Pacemaker battery case corrosion

Tom has a forty-year-old pacemaker can — titanium because it doesn't corrode in the body.

Lanthanum — I don't know any use of lanthanum except to make lanthanum hexaboride filaments for scanning electron microscopes. It's the lanthanide series, so it's famous for that. Titanium — 60,000 tons. Titanium is a fantastic metal in many ways. I have a little pacemaker can from forty years ago. Pacemaker that you put in your heart, to signal your heart with a pump. They've been making them out of titanium for fifty years, because titanium just doesn't corrode in the body. It also doesn't corrode in heat exchangers. It's got good high temperature capability. The Concorde flies on temperatures — the SR-71 Blackbird had a titanium skin. It was one of the first titanium aircraft. Aluminum wouldn't make it to 90,000 feet at the temperatures you get from frictional heating at the speeds those things go, Mach 3 or 4. The B-2 bomber is mostly titanium in terms of its skin.

Stainless pacemaker battery cases (for three major pacemaker companies) showing intergranular pitting; root cause traced to deionized water with pH 3.

Passivation of the stainless is something that comes up all the time. Most recently I was looking at, last night, one of my co-workers gave me this — a scanning electron microscope photograph of a pit. [Tom passes around a sample.] This is a titanium pacemaker case. This one's almost 35, 40 years old. They still make them sometimes out of titanium, but the battery cases are actually made out of stainless.