Components Of Corrosion Products Research Articles

Effect of corrosion on mechanical properties for CFRP/aluminum adhesive joints under a salt spray environment

In this study, we aim to investigate the effect of galvanic corrosion on the mechanical properties of aluminum-CFRP adhesive joints. Aluminum-CFRP, aluminum-aluminum, and CFRP-CFRP adhesive joint specimens were prepared. Subsequently, the specimens were subjected to accelerated aging treatment in a salt spray environment, and the tensile shear adhesive strength, the transition of the failure surface and the deposition state and the components of corrosion products with aging time were quantitatively evaluated. As a result, in aluminum-CFRP adhesive joints under the salt spray, galvanic corrosion of the aluminum substrate occurred within 24 hours, and the adhesive-adherend interfacial strength decreased significantly compared to aluminum-aluminum and CFRP-CFRP adhesive joints. In addition, the failure mode of aluminum-CFRP adhesive joints changed from the mixed failure of interfacial failure, cohesive failure, and fiber tear failure to interfacial failure. Furthermore, it was found that the deposition amount of Al2O3 increased under the influence of the salt spray environment.

Corrosion sensitivity analysis of pipelines in CO2 and H2S coexisting environment in the South China Sea

Abstract The purpose of the present work is to investigate the corrosion sensitivity of pipelines of oil and gas wells under complex environmental conditions (i.e., the primary and secondary relationship of the influence of different environmental factors on pipeline corrosion). The orthogonal experiment is introduced to design the experimental scheme. The weight loss method is employed to analyze the average corrosion rate of N80 steel under different environmental conditions. And then the scanning electron microscope is used to explore the surface and cross-section corrosion morphology of the corrosion products. Besides, the components of corrosion products are obtained by the energy spectrum analysis. The research results indicate that H2S partial pressure is the most sensitive factor to the corrosion of N80 pipeline and the influence of CO2 partial pressure on corrosion of N80 pipeline is weaker than Cl− concentration and temperature in the South China Sea. The study can help the oil drilling engineering search for direct and effective corrosion inhibitors under complex environmental conditions.

Archaeometric Analysis of the Objects from the Scala Santa (Holy Stairs) in the Crypt under the Piarist Church in Cracow (Poland)

Conservators extracted and preserved reliquaries hidden in the steps of the right flight of the Holy Stairs erected in the Piarist church crypt in Cracow (Poland). Three items from among 59 reliquaries were selected for specialist analyses: a framed, transparent cross containing a particle of the True Cross, and two opaque beads; an ornamented blue one without a hole and a drilled black one were analysed using non-destructive and non-invasive methods. The methods included scanning electron microscopy coupled with energy dispersive X-ray spectrometry, Raman microspectroscopy and X-ray diffractometry. The reliquary cross was found to be made of rock crystal and framed with an alloy of gold, silver and probably copper. The beads are made of glass; the blue bead represents forest plant-ash potash–lime glass and the black one, plant-ash soda–lime glass. Cobalt, probably along with copper, was used to produce the colour of the blue bead; manganese and iron ions were used to produce that of the black bead. Lead was present in both beads as one of the minor components and also as a component of corrosion products on their surfaces and probably also as part of the filler for the ornamentation of the blue bead. Nevertheless, it cannot be ruled out that the lead compounds were introduced intentionally to emphasize the bead ornamentation. The possible place and date of manufacture of the artefacts were also discussed.

Corrosion Behavior of 20MnSiCrV Corrosion Resistant Rebar in Chloride Containing Environment

Corrosion resistance and corrosion sensitivity to chloride containing environment of 20MnSiCrV steel and 20MnSiV steel was comparatively investigated by salt-spray corrosion test with 3.5%NaCl solution, as well as electrochemical impedance spectroscopy and polarization curve measurements in chloride containing alkaline solutions. The formed corrrosion product scales were characterized by SEM, EPMA and XRD. The results show that the corrosion resistance to Cl - of 20MnSiCrV steel was 1.5 times over that of 20MnSiV steel. The average corrosion rate and depth of corrosion pits of 20MnSiCrV steel were 58% and 74% of those of 20MnSiV steel, respectively. The major components of corrosion products of the two steels were Fe3O4, α-FeOOH and γ-FeOOH. Corrosion scale of 20MnSiCrV steel can be differentiated into an inner layer and an outer layer. The inner layer is enriched in Cr and Si, thereby beneficial to the corrosion resistance of the steel.

Corrosion mechanism of 13Cr stainless steel in completion fluid of high temperature and high concentration bromine salt

Abstract A series of corrosion tests of 13Cr stainless steel were conducted in a simulated completion fluid environment of high temperature and high concentration bromine salt. Corrosion behavior of specimens and the component of corrosion products were investigated by means of scanning electron microscope (SEM), confocal laser scanning microscopy (CLSM) and X-ray photoelectron spectroscopy (XPS). The results indicate that 13Cr steel suffers from severe local corrosion and there is always a passive halo around every pit. The formation mechanism of the passive halo is established. OH − ligand generates and adsorbs in a certain scale because of abundant OH − on the surface around the pits. Passive film forms around each pit, which leads to the occurrence of passivation in a certain region. Finally, the dissimilarities in properties and morphologies of regions, namely the pit and its corresponding passive halo, can result in different corrosion sensitivities and may promote the formation of macroscopic galvanic pairs

μRaman Analysis of the Rust Layer on Rusted Cast Iron Artifacts

The components of corrosion products on rusted cast iron artifacts in a wet/dry atmospheric environment have been studied by micro-Raman spectroscopy. The observations show that microstructures of outer and inner interfaces are different; indicating that active corrosion occurred on the rusted specimen covered with many cracks and pores. The μRaman spectra of outer and inner layer results prove to be composed of three main iron oxyhydroxides. In addition, Fe3O4 only exists in the inner layer.

Effect of Rare Earth Elements on Corrosion Behavior of Q345B Steel in CSP

The effects of rare earth elements (RE) on corrosion behavior of Q345B steel at marine atmospheric environment in Compact strip production (CSP) technology was studied using alternate immersion test in this paper. The influences of RE on the microstructure, the components of corrosion products, the corrosion dynamic laws as well as the electrochemical properties were also investigated by optical microscope, SEM, XRD, polarization curve and EIS measurements. The results show that the microstructure of Q345B steel in CSP is finer and the corrosion is mitigated due to relatively compact corrosion products with the addition of RE. The corrosion current density of Q345B steel with RE is lower than that of Q345B steel without RE and the corrosion resistance of Q345B in CSP is improved to a certain extent by RE.