THE EFFECT, OF INCREASED POROSITY UPON THE STRUCTURE AND PROPERTIES OF SILICA BASED CORE MATERIALS

摘要

The investment casting technique has been successfully developed for the manufacture of turbine blades for aerospace applications. As the operating temperatures within the turbine section of jet engines has increased to greater than the melting temperature of the alloy, the incorporation of cooling passages becomes essential. Disposable ceramic cores, usually silica based, are used to produce complex internal features. However, some casting scrap can be attributed to wall section tolerance problems due to core movement. Decreased scrap rates may be achieved by gaining an understanding of the fundamental physical and mechanical properties of the core materials, including deformation characteristics and the role of phases which control this. Variations in porosity size, amount and distribution will affect resistance to deformation, metal penetration and core leachability. This paper presents the results of research to assess the effect of increased porosity upon the structure and properties of a commercially available silica core for use in directional solidification, single crystal and equiaxed castings.