A study on preparation and corrosion behavior of nano rare earth oxide‐modified chromized coatings

Abstract

The corrosion resistance of carbon steel in a harsh environment was improved by preparing a chromized coating on the surface through the method of pack cementation. Nano rare earth‐oxides (NREOs), Y2O3, CeO2, and La2O3 were added to the pack and to further enhance the performance of the chromized coatings. Morphological results showed that NREO refined the microstructure of chromized coatings by retarding the growth of grains. The Mott–Schottky plots demonstrated that coating Cr–La2O3 displayed fewer defects than the other two composite coatings, which was beneficial to reduce the corrosion tendency. In addition, the potentiodynamic polarization and impedance spectroscopy analysis showed that the order of the corrosion rates of the achieved coatings was pure Cr > Cr–Y2O3 > Cr–CeO2 > Cr–La2O3, which revealed that the corrosion resistance increased accordingly.

A Novel Fe-Based Metallic Glass as the Bipolar Plate for Proton Exchange Membrane Fuel Cells

“…Based on the EIS features of both samples, namely a typical semicircle in the Nyquist diagram and the one time constant feature in the Bode diagram, an equivalent circuit with one time constant, R s ( QR ct ), was used to fit the EIS data through the ZSimpWin software, and the model image is provided as an insert in the corresponding Nyquist plot (Figure b). The selected equivalent circuit R s ( QR ct ) consists of three elements: R s is the electrolyte resistance between the working electrode and reference electrode; R ct represents the charge transfer resistance, and Q stands for the charge transfer capacitance. , The constant phase element (CPE) Q is the indicator of the deviation from an ideal capacitor, and it is defined as Q = [ C ( jω ) n )] −1 , , where C is the capacitance of an ideal capacitor, j is the imaginary number, ω is the frequency, and n is the exponent of CPE ranging from 0–1, representing the deviation from an ideal capacitor …”

“…22,23 The constant phase element (CPE) Q is the indicator of the deviation from an ideal capacitor, and it is defined as 24,25 where C is the capacitance of an ideal capacitor, j is the imaginary number, ω is the frequency, and n is the exponent of CPE ranging from 0−1, representing the deviation from an ideal capacitor. 26 The fitting results of the impedance spectra using the R s (QR ct ) equivalent circuit are presented in Table 3. A low chi-square (χ 2 ) value indicates there is good agreement between the experimental and simulated data.…”

A novel FeCrMoCSi metallic glass with excellent corrosion resistance and in vitro cellular response for biomedical applications

“…represents the deviation from an ideal capacitor [34]. Rs and Rp represent the resistance of the test electrolyte and the passive film, respectively [35].…”

Erosion-Corrosion Behavior and Mechanism of Heated Electroless Ni–P Coating under Flow

“…The relevant polarization resistance (R p ) was evaluated by the mathematical sum of R ct and R f . 28) Meanwhile, the material had higher corrosion resistance when the R p was larger. The R p s of NiP (a) and h-NiP (b) in 0.6 mol/L NaCl solution without (liquid flow) and with SiO 2 particles (solid-liquid flow) at different speeds were summarized in Fig.…”