基于光固化3D打印成形的钛合金闭式叶轮精密铸造

Precision Casting of Titanium Alloy Closed Impeller via Stereolithography 3D Printing

摘要:

针对钛合金闭式叶轮精密铸造中型壳一体化成形难、传统方法制造周期长等难题，开发了一种基于光固化3D打印成形的钛合金闭式叶轮制备工艺。通过多级颗粒级配优化粉体堆积密度，结合pH=10.0的碱性环境与1.5wt%柠檬酸铵分散剂的协同调控，制备出固相含量62vol%、粘度394 mPa·s的高稳定性水基浆料，有效抑制Y₂O₃颗粒水化反应，解决了Y₂O₃易水化导致的浆料失稳问题。研究了工艺因素对铸型性能的影响规律，固相含量62vol%时坯体抗弯强度达18.9 MPa，经20wt%纳米氧化钇分散液两次真空浸渍后提升至25.4 MPa。采用光固化3D打印树脂原型与凝胶注模工艺，成功实现复杂流道结构氧化钇铸型的一体化制备，采用真空重力铸造工艺实现钛合金闭式叶轮完整成形，经陶瓷铸型完全清理，表面未发现化学粘砂，铸件组织特征和α层厚度与常规熔模铸造ZTC4钛合金铸件基本一致。实验表明：该工艺较传统熔模铸造周期显著缩短，为高性能钛合金复杂构件的低成本精密铸造提供了新方法。

Abstract:

To address the challenges of integrated shell molding in precision investment casting of titanium alloy closed impellers and the prolonged cycle time of conventional methods, a fabrication process for titanium alloy closed impellers based on stereolithography 3D printing has been developed. By optimizing powder bulk density by multilevel particle gradation and using ammonium citrate dispersants of 1.5wt% combined with alkaline environment of pH=10.0, a stable aqueous slurry with 62vol% solid content and 394 mPa·s viscosity was achieved, effectively suppressing Y₂O₃ hydration-induced slurry instability. The effect of key process parameters on molding performance was systematically investigated: the green body exhibits 18.9 MPa flexural strength at 62vol% solid content, which increases to 25.4 MPa after two vacuum impregnations with 20wt% nano-Y₂O₃ dispersion. Stereolithography 3D-printed resin prototypes combined with gel casting enable one-step fabrication of yttria molds with complex flow channels. Vacuum gravity casting successfully produces fully formed titanium alloy closed impellers, with no chemical sand adhesion observed after mold removal, and the microstructure characteristics and α layer thickness of the casting are essentially identical to those of ZTC4 casting produced by traditional investment casting process. Experimental results demonstrated that this process significantly shortens the lead time compared to traditional investment casting, providing a novel approach for cost-effective precision casting of high-performance titanium alloy components with complex geometries.