In-situ formation of SiC nanowires for self-healing ceramic composites using liquid silicone resin

Abstract

Ceramic shells are essential for fabricating turbine blades in aero-engines via directional solidification and are required to have excellent mechanical properties and low linear expansion rates for industrial production. However, defects in traditional processes lead to the propagation of interlayer microcracks, which limit the performance of the ceramic shells and fail to meet the high-temperature service requirements. Therefore, this study aims to address these issues by using liquid silicone resin for crack self-healing in the ceramic matrix. The results demonstrated that cracks in the green shells were healed through the inherent bonding properties of the liquid silicone resin. During the high-temperature sintering process, the pyrolyzed SiO₂ content rose with higher liquid silicone resin content, forming a bonding phase between the particles. Moreover, in-situ formed network-like SiC nanowires, generated from the pyrolysis of the silicone resin precursor, became the dominant mechanism for crack healing. Thus, the minimum linear expansion in the x- and y-axis directions of the samples was measured as 0.93 % and 0.15 %, respectively, at 32 wt% liquid silicone resin content and a sintering temperature of 1500 °C, with a maximum bending strength of 21.96 MPa. This research provides valuable insights into improving the mechanical performance and shortening the fabrication cycle of ceramic shells, with potential applications in high-temperature engineering components.