Binder Jet Additive Manufacturing with Granulated Ceramic Powders

目前，由粘合剂喷射增材制造制成的陶瓷零件密度低，机械性能差;该奖项支持基础研究，解决颗粒陶瓷纳米粉末用于粘合剂喷射增材制造以解决这些缺点。纳米颗粒难以结合到最常见的增材制造方法中，但是使用陶瓷纳米颗粒与粘合剂的造粒允许使用纳米颗粒而没有有限的铺展性的正常缺点。颗粒状纳米颗粒由纳米颗粒与聚合物粘合剂组合而成，然后将聚合物粘合剂机械加工或研磨以产生直径为几十微米的颗粒，该颗粒包含许多纳米颗粒。这允许使用造粒而不会使增材制造机器中的粉末扩散复杂化，并且允许使用纳米颗粒在增材制造中生产更致密、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，以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，因此该提案直接对经济福利和国家安全产生积极影响。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，谁将进行实验和分析实验结果。研究目的是检验三组假设：（1）颗粒粉末导致比纳米粉末和微米粉末更高的印刷和烧结密度;（2）颗粒粉末具有与微米粉末相似的流动性，但比纳米粉末更高的流动性;和（3）颗粒粉末具有与纳米粉末相似的烧结性，但比微米粉末更高的烧结性。将通过使用阿基米德方法测量来自三种粉末（颗粒粉末、纳米粉末和微粉）的打印和烧结样品的密度并对结果进行统计学比较来检验第一组假设。第二组假设将通过比较三种粉末的豪斯纳比（每种粉末的振实密度和表观密度之间的比率）进行检验。第三组假设将通过比较三种粉末通过传统的压制和烧结手段实现的密度来测试。通过对这三组假设的测试，将获得关于造粒对粘合剂喷射增材制造的影响以及颗粒粉末、纳米粉末和微粉的流动和烧结行为的新知识。该奖项反映了NSF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.