Self-compensating spiral for a spiral balance-wheel in watchwork and process for treating this spiral

摘要

This self-compensating spiral for a mechanical spiral balance-wheel oscillator in watchwork or other precision instrument, made of a paramagnetic alloy, contains at least one of the elements Nb, V, Ta, Ti, Zr, Hf and is covered with a substantially uniform oxide layer having a thickness greater than or equal to 20 nm, formed by subjecting the said spiral to an anodizing treatment.