• 한국표면공학회지
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• 제54권1호
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• pp.30-36
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• 2021

In this study, double-layered anodizing films were formed on Al 5052 and Al 6061 alloys consecutively first in sulfuric acid and then in oxalic acid, and hardness, withstand voltage, surface roughness and acid resistance of the anodizing films were compared with single-layered anodizing films in sulfuric acid and oxalic acid electrolytes. Hardness of the double-layered anodizing film decreased with increasing ratio of inner layer to outer layer for both Al 5052 and Al 6061 alloys, suggesting that outer anodizing film formed in sulfuric acid electrolyte is damaged during the second anodizing in oxalic acid electrolyte. Withstand voltage of the double-layered anodizing films increased with increasing the thickness ratio of inner layer to outer layer. Surface roughness of the double-layered anodizing films were comparable with that of single-layered anodizing film formed in sulfuric acid but higher than that of single layer anodizing film formed in oxalic acid electrolyte. In acid resistance test, all of the double-layered and single-layered anodizing films showed good acid resistance more than 3 h without any visible gas evolution, which is attributable to sealing of pores. Based on the experimental results obtained in this work, it is possible to design a double-layered anodizing film with cost-effectiveness and improved physical and electrical properties by combining two consecutive anodizing processes of sulfuric acid anodizing and oxalic acid anodizing methods.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.43-48
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• 2002

This study is experiment results that carried out the sulfuric acid immersion of the mortar containing blast furnace slag powder, based ell the mechanism of the sulfuric acid corrosion for concrete which was caused by the H$_2$S gas. The used materials is OPC, slag powder and gypsum, and the proportion of cement is total 13 levels which are 0~70% of the contents of slag, 0~6％ of the contents of gypsum. The specimen is immersed by 5% H$_2$SO$_4$ solution after 28 days and its weight loss is measured at intervals of 7 days. The results of experiment showed that the substitution ratio of 70% slag was excellent at a point of view for the sulfuric acid resistance and the sulfuric acid resistance was not improved by tile increase of the blaine of slag(8, 000longrightarrow10, 000$\textrm{cm}^2$/g) and the addition of gypsum.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.281-286
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• 2003

This study presents the results of investigations with the object to determine the resistance to sulfuric acid for some kinds of cements containing 0%-70% of slag powder. The specimen is immersed 5% H$_2$SO$_4$ solution after the 28th days, is measured chemical analysis, XRD, SEM and etc after the immersed 35th days and is measured the erosion depth after the immersed 168th days. The results of experiment are founded out that alumina cement containing slag power was excellent at a point of view for the sulfuric acid resistance and the erosion depth was suitable to the evaluated method of the sulfuric acid resistance in the stead of the evaluated method of weight loss.

• Corrosion Science and Technology
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• 제3권5호
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• pp.194-197
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• 2004

The corrosion resistance of several kind of ME (Metal Evaporated) tape has been investigated both in mild sulfuric acid solution and NaCl solution by electrochemical impedance spectroscopy. It was found that the degradation of ME tapes was accelerated with increasing the concentration of sulfuric acid. There was no significant change in corrosion resistance when the concentration of NaCl was under 3.5 wt%. However, the impedance value decreased when the concentration of NaCl was up to 10 wt%. The degradation of backside of ME tapes was also investigated by AC impedance measurements. The results showed that the impedance behavior of backside plastic film changed with the concentration of sulfuric acid even at the beginning of immersion, implying the changing of the permeability for the backside of ME tapes. It was also found that the corrosion resistance of DVC (Digital Video Cassette) ME tape was better that that of Hi-8mm ME tapes in sulfuric acid solutions. Also, the backside of DVC ME tape showed better water resistance than that of Hi8 ME tapes.

• 한국결정성장학회지
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• 제27권4호
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• pp.167-172
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• 2017

본 연구는 경량 및 내황산 특성을 가진 단면복구 모르타르 개발의 관한 연구로 Type I의 경량 및 폴리머 모르타르와 Type II의 내황산 단면복구 모르타르의 성능평가를 진행하였다. 성능평가는 KS F 4042의 품질기준으로 이루어졌으며, 그 결과 경량 및 내황산성이 우수하며 KS F 4042의 품질 기준을 모두 만족하는 결과를 도출하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.719-722
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• 2004

Resins using recycled PET offer the possibility of a lower source cost of materials for making useful polymer concrete products. The purposed of this paper is to form a part of reducing the damage of sulfuric acid, through investigating recycled PET polymer concrete, . immersed at sulfuric acid solution for 84 days. Recycled PET PC is excellent chemical resistance, resulting in the role of unsaturated polyester resin which consists of polymer chain structure accomplishes bond of aggregates and filler strongly. Also, Recycled PET PC, used fly-ash as filler, is stronger resistance of sulfuric acid corrosion than $CaCO_3$, because it is composed of $SiO_2$ and very strong glassy crystal structure. Therefore, Recycled PET PC, used fly-ash as filler, is available under corrosion circumstances like sewer pipe or waste disposal plant.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 추계 학술논문 발표대회
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• pp.25-26
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• 2019

The Reinforced concrete structure is deteriorated in durability due to various deterioration factors such as acid, salt, etc., and thus requires repair and reinforcement. In this study, compressive strength and weight change were measured by substituting blast furnace slag with excellent chemical resistance. As a result, the decrease in compressive strength decreased in proportion to the blast furnace slag substitution rate, and in the case of BFS40, the strength increased after sulfuric acid immersion. The weight change also decreased in proportion to the replacement amount.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 추계 학술논문 발표대회
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• pp.137-138
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• 2015

The use of the cement and increased with the recent development of the construction industry. If the cement is the environmental problems caused by generating a large quantity of CO₂ and the production process. Accordingly, this study is the test to determine the sulfuric acid and hydrochloric acid resistance properties of the Light weight matrix product of blast furnace slag-based light. A result, the compression strength of the sulfuric acid and hydrochloric acid immersion showed alower strength than the Plain.

• 콘크리트학회논문집
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• 제19권3호
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• pp.385-389
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• 2007

In this study, it was investigated the resistance of OPC, 60% GGBS, 20% PFA and 10% SF mortar specimens against sulfuric acid corrosion. As an index for degree of acid corrosion, the corrosion depth was evaluated. Then, it was found that an increase in the duration of immersion and a decrease in the pH, as expected, resulted in a more severe corrosion irrespective of binders; 60% GGBS mortar specimen was the most resistant to sulfuric acid corrosion. From the laboratory testing of sulfuric acid corrosion, an empirical prediction model was suggested as a power function of time and the pH of sulfuric acid, and was applied to an assessment of concrete structures exposed to an acidic environment. It was found that the empirical model gave a more precise prediction of sulfuric acid deterioration of concrete rather than a conventional model, mostly used for predicting carbonation of concrete.

• 한국재료학회지
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• 제21권1호
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• pp.1-7
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• 2011

Methods of producing hydrogen include steam reforming, electrochemical decomposition of water, and the SI process. Among these methods, the Sulfur iodine process is one of the most promising processes for hydrogen production. The thermochemical sulfur-iodine (SI) process uses heat from a high-temperature-gas nuclear reactor to produce $H_2$ gas; this process is known for its production of clean energy as it does not emit $CO_2$ from water. But the SI-process takes place in an extremely corrosive environment for the materials. To endure SI environments, the materials for the SI environment will have to have strong corrosion resistance. This work studies the corrosion resistances of the Fe-Si, Ni-Ti and Ni Alloys, which are tested in SI-process environments. Among the SI-process environments, the conditions of boiling sulfuric acid and decomposed sulfuric acid are selected in this study. Before testing in boiling sulfuric acid environments, the specimens of Fe-4.5Si, Fe-6Si, Ni-4.5Si, Ni-Ti-Si-Nb and Ni-Ti-Si-Nb-B are previously given heat treatment at $1000^{\circ}C$ for 48 hrs. The reason for this heat treatment is that those specimens have a passive film on the surface. The specimens are immersed for 3~14 days in 98wt% boiling sulfuric acid. Corrosion rates are measured by using the weight change after immersion. The corrosion rates of the Fe-6Si and Ni-Ti-Si-Nb-B are found to decrease as the time passes. The corrosion rates of Fe-6si and Ni-Ti-Si-Nb-B are measured at 0.056 mm/yr and 0.16 mm/yr, respectively. Hastelloy-X, Alloy 617, Alloy 800H and Haynes 230 are tested in the decomposed sulfuric acid for one day. Alloy 800H was found to show the best corrosion resistance among the materials. The corrosion rate of Alloy 800H is measured at -0.35 mm/yr. In these results, the corrosion resistance of materials depends on the stability of the oxide film formed on the surface. After testing in boiling sulfuric acid and in decomposed sulfuric acid environments, the surfaces and compositions of specimens are analyzed by SEM and EDX.