Today, metal represent the fastest-growing segment in the 3D printing industry. 3D metal powders already include various grades of stainless steel, low alloy steels, nickel and cobalt alloys, or other metal alloys, but many researchers are trying to create metal powders with titanium, which is valued for its distinctive properties and wide range of uses. (Read New Research on 3D Printing with Titanium.) Titanium is an especially important material in the surgical implant industry because the metal is not only strong and durable but also nontoxic and biocompatible. Here we highlight a few recent reports on new biomedical applications for 3D-printed titanium alloys.
Titanium + tantalum= better orthopedic implants
According to the A*Star Research web site, researchers from A*STAR’s Singapore Institute of Manufacturing Technology (SIMTech) and Wai Yee Yeong from the Singapore Centre for 3D Printing (SC3DP) have found a way to produce customized, patient-specific implants with improved stress absorption using a titanium-tantalum powder. Alloys with titanium and tantalum are desirable because they are biocompatible and mechanically superior to titanium alone, but tantalum doesn’t work well with the selective laser melting (SLM) process used to produce orthopedic implants. To overcome this problem, the team created an innovative titanium-tantalum alloy that can be printed into 3D shapes by SLM.
FDA approves novel spinal implants and custom cranial implants
3ders.org recently reported that a global medical device company received U.S. Food and Drug Administration (FDA) clearance for two of its 3D-printed spinal solutions; both designs allow for “bony integration” throughout the implant to mimic the lamellar structure of real human bones. The implants are 3D-printed using a titanium powder which is subjected to a high-energy laser beam, resulting in a precise lamellar pattern with a 3–5 μm surface roughness, which is impossible to create using any casting technique.
The FDA also recently approved the first 3D-printed cranial/craniofacial plate implant to be made from titanium, according to Med Device Online. Each implant is custom-made using MRI and CT scans from the individual patient, and 3D-printed using electron beam melting (EBM) technology, which allows for extremely precise specifications by using electron beams to melt and shape powdered alloys.
Titanium powder QC
According to 3D Printing Industry, gas atomization has become the most common technique to produce metal powders for additive manufacturing. Gas atomization is mostly used for Fe, Ni and Co alloys, but is also available for Al and Ti alloys.
After production, powders can be characterized according to various standard techniques. Just as with traditional metal manufacturing, these metal powders can undergo chemical composition analysis to determine the amount of metallic or non-metallic impurities (elemental form, or in dissolved form as solid solution or as compounds). Wavelength-dispersive x-ray fluorescence (WDXRF) is an elemental analysis technology that easily and positively characterizes any metal powder.
Other analytical techniques used on metal powders include:
- Hall flow: Flow rate and apparent density.
- Powder flow and rheological properties analysis.
- Angle of repose: Steepest angle of descent to which powders are piled without slumping.
- Tapped density: Bulk density of the powder after consolidation/compression.
- Morphology by scanning electron microscopy.
- Entrapped porosity by scanning electron or optical microscopy.
- Laser diffraction: Analysis of the particle size.
- Sieve analysis: Assess the particle size distribution.
Who knows where the next decade of 3D printing with metal powders will bring us. Let us know your thoughts.