Thermal Stability of Nanocrystalline Diamond Films Grown by Microwave Plasma Chemical Vapor Deposition

ABSTRACTIn this work, the open-air thermal stability of nanocrystalline diamond films grown on mirror-polished titanium alloy substrates by the Microwave Plasma Chemical Vapor Deposition (MPCVD) technique was studied. The results of this investigation show that nanocrystalline diamond films are highly stable in air up to 600°C with no significant change in mechanical properties. Samples annealed between 600°C and 650°C, however, exhibit values of hardness lower by as much as 40% compared to as-grown samples. Above 650°C serious delamination effects were observed in the coatings.