uy Sémon speaks about the highly innovative carbon nanotube hairspring of the TAG Heuer Carrera Calibre Heuer 02T Tourbillon Nanograph.

“Since 1675, the year when Huygens invented the balance spring, nothing has changed. Except for the introduction of silicon. Ok, it’s antimagnetic, but the process is expensive and complicated – all that to make something that breaks. What’s more, LVMH does not have access to silicon, which was more reason to tackle the problem and give LVMH the capacity to produce its own hairsprings, independently. That’s where R&D comes in.

CARRERA HEUER 02T TOURBILLON NANOGRAPH

TAG Heuer Calibre Heuer 02T tourbillon manufacture movement with new in-house hairspring made of carbon composite, diameter 31mm, 33 jewels, balance oscillating at a frequency of 28,000 vibrations per hour (4Hz), 65-hour power reserve. Chronometer certified automatic tourbillon chronograph: hour and minute counters; tourbillon, hour, minute and seconds. 45mm case and lugs in black PVD titanium, carbon bezel with tachymeter scale, sapphire crystal with anti-reflective treatment on both sides, water-resistant to 100 metres (10 bar). Black open-worked dial with hexagon pattern, black flange with 60 seconds scale, black-gold plated chronograph minute and hour counters and tourbillon frame, rhodium-plated indexes and hands filled with SuperLuminova®, hexagon pattern. Price: CHF 24,900. Special packaging with integrated watch winder.

It’s a long story but I’ll make it brief. Back then I was doing some research into flexible materials. I was visiting a laboratory in New Mexico. On Sundays I’d get bored, so I’d read scientific literature. And that was when I came across an article on carbon. I went to take a closer look, in Utah, and I realised you could make hairsprings with carbon.

So I hired a Mormon PhD student, Jason, who was doing theoretical work on carbon and had designed chemical reactors to produce graphite-and-diamond-based composites, two carbon atoms but organised differently.

Graphene had already been discovered back in 1996, and with it you can produce nanotubes with interesting properties: no fatigue, no wear. But the laws of physics are different at the atomic scale and the macroscopic scale – the scale of a hairspring. They are not transposable. But with my teams I succeeded in developing a passage from the atomic to the macroscopic scale. It was a major theoretical advance, with major applications in physics and will soon be the subject of a publication.

Basically, it’s like making a cake while building the oven and thinking up the recipe. You mathematically calculate the geometry of the hairspring you want according to the required specifications, frequency etc., and with the aid of a molecular crayon, you draw it with iron atoms on a silicon base – a wafer – covered with a layer of aluminium oxide (like the butter in a cake tin). You then bake it in a reactor (the oven that we designed), the enclosure of which is made of solid quartz and which works at 950°. Into it we pump two gases, a hydrogen vector and an ethylene precursor, which release the carbon molecules. These molecules come to rest on the iron atoms and create a catalytic reaction, forming carbon tubes, like a field of wheat.

These nanotubes are empty, made up of empty mesh, their interiors are empty, the whole thing is 95% emptiness. Between these different carbon nanotubes that have sprung up following the hairspring shape we drew, we infuse carbon atoms that act like molecular glue.

The end result is a modulus of elasticity, which is nondeforming and springs back to its original position – the essential characteristic of a hairspring – without fatigue or creep. The hairspring is very lightweight, which reduces the effect of shocks. It can withstand up to 5,000g/1m fall. It is anti-magnetic, and with its anodised aluminium balance, perfectly thermo-compensated. Setting the watch is done in the traditional way with an inertia block and a standard index – which is not possible with silicon.

This carbon nanotube hairspring is extremely flat, which facilitates assembly, and 100% are chronometers. With our two machines, we’ve already attained a capacity of 120,000 items a year, but we’re planning to increase this. For its release, we chose to implement it in a tourbillon watch, a 4Hz movement, but with this extremely innovative process we can easily produce hairsprings for any frequency.

So it’s no marketing ploy, it’s science with substance and it offers LVMH the chance of becoming completely autonomous, and innovative, where hairsprings are concerned.”