Microstructure and mechanical properties of bonding interface for CBN superabrasive tool using ultrasonic vibration-assisted brazing method

Abstract

Single-layer brazed cubic boron nitride (CBN) abrasive tools exhibit numerious advantages, such as high abrasive bonding strength, a large chip storage space, and good sharpness, and have been widely used to machine various difficult-to-cut materials in the aerospace field. However, the problems have to be faced, including uneven filler layer thickness, numerous pores inside the interface area, resulting in a significant reduction in bonding strength between the bonding alloys and the abrasive, and the eventual service life reduction of tools. In this paper, ultrasonic vibration-assisted brazing is proposed to improve the bonding strength of abrasive grains. Results show that for ultrasonic vibration-assisted brazing, the filler alloy spreads more evenly, and the size of internal pores is smaller. In particular, the number of pores in the same area is reduced by 75%, and the shear force of a single CBN abrasive is increased by 27.7%. After the grinding trials with Ti-6Al-4V alloys using brazed CBN tools, the normal and tangential grinding forces are reduced by 4.1%～19.6% and 8.3%～26.4%, respectively, as well as the declination of the grinding temperature by 5.3%～17.9% once employing ultrasonic vibrations into induction brazing processes. Additionally, the ultrasonic vibration-assisted brazed tools show a significant reduction in large-block breakage at the same material removal volume, indicating the more excellent wear-resistance ability and longer service life of the tools.

Keywords

• ultrasonic vibration-assisted brazing
• abrasive tools
• micromorphology
• bonding strength
• grinding performance