Corrosion Weight Gain Research Articles

Hardness and Corrosion Behavior of Aged 6063 Al Alloy

The effect of artificial aging on the corrosion properties of 6063 Al alloy was investigated by optical microscope, field emission scanning electron microscope (FE-SEM) and accelerated corrosion test. Accelerated corrosion test revealed that the corrosion resistance of the alloy strongly depended on artificial aging times, and the corrosion weight gain curve of the aged alloy was greatly in agreement with that of hardness vs. aging times, showing that the lowest corrosion resistance was exhibited at peak aged condition. It is found that pitting is the main corrosion form for the 6063 aluminum alloy aged with different times at 210°C, and slight intergranular corrosion is also found at peak hardness. It is believed that pitting results from galvanic corrosion between Al9Fe2Si2 particles and matrix Al while intergranular corrosion results from galvanic corrosion between Mg2Si and matrix Al.

Effect of sulphur dioxide on the corrosion of a low alloy steel in simulated coastal industrial atmosphere

This investigation aims to study the effect of SO2 on the corrosion of a low alloy steel in simulated coastal industrial atmospheres. The results indicate that the corrosion weight gain of the steel firstly increases with increasing SO2 content to a certain level and then decreases with further increasing the SO2 content. Besides, higher SO2 content promotes the formation of α-FeOOH and inhibits the formation of γ-FeOOH. Moreover, it seems that the deterioration effect of SO2 to steel corrosion is not obvious in the initial corrosion stage and SO2 begins to accelerate the steel corrosion as the corrosion process increases.

A study of the evolution of rust on weathering steel submitted to the Qinghai salt lake atmospheric corrosion

The corrosion evolution of weathering steel in Qinghai salt lake atmospheres as a function of exposure duration (up to 30 months) was investigated by corrosion weight gain, XRD, SEM, EDX and electrochemical techniques. The results indicated that the corrosion kinetics was closely related to the characteristics of the rust layer including composition, structure and electrochemical properties. The weight loss monotonically increased as exposure time prolonged with the fluctuations of average corrosion rate. The rust composition was mainly changed from γ-FeOOH and β-FeOOH (6 months), via β-FeOOH and magnetite (18 months), to magnesioferrite and iowaite (30 months). Correspondingly, the rust structure altered from loose and porous (6 months), via relative dense and adherent (18 months), to incompact and discontinuous again (30 months). The result of electrochemical measurements showed that rust resistance was very small, indicating that the rust layer had a poor barrier function which cannot prohibit the corrosion of steel effectively. The presence of iowaite (Mg4Fe(OH)8OCl·4H2O), which could attract Cl ions due to its special structure, was detrimental to the corrosion resistance of the rust layer and responsible for the poor weatherability of weathering steel.

Evolution of corrosion of MnCuP weathering steel submitted to wet/dry cyclic tests in a simulated coastal atmosphere

The evolution of rust on MnCuP weathering steel submitted to a simulated coastal atmosphere was investigated by corrosion weight gain, scanning electron microscopy, X-ray diffraction, and electrochemical methods. The results indicate that the higher corrosion rate during the first stage than that during the second stage is related closely to the rust composition and electrochemical properties. The corrosion rate evolution is caused by the formation of a protective rust layer with a higher relative amount of α-FeOOH. The rust initially enhances and then stabilizes the cathodic process, but the anodic process tends to be inhibited by the protective rust layer.

Rusting Evolution of MnCuP Weathering Steel Submitted to Simulated Industrial Atmospheric Corrosion

The rusting evolution of MnCuP weathering steel in a simulated industrial atmosphere as a function of corrosion duration was investigated by corrosion weight gain, scanning electron microscopy, X-ray diffraction, and electrochemical methods. The results indicate that the corrosion kinetics is related closely to the rust composition and electrochemical properties. The corrosion rate is higher during the first corrosion stage, and it is lower during the second corrosion stage. During the first corrosion stage, the rust layer is in low density, discontinuous, and loose, with a lower relative abundance of α-FeOOH. During the second corrosion stage, a compact and protective inner rust layer forms with a higher relative abundance of α-FeOOH, contributing to enhanced rust layer resistance. The rust initially enhances and then stabilizes the cathodic process, but the anodic process tends to be inhibited by the protective rust layer. Electrochemical impedance spectroscopy tests indicate that it is more scientific to evaluate the rust layer protective ability by charge transfer resistance.

A study of the evolution of rust on Mo–Cu-bearing fire-resistant steel submitted to simulated atmospheric corrosion

The corrosion evolution of a Mo–Cu-bearing fire-resistant steel in a simulated industrial atmosphere was investigated by corrosion weight gain, XRD, EPMA, XPS, and polarization curves. The results indicate that the corrosion kinetics is closely related to the rust composition and electrochemical properties. As the corrosion proceeds, the relative content of γ-FeOOH and Fe 3O 4 decreases and α-FeOOH increases, and the rust layer becomes compact and adherent to steel substrate. Molybdenum and copper enrich in the inner rust layer, especially at the bottom of the corrosion nest, forming non-soluble molybdate and Cu(I)-bearing compounds responsible for enhanced corrosion resistance of the rust layer.

Computation model for corrosion resistance of nanocrystalline zircaloy-4

A computation model of the corrosion rate versus grain size of nanocrystalline zircaloy-4 was presented. The influence of the second phase on the conductivity of alloy was considered. By this model, the corrosion rate of nanocrystalline zircaloy-4 at different temperature was calculated. The results show that the corrosion rate constant and weight gain of nanocrystalline zircaloy-4 decrease with the decrease of grain size, and that the corrosion weight gain of nanocrystalline zircaloy-4 is less than that of zircaloy-4 of coarse grain. The computational result is coincident with the experimental result.

INFLUENCE OF Cl- DEPOSITION CONTENT ON CORROSION OF LY12

A series of accelerated corrosion tests were conducted in the simulated marine atmosphere environment to study the corrosion of LY12 aluminum alloy under different Cl - deposition content. The change of corrosion morphology, weight gain and electrochemical parameters (Corrosion Electric Potential, AC Impedance) were inspected in the corrosion course. The different corrosion behaviors caused by the variation of Cl - deposition content were also discussed.

Atmospheric Corrosion of Electroplated Cu Thin Film in Moist Oxygen Environment

Atmospheric corrosion of electrodeposited Cu thin film in water vapour with oxygen was studied using a quartz crystal microbalance. The adsorption of water with N2 carrier gas without oxygen was reversible and roughly proportional to the relative humidity. The corrosion weight gain exhibited an initial linear rate law region followed by a parabolic rate law one. The rate for both regions was influenced by both relative humidity and O2 partial pressure. The electrochemical oxidation process of Cu might occur under an adsorbed water layer. It is considered that the water adsorbed as clusters and corrosion progressed under the water cluster, the thickness and surface coverage of which varied with relative humidity. The rough estimation revealed that the kinetic constants for both first linear rate and parabolic rate laws is proportional to the ratio of surface coverage by water cluster. However, the rate constant is independent of R.H., if normalized by the area of water clusters.

Influence of SO<sub>2</sub> Concentration on Initial Corrosion of Aluminum in Marine Atmosphere

Influence of SO2 concentration on initial corrosion of aluminum was studied in simulated marine atmosphere. Variation of initial corrosion morphology, relation between weight gain and time in the course of initial corrosion, corrosion speed (token with maximum pitting depth and weight gain) were analyzed and discussed. Primary results is list below: In marine atmosphere, SO2 sedimentation above 0.1 mg/100cm2 can accelerate Al pitting with low Cl- sedimentation. Both corrosion weight gain and pitting depth increase obviously. For pitting surface of LY12 with SO2 and Cl- sedimentation, corrosion potential change little, Nyquist Graph was single arc of capacitance resist with retractile real part, Rr can’t reflect corrosion degree.

572. β相から種々の速度で冷却したジルカロイー2の高温水および水蒸気中での腐食

Specimens of the subject material were immersed in water at 360°C under 190kg/cmcm2 and in steam at 400°C under 100 kg/cmcm2 up to 175 days, and their behavior was examined by weight gain measurements and metallographic examination. The results yielded the following information.(1) In the case of as-cooled zircaloy, the effect of differences in cooling rate on the corrosion weight gain is found only in the early stages of steam corrosion, and this is attributed to blistering of the oxide films found between the grain boundaries on the surfaces of the alloy.(2) Preferential oxidation of grain boundaries is found on as-cooled specimens corroded in water, and this is attributed to galvanic-type corrosion accelerated by local dilution of the solute elements around the precipitates on the grain boundaries.(3) The Breakaway phenomena in zircaloy corrosion kinetics is explaind in terms of the mechanical detachment of the protective oxide films from the alloy surfaces by stresses which arise during film growth, and rapid propagation of this cleavage favored by the change occasioned on the microstructure of the oxide films.(4) Among the alloying elements of zircaloy-2, Fe, Cr and Ni are found to precipitate with Zr as intermetallic compounds, thus forming discontinuities on the oxide film, and these elements consequently contribute to relieving the stresses and to improving the corrosion resistance of the alloy.

Effect of Five Impurities on the High Temperature Water And Steam Corrosion Resistance of Zircaloy-2

Abstract Five impurities (aluminum, manganese, nitrogen, copper and silicon), each at two concentrations, were studied in relation to the effect they had on the high temperature water and steam corrosion of Zircaloy-2. Sixteen ingots were fabricated to strip, and 36 specimens were taken from each ingot for corrosion testing. To investigate the heat treatment-impurity element interaction, three heat treatment conditions were incorporated in the experimental design. The average of all the furnace-cooled coupons had a some-what lower corrosion rate than the average air-cooled or as-received coupons, but the initial weight gains were higher. Results showed that aluminum is detrimental to the 750 F steam test and 680 F water corrosion, resistance of Zircaloy-2. Silicon at certain levels is beneficial in normalizing the corrosion weight gain of material furnace cooled. Manganese slightly increases the corrosion rate in 750 F steam and 680 F water, but is not considered significantly detrimental in the concentra...