GROWTH, PREPARATION AND SURFACE MODIFICATION OF MICROCRYSTALLINE DIAMOND POWDER FOR THE SYNTHESIS OF DIAMOND CERAMICS

Chemically modified microcrystalline diamond surfaces have been prepar ed and investigated on the basis of thermodesorption measurements, X-r ay diffraction and X-ray photoemission spectroscopy. X-ray investigati ons and SEM-images show that the synthesized diamond powder consists o f pure carbon crystals of cubic modification with unbroken facets. Inv estigation of acidic functional groups, having different oxygen conten t and bound on the diamond surface by an oxidizing process, was carrie d out by the method of neutralization with different alkaline reagents . It has been shown that the concentration of the groups neutralized b y each reagent decreases as the temperature of the heat treatment duri ng preparation is raised. Under thermal treatment, the oxy- functional groups decompose at T>600 degrees C, leaving a hydrogen terminated di amond surface. Hydrogen desorbs at T>1000 degrees C, thus generating a n atomically clean surface, such as is required for direct bonding of the nano- and micro-crystals during sintering.