Self-healing coatings have been developed as smart surface coatings for Mg and its alloys to retain local corrosion from the coating damages. In this study, we prepared dicalcium phosphate dihydrate (DCPD) coating on biomedical Mg, and found that the artificial scratches in DCPD coating can be efficiently sealed by anti-corrosive products in both Hank's and normal saline (NS) solutions. Besides, the in-depth study revealed that DCPD was served as not only a physical barrier but also a self-healing agent, demonstrating an autonomous self-healing coating without embedded extra corrosion inhibitors. Moreover, Hank's solution provided foreign-aid film-forming ions to promote self-healing behavior. The findings might offer new opportunities for further studies and applications of efficient self-healing coatings on biodegradable Mg implants.

Cerium-based sealing treatment was developed for Mg-Al hydrotalcite film on AZ91D Mg alloy, and the influence of cerium salt solution was investigated to modify the surface integrity and corrosion resistance. Scanning electron microscope (SEM) and X-ray diffraction (XRD) measurements were carried out to analyze the surface morphology and phase composition. The corrosion resistance of Mg-Al hydrotalcite film after sealing treatment was evaluated by the polarization curve and electrochemical impedance spectroscopy (EIS) tests. The results showed that lower concentration of Ce-containing solution was beneficial to seal the micro-cracks on Mg-Al hydrotalcite film, and improve the surface integrity and corrosion resistance; higher concentration of Ce-containing solution could seal fewer micro-cracks, and the corrosion resistance was decreased owing to the disintegration of Mg-Al hydrotalcite film

Metal corrosion has been one of the most urgent problems bringing about great economic loss and life threats worldwide. Corrosion inhibitors can prevent metal from corrosion when directly added to corrosive media, which is a low-cost and efficient strategy towards corrosion protection. However, the corrosion protection ability cannot be durable without continuous additions of corrosion inhibitors. Micro/nano-containers encapsulated with corrosion inhibitors offer promising opportunities for delaying the corrosion process and prolonging the service period, regarded as smart corrosion inhibitors that can respond to stimuli spontaneously and release on demand. The review focuses on the diverse ambient stimuli and actively responsive mechanisms of smart corrosion inhibitors. Furthermore, the present drawbacks and underexplored possibilities of current research studies are pointed out, and future perspectives are prospected for smart corrosion inhibitor applications. Abbreviations: 2-2LP, 2,2″-bipyridine; 2-MBI, 2-mercaptobenzimidazole; 2-MBT, 2-mercaptobenzothiazolate;3-APTES, 3-aminopropyltriethoxysilane;8-HQ, 8-hydroxyquinoline;BBA, Barbituric acid;BDT, Beidellite;BIA, Benzimidazole;BTA, Benzotriazole;CB[7], Cucurbit[7]uril;CNT(s), Carbon nanotube(s);CTAB, Cetyltrimethylammonium bromide;DEDTC, Diethyldithiocarbamate;EE100, Eudragit E100;GO, Graphene oxide;HMCe, Hierarchically mesoporous cerium oxide;HNT(s), Halloysite nanotube(s);IDC, Imidazole dicarboxylic acid;IE, Inhibition efficiency;IMPACT, International Measures of Prevention, Application, and Economics of Corrosion Technologies;LDH(s), Layered double hydroxide(s);Met, DL-methionine;MF, Melamine-formaldehyde;MMT(s), Montmorillonite(s);MSiO₂, Mesoporous silica;NACE, National Association of Corrosion Engineers;PA, Phytic acid;PAA, Polyacrylic acid;PCL, Poly (ϵ-caprolactone);PDDA, Poly(di-allyldimethylammonium chloride);PDMAEMA, Poly(N,N-dimethylaminoethyl methacrylate);PEI, Polyethylenimine;PMAA, Polymethacrylic acid;PNIPAM, Poly(N-isopropylacrylamide);PPEGMA, Poly(poly(ethylene glycol)methacrylate);PSS, Poly(styrene sulphonate);rGO, Reduced Graphene oxide;Silk-KP, Silk fibroin-K₃PO₄;SO, Sodium oleate