The Bonding Structure of the Various High Purity or BinderlessPolycrystalline Cubic Boron Nitride Compacts Sintered at 5 to 7GPaand 1600 to 2000 °C

摘要

The cBN-cBN direct bonding structure of some cBN compacts made by the method of thedirect conversion of the pyrolytic-BN (pBN) or wurtzite-BN (wBN) to cubic-BN at the pressure of7GPa and temperature 2000 °C and the cBN compact made by the method of sintering the cBNpowder along with polyvinylidene chloride (PVDC) at the condition of 5.5GPa and 1600 °C has beenstudied. The XRD, SEM, TEM analysis and the wear resistance on the ductile cast iron machining hasbeen investigated. While the XRD analysis of the above cBN samples showed that all samples consistonly of cBN, and the SEM observation showed that they all have the cBN-cBN direct bondingstructure, A STEM analysis showed the existence of the impurities at the cBN crystal boundary. Thestarting materials and the sintering method affect the degree of these impurities.