Influence of debinding parameter and nano-ZrO2 particles on the silica-based ceramic cores fabricated by stereolithography-based additive manufacturing

Abstract

The silica-based ceramic core is an essential part of the investment casting of hollow turbine blades due to their excellent thermal stability and easy demoulding. In this study, the green bodies of silica-based ceramic cores with nano-ZrO2 were fabricated by stereolithography (SLA). Firstly, the effects of the burying process and debinding heating rates on the performance and microstructure of silica-based cores were investigated. The results revealed that the burying powders provide support and a stable thermal field for the SLA ceramic cores during debinding and sintering. Ceramic cores with smaller shrinkage and higher apparent porosity were produced during the burying process at a heating rate of 0.5 °C/min. In addition, the influence of nano-ZrO2 content on the mechanical properties of silica-based ceramics was investigated. Nano-ZrO2 particles can improve bulk density and mechanical properties by promoting sintering. Additionally, it can reduce the cracks on the surface of ceramic samples. The optimal content of nano-ZrO2 should be between 1.5 and 2 wt%, producing silica-based cores with low shrinkage rate (2.91–3.19%), high apparent porosity (27.11–27.97%) and high flexural strength at room temperature (24.51–24.65 MPa) and high temperature (27.81–29.69 MPa). This work provides promising ways to fabricate high-quality ceramic cores for turbine blade application.