Study of the proportioning design method and mechanical properties of a cBN–TiN composite

Abstract This study provides a proportioning design method for the polycrystalline cubic boron nitride (PcBN) composite based on dense packing theory with the use of the Horsfield dense filling theory and Dinger–Funk equation. Subsequently, three proportioning schemes of the cBN–TiN system were designed with different titanium nitride content. The samples were analysed through X-ray diffraction, scanning electron microscopy and transmission electron microscopy for density, hardness and actual cutting performance, respectively. The predicted optimal values were consistent with the experimental results, which proved the validity of the method. Three samples designed from the method had sufficient sintering reaction under high pressure and high temperature to form a uniform and compact sintering structure, which had excellent mechanical properties to meet the industrial application. A surface reaction zone was formed on the W grains and the substitution reaction between cBN and TiN occurs and directly combines with each other to form an obvious grain boundary. It also indicated that appropriate PcBN proportioning scheme, workpiece characteristics, and cutting parameters should be sufficiently considered and reasonably adjusted in order to achieve a higher tool life and excellent workpiece surface roughness in the actual cutting application.