Shaping of ceramic parts by selective laser melting of powder bed
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aser additive manufacturing allows the production of polymeric or metallic parts with complex shapes. A major advantage of this contactless technology is that it allows reaching very high energy densities with an excellent precision in short times. This is very suitable for processing hard refractory metals for instance. Unfortunately, current results are less satisfactory for ceramics as a consequence of their intrinsic properties such as a low thermal shock resistance and very high refractoriness. Another significant limitation is related to the poor absorptivity of oxide ceramics in the near-infrared region which is typical for most commercial selective laser melting (SLM) machines. This study considers an alternative to overcome the above-mentioned limitations, especially the lack of absorptivity. SLM of oxide ceramics has become possible. Large parts with complex shapes and relative densities up to 90% have been manufactured on a commercial SLM machine.
I. INTRODUCTION
During the last 10 years, the rapid prototyping and manufacturing techniques have received more and more interest from the industry. These techniques allow shaping of three-dimensional (3D) technical parts from a 3D-computer aided design (3D-CAD) representation. As a noticeable consequence, these techniques lead to a dramatic reduction of the processing time to produce a functional prototype. The cost effectiveness of these prototyping processes is considerably enhanced. The most popular solid freeform fabrication processes are fused deposition modeling, laminated object manufacturing, stereolithography, and selective laser sintering/melting (SLS/SLM).1,2 Nowadays, SLM is considered as an almost mature technique to process metals and polymers.3 Processing of ceramics with this technology is unfortunately more complicated due to their intrinsic brittleness, low thermal shock resistance, and high refractoriness. Nevertheless, several researches are focused on the fabrication of ceramic coatings or monolithic parts by laser processes.1–9 One of the primary challenges is to perform SLS or melting in two dimensions (on coatings or powder beds) which is a prerequisite to build up 3D ceramic parts. The secondary challenge is to fabricate 3D parts which may compete with those produced by more conventional techniques (mostly in terms of strength, toughness, dimensional accuracy, and roughness). The objective of this article concerns the additive manufacturing of dense ceramic parts by selective laser process. The results reported here are related to selective a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2014.127 2086
J. Mater. Res., Vol. 29, No. 17, Sep 14, 2014
http://journals.cambridge.org
Downloaded: 17 Mar 2015
laser treatments performed on alumina powder beds with the aim to find out the most suitable parameters to achieve melting or sintering. Tests were carried out with a fiber laser emitting at 1070 nm, a wave length typical for most of SLM machines and for which alumina is almost nonabsorbent. Even if
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