Last modified: 2014-11-25
Abstract
The paper present the results of the analysis of sintering, microstructure, properties, and performance of a binderless cBN tool material sintered. The optimum range of sintering temperatures was found to be 2200 – 2300 ºC. Lower temperature results in incomplete diffusion bonding between cBN grains, while higher temperature results in high degree of recrystallization of initial structure, grain growth, and even formation of hexagonal boron nitride in triple joints. Introduction of stress-inducing β-Si3N4 minor inclusions resulted in high overall mechanical and thermal properties: HK ≈ 41 GPa; KIC = 12.6 MPam1/2; λ≈200 W/(mK). Machining experiments show that the material provides high performance in terms of resistance to tool cratering, chipping, and tool fracture.