|Title: ||Comparison of different powder metallurgy processes to produce alumina parts through indirect Selective Laser Sintering|
|Authors: ||Deckers, Jan ×|
Kruth, Jean-Pierre #
|Issue Date: ||2014 |
|Publisher: ||Elsevier Sequoia|
|Series Title: ||Materials Science and Engineering A, Structural Materials: Properties, Microstructure and Processing|
|Abstract: ||Additive manufacturing (AM; aka 3D printing) has the potential to rapidly shape parts with an almost unlimited shape freedom. Variants of the following powder metallurgy (PM) route, with an additive manufacturing shaping step, were explored to produce ceramic parts: (i) powder synthesis, (ii) additive manufacturing, (iii) binder removal, (iv) furnace sintering and alternative densification steps. In this study, alumina (Al2O3) parts were produced since Al2O3 is currently the most commonly used ceramic material for technical applications. For the production of the alumina parts, indirect Selective Laser Sintering (indirect SLS) was used as the AM method during the shaping step.
To explore indirect SLS, different powders, with an agglomerate size of about 10-100 µm and consisting of a 0.3 µm alumina particles and a polymer binder phase (i.e. composite alumina-binder agglomerates), were irradiated by a laser beam. Five different alumina-binder agglomerates were investigated: alumina-polyamide agglomerates produced by ball milling, alumina-polystyrene powder produced by dispersion polymerization and alumina-polyamide, alumina-polypropylene and alumina-carnauba wax-low density polyethylene powders produced by temperature induced phase separation (TIPS). During subsequent SLS, the laser irradiation, which melts only the binder phase, selectively consolidates the powder agglomerates layer by layer. After subsequent binder removal and furnace sintering, alumina parts, containing inter-agglomerate pores, were obtained. In order to reduce the inter-agglomerate voids, the possibility to include the following steps into the PM process chain was explored: (i) irradiating the powder layers multiple times instead of only once (i.e. laser re-melting), (ii) cold, quasi and warm isostatic pressing the SLSed parts and (iii) infiltrating the parts obtained at different stages of the PM process. As a result, freeform shaped alumina parts with densities up to approximately 90% could be obtained. In order to produce higher quality ceramic parts through indirect SLS, the inter-agglomerate pores should be avoided or eliminated.
|Publication status: ||submitted|
|KU Leuven publication type: ||IT|
|Appears in Collections:||Production Engineering, Machine Design and Automation (PMA) Section|
Surface and Interface Engineered Materials