Effect of polyvinylpyrrolidone on the corrosion resistance of steel

The effect of polyvinylpyrrolidone (PVP) on the corrosion resistance of steel reinforced concrete was assessed by measuring the corrosion potential, linear polarization resistance and AC impedance during 60 days immersion in NaCl and NaCl + PVP solutions. Polarization resistance (R_p) values of PVP added reinforced concrete were much higher than those without PVP. The relationship between corrosion potential and linear polarization resistance was analysed. Results from corrosion potential measurements were well comparable with the linear polarization resistance data. AC impedance spectra revealed that the resistance of PVP mixed electrodes was also quite higher than the other electrodes. The mechanical properties of concrete were measured. It was observed that the compressive strength of concrete had increased approximately 44% in the specimens containing PVP.     

变形热处理对Zr-1.0Nb合金耐腐蚀性能的影响

为了探究显微组织对Zr-1.0Nb合金耐腐蚀性能的影响,将Zr-1.0Nb合金样品分别进行680℃/500℃、680℃/560℃、800℃/500℃、800℃/560℃和1000℃/560℃五种变形热处理,然后在350℃、16.8 MPa、0.01mol.L-1的L iOH水溶液中腐蚀,并用透射电镜(TEM)研究其显微组织.其中800℃-1 h/冷轧/500℃-30 h处理样品的耐腐蚀性能最好,基体αZr中Nb元素固溶含量最低.通过变形热处理降低基体αZr中Nb元素固溶含量是提高Zr-1.0Nb合金耐腐蚀性能的一个关键因素.     

Effect of Al addition and heat treatment on the microstructures and corrosion resistance of Mg-Cu alloys

The effects of Al content and annealing condition on the microstructures and corrosion performances of Mg-3 wt.％Cu-xAl(x=0,4 wt.％,8 wt.％)alloys were investigate...     

Effect of phase transitions in Fe-Cr-Al alloys on their corrosion resistance in gases and liquid metals

We investigate the process of oxidation of Fe-Cr-Al alloys in argon and liquid sodium at a temperature of 650°C for 1000 h, analyze distinctive features of the process of formation of surface oxide and sub-oxide layers, and demonstrate the effect of phase transitions in alloys on the corrosion losses in these media. The process of oxidation of ferrochrome alloys in the region of homogeneity of -solid solutions in both media results in the formation of oxide layers based on Al₂O₃ on the surface of aluminum-containing alloys. In an atmosphere of argon, the intense growth of the oxide layer promotes the formation of residual stresses followed by its destruction and exfoliation, which leads to an increase in corrosion losses. In liquid sodium, aluminum improves the corrosion resistance of ferrochrome alloys, which is explained both by the suppression of formation of unstable compounds (sodium chromites and ferrates) and the appearance of an interlayer of -phase inclusions between the Al₂O₃ film and the matrix. This interlayer inhibits the growth of the protective oxide layer and enhances its adhesion to the matrix. The -phase is formed in homogeneous ferrochrome -alloys as a result of saturation of their surface layers with carbon present in sodium. If the composition of Fe-Cr alloys is close to equiatomic, their corrosion resistance catastrophically decreases as a result of the bulk transformation which is typical of both media.Karpenko Physicomechanical Institute, Ukrainian Academy of Sciences, L'viv. Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 31, No. 6, pp. 59–66, November – December, 1995.     

Effect of diffusion chromizing on some physico-mechanical properties of carbon steel

The effect of gaseous diffusion chromizing on the ability of carbon steel to carry static and cyclic loads was studied. The possibility of obtaining a substantial increase in corrosion-fatigue strength by producing sufficiently thick and dense diffused layers was demonstrated.     

Effect of aging on the corrosion resistance of 2101 lean duplex stainless steel

The microstructure and localized corrosion behavior of a 2101 lean duplex stainless steel aged at 700 °C were investigated. The results showed that changes in the microstructure of the duplex stainless steel, due to the formation of precipitates, affected its pitting corrosion resistance. The values of the pitting potential and the critical pitting temperature dropped drastically before aging time up to 30 min. The potentiostatic pitting corrosion measurement indicated more sensitive to the small amount of precipitates compared to the potentiodynamic test. Pitting nucleated mainly in the ferrite phase for the solution-annealed specimen, while the initiation of pitting corrosion for the aged specimen took place at Cr-depletion area around the precipitates, i.e. in the newly formed secondary austenite phase.     

Effect of the melting conditions on the corrosion cracking resistance of cast magnalium alloys

Translated from Fiziko-Khimicheskaya Mekhanika Materialov, No. 1, pp. 57–60, January–February, 1989.     

Plasma surface treatment of AISI 4140 steel for improved corrosion resistance

Alloy AISI 4140 steel was plasma-nitrided in a low-pressure abnormal glow discharge in 75% N₂+25% H₂ atmosphere (P=3 torr andT = 540°C for 2 h) using a home-made laboratory reactor. The corrosion behaviour was evaluated in a chloride environment by potentiostatic and potentiodynamic polarization as a function of thermal treatment and cooling cycle. Results from potentiodynamic polarization in NaCl (3%) indicated the presence of a low anodic dissolution current of about 1 A cm^–2 for ionitrided steel having layers thickness >5 m as compared to 0.1 A cm^–2 for untreated steel. In addition, the open circuit potential shifted to noble potential clearly indicating that the ionitridation process is a very efficient process for corrosion protection of AISI 4140 steel. Typical results obtained from samples oxidized during the cooling cycle showed an improvement in the corrosion resistance. The potential for pitting initiation and propagation as well as for pitting protection has been determined in a chloride environment. The use of electrochemical techniques as a control of standard parameters has been suggested.     

The effect of Nb and heat treatment on the corrosion behavior of ferritic stainless steel in acid environments

The corrosion properties of ferritic stainless steel with admixtures of 0.5, 1.0, and 3.0 wt.% Nb are studied in 0.1M H₂SO₄ and 0.3M HCl solutions. The results obtained by the impedance and mass-loss methods demonstrate that the procedure of alloying with niobium and diffusion treatment positively affect the corrosion resistance of steel in these solutions. Published in Fizyko-Khimichna Mekhanika Materialiv, Vol. 44, No. 4, pp. 89–94, July–August, 2008.     

Effect of heat treatment on corrosion of laser-textured aluminum alloy surfaces

The kinetics of electrochemical corrosion of aluminum alloy (AlMg6) surfaces with different wettability was analyzed. The surfaces were processed by three different methods, in particular, polishing, laser texturing, the combination of laser texturing and low-temperature heating. After laser processing, the dimple-like texture was formed on the surface, and the wettability significantly enhanced. Low-temperature heating of laser-textured AlMg6 alloy surfaces led to the wettability inversion from strongly hydrophilicity to superhydrophobicity. Microscopic and profilometric methods were used to estimate the surface degradation due to corrosion when aggressive solution droplets (a mixture of NaCl and hydrogen peroxide aqueous solutions) evaporated. The potentiodynamic polarization measurements of AlMg6 alloy surfaces were conducted. The typical modes of corrosion and evaporation of aggressive solution droplets were detected. The kinetics of corrosion was estimated by the behavior of the corrosion area evolution. In addition, when immersing laser-textured sample with strongly hydrophilic properties into aggressive solution, the higher corrosion rate was found in the liquid meniscus region (aggressive mixture / alloy / air interface) compared to the textured site immersed in the mixture. This was explained by convection increasing the rate of reaction products removal and promoting a stronger deviation from the equilibrium state in the aggressive mixture. Experimental results of the potentiodynamic polarization measurements revealed that laser-textured samples exhibit enhanced corrosion protective properties compared to polished samples.

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