Electromagnetic acceleration plasma generators, which are called Magneto-Plasma-Dynamic (MPD) arcjet generators, can produce higher-velocity, higher-temperature and higher-density plasmas than those of conventional thermal plasma torches, because MPD arcjet plasma is efficiently accelerated by electromagnetic body forces in MW-class input power operation. These properties are effective for deposition of rigid coatings adhering strongly to substrate surfaces. In the present study, we newly developed an ablation type MPD arcjet generator for titanium nitride (TiN) reactive spray coatings. The coatings were deposited onto steel substrate. The phase structure and the composition of the coatings were analyzed by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD), and their Vickers hardness were measured. These analyses showed that the MPD spray process could successfully form dense and uniform titanium nitride coatings. The properties of the titanium nitride coatings were highly sensitive to the titanium cathode diameter and discharge current.

The quasi-steady magneto-plasma-dynamic (MPD) arcjet generator is a promising plasma accelerator, which has a coaxial electrode structure similar to those of conventional plasma torches. The MPD arcjet generator utilizes principally electromagnetic acceleration of the interaction between the discharge current of kiloamperes and the azimuthal magnetic field induced by the discharge current, although the working gas is accelerated aerodynamically through a nozzle in a thermal arcjet generator. In this paper, ablation-type MPD arcjet generators are developed for ceramic coatings. Discharge voltages and ablation rates of ceramic materials are examined, and front velocities of ablated atoms of ceramic component are also estimated using a streak camera. The Vickers hardness of coating is measured. Their cross sections are observed with a scanning electron microscope, and their surfaces are analyzed by means of x-ray diffraction and x-ray photoelectron spectroscopy. Paper includes a German-language abstract.