Biomedical parts created using the new cold spray 3D printing process


Researchers led by Cornell scientists have developed a new 3D printing technique that creates cellular metal materials using a unique process that shatters dust particles together at supersonic speeds. The technology is known as “cold spray” and creates a mechanically strong and porous structure that is 40% stronger than similar materials made with conventional manufacturing processes. The small size of the structures and the porosity make them suitable for building biomedical components, such as spare joints.

The lead author of the research article is Atieh Moridi. He says the cellular structures the team focused on have applications in thermal management, energy absorption, and biomedicine. Instead of using heat as the driving force behind bonding, the new technique uses plastic deformation to bind dust particles together. Rather than carving a shape from a large block of material, the additive manufacturing technique used here builds the product layer by layer.

A disadvantage of additive manufacturing is that typically metallic materials must be heated to high temperatures to exceed their melting point resulting in the accumulation of residual stresses, distortions and unwanted phase transformations. The researchers developed their new method to eliminate these problems by using a compressed gas nozzle to shoot titanium alloy particles at a substrate.

The particles used in the process have a diameter between 45 and 106 microns and travel at about 600 meters per second. The team notes that they don’t just throw metal particles as fast as possible. They had to carefully calibrate the ideal speed of the titanium alloy. The team determined the velocity that was just below the critical velocity of the alloy particle.

The particles thrown at that speed create a more porous structure ideal for biomedical applications, such as artificial joints and cranial or facial implants. The team says these porous constructions allow bone to grow within the pores to create biological fixation. This reduces the likelihood of the implant loosening and causing pain.

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