proportion to the cubic root of immersion time. However the passivation kinetics did not seem fast enough and hydrogen could evolve considerably until stable films are formed on steel. Therefore nitrate may be added into the absorbent as an assistant oxidizer especially at the start of operation. Mabuchi et al. 11) tested nitrate/molybdate mixture for inhibition of carbon steel in the concentrated LiBr solutions. The result indicated that the addition of nitrate decreased the amount of hydrogen evolved although the corrosion loss of carbon steel could increase slightly depending on the concentration of nitrate. Thus, it is very important practically to control the initial passivation process of carbon steel in the absorption refrigeration systems. It is expected to be useful to monitor the corrosion potential of an iron electrode during the initial passivation period for the better understanding of a role of nitrate in the concentrated LiBr solution containing Li 2 MoO 4 . The purpose of this research is to follow the passivation process of iron in the concentrated LiBr solutions containing molybdate and nitrate through measurements of corrosion potential and surface film analysis. We would note that all conditions are not identical as in commercial machines in the following laboratory experiments. Solutions are not dynamic but static. System is not evacuated but filled with argon. The ratio of solution volume to steel surface area is not same but much larger. Nevertheless, the following laboratory data would help us to understand the cooperative action of molybdate and nitrate, which is really effective in commercial machines.Commercially available Fe rod ( 99.5 , 3 mm) was used after polishing down to 6/0 of SiC paper. The Fe rod was covered with a heat-shrinkable PTFE tube leaving the top of 20 mm. The Fe plate ( 99.95 , 30 30 1 mm) specimen for the purpose of films analysis was further polished and finished using alumina powder of 0.06 m. The specimens were degreased by ultrasonic cleaning in acetone.Commercial reagents of LiBr...

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Corrosion of steel in lithium bromide solution containing inhibitor

Liang

Huang

et al. 2012

Corrosion Engineering, Science and Technology

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The corrosion behaviour of carbon steel in 55% lithium bromide solution containing a complex organophosphonate-molybdate inhibitor has been studied using weight loss tests, electrochemical measurements, SEM and X-ray photoelectron spectroscopy. The results showed that the species provides an excellent inhibition performance in 55% lithium bromide solution. When its concentration reached 0?8 kg m 23 in 55% lithium bromidez0?07 mol dm 23 lithium hydroxide at 240uC, the carbon steel's corrosion rate decreased to 25?02 mm/year, and the anodic passivation region and the passive current density of carbon steel were ,700 mV and 1 mA cm 22 respectively. At the same time, the capacitance value of electric double layer decreased, and the charge transfer resistance increased. The compact compound film formed on the surface of carbon steel in the inhibited LiBr solution was mainly composed of iron oxide and molybdenum oxide.

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Corrosion Inhibition of Carbon Steel by Lithium Molybdate in Concentrated LiBr Solutions at Elevated Temperatures

Cited by 11 publications

References 0 publications

Polarization Curves of Carbon Steel in Concentrated LiBr Solutions Containing LiOH and Li<sub>2</sub>MoO<sub>4</sub> at Different Temperatures after Short Immersion

Polarization Curves of Carbon Steel in Concentrated LiBr Solutions Containing LiOH and Li<sub>2</sub>MoO<sub>4</sub> at Different Temperatures after Short Immersion

Passivation Behavior of Iron in Concentrated LiBr Solutions Containing Molybdate and Nitrate at Elevated Temperature

Corrosion of steel in lithium bromide solution containing inhibitor

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