THE EFFECT OF CHEMICAL STRUCTURE OF FOUNDRY BINDER DILUENT ON SURFACE PROCESSES AND SAND STRENGTH

摘要

The paper presents the results of investigations of the dynamics of wetting in a quartz-binder system. It has been proved that the two-stage process of wetting (unsteady state passing into the steady state) is important for the practice of moulding sands and depends on physico-chemical parameters of binder, especially on its viscosity. A mathematical description of the wetting phenomena was given and it was demonstrated that the course of the wetting dynamics is determined by the viscosity which depends on the chemical structure and concentration of added diluent. The wetting dynamics is characterised by the difference Δθ between the values of the initial θ_0 and equilibrium θ_r contact angle and by the time τ_r that the system needs to reach a steady state. It has been shown that the dynamics of quartz wetting by the binder with diluent of a chain structure and high concentration is higher with simultaneous reducing of time τ_r. It has been verified that the resistance of moulding sands with binder and the diluent of chain structure and high concentration is higher compared to the strength of the sands with diluent of another structure.