Alkali Vapor Corrosion of Different Refractories at High Temperatures

Commercial high purity corundum brick,corundum-mullite brick,mullite brick,calcium hexaaluminate brick and calcium hexaaluminate-corundum brick were studied to investigate their reaction state and alkali vapor corrosion mechanism at 1370 and 1500℃.The results show that:(1)served in hot alkali vapor,the high-purity corundum brick has no obvious slag layer but expands dramatically;(2)the corundum-mullite brick shows obvious reactive expansion at 1370℃and melting corrosion happens at 1500℃;(3)at 1370℃alkali vapor and mullite brick react and form a slag layer without volume effect;when the temperature increases to 1500℃,the reaction melting corrosion intensifies;(4)the calcium hexaaluminate brick and the calcium hexaaluminate-corundum brick form a thin slag layer in alkali vapor,and the sample surface absorbs Na+to form a dense layer with small volume effect.

Water vapor corrosion behaviors of high-entropy pyrosilicates

In this study,the water vapor corrosion resistance of two types of high-entropy pyrosilicates((Yb_(0.2)Y_(0.2)Lu_(0.2)Ho_(0.2)Er_(0.2))_(2)Si_(2)O_(7)((5RE1/5)_(2)Si_(2)O_(7))and(Yb_(0.2)5Lu_(0.2)5Ho_(0.2)5Er_(0.2)5)_(2)Si_(2)O_(7)((4RE_(1/4))_(2)Si_(2)O_(7)))and two single-component pyrosilicates(Yb_(2)Si_(2)O_(7) and Lu_(2)Si_(2)O_(7))were evaluated at 1350℃ for 50e100 h,and the initial corrosion behaviors of these pyrosilicates were studied.The results showed that the final corrosion products of the four types of pyrosilicates were all X2-type monosilicates,exhibiting similar corrosion phenomena.However,(4RE_(1/4))_(2)Si_(2)O_(7) generated many nanoscale monosilicate grains during corrosion.The corrosion resistance of Lu_(2)Si_(2)O_(7) was clearly better than those of the others,and(4RE_(1/4))_(2)Si_(2)O_(7) exhibited the worst corrosion resistance.The corrosion mechanism of the pyrosilicate blocks was analyzed from the perspectives of grain size,bulk hydrophobicity,and binding energy.This study potentially provides a theoretical basis for the preparation of high-entropy pyrosilicates with different atomic ratios according to the different properties of the various rare earth elements.

Large-area chemical vapor deposition-grown monolayer graphene-wrapped silver nanowires for broad-spectrum and robust antimicrobial coating

New types of antimicrobial systems are urgently needed owing to the emergence of pathogenic microbial strains that gain resistance to antibiotics commonly used in daily life and medical care. In this study we developed for the first time a broad-spectrum and robust antimicrobial thin film coating based on large-area chemical vapor deposition （CVD）-grown graphene-wrapped silver nanowires （AgNWs）. The antimicrobial graphene/AgNW hybrid coating can be applied on commerdal flexible transparent ethylene vinyl acetate/polyethylene terephthalate （EVA/PET） plastic films by a full roll-to-roll process. The graphene/AgNW hybrid coating showed broad-spectrum antimicrobial activity against Gram-negative （Escherichia coli） and Gram-positive bacteria （Staphylococcus aureus）, and fungi （Candida albicans）. This effect was attributed to a weaker microbial attachment to the ultra-smooth graphene film and the sterilization capacity of Ag＋, which is sustainably released from the AgNWs and presumably enhanced by the electrochemical corrosion of AgNWs. Moreover, the robust antimicrobial activity of the graphene/AgNW coating was reinforced by AgNW encapsulation by graphene. Furthermore, the antimicrobial efficiency could be enhanced to -100% by water electrolysis by using the conductive graphene/AgNW coating as a cathode. We developed a transparent and flexible antimicrobial cover made of graphene/AgNW/EVA/PET and an antimicrobial denture coated by graphene/ AgNW, to show the potential applications of the antimicrobial materials.