Evolution of Biofilm and Its Effect on Microstructure of Mortar Surfaces in Simulated Seawater

To explore the role of biofilm formation on the corrosion of marine concrete structures, we investigated the attachment of biofilm on mortar surfaces in simulated seawater and the influence of biofilm on the microstructure of mortar surfaces. The results show that the evolution of biofilm on mortar surfaces in simulated seawater is closely related to the corrosion suffered by the mortar, and the process of biofilm attachment and shedding is continuous and cyclical. It is found that the specimens in the absence of biofilm attachment are more severely eroded internally by the corrosive medium in simulated seawater than those in the presence of biofilm attachment. For the specimens without biofilm attachment, after 60 days, gypsum forms,and after 120 days, the number of pores in the mortar is reduced. In contrast, for the specimens in the presence of biofilm attachment, gypsum could only be detected after 90 days, and fewer pores are filled. Therefore, the formation of biofilm could delay the invasion of the corrosive medium into the interior of mortar during the evolution of biofilm on mortar surfaces, mitigating the corrosion of mortars in seawater.

Effect of rare earths on corrosion resistance of Cu-30Ni alloys in simulated seawater

Cu-30Ni-xRE(x=0–0.213 wt.%) alloy was prepared by adding rare earths(RE) in melted Cu-30Ni alloy using metal mould casting method.The effects of RE on corrosion resistance of the alloy in simulated seawater were investigated using optical microscope,scanning electronic microscope with energy-dispersive spectrometer and electrochemical measurement system.The results showed that the corrosion resistance of Cu-30Ni alloy was greatly improved by adding proper amount of RE,whereas excess addition of RE worsened ...

Controlled Growth of NiMoO_(4) Nano-rods on Carbon Cloth:A Novel Electrode for the Hydrogen Evolution Reaction in Alkaline Media and Simulated Sea Water

A series of NiMoO_(4)-nano rod/carbon cloth composite electrodes with different loadings(x)of NiMoO_(4)-NRs was synthesized with a view to implementing an efficient hydrogen evolution reaction(HER).The NiMoO_(4) nano-rods(NRs)were prepared by growing them directly on carbon cloth(CC)via a simple hydrothermal reaction coupled with an annealing treatment.The resulting NiMoO_(4)-NR/CC-x composites served directly as electrodes for electrolysis of an alkaline medium and a simulated sea water.The results indicated that among the NiMoO_(4)-NR/CC-x composites,the NiMoO_(4)-NR/CC-10 composite possessed the highest HER activity with an overpotential of 244.8 mV at 10 mA/cm^(2),a Tafel slope of 95 mV/dec,the fastest charge transfer rate(R_(ct)<1Ω)and good stability in alkaline media.Even in simulated seawater,the NiMoO_(4)-NR/CC-10 composite showed good stability.The outstanding HER activity and stability may originate from the strong interaction between Ni and Mo in the NiMoO_(4) NRs as well as the efficient charge transfer process and the rate of the HER due to the synergistic effect involving the CC and NiMoO_(4) NRs.