CAREER: Novel Powder-Bed Ceramic Additive Manufacturing Assisted with Water-Based Inks, Layerwise Uniaxial Compression and Temperate Heating for Selective Particle Fusion

结构陶瓷在许多特殊应用中具有重要的战略意义，包括隔热材料，装甲，植入物和传感器。然而，复杂陶瓷部件的制造一直存在问题，并且由于其独特的性能，例如高熔点和过高的硬度，可能成本高昂且费力。增材制造（AM）为生产具有复杂几何形状的零件提供了一种替代方案，这些零件使用传统制造工艺很难制造。虽然具有巨大的潜力，但目前的陶瓷增材制造技术在制造厚壁复杂结构（例如，厚度超过10毫米）方面仍然存在局限性，因为使用了有机粘合剂，并且在脱粘过程中难以完全去除。该学院早期职业发展（Career）奖支持基础研究，以调查和成熟一种新的陶瓷粉末床AM工艺，该工艺由水性油墨辅助，因此无需去除粘合剂，随后进行压缩和温和加热以实现颗粒融合。如果成功，这一工艺将使复杂的厚壁陶瓷部件的商业规模制造成为可能，并有助于加速陶瓷增材制造在许多行业的广泛采用，包括医疗保健、能源和国防。该项目还将通过陶瓷打印项目激发不同年级学生对陶瓷AM的兴趣，包括针对视力障碍学生的“黑暗面打印”，针对K-12学生的“陶瓷艺术3D打印”，以及针对本科生的跨学科陶瓷打印计划。本CAREER研究旨在了解一种新型陶瓷增材制造复杂厚壁陶瓷零件的加工机制，方法是采用选择性沉积的水性油墨，然后逐层进行单轴压缩。一旦打印完成，对构建的粉末床进行温和的加热（50至200摄氏度），其中由于加热而使油墨蒸发，油墨湿润区域的颗粒将融合在一起。该项目将研究由钼酸锂、磷酸钙和钛酸钡制成的陶瓷颗粒，并采用仪器压缩测试（高达100兆帕斯卡）、多尺度实验表征和孔尺度数值模拟来阐明不同的加工条件和材料性能对陶瓷颗粒融合机制和程度的影响，包括油墨化学和饱和度、压缩幅度、持续时间和周期。以及加热温度和时间。研究结果有望揭示所研究的陶瓷增材制造工艺中陶瓷颗粒之间颈部形成和生长的机制，确定决定颗粒融合密度和强度的关键因素，最终实现制造缺陷最小、密度全、性能增强的复杂厚壁陶瓷部件。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Structural ceramics are strategically important in many specialty applications, including thermal insulators, armors, implants and sensors. Manufacturing of complex ceramic components, however, has always been problematic and can be costly and laborious due largely to their unique properties, e.g., high melting points and excessive hardness. Additive manufacturing (AM) offers an alternative to produce parts with complex geometries that are challenging to make using traditional manufacturing processes. While of a great potential, current ceramic AM technologies still have limitations in making complex structures with thick walls (e.g., thicker than 10 mm), because of the use of an organic binder and the difficulty in its complete removal during de-binding. This Faculty Early Career Development (CAREER) award supports fundamental research to investigate and mature a new ceramic powder-bed AM process that is assisted with water-based inks, so to eliminate the need of binder removing, followed by compression and mild heating to achieve particle fusion. If successful, this process will enable complex thick-walled ceramic component manufacture in a commercial scale and help accelerate wider adoption of ceramic AM in many industries, including healthcare, energy and defense. This project will also pique the interest of students at different grades in ceramic AM through ceramic-printing programs, including “Print-in-the-Dark-Side” for students with vision impairment, “Ceramic Art 3D Printing” for K-12 students, and cross-discipline ceramic printing initiatives for undergraduate students.This CAREER research aims to understand the processing mechanism of a new ceramic AM in making complex thick-walled ceramic parts through employing a selectively deposited water-based ink, followed by uniaxial compression layer by layer. Once the print is completed, mild heating is applied (50 to 200 Celsius) to the built powder bed, in which upon evaporation of the ink due to heating, particles in the ink-wetted region will be fused together. The project will study ceramic particles made of lithium molybdate, calcium phosphate and barium titanate, and employ instrumented compression tests (up to 100 megapascals), multi-scale experimental characterizations, and pore-scale numerical simulations to elucidate the effects of different processing conditions and material properties on the fusion mechanism and degree of ceramic particles, including the ink chemistry and saturation level, the compression magnitude, duration and cycles, as well as the heating temperature and time. The research findings are expected to uncover the mechanism that governs the neck formation and growth between ceramic particles in the studied ceramic AM process, identify the key factors that determine the particle fusion density and strength, and ultimately, enable making complex thick-walled ceramic components with minimum defects, full density and enhanced properties.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.