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Capillary suspension based additive manufacturing of highly porous, cellular ceramic structures with unprecedented mechanical strength/density ratio

基于毛细管悬浮液的增材制造，具有前所未有的机械强度/密度比的高孔隙度多孔陶瓷结构

基本信息

批准号：
340671862
负责人：
Professor Dr. Norbert Willenbacher
金额：
--
依托单位：
Arbeitsgruppe Angewandte Mechanik (AM)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2017
资助国家：
德国
起止时间：
2016-12-31 至 2020-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/340671862?language=en
关键词：
Capillary suspension based additive manufacturing

项目摘要

Porous ceramics are used in a broad range of applications including filtration membranes, catalyst carriers, bone scaffolds or composite materials for lightweight construction elements. Recently, we have developed a new processing route for highly porous sintering materials based on well-established unit operations. This innovative concept uses so-called capillary suspensions (three-phase systems solid/fluid/fluid) as pre-cursor to fabricate highly porous sintering materials. Thus open porosities between 50% and 80% and pore sizes ranging from 0.5 µm to 50 µm can be obtained easily. Here we want to advance this technology to fabricate highly porous ceramic structures with so far unmatched mechanical strength. Two strategies will be developed and evaluated in parallel:1. An additive manufacturing technique, the so-called Direct Ink Writing (DIW) method, shall be used to create cellular structures with highly porous ceramic struts. This is supposed to result in ceramic bodies with porosities > 90% and high strength/density ratio close to Balsa wood. Pastes optimized for this printing technique will be developed, and capillary suspensions are especially suited due to their high yield stress and pronounced shear-thinning behavior. Preliminary experiments suggest that carefully prepared capillary suspensions enable to create fine feature sizes (~ 50 µm) previously not accessible with DIW. Cellular structures will be fabricated using DIW and tested with respect to their mechanical strength.2. Capillary suspensions will be utilized to obtain ceramic materials with outstanding mechanical strength at a given porosity. The basic idea of this approach is to use the secondary liquid of the three-phase capillary suspension as a carrier for targeted deposition of small, sinter-active particles at the contact zones of the large particles. This should result in higher pore roundness and reinforced sintering necks finally resulting in an increased mechanical strength of the porous ceramic bodies. In preliminary experiments e.g. the compressive strength of porous Al2O3 ceramics could be tripled via addition of a fine ZrO2 fraction. Chemical composition and size of the fine particles will be varied systematically and the resulting structures will be carefully analyzed for a targeted further enhancement of mechanical strength. Finally, the insight from both subprojects shall be combined using DIW and appropriate material combinations for manufacturing porous ceramic structures with unprecedented specific mechanical strength. The fully open porous struts of capillary suspension based cellular structures makes the materials fabricated according to our new approach promising candidates for filtration and separation applications. Accordingly, DIW will be used to print a filter demonstrator and its separation properties will be evaluated.

多孔陶瓷应用广泛，包括滤膜、催化剂载体、骨支架或用于轻质建筑元件的复合材料。最近，我们在完善的单元操作的基础上，开发了一条新的高孔率烧结材料的加工路线。这一创新的概念使用所谓的毛细悬浮液(固/液/液三相体系)作为前光标来制备高孔隙率的烧结材料。因此，可以很容易地获得50%到80%的开孔率和0.5到50微米的孔径。在这里，我们想要推进这项技术，以制造到目前为止无与伦比的机械强度的高孔性陶瓷结构。将同时开发和评估两种策略：1.将使用一种添加剂制造技术，即所谓的直接墨水写入(DIW)方法，来制造具有高度多孔性的陶瓷支柱的蜂窝结构。这将导致陶瓷体的气孔率&gt；90%和高强度/密度比接近巴尔萨木材。为这种印刷技术优化的浆料将被开发出来，而毛细管悬浮液由于其高屈服应力和显著的剪切稀化行为而特别适合。初步实验表明，精心配制的毛细管悬浮液能够产生以前通过DIW无法获得的精细特征尺寸(~50微米)。将使用DIW制造蜂窝结构，并测试其机械强度。毛细管悬浮液将被用来获得在给定孔隙率下具有突出机械强度的陶瓷材料。这种方法的基本思想是利用三相毛细管悬浮液的二次液体作为载体，在大颗粒的接触区定向沉积小的、烧结活性的颗粒。这将导致更高的气孔圆度和增强的烧结颈缩，最终导致多孔陶瓷体的机械强度增加。在初步实验中，例如，通过添加细小的氧化锆粉，可以将多孔氧化铝陶瓷的抗压强度提高两倍。细小颗粒的化学成分和大小将被系统地改变，所产生的结构将被仔细分析，以便有针对性地进一步提高机械强度。最后，利用DIW和适当的材料组合，将来自两个子项目的见解结合在一起，以制造具有前所未有的比机械强度的多孔陶瓷结构。基于毛细管悬浮液的细胞结构的完全开放的多孔支柱使根据我们的新方法制造的材料成为过滤和分离应用的候选材料。因此，将使用DIW打印过滤器演示器，并对其分离性能进行评估。