Slurry development for lithography-based additive manufacturing of cemented carbide components

Abstract

This article describes slurry development for lithography-based additive manufacturing (AM) of cemented carbide components. Due to their superior material properties compared to steels, tungsten carbide‑cobalt hardmetals are an exciting material for manufacturing tools. AM technologies' geometric freedom makes it possible to design more efficient tools compared to other manufacturing techniques. These technologies are known as resource-efficient and sustainable processes. The material that is not required for manufacturing is re-used for the production of additional components. The high energy input in laser powder bed-based AM processes leads to strong grain growth and brittle phases, so the achievable mechanical properties are significantly limited. Lithography-based additive manufacturing shows high potential due to the manufacturing of a polymer-bound green body and a subsequent heat treatment. Tungsten carbide‑cobalt (88–12 wt%) slurries were developed with a solid content of 40 vol%, based on the resin's reactive components. Dispersants made it possible to increase the maximum processable volume fraction of solid particles. A thixotropic agent helped stabilize the slurry. Rheological investigations characterized these effects. The influence of the photoinitiator concentration and the volume fraction of tungsten carbide and cobalt particles on the curing depth was analyzed. Prepared slurries and manufactured multi-layered green bodies were evaluated for homogeneity using quantitative microstructure analysis.