Binder Jet Additive Manufacturing with Granulated Ceramic Powders

目前，用粘结剂喷射增材制造的陶瓷零件密度低，力学性能差；该奖项支持解决颗粒陶瓷纳米粉末用于粘合剂喷射增材制造的基础研究，以解决这些缺点。纳米颗粒很难整合到最常见的增材制造方法中，但是使用带有粘合剂的陶瓷纳米颗粒可以使纳米颗粒的使用没有通常的涂抹性有限的缺点。颗粒状纳米颗粒由纳米颗粒与聚合物粘合剂结合而成，然后将其加工或碾磨成直径几十微米的颗粒，其中包含许多纳米颗粒。这允许在增材制造机器中使用颗粒而不复杂的粉末扩散，并使用纳米颗粒在增材制造中生产更密集，更坚固的部件。该项目的研究成果将有助于实现高密度陶瓷部件的增材制造，从而经济地生产耐磨部件。最终的应用是下一代骨科植入物，这对美国来说是一个非常重要的经济领域。此外，在航空航天、国防和汽车领域也有溢出应用，因此这一建议直接和积极地影响经济福利和国家安全。这项研究将涉及本科生和研究生，包括那些来自代表性不足的群体的学生，他们将进行实验并分析实验结果。研究目的是验证三组假设：(1)颗粒状粉末比纳米粉末和微粉末具有更高的印刷和烧结密度；(2)颗粒状粉体的流动性与微粉体相似，但流动性高于纳米粉体；(3)颗粒状粉体的烧结性能与纳米粉体相似，但烧结性能高于微粉体。第一组假设将通过用阿基米德的方法测量三种粉末（粒状粉末、纳米粉末和微粉末）的印刷和烧结样品的密度，并对结果进行统计比较来检验。第二组假设将通过比较三种粉末的豪斯纳比（每种粉末的密度与表观密度之比）来检验。第三组假设将通过比较三种粉末的实现密度通过传统的压制和烧结手段进行测试。测试这三组假设将使我们对造粒对粘合剂喷射增材制造的影响，以及造粒粉末、纳米粉末和微粉末的流动和烧结行为有新的认识。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。

Currently, ceramic parts made by binder jet additive manufacturing have low density and poor mechanical properties; this award supports fundamental research addressing the use of granulated ceramic nanopowder for binder jet additive manufacturing to address these shortcomings. Nanoparticles are difficult to incorporate into the most common additive manufacturing approaches, but the use of granulations of ceramic nanoparticles with binders allows the use of nanoparticles without the normal drawbacks of limited spreadability. A granulated nanoparticle consists of nanoparticles combined with a polymer binder, which is then machined or milled to produce a particle a few tens of micrometers in diameter, which contains many nanoparticles. This allows the use of granulations without complicating spreading of powder in an additive manufacturing machine, and the use of nanoparticles to produce denser, stronger parts in additive manufacturing. Research results from this project will help enable additive manufacturing of high-density ceramic parts to produce wear-resistant parts economically. The ultimate application in mind is next-generation orthopedic implants, which is an economic area of great importance to the US. In addition, there are spillover applications in the aerospace, defense and automotive sectors, so that this proposal directly and positively impacts economic welfare and national security. The research will involve undergraduate and graduate students, including those from the underrepresented groups, who will conduct experiments and analyze experimental results. The research objective is to test three sets of hypotheses: (1) granulated powder leads to a higher printed and sintered density than both nanopowder and micropowder; (2) granulated powder has a similar flowability to micropowder but a higher flowability than nanopowder; and (3) granulated powder has a similar sinterability to nanopowder but a higher sinterability than micropowder. The first set of hypotheses will be tested by measuring the densities of printed and sintered samples from the three powders (granulated powder, nanopowder, and micropowder) with Archimedes' method and statistically comparing the results. The second set of hypotheses will be tested by comparing the Hausner ratios (the ratio between tap and apparent densities of each powder) of the three powders. The third set of hypotheses will be tested by comparing the achieved densities of the three powders by a traditional pressing and sintering means. Testing these three sets of hypotheses will result in new knowledge about effects of granulation on binder jet additive manufacturing, and flowing and sintering behaviors of granulated powder, nanopowder, and micropowder.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.