Additive Manufacturing of Ceramics Using a Fused Deposition Modeling (FDM)-Type 3D Printer and Their Microwave Sintering and HIP Treatment

Abstract

Fused deposition modeling (FDM) with a 3D printer, one of so-called "Additive Manufacturing (AM)", is a promising advanced industrial production method. However, there are much difficulty in the fabrication of dense ceramics using a FDM-type 3D printer; i) preparation of "filament" used for supplying raw materials to the printer, ii) thermal management during AM to adjust both the viscosity and yield stress of melting filament appropriately, and iii) sintering densification of powder compacts. To meet these requirements, ceramics powders consisting of bimodal fine/coarse particles in zirconia-alumina system and unimodal hydroxyapatite powders were adopted for the starting raw materials. Homogenous filament with the compositions of (ZrO 2 -Al 2 O 3 )/binder = 65/35vol% were prepared by reducing the thickness of resin layer to 110~140 nm and extruded into the strand filaments with the diameter of 1.8-2.0 mm around 423 K. After AM under the viscosity γ and yields stress σ y , less than 1.60•10 2 Pa•s and 2.0 MPa, respectively, of kneaded body, and defatting at 773 K in air, the powder compacts were densified by microwave sintering at 1723 K for 6.0•10 2 s in N 2 . As-obtained material showed a high relative density more than 95.0%. In addition, capsule-free HIP treatment brought much densification by removing the closed pores inside materials.