Onion-like carbon deposition by plasma spraying of nanodiamonds Original Research Article

A deposit of carbon nanoparticles based on an onion-like structure was fabricated from detonation nanodiamond powders by a novel plasma spraying process, electromagnetically accelerated plasma spraying (EMAPS). EMAPS was able to transform nanodiamonds to onion-like structured carbon within 300 μs through a thermal graphitization process in which the temperature of the particles would be in the range of 2700–4500 K. Synthesized onion-like carbon nanoparticles were spherical or polyhedral. The G-band in the UV–Raman spectra of the produced deposits was found to be a superposition of a characteristic band of well-formed carbon onions at 1571 cm−1 and the G-band of defective carbon onions at 1592 cm−1. The availability of a plasma spraying process for developing solid lubricant coatings incorporating nanodiamond and onion-like carbon was demonstrated.