Effect of MgO sintering additive on mullite structures manufactured by fused deposition modeling (FDM) technology

Fateme Sarraf,Edoardo Abbatinali,Lovro Gorjan,Tutu Sebastian,Paolo Colombo,Sergey V Churakov,Frank Clemens

doi:10.1016/j.jeurceramsoc.2021.06.012

Abstract

An optimized recipe for 3D printing of Mullite-based structures was used to investigate the effect of MgO sintering additive on the processing stages and final ceramic properties. To achieve dense 3:2 mullite, ceramic filaments were prepared based on an alumina powder, a methyl silicone resin, EVA elastomeric binder and MgO powder. Using 1 wt% MgO and a dwell time of 5 h at 1600 °C, a dense mullite structure could be obtained from filaments with a diameter of 1.75 mm. Ceramic structures with and without sintering additive were printed in vertical and horizontal direction, to investigate the effect of printing direction on mechanical strength after sintering. Using four-point bending test, it was demonstrated that by using MgO, the printing orientation did not affect the mechanical strength significantly anymore. The low Weibull modulus could be explained by the closed porosity that emerge during the degassing of the preceramic polymer due to cross-linking.

Highlights

Mullite, e.g. a mixed oxide ceramic based on 3Al2O3⋅2SiO2, is one of the most commonly used ceramic materials because of its remarkable thermal and mechanical properties [1,2]
We investigated the effect of MgO sintering additive on thermoplastic processing, sinterability, mechanical and microstructural characteristics of filaments and Fused deposition modeling (FDM)/FFF printed structures derived from preceramic polymer- γ-alumina mixtures, to achieve full mullite transformation and densification
The γ-Al2O3 (UF5) and MgO ceramic powders were characterized and the results are summarized in Table 2 and Fig. 1

Summary

Introduction

E.g. a mixed oxide ceramic based on 3Al2O3⋅2SiO2, is one of the most commonly used ceramic materials because of its remarkable thermal and mechanical properties [1,2]. The use of mullite in heat protection systems relies on its low thermal conductivity and refracto riness. Consid ering its low electric conductivity and dielectric constant, mullite can be employed for electrical insulation applications, for instance, a substrate for electronic devices as well [6]. Mullite is a rarely found natural ceramic ma terial, but often it is synthesized using alumina and silica-based raw materials by various methods, such as conventional powder metallurgy [7], atomic layer deposition (ALD) [8], sol-gel [9,10,11,12], co-precipitation [13], combustion [14], chemical vapor deposition (CVD) [15,16,17] and transient viscous sintering (TVS) [18,19]

Methods

Results

Conclusion