Impact of Zirconia Slurry Doping on 316L Stainless Steel Prepared by Laser Powder Bed Fusion for Biological/High Corrosion Applications

Laser Powder Bed Fusion (LPBF) is a versatile additive manufacturing (AM) method used primarily for processing plastics and metals. Stainless steel (type 316L) is a biocompatible metal used extensively for LPBF and commonly for medical applications. Zirconium Dioxide (zirconia) is a common engineering material used in applications ranging from dental implants to oxide dispersion strengthening of metals. This paper presents the process development and results of in- situ deposition of small quantities of zirconia nanoparticles in a stainless steel (316L) powder bed prior to fusion in the LPBF process. The zirconia slurry was deposited as an atomized mist. The deposition process may be adapted to selectively dope a powder bed to form parts with spatially varying properties for use in complex parts. In this work, the added zirconia was shown to be partially distributed in the matrix, but a large portion segregated to grain boundaries and surfaces.
Porosity increased in multi-layer parts with the zirconia agglomerated on the porous surfaces. This is undesirable for many applications but may be useful for creating porous surfaces for heat exchanger or bio-integration applications. The deposition of zirconia limits the anisotropic crystal growth throughout the entire doped region.