In order to develop waterborne silicate anticorrosive coatings to replace solvent-based anticorrosive coatings used widely in the shipping industry, epoxy modified silicate emulsions were synthesized with different contents of epoxy resin, then aqueous silicate zinc-rich coatings were prepared with the synthesized silicate emulsion, triethylamine, and zinc powder. The influence of the content of epoxy on the properties and chemical structure of the modified emulsion, mechanical properties of the silicate coatings, and corrosion behavior of the silicate zinc-rich coatings in 3.5% NaCl solution were investigated. The coating samples on steel were measured by the immersion test, Tafel polarization test, and electrochemical impedance spectroscopy (EIS) test with different immersion times. The results showed that epoxy modified silicate emulsions were successfully synthesized. With the increase in epoxy content, the viscosity and solid content of the modified emulsion increased, the impact resistance of the silicate coating rose, the pencil hardness decreased, but the adhesion was not affected. Epoxy modification can reduce, to a certain extent, the corrosion driving force of the zinc rich coating and increase the impedance of the zinc-rich coating, which decreases with the increase of immersion time in 3.5% NaCl solution. With the increase in the epoxy content, the impedance value of the zinc-rich coating increases, indicating that the ability of the coating to resist corrosive media is enhanced.

To study the effect of cast defects on the corrosion behavior and mechanism of the UNS C95810 alloy in seawater, an investigation was conducted by weight loss determination, scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), X-ray diffraction (XRD) and electrochemical testing of the specimen with and without cast defects on the surface. The results show that the corrosion rate of the alloy with cast defects is higher than that of the alloy without cast defects, but the defects do not change the composition of the resulting corrosion products. The defects increase the complexity of the alloy microstructure and the tendency toward galvanic corrosion, which reduce the corrosion potential from −3.83 to −86.31 mV and increase the corrosion current density from 0.228 to 0.23 μA⋅cm⁻².

To study the effect of weld and defects on the corrosion behavior of nickel aluminum bronze (UNS C95810) in 3.5% NaCl solution, the weight loss, X-ray diffraction, optical microscope, scanning electron microscope and electrochemical test of the specimen with weld and defects were investigated. The results show that the presence of weld and defects increases the corrosion rate of bronze. Weld does not change the structure of the corrosion product film, but defects induce a lack of the protective outermost corrosion product in bronze. Weld makes the corrosion product film in the early stage more porous. Defects always produce an increase in the dissolution rate of the bronze.

The use of soldering based on metallurgical bonding, as opposed to conventional rubber sealing, is capable of achieving the firm sealing of stainless-steel subway car bodies, though the corrosion resistance of such joints has rarely been investigated. In this study, two typical solders were selected and applied to the soldering of stainless steel, and their properties were investigated. As indicated by the experimental results, the two types of solder exhibited favorable wetting and spreading properties on stainless-steel plates, and successfully achieved sealing connections between the stainless-steel sheets. In comparison with the Sn-Zn9 solder, the Sn-Sb8-Cu4 solder exhibited lower solidus–liquidus, such that it can be more suitably applied to low-temperature sealing brazing. The sealing strength of the two solders reached over 35 MPa, notably higher than that of the sealant currently used (the sealing strength is lower than 10 MPa). In comparison with the Sn-Sb8-Cu4 solder, the Sn-Zn9 solder exhibited a higher corrosion tendency and a higher degree of corrosion during the corrosion process.