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.
1 October 2023 in Journal of Central South University
Acrylic materials exhibit favorable grouting repair performance. However, their curing products are easily inclined to drying shrinkage, and their concrete impermeability repair characteristics have seldom been investigated. To improve material properties, reveal the impermeability repair mechanism, and address drying shrinkage, this study proposed the addition of styrene–acrylate copolymer emulsion (styrene–acrylic emulsion) to the grouting material to prepare two-component acrylate grouting materials. Using orthogonal and single-factor tests combined with physical and mechanical properties, the mechanical properties and impermeability repair performance (physical and mechanical properties combined) of grouting materials were analyzed and studied, and the optimal ratio of each component of acrylate grouting materials was determined. Results show that (1) the hydrogel produced by the reaction of sodium methacrylate with hydroxyethyl acrylate has good physical and mechanical properties. (2) With the increase in the accelerator dosage, the setting time of slurry initially decreases and then increases; as the initiator dosage increases, the setting time of slurry decreases, which is negatively correlated with the initiator dosage. (3) Talcum powder can improve the physical and chemical properties of gel and enhance the reliability and durability of acrylate grouting materials, and the comprehensive performance is the best at a dosage of 3%. (4) Styrene–acrylic emulsion can increase the solid content and reduce the volume drying shrinkage when added to grouting materials. The fractured impermeable specimens were repaired by grouting with prepared acrylate grouting materials and cured for 24 h for the impermeability test, and the water pressure for the 24 h impermeability repair was 1.0 MPa. This study’s results provide important reference and basis for revealing the impermeability principle of acrylate grouting materials and evaluating their impermeability.
TiO2 has attracted significant research interest, principally due to its nontoxicity, high stability, and abundance. Carbon-doped TiO2 can improve light absorption efficiency. In order to prepare high-efficiency photocatalysts, carbon-doped composites were prepared by hydrothermal reaction in a high-pressure reactor, and then TiO2/CNT mesoporous composites were prepared by the sol–gel method in an ultrasonic environment. Characterized by SEM and TEM, the composite materials contained TiO2 nanoparticles as well as CNT. After phase analysis, it was the anatase-doped phase. The following infrared light absorption performance and Escherichia coli bactericidal performance tests showed that it had better infrared and visible light absorption performance than pure TiO2. The TiO2/CNT mesoporous nanomaterials synthesized in this work are possible for clean industrial productions.