Investigation of laser sintering for freeform fabrication of zirconium diboride parts

This paper presents a study wherein the Laser Sintering (LS) process is used to perform additive manufacturing of zirconium diboride (ZrB2) parts. Experiments were conducted to determine values of LS process parameters (laser power, scan speed, energy density, line spacing, and layer thickness) that can be used to improve building of ZrB2 parts. A sacrificial plate with a proper number of layers was first constructed in order to reduce thermal gradients in building the main part. The sacrificial plate was found to eliminate cracks that would otherwise occur in the bottom of the main part. The fabricated green parts went through post-processing steps, including binder burnout and sintering at appropriate heat treatment schedules, to remove the binder and sinter the ZrB2 particles. The test bars after sintering had an average relative density of 87% and an average flexural strength of 250 MPa.