Active corrosion protection of super-hydrophobic corrosion inhibitor intercalated Mg-Al layered double hydroxide coating on AZ31 magnesium alloy

Magnesium alloys,the advanced lightweight structural materials,have been successfully applied in the manufacturing field.Unfortunately,their poor corrosion resistance restrains the potential wide applications.In this work,anti-corrosion coatings were fabricated via the insitu growth of the corrosion inhibitors intercalated magnesium-aluminum layered double hydroxide(Mg-Al LDH)on AZ31 magnesium alloy and then post-sealing it by a super-hydrophobic coating.SEM,XRD,EDS,FTIR,XPS and contact angle test were conducted to analyze physical/chemical features of these coatings.Potentiodynamic polarization curves and electrochemical impedance spectroscopy were recorded to assess the anti-corrosion performance of prepared coatings.Surprisingly,Mg-Al LDH with molybdate intercalation and lauric acid modification achieves the excellent corrosion inhibition performance(99.99%)due to the multicomponent synergistic effect such as the physical protection of Mg-Al LDH,the corrosion inhibition of molybdate and super-hydrophobic properties of lauric acid.This work presents a scientific perspective and novel design philosophy to fabricate the efficient anti-corrosion coating to protect magnesium alloys and then expand their potential applications in other field.

Vulnerability Assessment of Tourism Environment in the South China Sea Islands : Construction of Evaluation Model Based on Interpretation System of Formation Mechanism

Tourism vulnerability research is an important theoretical basis for sustainable research of tourism.In this study,it hopes to establish a comprehensive evaluation index system for vulnerability of tourism environment in the South China Sea Islands,to achieve the sound development of island tourism in the South China Sea.Therefore,based on the study of the geographical environment and geographical background of the South China Sea Islands,the mechanism analysis method is used to form three interpretation systems.First,interpretation system of meridional causality mechanism.4 evaluation levels and 52 indicators are screened out,and the mathematical and physical criteria for each indicator is established.Second,interpretation system of latitudinal factor relationship mechanism.The AHP is used to obtain the weights of each index,and the contribution rate of factor at each level to the vulnerability is determined.Third,sharing platform of connecting meridional and latitudinal interpretation system.Likert 5-level scale is used to make the factors belong to different orders of magnitude,and factors from different systems could be comparable.Finally,through the formulation of mathematical and chemical standards of indexes and weights of evaluation indexes,a comprehensive evaluation model for vulnerability of tourism environment in the South China Sea Islands is established.

Formation of groundwater-induced damage in Zhu Yuelian’s tomb and protection methods

Zhu Yuelian’s tomb has been exposed to groundwater for many years,and this exposure has caused many defects,including erosion,encrustation,patina,and spot marks related to groundwater,seriously affecting the artistic and ornamental value of cultural relics.In this study,high-density microelectrode spacing resistivity and ultrasonic transverse wave reflection were used to detect hidden damage in the burial chamber,and the results revealed hidden damage,corrosion,cracks,and pores in the surrounding geological body,concealed cracks in the sidewalls,and internal defects in the columns.An outdoor high-density resistivity test and hydrological observation experiment indicated that the tomb is located in a weakly permeable aquifer,and the groundwater head has been higher than the bottom of the tomb for many years.Natural groundwater flows from northeast to southwest in the aquifer,and the tomb forms an artificial concave cone,causing groundwater around the area to continually flow into the tomb.A chemical composition analysis of the groundwater and scale revealed that the groundwater within the tomb area is slightly corrosive,and the groundwater seepage along the fissures of the compacted layer induces damage.The threedimensional(3D)seepage numerical simulation results indicated that the combined use of drainage and impervious curtains can cause the water head in the curtain to drop significantly and control the water head to be lower than 8 m from the bottom floor of the tomb,meeting the requirements for seepage prevention and protection of the tomb without long-term maintenance.