Nowadays, additive manufacturing is well known for its outstanding potentials in fabricating components for special applications. In the sector of ceramics, the LCM-method (Lithography-based Ceramic Manufacturing) has been established as an auspicious technique to produce highly complex shaped parts. In order to assess the quality and to determine the reliability of alumina produced by the LCM technology, two different types of the material were investigated deeply. The aim of this master thesis was therefore the basic materials characterization and the determination of the mechanical properties. One the one hand, the samples were geometrically analyzed in respect to distortions and warping after the sintering process. On the other hand, the microstructures of the materials were examined and the grain size distributions were obtained. The microstructure of the material of one serial is indeed relatively fine, although the homogeneity level is low and therefore differences in respect to its printing directions were found. In relation to that, the other materials are more homogeneously. However, small amounts of second phases can be found. Furthermore, the hardness and the density were determined and the influences of several sintering parameters on the surface qualities of one serial were studied successfully. Another focus of this work was to investigate the strength behavior of LCM-alumina. Therefore, uniaxial and biaxial bending tests were carried out. In combination with fracture analyses it was possible to track several types of defect populations, which are conditional to the manufacturing process. Hence, the effect of the surface conditions, the microstructures, the detected defects as well as the printing directions on the Weibull parameters were discussed respectively. Additionally, the fracture toughness was determined by using the SEVNB-method. It was found that the values of the fracture toughness are in fact quite similar in all testing directions. In addition, the residual stresses were determined by using Vickers indentation cracks. The stress components in and perpendicular to the printing direction are different. These results were compared with the ones of RAMAN-measurements. Based on all these conducted investigations it can be summed up, that LCM-alumina is a quite promising material with adequate properties.
|Translated title of the contribution
|Characterization of Additive Manufactured Alumina
|28 Jun 2019
|Published - 2019
Bibliographical noteembargoed until null
- additive manufacturing
- mechanical properties