WatchTech - Well, I dont think 99% is good enough for wacthes running +20K bpm.

Well, I dont think 99% is good enough for wacthes running +20K bpm.

Thank you for the reply. I appreciate the time you took to respond. As another, but occasional, nanolab user, I respectfully disagree with your assessment. Being able to synthesize 99% purity Si (or even 100% Si) does not guarantee a crystal defect free hairsping that also has a very large aspect ratio (length/approx. diameter>100). In addition, the curvature of the hairspring undoubtedly will induce internal stress gradient across the thickness. Therefore, the hair spring is not subjected to uniform stress. Considering also the fact that we do not live in a world at absoute zero termperature, vibrations of atoms in the crystal lattice can result in the hopping (i.e. transport) of atoms, e.g. O or some other impurities, as well as vacancies within the Si hairspring, and this can result in the accumulation of imperfections (aka cracks) ultimately leading to failure somewhere within hair spring. Now, if Si crystals that can self-heal the nano-cracks were to be developed, then that will be a different story. Of course, this is already happening in the research labs as we communicate, and may have already been done and published in the literature.

Cheers

Jim

What is the current status of mean failure time of silicon balance springs ?

By: jimjenkins : December 26th, 2013-12:12

Dear Watch Enthusiasts: First, by best wishes to you all for the 2014 and beyond. I have occasionally been following the increased uses of silicon as a balance spring (hair spring). The stated purpose for such use is to eliminate the magnetization problem...

That's a great question ...

By: nilomis : December 26th, 2013-15:41

I consider horology as a class of "slow science", since it must deal with items that we expect should last for a time span that is greater than our existence. New materials, like the silicon balance spring IMHO will be validated after we ... depart. Same ...

Here's an interesting article on the subject

By: ianny : December 27th, 2013-03:04

Regards, ian

Excellent question...

By: DonCorson : December 27th, 2013-03:20

Excellent question. I have heard that the silicon springs are more stable than steel. They return to form in cases where steel are deformed. There is certainly a limit at which they break and as you say the purity of the crystals will play a big part in t...

Some thoughts

By: iim7v7im7 : December 28th, 2013-04:48

Personally, I am less concerned about fracture mechanic induced failures from fatigue than I am from watchmaker induced component damage. At 4 Hz and beyond, > million cycles is achieved in days (a 4hz watch sees 245 million beats per year). Fatigue ba...

Very good point...

By: jimjenkins : December 28th, 2013-11:19

So another question to ask will be how does a silicone mainspring will respond to technicians nicks and bruises compared to metallic ones. My initial concerns were based on the manufacturing process, which is imperfect. However, your point is extremely im...

I'm a bit confused as to why liquidmetal

By: Ed. W : January 15th, 2014-18:59

hasn't been used or at least considered. It's much more resistant and in theory should not be prone to the cracking you described.

A couple things to note

By: nmanousos : January 31st, 2014-19:59

"Since it is very difficult to synthesize perfect crystals of silicon spring, some nano-sized cracks or surface imperfections can remain" Silicon can very easily be made with very high purity, beyond 99%. All of the semiconductors in your computer and pho...

Well, I dont think 99% is good enough for wacthes running +20K bpm.

By: jimjenkins : February 8th, 2014-11:05