Effect of the passive films on CaCO3 scale depositing on Q235 steel: electrochemical and surface investigation

In this study, calcium carbonate (CaCO3) microparticles having pH-sensitive properties were loaded with sodium lignosulfonate (SLS), a corrosion inhibitor. Scanning electron microscope (SEM), UV–VIS spectrophotometer (UV-vis), X-ray diffraction (XRD), and attenuated total reflection-Fourier-transform infrared spectroscopy (ATR-FTIR) were applied to evaluate the properties of the synthetic microparticles. This material could lead to the release of corrosion inhibitor under different pH conditions of the aqueous media. However, the extent of release of the corrosion inhibitor in the acidic media was higher, leading to enhanced shielding effect of the Q235 steel. These microparticles can serve as anti-corrosion additive for epoxy resin-coated Q235 steel. Electrochemical experiments were used to assess the anti-corrosive ability of the epoxy coatings in simulated concrete pore (SCP) solution, confirming the superior corrosion inhibition of the epoxy coating via incorporation of 5 wt % calcium carbonate microparticles loaded with SLS (SLS/CaCO3). The physical properties of coating specimens were characterized by water absorption, contact angle, adhesion, and pencil hardness mechanical tests.

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Pitting Corrosion of Type 316L Stainless Steel Elaborated by the Selective Laser Melting Method: Influence of Microstructure

Journal of Materials Engineering and Performance ◽

10.1007/s11665-021-05621-7 ◽

2021 ◽

Author(s):

V. Vignal ◽

C. Voltz ◽

S. Thiébaut ◽

M. Demésy ◽

O. Heintz ◽

...

Keyword(s):

Corrosion Behavior ◽

316L Stainless Steel ◽

Electrochemical Impedance ◽

Chemical Properties ◽

Passive Films ◽

First Order ◽

Average Grain Size ◽

Type 316L ◽

Pure Matrix ◽

Type 316L Stainless Steel

AbstractThe microstructure of two sets of 316L alloys (SLM and wrought structure) is determined using SPECTROMAXx stationary metal analyzer, FE-SEM/EDS and XRD. The physical–chemical properties of the passive films are also investigated by means of XPS, Auger after sputtering and electrochemical impedance spectroscopy measurements. Differences and similarities between the two sets of alloys are then identified. The corrosion behavior of alloys is investigated in NaCl solution at the macro- and microscale (microcapillary technique). It was found that the inclusion/particles cleanliness is the first-order parameter explaining differences between 316L(WS) and 316L(SLM). In the absence of particles (pure matrix), the two sets of alloys have the same corrosion behavior. Residual stresses, the average grain size, the PREN and the passive films properties are of second order.

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Design an Epoxy Coating with TiO2/GO/PANI Nanocomposites for Enhancing Corrosion Resistance of Q235 Carbon Steel

Materials ◽

10.3390/ma14102629 ◽

2021 ◽

Vol 14 (10) ◽

pp. 2629

Author(s):

Shimin Chen ◽

Bo Li ◽

Rengui Xiao ◽

Huanhu Luo ◽

Siwu Yu ◽

...

Keyword(s):

Carbon Steel ◽

Photocurrent Density ◽

Photoelectrochemical Performance ◽

Q235 Steel ◽

Protective Barrier ◽

Barrier Coating ◽

Pani Composite ◽

Steel Protection ◽

Q235 Carbon Steel

In this work, a ternary TiO2/Graphene oxide/Polyaniline (TiO2/GO/PANI) nanocomposite was synthesized by in situ oxidation and use as a filler on epoxy resin (TiO2/GO/PANI/EP), a bifunctional in situ protective coating has been developed and reinforced the Q235 carbon steel protection against corrosion. The structure and optical properties of the obtained composites are characterized by XRD, FTIR, and UV–vis. Compared to bare TiO2 and bare Q235, the TiO2/GO/PANI/EP coating exhibited prominent photoelectrochemical properties, such as the photocurrent density increased 0.06 A/cm2 and the corrosion potential shifted from −651 mV to −851 mV, respectively. The results show that the TiO2/GO/PANI nanocomposite has an extended light absorption range and the effective separation of electron-hole pairs improves the photoelectrochemical performance, and also provides cathodic protection to Q235 steel under dark conditions. The TiO2/GO/PANI/EP coating can isolate the Q235 steel from the external corrosive environment, and may generally be regarded a useful protective barrier coating to metallic materials. When the TiO2/GO/PANI composite is dispersed in the EP, the compactness of the coating is improved and the protective barrier effect is enhanced.

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