Polycrystalline Diamond Characterisations for High End Technologies

Abstract

Characterisations of polycrystalline diamond (PCD) coatings have routinely been done over the past three decades of diamond research, but there is less number of reports on some of its very unique properties. For example, diamond is the hardest known material and, in probing such hard surfaces with any indenter tip, it may lead to damage of the instrument. Due to such chances of experimental accidents, researchers have performed very few attempts in evaluating the mechanical properties of PCDs. In the present work, some of these very special properties of diamond that are less reported in the literature are being re-investigated. PCDs were characterised by photoluminescence (PL), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscope (TEM), and X-ray diffraction (XRD) techniques. The diamond surface was also polished to bring the as-grown micron level of surface roughness (detrimental for wear application) down to few hundreds of nanometer. The tribological properties of such polished and smooth surfaces were found to be appropriate for wear protective coating application. This chapter revisits some of the unreported issues in the synthesis and characterisation of PCD coatings grown on Si wafer by the innovative 915 MHz microwave plasma chemical vapour deposition (MPCVD) technique.

Synthesis of Polycrystalline Diamond Films in Microwave Plasma at Ultrahigh Concentrations of Methane

“…High hardness and thermal conductivity, wear resistance and chemical inertness are the key properties of diamond-based materials [1][2][3], so polycrystalline diamond (PCD) films and composites [4][5][6] can be used in heat sinks [7][8][9][10], hard coatings for cutting tools [11][12][13] and protective layer applications [14][15][16]. Based on the average size of diamond grains, polycrystalline diamond materials are classified as microcrystalline (MCD), nanocrystalline (NCD) and ultrananocrystalline (UNCD) [17][18][19][20].…”