• 보존과학연구
• /
• 통권32호
• /
• pp.89-98
• /
• 2011

철 부식화합물은 부식인자들과 함께 다양한 결정구조를 가지며 2가지 이상의 부식화합물들이 혼합되어 존재하므로 각각의 특성을 밝혀내기가 매우 어렵다. 본 연구는 표준 철 부식물을 대상으로 Raman Micro-Spectroscopy 분석을 실시하여 표준 Raman Data 확보를 목적으로 수행하였다. 표준 철 부식물에 대한 신뢰성을 향상시키기 위하여 SEM-EDS 분석과 XRD 분석을 추가로 실시하였다. SEM-EDS 분석결과 모두 표준 철 부식물의 구성성분과 일치하였으나 Goethite의 경우 철 이외의 비철금속 성분이 검출되었다. XRD 분석 결과 모두 표준 철 부식물의 구조와 일치 하였으나 Iron sulfate($FeSO_4{\cdot}6H_2O$)의 경우 Rozenite($FeSO_4{\cdot}4H_2O$)로 확인되었다. Raman Micro-Spectroscopy 분석결과 기존에 연구되었던 수산화철, 산화철의 Wavenumber에서 새로운 peak이 발견되었는데 이는 레이저 파장의 변화에 따른 것으로 사료 된다. 염화철과 황산철에서 Wavenumber가 새롭게 확인되어 표준 Raman Data 8건을 확보하였다. Raman Micro-Spectroscopy는 적은양의 시료를 이용하여 물질의 특성과 구조를 비교적 간단하게 분석 할 수 있어 미세한 부분이나 시료의 양이 한정된 문화재에 활용도가 높을 것으로 판단된다.

• Tribology and Lubricants
• /
• 제19권1호
• /
• pp.31-35
• /
• 2003

This paper reports the studies on the wear-corrosion behavior of ductile cast iron in the various pH environments. In the variety of pH solutions, corrosion and wear-corrosion loss of GCD 600 were investigated. Also, the anodic polarization test of GCD 600 using potentiostat/galvanostat was carried out. And rubbed surface of GCD 60 using scanning electron micrographs after immersion and wear-corrosion test was examined in the environment of various pH values. The main results are as following In alkali zone, the wear-corrosion loss of GCD 600 increases, but corrosion loss decreases. The unevenness and crack of wear-corrosion surface in neutral zone becomes duller than that in alkali zone. As the corrosive environment is acidified, wear-corrosion behavior of GCD 600 with passing immersion time becomes sensitive.

• Corrosion Science and Technology
• /
• 제2권5호
• /
• pp.219-224
• /
• 2003

Crevice corrosion of stainless steels in natural seawater was investigated for several post weld treatments; as-annealed, as-welded, pickled, and ground. The results confirmed the effect of the biofilm on the cathodic reaction leading to an ennoblement of the rest potential. The degree of ennoblement of corrosion potential depends on the surface finish. As-annealed and pickled samples show stable corrosion potential approaching to 200 ~ 300 mV (SCE) while as-welded and ground samples show the fluctuating corrosion potential. This points to a situation where there are conflicting effects determining the trend in free corrosion potential. Crevice corrosion initiation will tend to pull the free corrosion potential in the active direction, whereas the presence of biofilm will tend to ennoble corrosion potential. There was no visible attack on UNS S31803, S32550, and 2205W. Therefore, those stainless steel grades appeared to be resistant to crevice corrosion in natural seawater on condition of weld metal.

• 한국환경과학회지
• /
• 제9권6호
• /
• pp.505-509
• /
• 2000

The purpose of this study was to evaluate the effects of $Ca(OH)_2$ and $CO_2$ additions on the corrosion of metal coupons(ductile iron, galvanized steel, copper and stainless steel). Corrosion rate and released metal ion concentration of ductile iron and galvanized steel decreased by adjusting alkalinity, calcium hardness and pH with $Ca(OH)_2$ & $CO_2$ additions on copper and stainless steel were less than those on ductile iron and galvanized steel. When ductile iron coupon was exposed to water treated with Ca(OH)$_2$&$CO_2$, additions, the main components of corrosion product formed on its surface were $CaCO_3$ and $Fe_2 O_3 or Fe_2 O_4$ which often reduce the corrosion rate by prohibiting oxygen transport to the metal surface.

• Corrosion Science and Technology
• /
• 제4권2호
• /
• pp.51-55
• /
• 2005

The corrosion inhibitive effect of Poly (p-Anisidine) on iron in 1M HCl with various concentrations were studied by using electrochemical methods such as impedance measurements and polarization techniques. The inhibition efficiency (IE) of Poly (p- Anisidine) was compared with its monomer and it was observed that there is a remarkable increase for the polymer. Further, it is found that the value of IE increases with increasing concentrations for both monomer and polymer of p-Anisidine.

• Corrosion Science and Technology
• /
• 제21권5호
• /
• pp.418-421
• /
• 2022

Stir-accelerated corrosion test of a high chromium cast iron was attempted in 0.1 mol dm^-3 H₂SO₄ + 0.05 mol dm^-3 HCl + 10 wt% SiC solution for 48 h at room temperature or at 45 ℃. The high chromium cast iron was composed of 2.8 wt% C and 27 wt% Cr and balanced with Fe. The high chromium cast iron was positioned into a 500 mL beaker with stirring of the solution at 1050 rpm using a magnetic hot plate. The corrosion rate was increased by agitating the solution. In addition, the corroded depth of the high chromium cast iron surface was increased by agitating the solution. The surface morphology of the high chromium cast iron after the stir-accelerated corrosion test revealed that a dendritic austenite phase partially remained in the corroded region after agitating the solution, indicating that solution movement during agitating could accelerate the corrosion rate of the high chromium cast iron.

• 대한금속재료학회지
• /
• 제50권5호
• /
• pp.353-360
• /
• 2012

The corrosion product of archaeological iron objects is supposed to be removed because it causes re-corrosion. So far it is removed by scapel and sand blaster but they depend on the skill and experience of a conservator and the glass-dust of the sand blaster is harmful to humans. Therefore this study applies a laser cleaning system which is used in various industrial cleaning processes, to remove corrosion product from archaeological iron objects. In addition, this work studies the alternation of corrosion product after laser irradiation, which evaluates the reliability of the laser cleaning system. Optical microscopy, SEM-EDS, XRD, Raman have been used to observe and analyse the surface of the objects. The results show the capacity of laser cleaning some corrosion product, but blackening appears with increasing pulses and laser energy, and some corrosion products, goethite and hematite, are partially altered to magnetite. These problems, blackening and alternation of corrosion product, should be solved by further studies which find the optimal laser irradiation condition and use a wetting agent.

• Corrosion Science and Technology
• /
• 제8권1호
• /
• pp.21-26
• /
• 2009

The influence of $H_2S$ on the corrosion of iron and the corrosion prevention mechanism of an inhibitor was investigated with a differential capacitance measurement and a weight loss measurement method. The results show that $H_2S$ accelerates both the anodic iron dissolution and the cathodic hydrogen evolution in most cases. However, $H_2S$ acts as an inhibitor of the corrosion of iron under certain special conditions. An EIS method is proposed to explain the ability of inhibitors.

• 한국기계가공학회지
• /
• 제16권4호
• /
• pp.76-82
• /
• 2017

The cylinder liner of a diesel engine is commonly made of gray cast iron. However, this cylinder liner can be damaged by the cavitation phenomenon in wet conditions. This cavitation has remained an unsolved problem until now. In this study, the cause of cavitation corrosion due to antifreeze solution was examined using a scanning electron microscope (SEM) and a 3D microscope. The necessary data to prevent the damage caused by cavitation erosion and the corrosion of gray cast iron cylinder liner was obtained. Analysis determined that the gray iron structure consists of an ${\alpha}-matrix$, flake graphite, and steadite. Cavitation erosion was initiated in the coarse flake graphite and propagated into the steadite with pitting. Under repetitive reaction conditions, the ${\alpha}-matrix$ was partially separated from the gray cast iron. This study is expected to be used as the basic data for the prevention of gray cast iron cavitation erosion and corrosion by controlling the graphite and steadite phases.

• Tribology and Lubricants
• /
• 제18권4호
• /
• pp.299-304
• /
• 2002

This paper reports the studies on the wear-corrosion behavior of ductile cast iron in the acidic environment. In atmosphere and variety of pH solution, specific wear rate and wear-corrosion characteristics of GCD 60 with various sliding speed and distance were investigated. And electrochemical polarization test of GCD 60 was examined in the environment of various pH values. The main results are as following : As the contact pressure increases, the critical velocity of specific wear rate becomes transient at low sliding speed. As pH value becomes low, wear-corrosion loss increases in the aqueous solution. As the corrosion environment is acidified, corrosion potential of GCD 60 becomes noble and corrosion current density increases.