Technical-scientific feasibility study of conformation of high density aluminum oxide green bodies by the additive manufacturing technique of selective laser sintering - SLS

Abstract

The Additive Manufacturing (AM) does comprise a set of Technologies where a component is directly produced starting from its virtual model. In regards to a ceramic component conformation, in the existent AM Technologies, the Selective Laser Sintering (SLS) does highlight due to its versatility in regards to the raw material that can be used, including not just powders but also high concentration slurries (40 to 60% in volume). The most common SLS process for ceramics is based on using a low melting point material mixed to a ceramic powder, which acts as a bonding agent to the ceramic powder as it melts during the process. As so, a "green body" is formed, which one should be submitted to a post-thermal cycle for its sintering. In an early research, undertaking in the scope of PIPE program - Sirius Challenge II, the results were not enough conclusive to confirm the SLS technical route for high density ceramic components. However, according to the undertaking research, the direct sintering of SLS conformed components, without a previous treatment, like a Cold Isostatic Pressing after the SLS, results in final densities of 50 to 60% of the material theoretical density (TD), while with such treatment the final density can reach up 94% TD. Components with final density over 90%TD present mechanical features suitable for application as structural ceramic, segment where the proponent company is active. In this context, the presented Project aims the technical-scientific viability study for obtation of high density "green bodies", from the development of ceramic powders suitable for indirect Selective Laser Sintering (SLS) followed by post-conformation by Isostatic press and sintering, before final sintering of the parts. The justification for such Development Project is connected to the potential use of the SLS conformation process for the production of complex geometry ceramic parts, those are hardly obtained by the conventional conformation techniques like press and machinery, injection or even extrusion molding. As a final result, it is expected, to obtain components with final density over 90% TD from de combination of the above three process - SLS, post-conformation by cold isostatic pressing and sintering. The potential Market that is intended to be achieved is the one of structural ceramic components with complex geometry, for the use in equipments with special and several operational conditions (high magnetic fields, high vacuum, high temperature, etc.). Using as reference the application segments where the proponent company already acts, which means, small and medium size components, with high dimensional tolerances and finishing surface requirements, potential opportunities could be brought from the development of Additive Manufacturing technology. The market prospect conception results in a differentiated share on the proponent company existent business, with a more significant impact on value basis than in quantity, it may represents up to 3% of revenue over the current portfolio in a 5 year time frame. (AU)