Binder Jet Additive Manufacturing with Granulated Ceramic Powders

目前，通过粘结剂喷射添加剂制造的陶瓷部件密度低，机械性能差；该奖项支持使用颗粒陶瓷纳米粉末制造粘结剂喷射添加剂以解决这些缺点的基础研究。纳米颗粒很难融入最常见的添加剂制造方法中，但将陶瓷纳米颗粒与粘结剂一起使用允许使用纳米颗粒，而不会出现铺展有限的正常缺点。颗粒状纳米颗粒由纳米颗粒与聚合物粘结剂结合而成，然后经过加工或研磨，生成直径几十微米的颗粒，其中包含许多纳米颗粒。这允许使用造粒而不会使添加剂制造机器中的粉末扩散复杂化，并允许在添加剂制造中使用纳米颗粒来生产更致密、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添加制造，从而经济地生产耐磨部件。人们考虑的最终应用是下一代整形外科植入物，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、国防和汽车部门也有溢出应用，因此这一提议直接和积极地影响了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群体的学生，他们将进行实验并分析实验结果。研究目的是检验三组假设：(1)造粒粉末比纳米粉末和微粉都能产生更高的印刷和烧结密度；(2)造粒粉末具有与纳米粉末相似的流动性，但比纳米粉末具有更高的流动性；以及(3)造粒粉末具有与纳米粉末相似的烧结性，但烧结性高于微粉。第一组假设将通过阿基米德方法测量三种粉末(颗粒粉、纳米粉和微粉)的打印和烧结样品的密度并进行统计比较来验证。第二组假设将通过比较三种粉末的豪斯纳比率(每种粉末的TAP和表观密度之间的比率)来检验。第三组假设将通过比较传统压制和烧结方法获得的三种粉末的密度来检验。测试这三组假设将导致对造粒对粘结剂喷射添加剂制造的影响以及造粒粉末、纳米粉末和微粉的流动和烧结行为的新认识。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.