Formation of a Crack-Free and Debonding-Resistant Boron-Doped Diamond Thin Film on Titanium Using a Dual-Coating Strategy

Producing continuous, conductive diamond film on titanium is critical to using this metal for electrochemical electrodes, bipolar current collector plates in fuel cells, and prosthetic implants. A common problem with coating polycrystalline diamond on titanium is the stress-cracking that results from the difference of a factor of 10 in the thermal expansion coefficient for the two materials. A dual coating strategy was evaluated for its effectiveness at forming stress-free thin films of boron-doped diamond on titanium. Using microwave plasma-assisted chemical vapor deposition, a layer of boron-doped nanocrystalline diamond was first deposited on titanium, followed by deposition of a layer of boron-doped microcrystalline diamond.