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In order to reduce the energy consumption of the reaction, the magnesium alloy samples were immersed directly into three conversion solutions and reacted for 9 hours at 60 ℃ and pH=12.0 used the chelating agent-assisted method by adding three chelating agents, ethylenediaminetetraacetic acid tetrasodium (EDTA-4Na), sodium citrate (SC) and potassium sodium tartrate (PST) to aluminum nitrate (Al(NO3)3) solution, and Mg-Al layered double hydroxides (LDHs) films doped with different chelating agents can be prepared on the surface of magnesium alloys. The microstructure, phase composition, and corrosion resistance of each LDHs film were analyzed by SEM, XRD, FT-IR, etc. The results show that the chelating agent-assisted method can successfully prepare LDHs films with typical layered structure on the surface of magnesium alloys under normal pressure and 60 ℃ environment; and three kinds of Mg-Al LDHs films obtained can effectively improve the corrosion resistance of magnesium alloys. Then, by comparing the structural properties of three different LDHs film layers, it is found that the Mg-Al-PST LDHs film prepared by adding PST has the highest density and the largest thickness, reaching up to 1.4 μm. The improvement effect of three coatings on the corrosion resistance of magnesium alloys is as follows: Mg-Al-PST LDHs > Mg-Al-SC LDHs > Mg-Al-EDTA LDHs; The magnesium alloy covered with the Mg-Al-PST LDHs film compared to the blank magnesium alloy, the corrosion current density decreases by about two orders of magnitude, and the total corrosion resistance increases by about one order of magnitude. And based on the analysis of the structure and properties of the obtained LDHs films, it can be seen that the chelating agent-assisted method can prepare Mg-Al LDHs films with better corrosion resistance in-situ on the surface of magnesium alloys under the lower energy consumption condition. The reason may be that the carboxyl group in the chelating agent can accelerate the deposition of Al3+ on the magnesium substrate and promote the substitution of some Mg2+ in Mg (OH)2 by Al3+ to form LDHs.

Biomedical magnesium (Mg) alloys remain a challenge for their mainstream application, because the combination of bio‐mechanical stress and corrosive physiological environment leading to stress corrosion cracking (SCC). It is crucial to avoid the sudden brittle fracture of Mg alloys in vivo for predicting their service duration. However, the key factors, such as surface or physiological environment features, determining the origination or propagation of SCC behavior are still unclear. In the present study, a prefabricated surface defects coating was prepared by the phytic acid (PA, C6H18O24P6) conversion treatment. Four mimicking physiological media were used, ranging from simple to equivalent (Dulbecco's Modified Eagle Medium and Protein [DMEM+Pro]). The results showed that the PA film with numerous micro‐cracks provided limited protective ability in synthetic biological media. A striking finding was determined that although initial high corrosion rate of samples in DMEM+Pro led to an increased SCC nucleation, significant ductile fracture with elongation to failure (14.86%) was observed. Combined with the fracture features, the adsorption or deposition of biological composition into the tunnel of SCC cracks significantly inhibited the hydrogen embrittlement (HE) behavior. These results indicate that preventing the propagation of SCC crack by biological composition, rather than nucleation, plays a key role in avoiding the sudden fracture of Mg alloys. It provides a novel perspective to determine the non‐brittle fracture of Mg alloys for biomedical applications. Highlights: Prefabricated surface‐defective Mg novelty used to study stress corrosion crackingConfirming ductile fracture of Mg alloy in vitro organic‐containing mimic mediumInhibiting the micro‐crack propagation relied on biological composition depositionThe crack propagation than nucleation plays a key role in avoiding brittleness [ABSTRACT FROM AUTHOR]

In this study, S-doped graphitic carbon nitride (S-C3N4) was prepared using the high-temperature polymerization method, and then S-C3N4/AgCdS heterojunction photocatalyst was obtained using the chemical deposition method through loading Ag-doped CdS nanoparticles (AgCdS NPs) on the surface of S-C3N4. Experimental results show that the AgCdS NPs were evenly dispersed on the surface of S-C3N4, indicating that a good heterojunction structure was formed. Compared to S-C3N4, CdS, AgCdS and S-C3N4/CdS, the photocatalytic performance of S-C3N4/AgCdS has been significantly improved, and exhibits excellent photocatalytic degradation performance of Rhodamine B and methyl orange. The doping of Ag in collaboration with the construction of a Z-scheme heterojunction system promoted the effective separation and transport of the photogenerated carriers in S-C3N4/AgCdS, significantly accelerated its photocatalytic reaction process, and thus improved its photocatalytic performance. [ABSTRACT FROM AUTHOR]

Micro-arc oxidation (MAO) is widely applied to improve the corrosion resistance of Mg alloys by forming a ceramic passivation film on their surface. The high cohesive strength and randomly distributed micro-porous structure of MAO films have significantly expanded their operation scope, serving as the base or bonding layer for composite or multi-functional coatings. However, mechanical scratches or impacts during installation and service periods can damage the protective performance of MAO films, leading to local corrosion or the rapid loss of mechanical integrity in Mg alloys. Therefore, the development of MAO coatings with self-healing properties has been extensively studied in recent decades. This paper aims to illustrate the gaps between the anti-corrosion characteristics and self-repairing mechanisms dependent on the oxide composition or porous structure of MAO films. The progress in preparation and the principle of inhibitor loading in self-healing functional MAO-based composite coatings are summarized, and future directions are highlighted. [ABSTRACT FROM AUTHOR]