Key Takeaways & Executive Findings
- •• Addition of 15 vol.% zircon to Al2O3-based ceramic cores increases flexural strength by 315.8% at 25°C and 136.0% at 1,500°C, achieving 61.54 MPa and 11.59 MPa respectively. • Zircon addition reduces Z-axis shrinkage by 21%, significantly mitigating the anisotropy inherent in vat photopolymerization 3D printed ceramic cores. • The formation of ZrO2 and mullite phases through zircon addition enhances the comprehensive properties, addressing the trade-off between strength and porosity. • The successful 3D printing of high-performance Al2O3-based ceramic cores with zircon addition promotes industrial application for complex-structured cores in superalloy hollow blade fabrication.
Abstract
Ceramic cores are important in the fabrication of superalloy hollow blades, which are increasingly characterized by intricate internal cavity channels. This complexity poses significant challenges to traditional manufacturing processes. The vat photopolymerization 3D printing technology provides a new choice for ceramic cores with complex structures. However, the lamellar structure of the vat photopolymerization 3D printed ceramic cores leads to the anisotropy. Meanwhile, the low strength and high shrinkage of ceramic cores restrict their industrial application. In this study, using Al2O3 powder as the main material, the effects of zircon content on the sintering shrinkage, open porosity, flexural strength, and other properties of Al2O3-based ceramic cores were studied to address the aforementioned issues. The influencing mechanism of zircon distribution on sintering shrinkage was analyzed, and the strengthening mechanism of mullite on ceramic cores was discussed from both thermodynamics and dynamics aspects. Through the comprehensive evaluation of ceramic core properties, the Al2O3-based ceramic core with 15vol.% zircon exhibites the optimal performance. Compared with the core samples without zirconium addition, the flexural strength of the Al2O3-based ceramic core with 15vol.% zircon increases from 14.80 MPa to 61.54 MPa at 25 °C, an increase of 315.8%; and from 4.91 MPa to 11.59 MPa at 1,500 °C, an increase of 136.0%. The shrinkage in the Z-axis is reduced by 21%, which better weakens the anisotropy of the shrinkage of 3D printed Al2O3-based ceramic cores. ZrO2 phase and mullite phase are formed by zircon, which improve the comprehensive properties of Al2O3-based ceramic cores. The successful 3D printing of high-performance Al2O3-based ceramic cores via vat photopolymerization has promoted its industrial application for fabricating ceramic cores with complex structures.
1. Introduction
Hollow turbine blade is the key component of aeroengine [1-3], which has he complex inneral cooling channels to improve high temperature resistance [4,5]. The intricate cooling channels within hollow blades are fabricated using ceramic cores through precision casting [6-9]. Due to the high production efficiency, hot injection is widely used to prepare ceramic cores, which faces the challenge of preparing complex-structured ceramic cores [10-13]. The vat photopolymerization 3D printing solidifies the photosensitive resin layer by layer to obtain a solid model [14-16], which provides a new option for preparing complex-structured ceramic cores [17-20].
Ceramic cores usually include SiO2-based ceramic cores and Al2O3-based ceramic cores. Al2O3-based ceramic core has excellent chemical stability and creep resistance, and its operating temperature is higher than that of SiO2-based ceramic core [21]. Therefore, Al2O3-based ceramic cores are widely used in high-temperature casting of superalloy blades [22]. However, the very high chemical stability of Al2O3 poses challenges during the leaching process, making core removal difficult. To ensure the effective dissolution of the core after casting, the porosity of the Al2O3-based ceramic core should be greater than 20%. In addition, Al2O3-based ceramic cores require flexural strength greater than 20 MPa at 25 °C, and greater than 15 MPa at 1,500 °C [23]. The flexural strength and open porosity requirements are contradictory. The higher sintering temperatures improve the flexural strength but significantly reduce the porosity of the Al2O3-based ceramic cores. This limits its wider application prospects. Therefore, mineralizing agents are usually added to Al2O3.
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Bo-yang Qu, Rui-long Yu, Tian-chi Chen, Qiao-lei Li, Ang Li, Wei Liu, Xi-he Liu, Xin-yan Yue, Jing-jing Liang, Jin-guo Li (2025). Mitigating anisotropy of vat photopolymerization 3D printing Al2O3-based ceramic cores through zircon addition. China Foundry. https://doi.org/10.1007/s41230-025-5001-5
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Frequently Asked Questions
What is the main challenge in fabricating complex ceramic cores for hollow turbine blades?
The main challenge is the intricate internal cooling channels that require high precision and complex geometries, which traditional manufacturing processes like hot injection struggle to achieve.
How does zircon addition improve the properties of Al2O3-based ceramic cores?
Zircon addition forms ZrO2 and mullite phases, which enhance flexural strength and reduce shrinkage anisotropy, improving overall performance.
What are the optimal zircon content and resulting improvements?
The optimal zircon content is 15 vol.%, which increases flexural strength by 315.8% at 25°C and 136.0% at 1,500°C, and reduces Z-axis shrinkage by 21%.
Why is reducing anisotropy important in 3D printed ceramic cores?
Anisotropy can lead to dimensional inaccuracies and mechanical weaknesses, affecting the reliability and performance of the final cast blades.
What is the significance of this research for industrial applications?
It enables the production of high-performance ceramic cores with complex structures via vat photopolymerization, promoting industrial adoption for superalloy hollow blade casting.
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