Gloeckle Christopher, Konkol Thomas, Jacobs Olaf, Limberg Wolfgang, Ebel Thomas, Handge Ulrich A
Department of Mechanical Engineering and Business Administration, Technische Hochschule Lübeck, Mönkhofer Weg 239, 23562 Lübeck, Germany.
Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Strasse 1, 21502 Geesthacht, Germany.
Materials (Basel). 2020 Oct 3;13(19):4413. doi: 10.3390/ma13194413.
Fused filament fabrication (FFF) is a new procedure for the production of plastic parts, particularly if the parts have a complex geometry and are only needed in a limited quantity, e.g., in specific medical applications. In addition to the production of parts which are purely composed of polymers, fused filament fabrication can be successfully applied for the preparation of green bodies for sintering of metallic implant materials in medical applications. In this case, highly filled polymer-metal feedstocks, which contain a variety of polymeric components, are used. In this study, we focus on various polymer-metal feedstocks, investigate the rheological properties of these materials, and relate them to our results of FFF experiments. Small amplitudes of shear oscillations reveal that the linear range of the polymer-metal feedstocks under investigation is very small, which is caused by elastic and viscous interactions between the metallic particles. These interactions strongly influence or even dominate the flow properties of the feedstock depending on the applied shear stress. The magnitude of the complex viscosity strongly increases with decreasing angular frequency, which indicates the existence of an apparent yield stress. The viscosity increase caused by the high powder loading needed for sintering limits the maximum printing velocity and the minimum layer height. The apparent yield stress hinders the formation of smooth surfaces in the FFF process and slows down the welding of deposited layers. The influence of composition on the processing parameters (suitable temperature range) and part properties (e.g., surface roughness) is discussed on the basis of rheological data.
熔丝制造（FFF）是一种生产塑料零件的新工艺，特别是当零件具有复杂的几何形状且仅需要有限数量时，例如在特定的医疗应用中。除了生产纯聚合物组成的零件外，熔丝制造还可成功应用于制备用于医疗应用中金属植入材料烧结的生坯。在这种情况下，使用含有多种聚合物成分的高填充聚合物-金属原料。在本研究中，我们聚焦于各种聚合物-金属原料，研究这些材料的流变特性，并将其与我们的熔丝制造实验结果相关联。小幅度的剪切振荡表明，所研究的聚合物-金属原料的线性范围非常小，这是由金属颗粒之间的弹性和粘性相互作用引起的。根据所施加的剪切应力，这些相互作用会强烈影响甚至主导原料的流动特性。复数粘度的大小随角频率降低而大幅增加，这表明存在明显的屈服应力。烧结所需的高粉末负载导致的粘度增加限制了最大打印速度和最小层高度。明显的屈服应力阻碍了熔丝制造过程中光滑表面的形成，并减缓了沉积层的焊接。基于流变学数据讨论了成分对加工参数（合适的温度范围）和零件性能（例如表面粗糙度）的影响。
