陶瓷型芯是制备具有复杂散热内腔通道的航空用发动机涡轮叶片的重要部件，利用光固化增材制造技术制备陶瓷型芯打破了传统熔模铸造工艺受制于模具，阻碍高性能发动机生产研发的困境，为第三代镍基单晶高温合金涡轮叶片的设计、研发和制造提供了更大的助力。本文针对高固含量浆料的研发及硅基陶瓷型芯的制备进行了系统的研究。研究成果对高质量浆料的制备及适用于1300℃高温和1550℃更高温度叶片浇铸陶瓷型芯的制备具有一定的理论指导意义。对于高稳定性、低黏度和高固含量浆料的配制及打印参数对坯体尺寸精度的影响进行了系统的研究。研究了粒径尺寸、粒径级配和固含量对浆料黏度和稳定性的影响，制备出了可用于打印的放置264 h不发生明显沉降、黏度为26.1 Pa·s、固含量为80 wt%的SiO2陶瓷浆料。利用高质量浆料系统研究了打印层厚、光照强度和光照时间对坯体尺寸精度的影响规律，验证了入射能量与固化层厚之间遵循比尔朗博定律，为打印参数的选择提供了理论依据。研究了打印参数、浆料固含量、浆料粒径级配及最终烧结温度对SiO2陶瓷性能的影响。分析了打印层厚和打印方向对SiO2陶瓷性能的影响，因层内与层间颗粒分布的不均匀性而导致的陶瓷性能的各向异性。研究了固含量对陶瓷各项性能的影响，明确了高固含量能在一定程度上阻止裂纹的扩展，提高陶瓷的力学性能。通过对粒径级配的研究发现，合理的粒径尺寸配比有助于陶瓷性能的提升。方石英的含量随着烧结温度的升高而增加，适当含量的方石英有利于陶瓷力学性能的提升，而含量过高时则会损害陶瓷的力学性能。在SiO2陶瓷型芯的研究基础上，研究了在1550℃烧结温度下添加矿化剂对硅基陶瓷型芯的性能的影响。发现在固化层厚相同的情况下Al2O3 相较于ZrO2在水平方向上具有更高的固化精度。Al2O3在阻碍SiO2粘结流动方面效果显著，大粒径Al2O3在阻碍方石英产生上更具优势。本文首先制备了高稳定性、低粘度、适用于打印的高固含量SiO2浆料，在高固含量浆料的基础上，制备得到了适用于1300℃浇铸的SiO2陶瓷型芯和适用于1550℃浇铸的添加少量Al2O3的硅基陶瓷型芯。
Ceramic core is an important component in the preparation of aircraft engine turbine blades with complex thermal cavity channels. The preparation of ceramic core using photocuring additive manufacturing technology breaks the dilemma of traditional investment casting process limited by mold, and provides greater help for the design, development and manufacturing of the third generation nickel-based single crystal superalloy turbine blades. However, the problems of low solid loading of ceramic slurry and low casting temperature of silica-based ceramics are still common. The ceramic cores for blade casting at 1300℃ and 1550℃ were prepared by photocuring method. The effects of particle size gradation, solid loading, printing parameters and sintering temperature on the properties of silica-based ceramics were studied.The composition system of high stability, low viscosity and high solid loading slurry and the influence of printing parameters on the dimensional accuracy of the body were studied. The results show that the multistage particle size ratio can take into account the stability and viscosity of the slurry, and prepare the ceramic slurry with high stability and high solid loading of SiO2 which can be used for printing. The thickness of the printing layer is too small, which will lead to the abnormal increase of the body, and too large will lead to the reduction of the dimensional accuracy of the body. With the increase of illumination intensity and illumination time, the curing thickness and the degree of miscuring in the horizontal direction of the slurry increase, and Lambert-Beer law is followed between the incident energy and the curing layer thickness.The effects of printing parameters, slurry solid loading, slurry size gradation and final sintering temperature on the properties of SiO2 ceramics were studied. On the basis of taking into account the particle size and the size accuracy of the body, it is found that the comprehensive performance of SiO2 ceramics with larger printing layer thickness is better. The inhomogeneity of particle distribution in and between layers results in the anisotropy of ceramic properties. The printing direction perpendicular to the indenter has better performance. High solid loading can prevent crack propagation to a certain extent and improve the mechanical properties of ceramics. Reasonable particle size ratio is helpful to improve the performance of ceramics. With the increase of sintering temperature, the content of cristobalite will increase correspondingly, and the appropriate content of cristobalite is conducive to the improvement of mechanical properties of ceramics, while the content is too high will damage the mechanical properties of ceramics.The effect of mineralizing agent on the properties of silica-based ceramic cores at 1550℃ was also studied. It is found that the curing accuracy of Al2O3 in the horizontal direction is higher than that of ZrO2 when the curing layer thickness is the same. Al2O3 has a significant effect on blocking the bonding flow of SiO2 at high temperature, and large particle size Al2O3 has more advantages in blocking the generation of cristobalite.Based on the preparation of high stability, low viscosity and high solid loading SiO2 slurry suitable for printing, this paper explores the photocuring additive manufacturing parameters of SiO2 ceramic core suitable for casting at 1300℃ and silicon based ceramic core with a small amount of Al2O3 suitable for casting at 1550℃ and the corresponding performance of ceramic core.
