Yang Lei,Yan Xu,Qing Zeng,Jingyi Xia,Shaochun Xie,Bo You
The preliminary detection and instant repair of local metal corrosion under protective coatings is of great importance for long-term application of metal materials in their lifecycles and reduction of environmental impact and carbon emissions. Here, inspired by beanpod, a smart anti-corrosive epoxy coating based on pH-responsive microcontainer was fabricated. The beanpod-inspired microcontainer (micropod) was composed of high-capacity hollowed mesoporous silica nanoparticles/graphene oxide (MSN-NH 2 /GO microcontainer) loading indicator and inhibitor 1,10-phenanthroline (Phen). The pH-responsiveness of the micropod was derived from GO electrostatic valve interacting with MSN-NH 2 whose surface charge varied at different pH values to control the release of Phen. When under-coating corrosion happened with increasing pH value, Phen escaped from the detached micropod and coordinated with dissolved Fe 2+ to develop red-orange coloration and form passive complex film retarding the corrosion to realize corrosion sensing and inhibition. GO also enhanced the corrosion resistance of coating because of the high aspect ratio which can prolong the diffusion pathway of corrosive media in coatings. The Phen@micropod/epoxy anti-corrosive coating performed well in immersion test and salt-spray test and remained intact in 30-day immersion test, the R c of which was 1000 times higher than pure epoxy coating.
Tong Liu,Dawei Zhang,Rongjun Zhang,Jinke Wang,Lingwei Ma,Patrick Keil,Arjan Mol,Xiaogang Li
Organic coatings are one of the most used and versatile technologies to mitigate corrosion of metals. However, organic coatings are susceptible to defects and damages that may not be easily detected. If not repaired timely, these defects may develop into major coating failures due to corrosion occurring in the damaged region, thereby limiting the lifetime of the to be protected structure. Thus, the development of smart coatings that can accurately identify corrosion location and reliably recover the damage autonomously is of particular interest. Herein, we reported a robust, corrosion-sensing and self-healing coating which incorporated pH-sensitive ZIF-8-capped CaCO 3 microcontainers containing the healing agent tung oil (TO) and the corrosion indicator/inhibitor 1,10-phenanthrolin-5-amine (APhen). The spontaneous leakage of incorporated TO and APhen was restrained, and the release initiated when local pH variation occurred. The corrosion protection performance of the coatings implanted with different contents of smart microcontainers were evaluated. The intact epoxy coating containing 7.5 wt% of the microcontainers exhibited the best protection performance with low water absorption (0.65 wt%), low O 2 permeability (0.21 × 10 –15 cm 3 cm cm −2 s −1 Pa −1 ), and a high storage modulus (3.0 GPa). Electrochemical impedance spectroscopy (EIS) measurements in 3.5 wt% NaCl solution demonstrated superior durability of the composite coating after self-healing. The immersion test and neutral salt spray test confirmed the coating can accurately report corrosion sites via coloration.
Tong Liu,Dawei Zhang,Lingwei Ma,Yao Huang,Xiangping Hao,Herman Terryn,Arjan Mol,Xiaogang Li
Herein, we report the development of a self-sensing and active corrosion protection coating which incorporates pH-sensitive multilayer chitosan/alginate-covered CaCO 3 microcontainers containing 1,10-phenanthrolin-5-amine (APhen). The microcontainers can respond to pH variation to release APhen which serves not only as a corrosion indicator but also as an inhibitor. An epoxy coating doped with 5 wt% microcontainers exhibited improved corrosion performance and was capable of inhibiting corrosion spreading from the damaged area in a 3.5 wt% NaCl solution. The salt spray test showed that corrosion damage can be quickly detected by the appearance of a red color within 2 min.
危险品化学品经营许可证（带存储）