Substrate heating effects on hardness of an α-Al2O3 thick film formedby aerosol deposition method

Aerosol deposition method (ADM) is a novel method of ceramics film deposition based on impaction of sub-micrometer ceramic particles. Those particles are accelerated to a velocity of several hundred meters per second and impact onto the substrate: in this manner, alpha-Al2O3 films are deposited on substrates that are maintained at different temperatures. Micro Vickers hardness of a 10-mu m-thick film was measured at room temperature. It was as high as 2000 HV for films deposited at room temperature. Films deposited on heated substrates gradually decrease in hardness concomitant with increasing substrate temperature. Increased crystallite size in comparison to the crystal size of film deposited at room temperature was observed. No deposition occurred if the substrate temperature exceeded 500 degrees C. The ADM film formation mechanism differs from that of conventional ceramics processing. (c) 2004 Elsevier B.V. All rights reserved.