Research On Valence Electron Structure Of Materials With Corrosion Resistance To Molten Zinc

Intermetallic compounds, with excellent characters of antioxidation, heat-resistant, corrosion-resistant, abrasion–resistant, are widely used as high-temperature structural materials. In this paper, the corrosion property of Fe-Al, Fe-Si and Fe2B intermetallic compounds in molten zinc at 460℃was studied, compared with industrial pure iron under the same conditions, then the corrosion mechanism was discussed. At the meantime, the valence electron structures of FexM were calculated on basis of solid and molecule's empirical electron theory. Finally, the key to effect of bonding strength on the corrosion property was got, based on theories and experiments.The results show that industrial pure iron was corroded heavily after immersed in molten zinc for 5h~6h, and large amounts of zincilate were produced. The intermetallic compounds showed good corrsosion resistance after immersed in molten zinc for 24h, and small amounts of zincilate were produced. After calculations, it can be concluded that the corrosion rate of intermetallic compounds in molten zinc was much lower than which of industrial pure iron. The corrosion rate of FeSi, FeSi2 and Fe2B in molten zinc was significantly lower than which of other alloys. The corrosion products are mainly Fe-Zn compounds, and the corrosion mechanism is reaction diffusion.The bonding strength between two atoms (bond energy) in FexM crystal has been calculated based on its valence electron structure. Q is defined as the energy of all bonds around Fe atom in FexM crystal, and QA is defined as the maximum bond energy around Fe atom in FexM crystal. It has been found that the greater the parameter Q, the more stable the material in molten zinc, and the greater the parameter QA, the bigger the "potential barrier" of corrosion reaction of materials in molten zinc. Therefore the key is that the greater the parameters of Q, QA, the better the property of corrosion-resistant of FexM intermetallic compound in molten zinc. When the Q value of FexM near 1671.92 kJ ? mol-1 or higher, QA value near 219.74 kJ ? mol-1 or higher, the corrosion reaction of FexM is more difficult to happen in molten zinc.