Influence of Resin Composition on the Defect Formation in Alumina Manufactured by Stereolithography

Emil Johansson,Ola Lyckfeldt,Jan Johansson,Erik Adolfsson,Oscar Lidström

doi:10.3390/ma10020138

Abstract

Stereolithography (SL) is a technique allowing additive manufacturing of complex ceramic parts by selective photopolymerization of a photocurable suspension containing photocurable monomer, photoinitiator, and a ceramic powder. The manufactured three-dimensional object is cleaned and converted into a dense ceramic part by thermal debinding of the polymer network and subsequent sintering. The debinding is the most critical and time-consuming step, and often the source of cracks. In this study, photocurable alumina suspensions have been developed, and the influence of resin composition on defect formation has been investigated. The suspensions were characterized in terms of rheology and curing behaviour, and cross-sections of sintered specimens manufactured by SL were evaluated by SEM. It was found that the addition of a non-reactive component to the photocurable resin reduced polymerization shrinkage and altered the thermal decomposition of the polymer matrix, which led to a reduction in both delamination and intra-laminar cracks. Using a non-reactive component that decomposed rather than evaporated led to less residual porosity.

Highlights

Additive manufacturing of ceramics by stereolithography (SL) is a promising alternative to conventional manufacturing methods for the production of complex parts in small series where high resolution and surface quality is required
After a three-dimensional ceramic green object has been shaped, the formed polymer matrix is removed through thermal debinding, and the resulting powder body sintered to form a dense ceramic part [1]
With the addition of di(trimethylolpropane) tetraacrylate (DiTMPTA), this increased to 1.63 Pa·s, 1.32 Pa·s, and 1.89 Pa·s for M2, M2-Butoxy ethyl acetate (BEA), and

Summary

Introduction

Additive manufacturing of ceramics by stereolithography (SL) is a promising alternative to conventional manufacturing methods for the production of complex parts in small series where high resolution and surface quality is required. A ceramic green object is formed, layer by layer, by the selective photopolymerisation of a ceramic suspension containing photocurable monomer, photoinitiator, and ceramic powder [1]. Alumina parts with high density and mechanical strength comparable to that of conventional manufacturing methods have been successfully manufactured using commercially available photocurable ceramic suspensions and a DLP-based stereolithography apparatus (SLA) from Lithoz GmbH, Vienna, Austria [6]. The suspensions must exhibit a sufficient cure depth to provide adequate integration between layers [2,7]. D p and Ec of a Materials 2017, 10, 138; doi:10.3390/ma10020138 www.mdpi.com/journal/materials

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