Preparation and investigation of the structure and properties of Al2O3 plasma-detonation coatings

Using a specially designed and constructed plasmatron, combining the plasma and detonation technologies, aluminum oxide coatings with high adhesion an d strength (19.8 GPa) were obtained for the first time. The samples were st udied by the transmission electron microscopy and X-ray diffraction methods and characterized for the first time by the Rutherford backscattering and proton elastic resonance measurements. It was found that the aluminum oxide coatings are composed of 0.20-0.25 mum crystallites, belonging to the alph a-, beta-, gamma-, and delta -Al2O3 crystal modifications, and have a trans ition region containing AlFe nanocrystals with a size of 20-40 nm and a con siderable dislocation density. The aluminum oxide coatings exhibit signific ant carbonization, with a maximum carbon concentration on the surface reach ing 20 at. %. The relative phase composition calculated using the X-ray dif fraction data is as follows: gamma -Al2O3, 60%; alpha -Al2O3, 30%; beta- an d delta -Al2O3, balance to 100%. (C) 2000 MAIK "Nauka/Interperiodica".