Plasma-assisted boriding of pure titanium and TiAl6V4

Pulsed-DC plasma boriding in an Ar-BCl3 atmosphere was performed for pure titanium and the titanium alloy TiAl6V4 in the temperature range of 700-900 degreesC. The plasma boriding leads to the formation of TiB2 and TiB at the surface for pure titanium as well as for TiAl6V4, depending on the process parameters. These phases were identified using X-ray diffraction (XRD). The amount of boron, oxygen and the alloying elements at the surface and the depth profiles were examined by glow-discharge optical emission spectroscopy (GDOS). The hardness profile was measured on metallographic sections after boriding. The high hardness of the layer is similar to the hardness known for titanium boride layers formed by plasma-assisted chemical vapor deposition (PACVD). Scratch tests indicate that the adhesion strength is relatively high, thus indicating a high potential for industrial applications under tribological conditions. (C) 2001 Elsevier Science B.V. All rights reserved.