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

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.

Automated summary

Partially substituting MnO with MgO shows potential in improving the overall performance of SiO2-MnO-MgO-B2O3 fluxes for submerged arc welding. However, challenges remain in terms of structural and physical property variations due to limitations in experimental techniques. This study investigates the flux structure and thermophysical properties through molecular dynamics simulations, revealing the depolymerization of the bulk network and decreased viscosity and thermal conductivity when MgO is replaced by MnO. The findings also shed light on the interaction between MnO and MgO in the flux structure and provide insights into the underlying molecular mechanisms.