Uppsala University researchers, in collaboration with graphene materials company Graphmatech, demonstrated a method for lowering the reflectivity of copper powder. The work could lead to more densely printed parts through laser additive manufacturing (AM).
Copper poses certain challenges in the context of AM; at the wavelengths commonly used in laser powder bed fusion, which is the most common technique in metal AM, only a small portion of the energy is absorbed by the material, which results in low-density printed parts.
A newly introduced graphene coating significantly lowered the reflectivity of the copper powder. Courtesy of Uppsala University and Graphmatech.
With Graphmatech’s technology, the researchers — led by Ulf Jansson, a professor at Uppsala University — were able to modify the surface of the copper powder to reduce the reflectance by up to 67%, said Graphmatech CEO Mamoun Taher.
“By coating the surface of the copper powder with graphene, the powder surface characteristics — morphology, conductivity, roughness — are altered, changing the way the laser light interacts with the surface, and improving the absorption properties,” Taher told Photonics Media.
The graphene was also able to survive the printing process, which positively affected the density of the printed copper-graphene parts by making them less porous.
“The new process developed to coat metal powder with graphene opens up very interesting perspectives for the design of new materials in various applications,” Jansson said.
Taher noted that with electrification, the demand for copper has gone up significantly. By reinforcing copper with graphene technology, he believes inability to meet that demand can be alleviated.
“Not only could our composites mean less material would be needed for the same technical performance, but we can also boost the properties of other (less finite or energy intensive) materials to potentially substitute copper and other materials in a range of industrial applications,” Taher said.
The technology may also be able to reduce carbon emissions, and has the potential to positively affect a number of potential applications, including e-mobility, electronics, and defense.
“Copper is intensively used in automotive parts and electronics (as well as many other industrial applications) due to its ductility and high conductivity. But because of the issues with reflectivity, it has been extremely challenging to manufacture parts via additive manufacturing,” Taher said. As a result, he said, copper parts are often produced through methods that are more energy intensive, are less efficient, and offer less flexibility in design. Improving the processability of copper with the graphene technology may be able to increase production and reduce waste, enable the 3D printing of copper on a range of common 3D printers, and produce components that are potentially stronger, thinner, and more conductive than pure copper, as well as saving on weight and cost.
Taher said that the development of any new material or technology tends to pose a number of challenges, though as of yet, the researchers haven’t identified any drawbacks.
Graphmatech is now working to scale up the technology, and has already reported advances in a number of applications
“Graphmatech is working with industrial partners not only on a wide portfolio of coated metal powders, but also on metal composites, polymer composites, and energy storage or battery applications,” Taher said. “In each case, the graphene is incorporated and tuned according to application and the customers’ needs — whether they be improved processability for metallurgy with better-flowing powders, or improved strength, wear resistance or conductivity in plastics or rubbers, or higher-density energy storage.”
Taher also lists corrosion resistance and anti-bacterial properties as potential added functionalities with the technology. Other applications include more efficient, sustainable manufacturing, lightweight but strong automotive and aerospace parts, and lighter and more efficient electronics.