Vat Photopolymerization of Cemented Carbide Specimen.

Timo Bernthaler,Dirk Sellmer,Tim Schubert,Gerhard Schneider,Andreas Kopp,Thomas Rieger,Juliane Meese-Marktscheffel,Julian Schurr,Alexander Wolff,Michael Schwenkel

doi:10.3390/ma14247631

Timo Bernthaler, Dirk Sellmer + Show 8 more

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https://doi.org/10.3390/ma14247631

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Abstract

Numerous studies show that vat photopolymerization enables near-net-shape printing of ceramics and plastics with complex geometries. In this study, vat photopolymerization was investigated for cemented carbide specimens. Custom-developed photosensitive WC-12 Co (wt%) slurries were used for printing green bodies. The samples were examined for defects using quantitative microstructure analysis. A thermogravimetric analysis was performed to develop a debinding program for the green bodies. After sintering, the microstructure and surface roughness were evaluated. As mechanical parameters, Vickers hardness and Palmqvist fracture toughness were considered. A linear shrinkage of 26–27% was determined. The remaining porosity fraction was 9.0%. No free graphite formation, and almost no η-phase formation occurred. WC grain growth was observed. 76% of the WC grains measured were in the suitable size range for metal cutting tool applications. A hardness of 1157 HV10 and a Palmqvist fracture toughness of 12 was achieved. The achieved microstructure exhibits a high porosity fraction and local cracks. As a result, vat photopolymerization can become an alternative forming method for cemented carbide components if the amount of residual porosity and defects can be reduced.

Highlights

Cemented carbides are mainly used in the manufacturing industry for cutting, grinding, and drilling applications
A powder sample was homogeneously distributed on a scanning electron microscopy (SEM) sample holder using the Nebula Particle Disperser (Thermo Fisher Scientific, Dreieich, Germany)
This study shows that vat photopolymerization can be used to manufacture cemented carbide green bodies

Summary

Introduction

Cemented carbides are mainly used in the manufacturing industry for cutting, grinding, and drilling applications. These materials are characterized by high strength and wear resistance, especially at high temperatures and in corrosive environments [1]. Tools made of cemented carbides are usually manufactured through pressing and extrusion with subsequent sintering [4]. Metal powder injection molding (MIM) can be used to manufacture cemented carbide components [5]. Pressing and the MIM process require a specific and expensive tool for each individual component, which makes the manufacturing of small batches only rarely economically attractive. Post-processing has limited applicability and is expensive for cemented carbide components. Unused material can be reused for printing new components [6]

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