As everyone knows, the hairspring is a critical part of the movement. Well, it appears that they can be made of palladium! What is the advantage of this from a technical perspective. Link and photo below:

http://catalog.antiquorum.com/catalog.html?action=load&lotid=648&auctionid=209

 

Its all about stability at differing temperatures, steel changes its flexibility quite a bit with temperature, throwing off a timepieces rate.

If you really want to bend your brain, check out Gould's "The Marine Chronometer". Seems 200 years ago our friend Breguet made several experimental chronometers with GLASS hairsprings and cylindrical glass balances. These were too difficult to make to go into series production but were tough enough in use that when one was dropped, the balance staff broke, but not the glass spring.

 

So does Palladium change with temperature as much as steel? Also I'm guessing the glass was an idea for the silicon hairsprings...

 

I would assume palladium would change less than steel, that was always the goal of trying weird materials and alloys in hairsprings. "Elinvar", which I think really hit production in the 20s, was the great advance and I believe the name stood for "elasticity invariable" hinting at the alloys great stability over a wide range of temperatures.

I think the silicon hairsprings of today have more to do with silicone based plastics than glass. I used to be an engineer for a plastics firm and that stuff was showing up in all kinds of applications.

But then, I've consumed way too much espresso tonight and shouldn't be trusted to expound on any technical theories.

 

You can find thermal coefficients here for the elements:

https://en.wikipedia.org/wiki/Thermal_expansion_coefficients_of_the_elements_(data_page)

For "steel" you would have to know exactly what the "steel" was made of...