Roles of MnO and MgO on structural and thermophysical properties of SiO2-MnO-MgO-B2O3 welding Fluxes: A molecular dynamics study

H Yuan and ZJ Wang and YY Zhang and C Wang, JOURNAL OF MOLECULAR LIQUIDS, 386, 122501 (2023).

DOI: 10.1016/j.molliq.2023.122501

Partially substituting MnO with MgO appears to be a promising approach to enhance the overall performance of SiO2-MnO-MgO-B2O3 fluxes towards submerged arc welding. However, certain challenges with regard to structural and physical property variations still persist due to experimentally unattainable techniques. In the present study, we report detailed flux structural information in short- and medium-range order and predict viscosity and thermal conductivity via molecular dynamics simulations. It has been manifested that replacing MgO with MnO could depolymerize the bulk network, which is accompanied by reduced viscosity and dwarfed thermal conductivity. It is further demonstrated that Mn2+ with lower field strength are conveniently surrounding bridging oxygen- related units, whereas Mg2+ cations are prone to charge-balance the negative charge around free oxygen and non-bridging oxygen-Si. Our current findings may provide insight into the roles of MnO and MgO in flux structure and thermophysical properties and the underlying molecular mechanisms.

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