FORMATION OF HIGH-TEMPERATURE NANOFIBROUS-LIKE COATING STRUCTURE UNDER MAGNETRON SPUTTERING OF ALN- (TI,CR)B_2 TARGET

摘要

The structure, composition and properties of AlN-(Ti,Cr)B_2 coatings on Si, Al_2O_3 and GaAs mono-crystals were studied. These coatings were deposited using a radio-frequency magnetron sputtering of AlN-(Ti,Cr)B_2 target manufactured by powder metallurgy methods. It was established that the coating phase composition was differed from the target one due to the partial aluminum nitride oxidation. The coatings above were characterized by ultra-dispersion structure and great resistance to high-temperature oxidation owing to the partial formation of Al_2O_3-TiO_2, Al_2O_3-Cr_2O_3 and Al_2O_3-TiO_2- Cr_2O_3 solid solutions. Hereby the mass gain of target material proved to be only 1.4 mg/cm~2 at 1300℃. After oxidation, until 1500℃ the nanofibrous structure was reinforced with β-Al_2TiO_5 and Al_2O_3 fibers was formed. It was shown that the AlN-(Ti,Cr)B_2/Al_2O_3 (110) and AlN-(Ti,Cr)B_2/ GaAs (100) coatings were thermal-stable up to 900℃; they had high magnitudes of both microhardness (30 GPa) and fracture toughness (3.3 - 4.7 MN/m~(3/2)). The mechanical properties of coatings changed for the worse only after annealing at the temperature higher than 900℃. The composition and structure of coatings were investigated using an XRD, EPMA, Auger spectroscopy, and SEM methods. TG- and DTA- oxidation curves were obtained using the Setaram device with the rate of temperature change of 15°/min. The AlN-(Ti,Cr)B_2 target material can be recommended for deposition of wear- and corrosion- resistant coatings on parts working under the extreme conditions.