Mechanical Property and Microstructure of the Vitrified-Bonded Ti-Coated CBN Composites

Abstract

This paper investigates the mechanical property and microstructures of vitrified-bonded Ti-coated cubic boron nitride (CBN) composites under different sintering conditions. Three-point bending tests of the sintered vitrified-bonded Ti-coated CBN composite samples were carried out, and the microstructure, phase composition, and energy spectrum of the sintered composite samples were analyzed using SEM and X-ray diffraction. The test results indicate that the mechanical properties of the vitrified-bonded Ti-coated CBN composites improve with the increased temperature, and then show a declining trend. It was found that the titanium layer has a protective effect on the CBN abrasive. During the course of sintering, as the temperature increases, titanium in the titanium-coated layer is not only present on the CBN abrasive surface but is also diffused into the glass phase. In addition, oxidation reactions occur, which become stronger with the higher sintering temperature. Thus, the sintering temperature of the vitrified-bonded Ti-coated CBN composites should not be too high. It is better to sinter them in a vacuum rather than in air. Ti-coated CBN grains are not suitable for a vitrified bond with low refractoriness.