Ask the Expert: Solar Atmospheres Director of Sales Explains Heat Treating for Titanium Medical Components

1. When my titanium medical components are heat treated, should I be concerned about surface contamination?

YES! Surface contamination of titanium is typically caused by the presence of oxygen, nitrogen, and/or carbon gas while the titanium is at an elevated temperature. It is permanent unless removed mechanically or chemically. It can lead to fracture and component failure in service if not removed.

2. Is there a heat-treating temperature at which surface contamination starts to be a concern?

Yes. AMS 2801, which is a widely-used aerospace specification for the processing of titanium parts, requires one surface contamination test be performed on a sample from all heat treatments over 1000°F …even in vacuum. Although this is a widely used threshold, the design engineer of medical components should always carefully consider the risk of surface contamination caused by heat treating.

3. I have a finished titanium medical component and I need it heat treated. What do I do?

Find a heat-treat supplier that knows the risks and has the right tools for the job. The chosen heat-treat supplier will have an all-metal hot zone vacuum furnace capable of operating at a pressure near 1×10^-6 Torr …not just any vacuum furnace will be sufficient. That supplier should also be MedAccred accredited for the processing of titanium medical components.

4. If I want to test for surface contamination on my titanium medical components, how do I go about that?

Again, find a laboratory that is accredited by MedAccred to perform the test. MedAccred accreditation comes only after an intense audit which tests the competency of the laboratory performing the test. Any laboratory that is MedAccred accredited (for the specific test) is your best bet.

5. I want to join titanium to 304 stainless steel and copper with a hermetic seal, can that be done?

YES! Titanium may be effectively vacuum brazed to both of those materials, and others, to produce a hermetic seal easily capable of a leak rate less than 1×10^-9 standard cubic centimeter per second of helium at one atmosphere pressure differential. A leak of that rate would take 32 years to pass 1 cubic centimeter of helium gas! There may be size limitations for brazing based on the coefficient of thermal expansion of the materials being joined, however effective braze joints are made on titanium medical assemblies using the vacuum brazing process.

For more information: https://solaratm.com/markets/medical

And featured in Today’s Medical Developments: https://www.todaysmedicaldevelopments.com/article/heat-treating-titanium-medical-components