Microstructural Characterization of Metallic Parts Produced by Hot Embossing

The microfabrication technologies not only possess a considerable market potential but are also regarded as leading technologies of our days and key technologies for the future, due to the growing demand for microengineering applications such as micromoulds, micromechanical structures, sensors and micro-medical devices [1, 2]. Metal powder hot embossing is an emerging replicative process that can provide dimensional precision and microdetails of metallic parts. Metal powder hot embossing requires four distinctive steps: (1) preparation of feedstocks (implying the selection and characterization of powder and binder); (2) shape-forming of the part by hot embossing (green part); (3) debinding (brown part); and (4) sintering (final part). The goal of this study was to characterize metallic parts produced by micro metal hot embossing technology. To manufacture metallic parts with quality it was necessary to optimize all parameters involved in the four steps. To prepared the feedstock was used 316L stainless steel powder, which has a d50 =7.34 µm, with a commercial binder (Licomont, Lc). The production of feedstock was performed by torque rheometry at 140° C, during 45 minutes and using a blade speed rotation of 30 rpm. The feedstocks produced have a fixed powder load equal to 60 vol.% and the final torque average value was 2.2 N.m. Previous studies report the characterization of the powder and binder and show that the feedstocks are homogeneous mixtures [3,4]. Different pressures of embossing (4, 7, 14 and 28 MPa) were tested in order to optimize the process. To evaluate the replication of micro details, all the samples produced were observed in a stereomicroscope before and after sintering. Additionally, the best samples were analyzed by optical microscopy and Scanning Electron Microscopy (SEM) and 3D measured with Alicona IFM, before and after sintering.