Strategies for the selective volume sintering of ceramics
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Dongxu Yao State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China
Stephan Gräf and Frank A. Müller Otto-Schott Institute of Materials Research, Friedrich-Schiller University of Jena, Jena 07743, Gemany
Jens Günsterb) Institute of Nonmetallic Materials, Clausthal University of Technology, Clausthal-Zellerfeld 38678, Germany; and BAM Federal Institute of Materials Research and Testing, Division of Ceramic Processing and Biomaterials, 12205 Berlin, Germany (Received 5 March 2014; accepted 19 June 2014)
The present study is dealing with the basic physics for a novel way to generate a free-formed ceramic body, not like common layer by layer, but directly by Selective Volume Sintering (SVS) in a compact block of ceramic powder. To penetrate with laser light into the volume of a ceramic powder compact it is necessary to investigate the light scattering properties of ceramic powders. Compared with polymers and metals, ceramic materials are unique as they offer a wide optical window of transparency. The optical window typically ranges from below 0.3 up to 5 lm wave length. In the present study thin layers of quartz glass (SiO2) particles have been prepared. As a function of layer thickness and the particle size, transmission and reflection spectra in a wave length range between 0.5 and 2.5 lm have been recorded. Depending on the respective particle size and by choosing a proper relation between particle size and wave length of the incident laser radiation, it is found that light can penetrate a powder compact up to a depth of a few millimeters. With an adjustment of the light absorption properties of the compact the initiation of sintering in the volume of the compact is possible.
I. INTRODUCTION
Lasers are used for the local annealing, sintering, and melting of polymeric, metallic, and ceramic powders in so called additive manufacturing (AM) processes. AM describes a class of technologies in which a 3D object is directly generated from a virtual model by adding material in a layer-by-layer approach1 and is defined by ASTM F2792 - 12a (Standard Terminology for AM Technologies) as the “process of joining materials to make objects from 3D model data, usually layer upon layer, opposed to subtractive manufacturing methodologies, such as traditional machining.” The present study has been motivated by the idea to locally manipulate a ceramic powder compact within its volume by laser light, i.e., light can be locally dissipated into heat to initiate sintering selectively. With such an approach structures could be directly inscribed into the a)
Address all correspondence to this author. e-mail: [email protected] b) This author was an editor of this focus issue during the review and decision stage. For the JMR policy on review and publication of manuscripts authored by editors, please refer to http://www.mrs.org/jmr-editor-manuscripts/. DOI: 10.1557/jmr.2014.174 J. Mater. Res., Vol. 29, No. 17, Sep 14, 2014
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