Water Layer in Course of Corrosion of Copper in Humid Air Containing SO_2

Sasaki, Takeshi,Itoh, Jun,Ohtsuka, Toshiaki 한국부식방식학회 2003 Corrosion Science and Technology Vol.2 No.2

The technique for in situ simultaneous measurements of IR-RAS and QCM, which has been developed for investigation of corrosion in gaseous environments, was employed to study the effects of an extremely thin water layer on the corrosion rate. An evaporated copper film on a QCM element was exposed to air containing water vapor and SO?, and time-resolved IR-RAS spectra were measured and mass gains were simultaneously followed with QCM. The tested ranges of relative humidity (RH) and concentration of SO₂ were 60% - 90% and 1 - 20 ppm, respectively. On the basis of 2D-IR analysis, the corrosion products were determined to be Chevreul's salt (CuSO₃Cu₂SO₃·2HO₂) and CuSO₄·5H₂O. By constructing curves of the relations between band intensities of IR spectra and mass gains of QCM for the corrosion products, the time variations in each product were determined from spectral experiments on copper plates. The thicknesses of physically adsorbed water layers in course of the corrosion process were also determined from water band intensities. The results showed that the thickness of the physically adsorbed water layer increased with increase in RH, and it also increased with increase in accumulation of corrosion products. The latter is probably due to the capillary effect of the corrosion products.

650°C 의 SO2 가스 환경 하에서 T22와 T92 강의 고온 부식특성

김성종,정광후 한국부식방식학회 2019 Corrosion Science and Technology Vol.18 No.6

In this study, the corrosion characteristics of T22 and T92 steel were investigated in 6O2 + 16CO2 + 2SO2 gas environment at 650 °C. Corrosion characteristics were characterized by weight gain, oxide layer thickness, scanning electron microscope, optical microscope, energy dispersive X-ray spectroscopy, and X-ray diffraction. T22 and T92 steel tended to stagnate oxide layer growth over time. Oxidation kinetics were analyzed using the data of oxide layer thickness, and a regression model was presented. The regression model was significantly acceptable. The corrosion rate between the two steels through the regression model showed significant difference. The T92 steel was approximately twice as large as the time exponent and showed very good corrosion resistance compared to the T22 steel. In both steels, the oxide layer mainly formed a Fe-rich oxide layer composed of hematite (Fe2O3), magnetite (Fe3O4), and spinel (FeCr2O4). Sulfide segregation occurred in the oxide layer due to SO2 gas. However, the locations of segregation for the T22 and T92 steel were different.

Corrosion of Fe-17%Cr Steels in (Na₂SO₄+NaCl) Salts at 800 and 900℃

Dong Bok Lee,Xiao Xiao 한국표면공학회 2018 한국표면공학회지 Vol.51 No.4

Stainless steel grade 430 with a composition of Fe-17%Cr was corroded in Na₂SO₄ and (Na₂SO₄+NaCl) salts at 800 and at 900℃ for up to 20 h. It corroded mainly to Cr₂O3, along with a small amount of Fe₂O₃ and Fe₃O₄. The formed oxide scales were neither dense nor compact enough owing to their ensuing dissolution into the salt during corrosion, which facilitated internal corrosion. Corrosion occurred faster at 900℃ than 800℃. NaCl in Na₂SO₄ aggravated the scale adherence.

화력발전소용 Fe-18%Cr-10%Ni 강의 고온 SO₂ 가스 부식

이동복(Dong-Bok Lee) 한국표면공학회 2007 한국표면공학회지 Vol.40 No.5

The corrosion characteristics of Fe-18Cr-10Ni steels were studied between 600℃ and 1000℃ in Ar+(0.2, 1)%SO₂ gas for up to 300 hr in order to employ Fe-18Cr-10Ni steels in the coal-fired power plants. The corrosion resistance of Fe-18Cr-10Ni steels was good due mainly to the high amount of Cr, which formed Cr₂O₃ from the initial corrosion stage. Fe in the steels corroded to mainly Fe₂O₃ and Fe₃O₄. Ni was not susceptible to corrosion under the current corrosion condition. Relatively thin, single-layered scales formed.

발전소 공기예열기 소재의 배기가스 농도 및 온도에 따른 내식성 및 노점 분석

이승준 ( Seung-jun Lee ) 한국부식방식학회 2023 Corrosion Science and Technology Vol.22 No.5

Although many thermal power plants use heat recovery systems, high exhaust gas temperatures are maintained due to corrosion at dew points and ash deposits caused by condensate formation. The dew point of exhaust gas is primarily determined by the concentration of SO₃ and steam, and various experiments and calculation equations have been employed to estimate it. However, these methods are known to be less suitable for exhaust gases with low SO₃ concentrations. Therefore, in this study, since the temperature of the exhaust gas is expected to decrease due to the low-load operation of the coal-fired power plant, sulfuric acid condensation and low-temperature corrosion are anticipated. We aimed to conduct a quantitative evaluation to propose ways to prevent damage by limiting operating conditions and improving facilities. The experimental results showed that the corrosion rate increased linearly with rising temperatures at a certain sulfuric acid concentration. Furthermore, variations in sulfuric acid concentrations generated during the current power plant operation process did not significantly affect the dew point, and the dew point of sulfuric acid under these conditions was observed to be between 120 - 130 ℃.

High-temperature Corrosion of CrAlSiN Films in Ar/1%SO₂ Gas

Dong Bok Lee,Xiao Xiao,Junhee Hahn,Sewon Son,Shi Yuke 한국표면공학회 2019 한국표면공학회지 Vol.52 No.5

Nano-multilayered Cr25.2Al19.5Si4.7N50.5 films were deposited on the steel substrate by cathodic arc plasma deposition. They were corroded at 900℃ in Ar/1%SO₂ gas in order to study their corrosion behavior in sulfidizing/oxidizing environments. Despite the presence of sulfur in the gaseous environment, the corrosion was governed by oxidation, leading to formation of protective oxides such as Cr₂O₃ and α-Al₂O₃, where Si was dissolved. Iron diffused outward from the substrate to the film surface, and oxidized to Fe₂O₃ and Fe₃O₄. The films were corrosion-resistant up to 150 h owing to the formation of thin (Cr₂O₃ and/or α-Al₂O₃)-rich oxide layers. However, they failed when corroded at 900℃ for 300 h, resulting in the formation of layered oxide scales due to not only outward diffusion of Cr, Al, Si, Fe and N, but also inward movement of sulfur and oxygen.

제주도 대기환경의 부식성 평가

김귀식(GUI-SHIK KIM),양경조(KYEONG-CHO YANG),허철구(CHUL-GOO HU),송정화(JEONG-HWA SONG) 한국해양공학회 2005 韓國海洋工學會誌 Vol.19 No.5

This study has been conducted to investigate corrosivity of carbon steel, Cu, Zn and Al for one year from Sept. 2003 to Aug. 2004. A model of ISO 9223-ISO 9226 that represents the relation between metal corrosions and environmental parameters was used for atmospheric corrosion evaluations. Environmental parameters for these evaluations are time of wetness(TOW), SO₂ and Chloride. Corrosion rates for four metals which are exposed indoors and outdoors were measured on five locations in Jeju Island; Gosan, Seogwipo, Seongsan, Chuna hill and Jeju city. The environmental factor of atmospheric corrosion of Jeju Island for SO₂ class is P0, a clean area. TOW as T3 and T4 indicates that Jeju has the characteristics of a tropical area. Chlorides class within 3 km from the coast show the features of costal area as S2 and S3 classes. Chuna hill show the features of woodland as a S1 class. In Corrosion classes of each site which was measured outdoors is higher than indoors. Gosan is the highest class as the rank of C5, and indicated that they're ranked as C3 or C4.

Study of High Temperature of Inconel 740 Alloy in Air and Ar-0.2%SO₂ Gas

Dong Bok Lee(이동복),Min Jung Kim(김민정) 한국표면공학회 2021 한국표면공학회지 Vol.54 No.2

The Ni-based superalloy, Inconel 740, was corroded between 800 and 1100℃ for up to 100 hr in air and Ar-0.2%SO₂ gas in order to study its corrosion behavior in air and sulfur/oxygen environment. It displayed relatively good corrosion resistance in both environment, because its corrosion was primarily dominated by not sulfidation but oxidation especially in Ar-0.2%SO₂ gas. Such was attributed to the thermodynamic stability of oxides of alloying elements when compared to corresponding sulfides. The scales consisted primarily of Cr₂O₃, together with some NiAl₂O₄, MnCr₂O₄, NiCrMnO₄, and rutile-TiO₂. Sulfur from SO₂ gas made scales prone to spallation, and thicker. It also widened the internal corrosion zone when compared to air. The corrosion resistance of IN740 was mainly indebted to the formation of protective Cr₂O₃-rich oxides, and suppression of the sulfide formation.

SO₂ 가스 환경 하에서 1.25Cr-0.5Mo 강의 부식 및 강도 저하 특성

정광후(Kwang-Hu Jung),김성종(Seong-Jong Kim) 한국표면공학회 2018 한국표면공학회지 Vol.51 No.3

The corrosion and strength degradation characteristics of 1.25Cr-0.5Mo steels were studied under 650℃ in 76%N2+6%O₂+16%CO₂+2%SO₂ gas condition up to 500 hrs. Corroded specimens were characterized by weight gain, scanning electron microscope(SEM), energy dispersive X-ray spectroscopy(EDS), and Xray diffraction(XRD). The tensile test was conducted to evaluate the mechanical strength and fracture mode with corrosion at high temperature. As the results of the experiments, thick Fe-rich oxide layers over 200 ㎛ were formed on the surface within 500 hrs. The thick oxide layers are formed with reduction of the crosssectional area of the specimens. Thus, the strength tended to decrease with reduction of the cross-sectional area.

Fe-(2, 9, 11)% Cr 강의 고온 SO2가스 부식거동

최정호 ( Jung Ho Choi ),이동복 ( Dong Bok Lee ) 대한금속·재료학회 2007 대한금속·재료학회지 Vol.45 No.11