Mahmoudi Mohammadreza, Wang Chao, Moreno Salvador, Burlison Scott R, Alatalo Diana, Hassanipour Fatemeh, Smith Samantha E, Naraghi Mohammad, Minary-Jolandan Majid
Department of Mechanical Engineering, University of Texas at Dallas, Richardson, Texas 75080, United States.
Department of Aerospace Engineering, Texas A&M University, College Station, Texas 77843, United States.
ACS Appl Mater Interfaces. 2020 Jul 15;12(28):31984-31991. doi: 10.1021/acsami.0c08260. Epub 2020 Jun 30.
Achieving a viable process for three-dimensional (3D) printing of ceramics is a sought-after goal in a wide range of fields including electronics and sensors for harsh environments, microelectromechanical devices, energy storage materials, and structural materials, among others. Low laser absorption of ceramic powders renders available additive manufacturing (AM) technologies for metals not suitable for ceramics. Polymer solutions that can be converted to ceramics (preceramic polymers) offer a unique opportunity to 3D-print ceramics; however, due to the low viscosity of these polymers, so far, their 3D printing has only been possible by combining them with specialized light-sensitive agents and subsequently cross-linking them layer by layer by rastering an optical beam. The slow rate, lack of scalability to large specimens, and specialized chemistry requirements of this optical process are fundamental limitations. Here, we demonstrate 3D printing of ceramics enabled by dispensing the preceramic polymer at the tip of a moving nozzle into a gel that can reversibly switch between fluid and solid states, and subsequently thermally cross-linking the entire printed part "at-once" while still inside the same gel. The solid gel, which is composed of mineral oil and silica nanoparticles, converts to fluid at the tip of the moving nozzle, allows the polymer solution to be dispensed, and quickly returns to a solid state to maintain the geometry of the printed polymer both during printing and the subsequent high-temperature (160 °C) cross-linking. We retrieve the cross-linked part from the gel and convert it to ceramic by high-temperature pyrolysis. This scalable process opens up new opportunities for low-cost and high-speed production of complex three-dimensional ceramic parts and will be widely used for high temperature and corrosive environment applications, including electronics and sensors, microelectromechanical systems, energy and structural applications.
在包括恶劣环境下的电子和传感器、微机电设备、储能材料以及结构材料等众多领域，实现陶瓷的三维（3D）打印可行工艺是一个备受追求的目标。陶瓷粉末的低激光吸收率使得适用于金属的现有增材制造（AM）技术不适用于陶瓷。可转化为陶瓷的聚合物溶液（陶瓷前驱体聚合物）为3D打印陶瓷提供了独特的机会；然而，由于这些聚合物的低粘度，到目前为止，它们的3D打印只能通过将它们与专门的光敏剂结合，随后通过光栅光束逐层交联来实现。这种光学过程的速率慢、无法扩展到大型样品以及对特殊化学条件的要求是其基本限制。在此，我们展示了一种陶瓷3D打印方法，即通过将陶瓷前驱体聚合物在移动喷嘴的尖端分配到一种能够在流体和固态之间可逆切换的凝胶中，随后在仍处于同一凝胶内部时“一次性”对整个打印部件进行热交联。由矿物油和二氧化硅纳米颗粒组成的固体凝胶在移动喷嘴的尖端转化为流体，允许聚合物溶液被分配，并迅速恢复到固态，以在打印过程中和随后的高温（160°C）交联过程中保持打印聚合物的几何形状。我们从凝胶中取出交联后的部件，并通过高温热解将其转化为陶瓷。这种可扩展的工艺为低成本、高速生产复杂的三维陶瓷部件开辟了新机会，并将广泛应用于高温和腐蚀性环境应用，包括电子和传感器、微机电系统、能源和结构应用。
