Investigating the mechanisms of diamond polishing using Raman spectroscopy

Jonathan Hird (1) , Matthew Bloomfield (2) , Ian Hayward (2)

1 Cavendish Laboratory
2 Spectroscopy Products Division

Recent research has shown that a phase transformation of the diamond to a different form of carbon is involved when diamonds are polished in the traditional fashion. The question as to how this phase transformation is activated and maintained to produce high wear rates is of great technological interest since it may radically change the way we view the processing of diamond. This paper describes the use of Raman spectroscopy to examine debris produced on the diamond polishing wheel, both during its preparation and during polishing. In addition, polished diamond surfaces were examined for the possible existence of non-diamond surface layers in an attempt to identify material removal mechanisms. Raman spectroscopy proves ideal for these analyses because its relatively high spatial resolution is well suited to the analysis of small wear features and debris particles, and because of the wealth of information it reveals about chemical structure. This level of structural information has been lacking in previous analyses of diamond polishing debris. In addition to the non-diamond carbon found in the wear debris, significant quantities of two iron oxides – magnetite (Fe₃O₄) and hematite (α-Fe₂O₃) were also found. An interesting observation was that a transformation from magnetite to hematite could be induced either by using high power laser excitation, or by frictional heating during polishing. It is suggested that some of the Raman peaks previously attributed to lonsdaleite might better be explained by the presence of these oxides.

Mots clés: Physical Sciences

Jonathan Hird, Matthew Bloomfield, Ian Hayward. Investigating the mechanisms of diamond polishing using Raman spectroscopy. Philosophical Magazine, 2006, 87 (02), pp.267-280. ⟨10.1080/14786430600953772⟩. ⟨hal-00513765⟩