Improvement in refractoriness of ceramic shells for directional solidification casting of gas turbine components

Abstract

Columnar grained and single crystal superalloy blades and vanes for gas turbine applications are made by directional solidification process. In this process, the ceramic mould is subjected to high temperature 1500-1600uC. In order to improve refractoriness of the shell, fine alumina was added to the filler. The fine alumina reacted with silica in the binder forms mullite. The kinetics of formation of mullite and its effects on improvement of refractoriness was studied. Refractoriness is also improved by reducing the amount of sodium in the binder system which is used as a stabiliser. Binders with sodium 0?43 and 0?05% were used for making the shells. This paper would discuss improvement in the shell refractoriness and dimensional stability of the castings of gas turbine components made from Ni base superalloys by directional solidification process.

Fabrication of Integral Core/Shell Ceramic Casting Mould for Hollow Turbine Blade

“…The high-temperature performance of the ceramic casting mould should meet the requirements of directional solidification or single-crystal casting for turbine blades [11], so a strengthening treatment process was adopted. The sintered ceramic casting mould was immersed into an aqueous yttria sol for 30~40 minutes and taken out for drying, and then sintered at 1550℃ for 0.5~1 hour again.Fig.…”