Sintering of 3D‐Printed Glass/HAp Composites

Abstract

We report the sintering of 3D‐printed composites of 13‐93 bioactive glass and hydroxyapatite (HAp) powders. The sintering process is characterized on conventionally produced powder compacts with varying HAp content. A numeric approximation of the densification kinetics is then obtained on the basis of Frenkel, Mackenzie–Shuttleworth, and Einstein–Roscoe models, and optimized sintering conditions for 3D‐printed structures are derived. Fully isotropic sintering of complex cellular composites is obtained by continuous heating to 750°C at a rate of 2 K/min for a HAp content of 40 wt%. The approach can readily be generalized for printing and sintering of similar glass‐ceramic composites.

Additive Manufacturing of Ceramic‐Based Materials

“…Received: January 16,2014 Final Version: February 27, 2014 C [284] ZrC [160] TiC/Ni [289] Al 2 O 3 -ZrO 2 [191] Polymer-derived ceramics: see present work Functional ceramics BaTiO 3 [40,41] PZT [89] PZT [211,223,239] BaTiO 3 [150] SiO 2 -Al 2 O 3 -RO-glass [269] PZT [37,[45][46][47] BaTiO 3 [115] SiCN [225] PZT [145,146] LZSA-Glass [272] TiO 2 [43,44] PMN [192] PZT [282] LSMO/YBCO [48] LiFePO 4 [170] Li 4 Ti 5 O 12 BaZrO 3 , SrTiO 3 , BaMn 2 Al 10 O 19À x [193] ITO [119] ZnO [119,187] La(Mg 0.5 , Ti 0.5 )O 3 [167,188] Zr 0.8 Sn 0.2 TiO 4 [188] TiO 2 [119] Bioceramics HA [50,66,67,[69][70][71][72] Apatite-Mullite [107][108]…”

“…He quantified the optimal powder parameters such as the particle size (20-35 mm), compaction rate r Tapped /r Bulk (1.3-1.4), flowability ff c , defined as the ratio of consolidation stress s 1 and the compression strength s c (5-7), and powder bed surface roughness (10-25 mm). The need for at least one post-processing step (cold-isostatic pressing, [61] infiltration with preceramic polymers [62,63] or liquid metals, [51,64] chemical vapor infiltration, [65] and sintering [66,67] ) reduces the productivity of three-dimensional printing methods, so several approaches exist to increase the green density. It was observed that implementation of binder-coated particles effectively improves the green and sintered strengths.…”

“…Fierz et al [50] used sprayed-dried porous HA granules to create nano and macroporous scaffolds. A HA/ bioactive glass-ceramic composite was fabricated by Winkel et al [67] Custom-made specimens were also fabricated from tricalcium phosphate (TCP) [56,60,[73][74][75][76][77] or combined with bioactive glass, [78] demonstrating their potential use as implants for bone replacement applications. Scaffolds with a designed macroporosity were printed from submicron TCP powders with a layer thickness of 20 mm by Ref.…”

Recent developments in 3D printable composite materials

“…Large and complex structures may significantly deform because of a number of factors, such as gravity, intrinsic strain or temperature, surface tension and density gradients. 10 Such effects seen during the sintering of glass materials can be minimised by reducing the glass fraction of the composite materials. Winkel et al (2012) developed bioactive glass composites with HA powder to fabricate 3D scaffolds.…”

“…7 Running parallel to these technological developments, there has also been rapidly growing interest in the preblending of materials and/or the inclusion of 'fillers' into printable resins, which deliver distinct physicochemical properties into the resultant materials, thus producing 3D printed composites which exhibit unique characteristics and capabilities. [8][9][10][11][12][13][14][15] Indeed, in the area of composite design and production, 3D printing represents a technology with immense potential, again providing low cost, simple and rapid prototyping advantages over traditional methods for fabrication of composite materials and objects. rication methods, applications, advantages and limitations.…”