The invention discloses a binder-free polycrystalline cubic
boron nitride abrasive and a preparation method thereof. The preparation method of the
abrasive comprises the following steps: 1, adding
hexagonal boron nitride powder into a die, and carrying out molding preformation; 2, carrying out cold isostatic pressing treatment on the above preformed product under vacuum conditions; 3, adding the above obtained
hexagonal boron nitride block into a
tantalum cup in order to form an assembled block together with a pressure transmitting medium; and 4, carrying out high temperature
high pressure synthesis treatment on the assembled block, carrying out furnace cooling, demolding, crushing, and grading to prepare the
abrasive. The binder-free polycrystalline cubic
boron nitride abrasive has the ultrafine
crystal structure of submicron dimension cBN monocrystal, and the micro-fragmentation self-
sharpening effect and the
isotropy of the binder-free polycrystalline cubic
boron nitride abrasive overcome
passivation, cleavage,
anisotropy and other defects of monocrystalline cBN abrasives; and the binder-free polycrystalline cubic
boron nitride abrasive disclosed in the invention has high
hardness and strength, is suitable for high precision
processing of high
hardness quenched steel, especially electrical, electronic and optical devices, has very high social values and economic benefit, and is suitable for popularization and application.