Although a composite, most of Sandvik’s material is diamond. To make it printable and dense it needs to be cemented in a very hard matrix material, keeping the most important physical properties of pure diamond.
“Historically, 3D printing in diamond was something that none of us imagined was achievable,” explains Anders Ohlsson, delivery manager at Sandvik Additive Manufacturing. “Even now we are just starting to grasp the possibilities and applications that this breakthrough could have.
“On seeing its potential, we began to wonder what else would be possible from 3D printing complex shapes in a material that is three times stiffer than steel, with heat conductivity higher than copper, thermal expansion close to Invar, and density close to aluminium,” he adds. “These benefits make us believe that you will see this diamond composite in new industrial applications ranging from wear parts to space programmes, in just a few years from now.”
Mikael Schuisky, head of R&D and operations, says: “The additive manufacturing process used is highly advanced. We are printing in a slurry consisting of diamond powder and polymer using stereolithography.”
The step after 3D printing is, however, even more demanding. Here, Sandvik has developed a tailor-made, proprietary post-processing method that makes it possible to achieve the exact properties of the super-hard diamond composite.
“This step was extremely complicated,” says Schuisky. “However, after extensive R&D efforts and trials we managed to take control of process and made the first 3D printed diamond composite.”
Annika Borgenstam, professor at the Department of Materials Science and Engineering at Stockholm’s KTH Royal Institute of Technology, says: “Rather than looking to actually develop completely new materials, the big push within today’s industry involves the often radical restructuring of existing materials. Using processes such as additive manufacturing will open up completely new ways of using the same types of materials that we have today, by building in the properties that we need.”
Another key advantage of additive manufacturing is that it allows engineers to minimise material waste, making the technology more sustainable. The diamond powder in Sandvik’s process can be extracted from the polymer in the slurry after printing, and then be recycled and reused in another print job.
Sandvik’s diamond composite has been tested and found to have extremely high hardness and exceptional heat conductivity, while also possessing low density, and very good thermal expansion and corrosion resistance.
