Simulation of Hot Casting Shrinkage of Thermoplastic Beryllium Oxide Slurries with Ultrasonic Activation
Abstract
The article proposes a method for calculating the shrinkage of hot casting of thermoplastic beryllium oxide slurries. The thermoplastic slurry (hereinafter referred to as slurry) is a composition system with a dispersed phase (binder) having a low thermal conductivity compared to the dispersed phase (beryllium oxide). Ultrasonic treatment reduces the viscosity of the slurry and improves its casting property. Hot casting of beryllium oxide slurry is carried out without breaking the continuity of the system and depends on speed and temperature factors. Cooling-solidification of the slurry in the casting mould takes place in stages in a liquid state, a crystallization state with a phase transition and a plastic state of the casting. The cooling rate of the casting at all stages depends on the design of the cavity, the rheological properties of the slurry and the casting speed. The novelty of the work is the determination of shrinkage by the distribution of the concentration of the kinetically free binder. The slurry near the cooled wall is in a state of crystallization and plasticity, and in the rest may still be in the liquid phase. Along the cavity cross-section there is aт inhomogeneous distribution of temperature, respectively, density and concentration of kinetically free binder. This leads to compensation of shrinkage by the inflow of slurry from the liquid into the crystallization zones and the plasticity of the casting.