• 제목/요약/키워드: Resistance to sulfuric acid

검색결과 120건 처리시간 0.025초

알루미늄 합금의 연속식 양극산화법으로 형성시킨 이중 산화막층의 특성 (Properties of double-layered anodizing films on Al alloys formed by two consecutive anodizings)

  • 정나겸;최진섭
    • 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.

각종 시멘트의 황산에 의한 모르타르의 침식현상에 관한 연구 (A Study on The Corrosion Appearance of Mortar by The Sulfuric-Acid for Some Kinds of Cements)

  • 이웅종;정연식;김동석;양승규;유재상;이종열
    • 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.

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Monitoring of Degradation Process of Commercial ME Tapes under High Humidity Environment by AC Impedance Techniques

  • Take, Seisho;Shimanuki, Akiko;Itoi, Yasuhiko;Okuyama, Masaru
    • 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.

고로슬래그를 치환한 보수 모르타르의 내 황산성 평가 (Sulfuric Acid Resistance Evaluation of Repair Mortar Substituted Blast Furnace)

  • 김완수;장종민;이한승
    • 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.

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충전재 변화에 따른 PET 재활용 폴리머 콘크리트의 황산 부식에 관한 특성 (Characteristics of Sulfuric acid corrosion of Recycled PET Polymer Concrete with Different Filler)

  • 조병완;구자갑;박종화;박승국
    • 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.

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Service Life Prediction of Concrete Structures Exposed to a Sulfuric Acid Environment

  • 전종규;문한영;전찬기;송종화
    • 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.

고로슬래그 기반 경량 경화체의 황산 및 염산 저항 특성 (Sulfuric acid and Hydrochloric acid resistance properties of Light Weight Matrix Based on Blast furnace slag)

  • 김원종;이승호;박선규;이상수
    • 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.

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황산 환경에서 Fe-Si, Ni-Ti계 및 Ni 합금의 내부식성 특성 (Corrosion Characteristics of Fe-Si, Ni-Ti and Ni Alloy in Sulfuric Acid Environments)

  • 권혁철;김동진;김홍표;박지연;홍성덕
    • 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.

Effect of Ground Granulated Blast Furnace Slag, Pulverized Fuel Ash, Silica Fume on Sulfuric Acid Corrosion Resistance of Cement Matrix

  • Jeon, Joong-Kyu;Moon, Han-Young;Ann, Ki-Yong;Kim, Hong-Sam;Kim, Yang-Bea
    • International Journal of Concrete Structures and Materials
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    • 제18권2E호
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    • pp.97-102
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    • 2006
  • In this study, the effect of supplementary materials(GGBS, PFA, SF) on sulfuric acid corrosion resistance was assessed by measuring the compressive strength, corroded depth and weight change at 7, 28, 56, 91, 180 and 250 days of immersion in sulfuric acid solution with the pH of 0.5, 1.0, 2.0 and 3.0. 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: increased corroded depth and weight change, and lowered the compressive strength. 60% GGBS mortar specimen was the most resistant to acid corrosion in terms of the corroded depth, weight change and compressive strength, due to the latent hydraulic characteristics and lower portion of calcium hydroxide. The order of resistance to acid was 60% GGBS>20% PFA>10% SF>OPC. In a microscopic examination, it was found that acid corrosion of cement matrix produced gypsum, as a result of decomposition of hydration products, which may loose the structure of cement matrix, thereby leading to a remarkable decrease of concrete properties.

20% 황산 및 8% 황산 + 3% 옥살산에서 AA6061 합금 표면에 형성된 아노다이징 피막의 내전압 특성 (Dielectric breakdown of anodic oxide films formed on AA6061 in 20% H2O4and 8% H2SO4+ 3% C2H2O4 solutions)

  • 박철기;장재확;현윤석;문성모
    • 한국표면공학회지
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    • 제57권1호
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    • pp.8-13
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    • 2024
  • Anodizing of Al6061 alloy was conducted in two different electrolytes of 20% sulfuric acid and 8% sulfuric acid + 3 % oxalic acid solutions at a constant current or decreasing current density conditions, and its dielectric breakdown voltage was measured. The surface morphology of anodic oxide films was observed by TEM and thermal treatment was carried out at 400 ℃ for 2 h to evaluate the resistance of the anodic oxide films to crack initiation. The anodic oxide film formed in 8% sulfuric acid + 3 % oxalic acid solution showed higher dielectric breakdown voltage and better resistance to crack initiation at 400 ℃ than that formed in 20% sulfuric acid solution. The dielectric breakdown voltage increased 6 ~12% by applying decreasing current density comparing with a constant current density.