A new approach on enhanced near-infrared absorption for laser powder bed fusion using reduced graphene oxide will dramatically widen the number and capability of materials for laser processing.
Laser powder bed fusion (LPBF) is a revolutionary manufacturing technology that fabricates parts with unparalleled complexity, layer-by-layer. However, there are limited choices of commercial powders for LPBF, constrained partly by the laser absorbance, a research area that up until now, has not been well investigated.
Carbon additives are commonly used to promote near infra-red (NIR) absorbance of the powders but their efficiency is limited. Researchers from University College London (UCL) Materials, Structure, Manufacturing group at Harwell (MSM@H) in collaboration with Imperial College London, Research Complex at Harwell, Harwell XPS, and Diamond Light Source have achieved a first successful demonstration of reduced graphene oxide (rGO) as a near-infrared (NIR) absorber for additive manufacturing (AM) powder feedstock using an AM process replicator coupled with operando synchrotron X-ray imaging and chemical characterisation techniques.
This study, published in Applied Materials Today, shows the first in situ quantification of AM fused silica, revealing laser-matter interaction and powder consolidation mechanisms. The team also found that the NIR absorbance of rGO was 3 times better than conventional nano-carbon additives. AM of high NIR absorbance powder enabled the successful fabrication of overhang structures without pre/post heat treatment, and thus enhancing AM productivity. This approach will dramatically widen the palette of materials for laser processing and enable existing LPBF machines to process low absorbance powder, e.g. SiO2, using a NIR beam.
‘This work cannot be done without a great team. We are excited to showcase new ways to engineer next-generation feedstock materials for AM as well as making the process more efficient and sustainable.’ Dr. Chu Lun Alex Leung (UCL)
The full paper can be found at: https://doi.org/10.1016/j.apmt.2021.101009