Stability of reference masses: VII. Cleaning methods in air and vacuum applied to a platinum mass standard similar to the international and national kilogram prototypes
Peter J Cumpson, Naoko Sano, Anders J Barlow, Jose F Portoles
METROLOGIA | IOP PUBLISHING LTD | Published : 2013
Mercury contamination and the build-up of carbonaceous contamination are two contributing factors to the instability observed in kilogram prototype masses. The kilogram prototypes that lie at the core of the dissemination of the SI base unit were manufactured in the late 19th century, and have polished surfaces. In papers IV and V of this series we developed a method for cleaning noble metal mass standards in air to remove carbonaceous contamination. At the core of this 'UVOPS' protocol is the application of UV light and ozone gas generated in situ in air. The precise nature of the carbonaceous contamination that builds up on such surfaces is difficult to mimic demonstrably or quickly on new..View full abstract
The authors are very grateful to Dr Keith Moore of the Royal Society and Professor Martyn Poliakoff of Nottingham University for advice, making them aware of the existence of RS2 and for permission to clean it using their UV/ozone and GCIB procedures. J F Portoles is grateful for the support of the Newcastle/Durham EPSRC Knowledge Transfer Account (KTA). The authors are very grateful to Mr Mike Foster of Newcastle University for assistance with suitable reference weights for this work.