In-Situ Growth Of Zirconium-Based Doped Molybdenum Composite Nanomaterials And Their Application In Iron Corrosion Protection

China is one of the earliest countries in the world to invent iron-smelting technology,because iron is harder,sharper and easier to forge than bronze,iron gradually reduces and replaces the large-scale use of bronze.The use of iron promoted the development of agriculture,handicraft industry and commerce,thus enabling human society to enter the advanced iron age.However,among the many used metals,iron is more active and has poor chemical stability,iron and iron products are easily corroded when exposed to natural environment for a long time,which causes great economic losses every year.Therefore,the protection of iron and iron products is of great significance.The protection of iron and iron products generally adopts surface coating method,the coating technology is to protect metal by shielding corrosion medium directly eroding the substrate.Therefore,it is particularly important to develop new,non-toxic and efficient protective coatings to reduce the huge economic losses caused by metal corrosion.In this paper,Tafel-type polarization curve and electrochemical impedance spectroscopy（EIS）were used to compare the corrosion resistance of potassium fluorozirconate,sodium molybdate and its compounding and adding template compounding.The surface micro-morphology was observed by SEM,and the surface composition was analyzed by EDS,XRD and XPS.It was finally confirmed that the best corrosion resistance was the combination of potassium fluorozirconate and sodium molybdate added with TEAB,and the coating is a composite coating mainly composed of nano-ZrO₂/MoO₃,with a small amount of ZrO_xF_y and Fe₂O₃.The nano-ZrO₂/MoO₃ composite coating is continuous and dense,and its corrosion current(i_corr)is reduced by more than 1000 times compared with the blank.The Nyquist diagram of its impedance is fitted by Zview 2,and the obtained capacitor ring and charge transfer resistance(R_ct=1.69×10⁷Ω)are the largest,and the corrosion inhibition efficiency is also optimal.The corrosion current of the Tafel-type polarization curve was taken as the object of investigation,the effects of different proportion,concentration,temperature,time and different templates on corrosion current of nanocomposite film plating solution were studied by single factor test.Under the principle of minimum corrosion current and best corrosion resistance,the best corrosion resistance conditions are determined as follows:n（K₂ZrF₆）:n（Na₂MoO₄）=2:5,c（K₂ZrF₆）=2g/L,c（Na₂MoO₄）=5g/L,T=35℃,t=8h,template agent selection is TEAB,c（TEAB）=1.5g/L。In order to further investigate the long-term corrosion resistance of nano-ZrO₂/MoO₃ composite coating,salt water immersion test,salt water mass loss test,salt spray test and copper sulfate drip test were carried out on nano-ZrO₂/MoO₃composite coating and other plating solution treated coatings.The experimental datas show that the surface micro-morphology of nano-ZrO₂/MoO₃ composite coating after salt water immersion changes slightly,and there is no obvious crevice corrosion.The mass loss of salt water is 0.1214 mg/cm²,and the annual corrosion rate is 0.0113mm/a,which is the smallest.indicating that nano-composite coating has high corrosion resistance in 3%NaCl solution,and the experiment of copper sulfate resistance was over 729 seconds.The formation process and internal structure of nano-ZrO₂/MoO₃ composite coating were investigated by means of SEM and EDS.The results show that the coating is a gradual paving and filling process of particle accumulation,and the internal supporting structure of the coating is spherical with70⁹0 nm.The nano-ZrO₂/MoO₃ composite coating exhibits a pale yellow color,and then a large number of pre-experiments have been carried out on the rusted iron sample,the experiment shows that the nano-coating hardly changes its appearance and has good protection performance,therefore,its corrosion resistance is compared with that of traditional iron cultural relics corrosion inhibition methods such as tannic acid,BTA,sodium tungstate/SDS.The electrochemical polarization curves,salt water weightlessness test and salt spray accelerated corrosion test show that the corrosion resistance of nano-coatings is more prominent than that of traditional methods.In add-ition,the pre-experiment of iron relic protection was carried out on three rusty iron samples of different ages:modern iron sickles,iron spears in modern times and fragments of iron sword in Han Dynasty.The appearance changes slightly before and after treatment,and the corrosion current density is obviously small.Since the nano-ZrO₂/MoO₃ composite coating has obvious advantages over the traditional method,the technology is applied to an oil lamp in the Late Qing Dynasty for actual cultural relic protection and processing,and XRF,EDS and SEM analysis of the debris is carried out.The results show that the surface element composition of oil lamp after corrosion protection contains Zr and Mo elements,and the surface structure of iron base becomes more uniform and dense.This indicates that the nano-ZrO₂/MoO₃ composite corrosion-inhibiting coating is formed on the iron-based surface of the oil lamp.Therefore,the nano-ZrO₂/MoO₃ corrosion inhibition technology can be considered for the protection of iron artifacts.