Analysis on surface film formed on high-strength carbon steels in acidic phosphate solution and its relationship with localized corrosion in a 3.5% NaCl solution
“…For Bio-HEAs with Ti and Ta elements, their lower E corr indicates that they will both readily form protective passivation layers (usually oxides) ( Zheng et al, 2018 ). Most Bio-HEAs have no pitting reaction until 2V, which means promising applications in human environments around 0–0.2 V. No pitting and no localized corrosion due to the breakdown of the protective passivation films, dramatically increasing the lifetime of alloy implants ( Hwang et al, 2019 ; Li T. et al, 2021 ). The corrosion current density indicates the corrosion rate of the material.…”
With the continuous progress and development in biomedicine, metallic biomedical materials have attracted significant attention from researchers. Due to the low compatibility of traditional metal implant materials with the human body, it is urgent to develop new biomaterials with excellent mechanical properties and appropriate biocompatibility to solve the adverse reactions caused by long-term implantation. High entropy alloys (HEAs) are nearly equimolar alloys of five or more elements, with huge compositional design space and excellent mechanical properties. In contrast, biological high-entropy alloys (Bio-HEAs) are expected to be a new bio-alloy for biomedicine due to their excellent biocompatibility and tunable mechanical properties. This review summarizes the composition system of Bio-HEAs in recent years, introduces their biocompatibility and mechanical properties of human bone adaptation, and finally puts forward the following suggestions for the development direction of Bio-HEAs: to improve the theory and simulation studies of Bio-HEAs composition design, to quantify the influence of composition, process, post-treatment on the performance of Bio-HEAs, to focus on the loss of Bio-HEAs under actual service conditions, and it is hoped that the clinical application of the new medical alloy Bio-HEAs can be realized as soon as possible.
“…For Bio-HEAs with Ti and Ta elements, their lower E corr indicates that they will both readily form protective passivation layers (usually oxides) ( Zheng et al, 2018 ). Most Bio-HEAs have no pitting reaction until 2V, which means promising applications in human environments around 0–0.2 V. No pitting and no localized corrosion due to the breakdown of the protective passivation films, dramatically increasing the lifetime of alloy implants ( Hwang et al, 2019 ; Li T. et al, 2021 ). The corrosion current density indicates the corrosion rate of the material.…”
With the continuous progress and development in biomedicine, metallic biomedical materials have attracted significant attention from researchers. Due to the low compatibility of traditional metal implant materials with the human body, it is urgent to develop new biomaterials with excellent mechanical properties and appropriate biocompatibility to solve the adverse reactions caused by long-term implantation. High entropy alloys (HEAs) are nearly equimolar alloys of five or more elements, with huge compositional design space and excellent mechanical properties. In contrast, biological high-entropy alloys (Bio-HEAs) are expected to be a new bio-alloy for biomedicine due to their excellent biocompatibility and tunable mechanical properties. This review summarizes the composition system of Bio-HEAs in recent years, introduces their biocompatibility and mechanical properties of human bone adaptation, and finally puts forward the following suggestions for the development direction of Bio-HEAs: to improve the theory and simulation studies of Bio-HEAs composition design, to quantify the influence of composition, process, post-treatment on the performance of Bio-HEAs, to focus on the loss of Bio-HEAs under actual service conditions, and it is hoped that the clinical application of the new medical alloy Bio-HEAs can be realized as soon as possible.
“…It can be obtained from Figure 8(d) that LDH-PO 4 coating has the highest Volta potential, and the maximum ΔV value reduces to 264 mV after immersion for 4 h. The potential of LDH-PO 4 coating is higher and smoother than that of the blank sample, indicating that the loaded PO 4 3- in LDH-PO 4 released into the scratched area and protected it well [32]. The released PO 4 3- ions form a thin passive film on the scratched substrate, providing an active corrosion protection performance [33]. Figure 8 SKP maps of the scratched coatings after 0.5 and 4 h exposure to 0.5 M NaCl solution.…”
Section: Resultsmentioning
confidence: 99%
“…3ions form a thin passive film on the scratched substrate, providing an active corrosion protection performance [33].…”
Layered double hydroxides (LDHs) can serve as corrosion inhibitor reservoirs. In the present work, hydrotalcite-like LDHs were synthesized and employed as host matrixes for the release of phosphate. The morphological and structural properties of the as-prepared LDH-PO 4 were characterised by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The PO 4 3adsorption uptake was successfully confirmed by the XRD results. The corrosion resistance of the coating with LDH-PO 4 was investigated by electrochemical impedance spectroscopy (EIS), which was approximately 1 order of magnitude higher than that of the blank coating after immersion for 168 h. Results of the scanning Kelvin probe technique revealed that the potential of LDH-PO4 coating was higher and smoother than that of the blank coating after exposure to 0.5 M NaCl solution. This effect is attributed to the release of PO 4 3− that forms a phosphate protective film in the scratched region.
“…Based on the above results and relevant previous studies [28][29][30][31], a schematic of the corrosion product film on the 12Cr1MoV steel after corrosion in the TCSA solution is proposed, as is shown in Figure 9. In the early stage (1-3 d), there is a competitive adsorption of OH -, AlO2 -, and S2O3 2-in the solution.…”
When alumina is produced by the Bayer process with high-sulfur bauxite, the sulfur would strongly corrode the 12Cr1MoV steel made heat exchanger. This study investigated the initial corrosion behavior of the 12Cr1MoV steel exposed to a thiosulfate-containing sodium aluminate (TCSA) solution under the evaporation conditions of alumina production. The obtained corrosion rate equation is V = 6.306·t·exp(−0.71). As corrosion progressed, with the corrosion product film growing, the corrosion current density declines slowly, and the corrosion resistance of the steel is increased. At 1–3 days, the corrosion product film consisted of FeO, Fe2O3, and FeOOH. S2O32− lead to corrosion in local areas of the steel and pits appeared. AlO2− is transformed into Al(OH)3 and filled in the corrosion pits. At 4 and 5 days, Fe3O4 is generated in the outermost layer, and Al(OH)3 is shed from the corrosion pits. The corrosion mechanism of 12Cr1MoV steel in a TCSA solution is proposed based on the experimental results.
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