Influence of thermal boundary condition on casting process of metal matrix composite

摘要

Purpose: of this paper is to present a computer simulation as a tool for modelling the gravity casting process of metal matrix composite (MMCs) in the sand mould and predicting the arrangement of heterophase reinforcement particles in the composite and impact of the parameter which characterizes the thermal boundary condition on the course of solidification process (speed, direction) and thus, on the arrangement of reinforcement particles. Design/methodology/approach: Computer simulations have been earned out following the methods and procedures included in the program Fluent. The calculation are based on two-dimensional model in which the Volume of Fluid (VOF), enthalpy method and the Discrete Phase Model (DPM) have been applied to describe two-phase system, solidification and behaviour of reinforcement particles, respectively. The calculations also include the method which allows to model the contact resistance at the interface between mould wall and liquid alloy. Findings: Obtained results show that the cast solidification as well as final arrangement of heterophase reinforcement particles depend on the assumed thermal boundary conditions. The appearance of the contact resistance lengthens the solidification process and extends the effect of aggregation, sedimentation and particle engulfment or pushing ahead of solidification front. Research limitations/implications: The created model and procedures can be treated as a basis for more advanced researches. Practical implications: Presented simulations allows to study phenomena occurring during the easting process and predict the behaviour of the reinforcement particles (distribution of reinforcement) for the different thermal boundary conditions. Originality/value: The applied simulation methods allows to study the course of the casting process of metalmatrix composite and arrangement of the reinforcement particles.