01/11/2019
Silicon carbide turbine rotor produced by LSD-print Additive Manufacturing technology

Silicon carbide turbine rotor produced by LSD-print Additive Manufacturing technology

Source: BAM, Ceramic Processing and Biomaterials division, in collaboration with KYOCERA Fineceramics Precision GmbH

Silicon carbide (SiC) is an important technical ceramic material, combining properties such as low thermal expansion coefficient, high hardness, elastic modulus and thermal conductivity. For these reasons, SiC ceramics find application in different fields such as cutting tools, as structural materials, for high-temperature applications or for heating elements.

Silicon infiltrated silicon carbide (SiSiC) is a material produced by infiltrating metallic silicon into a porous SiC powder compact: a process which is advantageous since it involves a near-zero volume change. SiSiC shares many of the exceptional properties of SiC and it is one of most utilized SiC-based materials. Both SiC and SiSiC are however brittle and extremely abrasive materials, which causes the shaping of components to be challenging and expensive for complex geometries.

In the past 20 years, Additive Manufacturing (AM) technologies have been developed and are starting to find industrial application also in the field of technical ceramics. In AM, compared to subtractive manufacturing, a component is built by adding a material, typically layer-by-layer. These technologies offer great potential for novel applications as there have less geometrical limitations and the process is tool-less.
A popular AM technology is binder jetting, in which the shape of an object is defined by selectively jetting a binding material on thin layers of powder, which are deposited one upon another.

A typical limitation of this process is, however, that the powder packing density is not high enough to obtain final parts with sufficient density. For this reason, a process named Layerwise Slurry Depositon (LSD) was developed in the past years. In the LSD process, thin layers of a ceramic suspension are deposited by means of a hollow blade and dried subsequently. The process which results from the combination of LSD and binder jetting is named LSD-print. Major advantages of the LSD process, compared to the standard process using dry powder, are a higher versatility of powders that can be used and a high packing density, which is achieved during deposition and drying of the layers.

The current work presents for the first time results on the LSD-print of SiSiC parts, in which the AM of components with complex geometry was demonstrated.
Density measurements confirmed that the manufactured parts had high powder packing density and that these parts could be infiltrated with molten silicon to form high-density SiSiC. The density, microstructure and the mechanical strength of the manufactured material was also comparable to state-of-the-art SiSiC, which was manufactured conventionally and used as benchmark for the characterization.

Additive manufacturing of SiSiC by layerwise slurry deposition and binder jetting (LSD-print)
Andrea Zocca, Pedro Lima, Sarah Diener, Nikolaos Katsikis, Jens Günster
published in Journal of the European Ceramic Society, 2019, Volume 39, Issue 13, Pages 3527-3533
BAM, Ceramic Processing and Biomaterials division