The invention discloses a method for manufacturing
boron nitride toughened
polycrystalline diamond. The method includes dissolving
boron compounds (B<5>H<9> or B<6>H<10> or B<9>H<15> or B<10>H<14> or carbon
decaborane) in solvents; adding a calculated amount of
diamond micro-
powder into the solvents, uniformly stirring the
diamond micro-
powder and removing the solvents; filling
zirconium cups with the coated
diamond micro-
powder, compacting the diamond micro-powder in the
zirconium cups, placing the diamond micro-powder and carbon
tungsten alloy sheets into
molybdenum cups, compacting the diamond micro-powder and the carbon
tungsten alloy sheets in the
molybdenum cups, and weighting the calculated amount of coated diamond micro-powder, filling the coated diamond micro-powder in the
zirconium cups, paving, compacting, covering the coated diamond micro-powder with the carbon
tungsten alloy sheets, placing all in the
molybdenum cups, and secondarily compacting through a mold to form a pre-compaction block; filling the pre-compaction block, table salt tubes, insulating tubes,
graphite tube heating elements, conductive tablets, end caps and the like into a powder compression block to form complete
assembly; placing the assemblies in a six-surface diamond presser, and performing isostatic pressing
sintering on the assemblies at the temperature of 1480-1550 DEG C under the pressure of 5-5.5GPa to obtain
polycrystalline diamond composite sheets. Two types of micro-powder with two different grain sizes are mixed to form the diamond micro-powder, the grain size of the coarse powder is 8-14 micrometers, the grain size of the
fine powder is 0.5-2.5 micrometers, and a proportion of the coarse powder to the
fine powder is 3 / 1-5 / 1. The method has the
advantage that the diamond crystalline composite sheets manufactured by the aid of the method are high in
heat resistance and abrasion resistance.