Fine coatings of bio-seramics with using well controlled thermal plasmas

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With the use of the well-controlled thermal plasma reactor based on the newly designed forced constricted type dc plasma jet generator, application feasibility for advanced materials fine process is studied, mainly functionally graded coatings (FGC) of hydroxyapatite (HAP). Findings are as follows:1. The image spectroscopic system composed of a double wavelength optical system and the gated ICCD camera has been developed. This system can measure two dimensional temperature distribution and parameters of injected spraying particles. Relationship between parameters of injected spraying particles and quality of prepared films is discussed.2. Preparation of Ti-HAP FGC films are studied under various spraying conditions. The adhesion strength, the Vickers hardness, c-axis orientation and the porosity of prepared FGC films are well controlled with spraying conditions. Simulated body fluid test of HAP coatings is also discussed and apatite is newly formed on the surface of the coatings.3. A continuous synthesis method to produce carbon nanofibers (CNFs) including multi-walled carbon nanotubes is studied. CNFs production using catalyst powders (Fe, Ni) is more enhanced compared to that using only CH_4/H_2 gas mixtures.4. Plasma spray gun has been newly designed as dual anode type plasma spray gun which can generate stable and high power plasma jets for a long time at various operating conditions. Using this, under laminar plasma jets in the air, TiO_2 powders with anatase and rutile types mixtures are directly and effectively synthesized from raw Ti powders.