As the lightest structural materials, magnesium (Mg) alloys play a significant role in vehicle weight reduction, aerospace, military equipment, energy saving, and emission reduction. However, the poor corrosion resistance of Mg alloys has become a bottleneck restricting its wide application. Developing a good surface protective coating can effectively improve the corrosion resistance of Mg alloys. The silane-based sol-gel coating technology has been widely used in the corrosion protection of Mg alloys in recent years due to its advantages of simple process, accessible tailoring of film composition and structure, and excellent corrosion resistance. Whereas the synthesis of sol-gel coatings includes the hydrolysis and dehydration process, which may inherently contain micron or nano defects in the coatings, thereby making it detrimental to the anti-corrosion effect. Therefore, in order to enhance their protection against corrosion, the appropriate modification of sol-gel coatings has become a current research hotspot. This review is based on the modification methods of silane-based sol-gels on the surface of Mg alloys, which are divided into four categories: bare sol-gel, nanoparticles, corrosion inhibitors, and sol-gel-based composite coatings. The modification methods and corrosion protection mechanism are discussed respectively, and the application, development, and research strategies of silane-based sol-gel coatings are included.

Aluminum alloy 7075 is an important engineering material for ship structures. However, the corrosion of Al alloys generally exists in various environments, especially in the marine environment. Currently, the corrosion behaviors of Al alloy 7075 in sulfate-reducing bacteria (SRB) marine environment has not been well-addressed. In this paper, the corrosion effect of SRB on 7075 aluminum alloys was studied by adding SRB to real seawater. The microstructure and grain orientation of the super-hardness Al alloy 7075 were studied via the electron back-scattered diffraction (EBSD)technology, and the electrochemical impedance spectroscopy (EIS) test of the electrochemical corrosion behavior of 7075 in a variety of microorganisms, mainly SRB, in real seawater was continuously performed for 21 days. It was concluded that Al alloy 7075 has the strongest texture intensity on the (001), (111), (010), and (0–10) planes, which is 2.565. Adding SRB to real seawater accelerated the corrosion rate, and after corrosion on the 14th day, the protective film on the 7075 aluminum alloy surface was completely broken, and the impedance was significantly reduced.

Urgent action is required to mitigate the severe corrosion of carbon steel in low-latitude regions. The combination of high humidity, temperature, and salinity in these areas significantly accelerates steel corrosion, posing a substantial threat to the service safety of offshore engineering equipment. This study aims to elucidate the atmospheric corrosion mechanisms of 45# steel in low-latitude coastal areas. Samples of 45# steel were exposed to atmospheric conditions over various durations in the following three geographically distinct regions: Guangzhou, Wanning, and the South China Sea. The corrosion rates were calculated using weight loss tracking and potentiodynamic polarization measurements, while surface corrosion products were examined using X-ray diffraction (XRD) tests. The findings indicate a clear correlation between the corrosion rate of 45# steel and the latitude and specific location of the test area, with the highest to lowest rates observed in the South China Sea, Wanning, and Guangzhou, respectively. Similarly, the extent of corrosion rust penetration in defective coatings followed the same order. Moreover, the protection ability index (PAI) calculations revealed that none of the tested samples formed a protective corrosion film.