Abstract
Post-heat treatment recrystallisation is a significant cause of scrap in single crystal component production. This defect could be prevented by a reduction in the mechanical strength of the shell after the metal has solidified. Addition of a zirconia layer, to produce large cracks around grain boundaries and among the large grains during phase transformations, was considered as a method of reducing sintered strength. In this study, two types of zirconia stucco, monoclinic and partially stabilised, were introduced into the shell. The effect of the incorporation of a zirconia layer on the microstructure and mechanical properties of the shell were investigated. Shell with a monoclinic zirconia additional layer showed no reduction in the green strength but a better performance in high temperature deformation tolerance, maintaining shell performance during wax removal and metal casting. The shell strength after alloy solidification is reduced, suggesting that a reduction in recrystallisation may be possible with this method.
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