• Title/Summary/Keyword: corrosion resistant

Search Result 270, Processing Time 0.029 seconds

The Effect of Annealing on Corrosion Behavior of CoCrTa/CrNi Magnetic Recording Media (CoCrTa/CrNi 자기기록매체의 열처리에 따른 부식거동 변화)

  • 우준형;남인탁
    • Journal of the Korean Magnetics Society
    • /
    • v.9 no.4
    • /
    • pp.210-216
    • /
    • 1999
  • The objective of this paper is to investigate corrosion behaviors of CoCrTa/CrNi thin film and post heat-treatment effect. An electron beam evaporator was used for films deposition. After evaporation, post heat-treatment was carried out under $5.0{\times}10^3$ Torr vacuum condition. Annealing temperature and time were 400 $^{\circ}C$ and 30 min, respectively. To understand the effect of annealing on corrosion behavior of CoCrTa/CrNi, potentiodynamic polarization technique and accelerated corrosion chamber test were undertaken. Corrosion potential is higher for the annealed samples (CoCrTa 400$\AA$/CrNi 1000$\AA$) than for as-deposited one. This is attributed to an enrichment of Cr in the surface layer of the thinfilm resulting in a more corrosion resistant material.

  • PDF

Corrosion Property Evaluation of Copper Alloy Tubes against Sea Water

  • Pang, Beilli;Ong, Sang-Kil;Lee, Hong-Ro
    • Journal of the Korean institute of surface engineering
    • /
    • v.42 no.6
    • /
    • pp.280-286
    • /
    • 2009
  • In this study, the corrosion property of copper alloy tubes in seawater has been investigated. Three copper alloys of nominal composition Cu-20Zn-2Al(Al-Brass), Cu-30Ni(CN70/30) and Cu-10Ni(CN90/10) were considered. The samples were immersed in 3%NaCl flowing solution at $90^{\circ}C$ for 30, 50 and 80 days. Corrosion rate of copper alloy tubes in 3%NaCl flowing solution was investigated by weight-loss measurements and electrochemical test. The CN70/30 showed lowest corrosion rate among three copper alloy tubes. Because of passive films formation, corrosion rates of three types of copper tubes were decrease with time. Surface characteristics of copper alloy tubes were analyzed by optical micrograph(OM), scanning electronic microscopy (SEM), energy dispersive X-ray analysis(EDAX) and X-ray diffraction patterns(XRD). CN70/30 showed partly pitting problem on the surface owing to high Fe content, even though having high resistant against corrosion. Cracks appeared on the surface of CN90/10 and CN70/30 after more than 50 days immersion, which could be derived from high nickel contents.

A Study of Annealing Heat-treatment for Ti(Grade 2) by Electrochemical Methods (전기화학적 방법을 이용한 Ti(Grade 2)재의 최적 어닐링 열처리에 대한 연구)

  • 백신영
    • Journal of Advanced Marine Engineering and Technology
    • /
    • v.26 no.1
    • /
    • pp.90-98
    • /
    • 2002
  • In this paper, the annealing heat treatments for the best corrosion resistant of Ti(Grade 2) were studied in a 3.5% NaCl solution by electrochemical methods. The annealing heat treatments were accomplished at 650, 700 and $750^{\circ}C$ with different time of 30min., 1hour and 2 hours in a vacuum condition. The obtained results are: 1) in the case of solution heat treated $930^{\circ}C$ for 2 hours in a vacuum and air, the corrosion potentials were -348.7 and -567. 1mV, and current densities 2.32 and $22.62\mu\textrm{A}$, respectively, 2) as increase both annealing heat treatment temperature 650, 700, $750^{\circ}C$ and time 30min., 1 hour, 2 hours, the corrosion potential were decreased, whereas corrosion current density increased, 3) in the case of cyclic polarization, the measured charges were increased as increasing solution heat treatment temperature and time, 4) on the bases of corrosion potential, current density and charge, the best annealing temperature and time were measured as $700^{\circ}C$ and 30min. for Ti(Grade 2) material.

Molybdate Chemical Conversion Coating of Electro-Galvanized Steel (전기아연도금 강판의 몰리브데이트 화성처리)

  • 김헌태;김인수
    • Journal of the Korean institute of surface engineering
    • /
    • v.37 no.4
    • /
    • pp.200-207
    • /
    • 2004
  • Molybdate chemical conversion coating layer formed on EGI has been studied in view of corrosion resistance, surface morphologies, and phases formed. It was found that coating layer consists of$ MoO_3$, $MoO_2$, Mo oxides having lower valences than 4 and ZnO. It is interesting to note that the coating layer formed at high Mo concentration (30 g/l) in the temperature range of $40-60^{\circ}C$ exhibited relatively high corrosion resistance, although thickness of coating layer is nearly identical with those formed under the other conditions. It was believed that an increase of driving force due to high Mo concentration plays an important role in the formation of corrosion-resistant coating layer, probably due to tile formation of dense coating layer.

Life cycle reliability analyses of deteriorated RC Bridge under corrosion effects

  • Mehmet Fatih Yilmaz
    • Earthquakes and Structures
    • /
    • v.25 no.1
    • /
    • pp.69-78
    • /
    • 2023
  • Life-cycle performance analysis of a reinforced concrete box section bridge was generated. Moreover, Monte Carlo simulation with important sampling (IS) was used to simulate the bridge material and load uncertainties. The bridge deterioration model was generated with the basic probabilistic principles and updated according to the measurement data. A genetic algorithm (GA) with the response surface model (RSM) was used to determine the deterioration rate. The importance of health monitoring systems to sustain the bridge to give services economically and reliably and the advantages of fiber-optic sensors for SHM applications were discussed in detail. This study showed that the most effective loss of strength in reinforced concrete box section bridges is corrosion of the reinforcements. Due to reinforcement corrosion, the use of the bridge, which was examined, could not meet the desired strength performance in 25 years, and the need for reinforcement. In addition, it has been determined that long-term health monitoring systems are an essential approach for bridges to provide safe and economical service. Moreover the use of fiber optic sensors has many advantages because of the ability of the sensors to be resistant to environmental conditions and to make sensitive measurements.