Boron implantation into hard metals

(This work is supporting by the EC, contract BRPR CT97-0380.)

The surface properties of hardmetals determine their applications.
The boron ion implantation can be used to improve
  • wear and friction behaviour
  • tribological properties
  • strength and hardness
To explain the improvement of the life time of WC/Co compounds after ion implantation the knowledge of dependence of the physical properties on implantation parameters is very important.  Experiments were performed to test beam line ion implantation in cemented tungsten carbide at temperatures of <100°C , 450°, 700°, 900°C  using boron ions.  The ion fluences of boron from 1015 to 5x1017 ions/cm2 at an energy of 40 keV were investigated.

This study demonstrates that hardness and wear characteristics of the hard metal H3 (15%Co, WC, grain size ~1µm) can be improved by boron implantation. It wasn't detected a new phase formation. So it seems that the improvement of mechanical properties is caused by radiation induced defects.

Figure: Wear results of a 3 mm diameter tungsten carbide sphere, sliding under a load of 1 N on cemented WC (H3) samples after implantation with 40 keV boron at a fluence of  5x1017 ions/cm2  at different temperatures