Studies of molybdenum surface modification for growth of adherent CVD diamond film

Abstract

Surfaces with very poor mechanical and frictional properties can be improved, or even, acquire new properties similar to diamond if good adherent CVD diamond film is obtained on it. In this work, nitrogen ions were sub-implanted on pure molybdenum as a means to enhance CVD diamond film adherence. Deposition time from 2 up to 60 h were used for deposition of 10 to 400 µm thick CVD diamond films with very good adherence on sub-implanted molybdenum substrate. Characterizations were carried out by XPS, X-ray diffraction and nano indentation on prepared surfaces prior to diamond growth and after the onset nucleation. The ionic sub-implanta-tion with nitrogen possibly assists in adhesion, with the creation of a thin layer of nitrates and complexes. fect of intrinsic and extrinsic stresses involving diamond and DLC films on different kinds of substrate materials 6,7. More specifically, adherence between CVD diamond film and metallic substrate represent, for many research groups, the challenge to overcome. The main problems are related to difference in thermal expansion coefficient and adherence between the substrate and the diamond film. Using different kind of surface preparation and intermediate interface , good adherence between CVD diamond and WC-Co, Si 3 N 4 , SiC, and others 1,8,9 have been obtained with relatively success in order to improve the lifetime of different kind of tools. Stainless steel and tool steel have been tried as a permanent substrate for CVD diamond growth, where, at the first time, the sub-implantation was mentioned 9 as a surface preparation technique. Nitride films are known as a diffusion barriers in microelectronics devices and as well as superconductors 10. Synthesis and analysis of mo-lybdenum nitrites formed during ion implantation were investigated by some authors in order to improve molybde-num tribologycal properties and to understand the complexes formed 11,12 .