The effect of additives on properties of silica-based ceramic cores utilised in fabrication of multivane clusters for turbofan jet engine

Abstract

Ceramic cores for mapping internal cooling channels in multivane clusters for turbofan jet engine must satisfy rigorous requirements concerning material properties and dimensional precision. The effect of different additives (borosilicate glass, alumina and zirconium silicate) on features of silica-based ceramic cores was investigated. The elaborated in this paper material for cores fabrication composed of 64.0 wt% quartz glass, 11.0 wt% borosilicate glass, 13.0 wt% zirconium silicate and 12.0 wt% alumina reveals mechanical strength equal to 25.8 MPa, coefficient of thermal expansion of 3.52 . 10 −6 1/K , surface roughness equal to 2.3 μm, shrinkage less than 1.9% and average pore size diameter of 4.8 μm. The thin-walled long ceramic cores were shaped by the high-pressure injection moulding method, which covered the choice of a thermoplasticizer, feedstock development and determination of the processing parameters protecting the formed cores from imperfection and deformation. The after-shaping process of cores manufacturing included water and thermal debinding, sintering and dimension measurement. The high dimension accuracy of cores was verified by measurement results made on the coordinate measurement machine.