The Uses of Iridium: From Medicine to Aerospace

Samuel Matthews: Welcome to SAM Materials Insight. A podcast that explores the advanced materials shaping our world. I'm your host, Samuel Matthews. Today, we're discussing an element that operates at the absolute limits of performance: Iridium.

Despite being one of the rarest elements on Earth, its role in modern technology is critical. To help us understand why, I'm delighted to be joined by Dr. Elena Rostova, a professor and a leading global expert on high-temperature metals. Elena, welcome to the show.

Dr. Elena Rostova: Thank you, Samuel. It's a pleasure to be here.

Samuel Matthews: Elena, let's start with the basics. Iridium is often described in superlatives—the most corrosion-resistant, one of the densest. But from a practical standpoint, what does that truly mean for an engineer or a designer?

Dr. Elena Rostova: It means a fundamental shift in what is possible. When you work with Iridium, you're designing for environments that would destroy almost any other material. Its corrosion resistance isn't just about withstanding harsh chemicals; it is about maintaining integrity in molten metals or aggressive salts at temperatures exceeding 2 000 degrees Celsius. This represents enabling technology that would not exist otherwise.

Samuel Matthews: A compelling point. This brings to mind its use in laboratory crucibles. Could you elaborate on why Iridium is the material of choice here, and what industries rely on this capability?

Dr. Elena Rostova: Certainly. In materials research and production, particularly for high-purity crystals like those used in LEDs or semiconductors, even minute contamination can ruin a batch. Iridium crucibles provide an inert, high-strength container that does not react with the melt and can survive countless heating and cooling cycles. The entire field of producing certain single-crystal oxides relies heavily on this application.

Samuel Matthews: So, it is foundational for downstream innovation. Now, let's transition from the laboratory to life-saving medicine. The use of Iridium-192 in brachytherapy for cancer treatment is, to many, a surprising application. How does a materials scientist view this use case?

Dr. Elena Rostova: It is a clear example of material science directly impacting human health. Iridium-192 emits gamma rays with an energy profile that is effective for targeted radiation therapy. From a materials perspective, the challenge is not just the radioactivity; it is fabricating the source into a tiny, robust, and perfectly sealed capsule that can be safely implanted in the body. Iridium's metallurgical properties make it ideal for this precise and demanding fabrication.

Samuel Matthews: Balancing nuclear properties with mechanical integrity—a multidisciplinary challenge. Now, from the human body to the vacuum of space. Iridium's role in aerospace is significant. Beyond just "corrosion resistance," what specific performance metrics make it irreplaceable for satellite and spacecraft components?

Dr. Elena Rostova: In aerospace, we talk about mission-critical components. Take satellite thrusters, for example. Iridium is used in rocket engine nozzles and ion thrusters because it maintains its shape and strength under extreme thermal shock and erosion from high-velocity propellants. The cost of a satellite failure is substantial, so the material's reliability and its ability to perform for 15 years in orbit without maintenance is key. That reliability has a name: Iridium.

Samuel Matthews: "Reliability has a name." That succinctly captures its value proposition. Finally, in an increasingly electrified world, Iridium also finds a role in electrical contacts. Why is it selected over other precious metals?

Dr. Elena Rostova: While metals like gold or platinum are excellent conductors, they are relatively soft. In applications where electrical contacts must open and close frequently under load—such as in critical aerospace or defence relays—a phenomenon called "arc erosion" occurs, which degrades the contact. Iridium's exceptional hardness and arc erosion resistance ensure a stable, low-resistance connection over a significantly longer lifespan, which is crucial for safety and system integrity.

Samuel Matthews: Elena, thank you. This has been a masterclass in how a single element, through its unique properties, becomes a keystone for progress across such a diverse range of fields.

Dr. Elena Rostova: Thank you, Samuel. It was a pleasure to discuss it.

Samuel Matthews (to the audience): This is Samuel Matthews. If your projects are pushing the boundaries of the possible and demand the unique capabilities of Iridium or other platinum group metals, we invite you to connect with the technical team at Stanford Advanced Materials. Explore our portfolio and reach out to us to discuss how we can provide the material foundation for your next breakthrough.

Join us for our next episode, where we will have a closer look at piezoelectric crystals.