DEVELOPMENT OF A MATHEMATICAL MODEL OF THE SYNTHESIS OF A POLYCRYSTALLINE SUPERHARD MATERIAL BASED ON CUBIC BORON NITRIDE FROM WURZITE BORON NITRIDE MODIFIED WITH ALUMINUM

A mathematical model is developed for the technological process of synthesis under conditions of high pressures P and temperatures T of a polycrystalline superhard material based on cubic boron nitride (cBN). The superhard material is obtained from a wurtzite boron nitride (wBN) powder modified with aluminum Al, which is the initiator of the wBN→cBN phase transformation process. As a result of modelling, the boundary parameters Р and Т of the superhard material synthesis and the required amount of aluminum addition are calculated. It has been established that the synthesis of a material with a hardness of 28–30 GPa and crack resistance in the range of 7–10 MPa·m1/2 is carried out in the pressure range of 5–7 GPa at temperatures of 2.100–2.250 °C, and the aluminum additive content should be 7.5–10.0 wt.%.