Numerical modelling of the surface cracking tendency in solidifying ceramic materials

摘要

EUCOR is a ceramic material resistant to extreme heat and wear. A block made of EUCOR with dimensions of 350 x 200 x 400 mm was used for the numerical calculation and the experiment. The numerical model of the casting block temperature field determines the temperature gradients, the solidification rate and the local solidification time (i.e., the time between the liquidus and solidus temperatures). The local solidification time significantly affects the forming of the pouring structure of the given material and it makes one of the input parameters for the second cooperating chemical heterogeneity model. This model and its application on EUCOR samples prove that the applied measuring method of the chemical heterogeneity provides detailed quantitative information on the material structure and makes possible the analysis of the solidification process. The analysis of this process entails statistical processing of results of the heterogeneity measurements of the EUCOR components and it performs correlation of individual components during the solidification. The model of the chemical heterogeneity enables estimation of the structure parameters at any critical point of castings. The combining of both models makes it possible to estimate the structure parameter, which expresses the size of the crystallites in the resultant material structure. It is a tool for the estimation of the tendency to surface cracking and fracturing tendency at the critical point of casting made of EUCOR.