CERAMIC COATINGS USING MAGNETO-PLASMA-DYNAMIC ARCJET GENERATORS

For applications of quasi-steady magneto-plasma-dynamic (MPD) arcjet generators to ceramic coatings, an MPD arcjet generator with a cathode covered with a ceramic material was developed. The front velocities of ablated Al atoms inferred with a streak camera were much higher than velocities of 200-500 m/s for conventional plasma torches. This is effective for deposition of rigid films adhering strongly to substrate surfaces. The MPD plasma spraying showed that a dense uniform ceramic film with above 1200 Vickers hardness was deposited. Further-more, from the XPS spectra the peak area ratio of Si/Al for the coating almost equaled that for the raw ceramic material, and the valence numbers of Al and Si did not change.