Nanodiamond and Nanocarbon
Nanocrystalline diamond (NCD) is a thin film of diamond with nanometre size crystals, usually supported on a silicon wafer.
However, NCD can be grown on many other substrates such as metals, quartz and other transparent glasses, piezoelectrics etc. NCD has most of the extreme properties of diamond but at a substantially reduced cost, larger area and more practical format.
These films are grown by Microwave Plasma Chemical Vapour Deposition (CVD) under low pressures (see Diamond Growth). In this process methane gas diluted with hydrogen is activated by microwave energy to very high gas temperatures (3000 K) in a plasma. This plasma contains a complex mixture of hydrocarbons and atomic hydrogen. At the edge of this plasma, the carbon containing species condense into diamond. The atomic hydrogen etches back any non-diamond carbon so high purity diamond can be grown. Diamond is generally grown at 800 °C but can be grown below 400 °C at a reduced growth rate.
NCD has many diverse applications. The extreme mechanical properties make it an ideal material for Nano/Micro-Electro-Mechanical Systems. Its low friction and wear properties make it an advanced tribological coating. The surface stability, chemical inertness and electrochemical properties are currently being exploited for bio-sensing. The thermal conductivity properties are being investigated as a next generation insulator for silicon CMOS electronics. For more info please visit the Cardiff Diamond Foundry.
