Thermal Debinding of Ceramic-Filled Photopolymers

Abstract:

Within the large variety of different additive manufacturing technologies stereolithography excels in high precision and surface quality. Using the Digital Light Processing (DLP) Technology a stereolithography-based system was developed, which is specifically designed for the processing of highly filled photopolymers.The powder-filled suspension enables the 3D-fabrication of a so called ceramic green part. In order to get a dense ceramic structure, subsequent thermal processing steps after the 3D-printing process are necessary. First, the polymer-ceramic composites heated up to 400°C. During this processing step, called debinding, the organic components are burned out. The resulting part, consisting of powder particles stabilized by physical interactions, is further heated to sinter the particles together, and the final, fully dense ceramic part is obtained.The debinding step is the most critical process. The used components have different evaporation or decomposition temperatures and behaviors. Thereby a reduction in weight and also in dimension occurs, which depends on the portion and composition of the organic components and especially on the temperature cycle. Furthermore, the physical characteristics of the ceramic powder, such as the particle size and the size distribution influence the debinding behavior. To measure the changes in weight and dimension a thermo-gravimetric (TGA) and a thermo-mechanical analysis (TMA) can be used. To avoid too high internal gas pressures inside the green parts a preferably constant gas evolution rate is seeked. Also the ‘surface-to-volume ratio’ affects the debinding characteristics. Therefore, optimized debinding cycles for specific geometries allow the crack-free debinding of parts with a wall thickness up to 20 mm.

• Periodical: Materials Science Forum (Volumes 825-826)
• Pages: 75-81
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.825-826.75
• Online since: July 2015
• Authors: Markus Pfaffinger*, Gerald Mitteramskogler, Robert Gmeiner, Jürgen Stampfl
• Keywords: Additive Manufacturing, Ceramic, Digital Light Processing, Photopolymerization, Thermal Debinding

References

[1] Wohlers Associates, Inc. Wohlers Report 2012: Additive Manufacturing and 3D Printing State of the Industry Annual Worldwide Progess Report, Wohlers Associates, Inc., Fort Collins, Colorado, (2013).

[2] T. Chartier, C. Chaput, F. Doreau, M. Loiseau, Stereolithography of structural complex ceramic parts, Journal of Materials Science 37 (2002) 3141-3147.

DOI: 10.1023/a:1016102210277

[3] R. Felzmann, S. Gruber, G. Mitteramskogler, P. Tesavibul, A.R. Boccaccini, R. Liska, J. Stampfl, Lithography-based Additive Manufacturing of Cellular Ceramic Structures, Adv. Eng. Mater. 14 (2012) 1052–1058.

DOI: 10.1002/adem.201200010

[4] G. Mitteramskogler et al., Light curing strategies for lithography-based additive manufacturing of customized ceramics, Additive Manufacturing 1-4 (2014) 110-118.

DOI: 10.1016/j.addma.2014.08.003

[5] R. Felzmann, S. Gruber, G. Mitteramskogler, M. Pastrama, A.R. Boccaccini, J. Stampfl, Lithography-based Additive Manufacturing of Customized Bioceramic Parts for Medical Applications, in Biomed. Eng. ACTAPRESS, Innsbruck, (2013).

DOI: 10.2316/p.2013.791-129

[6] J.W. Halloran, M.L. Griffith, Freeform Fabrication of Ceramics via Stereolithography, J. Am. Ceram. Soc. 79.

[10] (1996) 2601-2608.

[7] G.A. Brady, J.W. Halloran, Stereolithography of ceramic suspensions, Rapid Prototyping Journal 3.

[2] (1997) 61-65.

[8] C. Hinczewski, S. Corbel, T. Chartier, Stereolithography for the fabrication of ceramic three-dimensional parts, Rapid Prototyping Journal 4.

DOI: 10.1108/13552549810222867

[3] (1998) 104-111.

[9] O. Dufaud, S. Corbel, Stereolithography of PZT ceramic suspensions, Rapid Prototyping Journal 8.

DOI: 10.1108/13552540210420952

[2] (2002) 83-90.

[10] R. Gmeiner, G. Mitteramskogler, J. Stampfl, A.R. Boccaccini, Stereolithographic Ceramic Manufacturing of High Strength Bioactive Glass, Int. J. Appl. Ceram. Technol. 12.

DOI: 10.1111/ijac.12325

[1] (2015) 38-45.

[11] G. Mitteramskogler, Generative Fertigung von Bauteilen aus TCP, Master Thesis, Vienna University of Technology, Vienna, (2011).

[12] S. Gruber, Lithography-based Additive Manufacturing of Alumina Parts, PhD Thesis, Vienna University of Technology, Vienna, (2013).