Protection of Ti6Al4V surfaces by laser dispersion of diborides

In this work, one- and two-step laser dispersing of Ti6Al4V surfaces by use of elemental boron (B) as well as TiB2, ZrB2, and CrB2 was carried out with CO2 and Nd:YAG lasers using an adapted apparatus to provide inert conditions. Depending on the laser system, melt pool depths between 200 µm and more than 1000 µm were achieved, and the boride precipitates allowed an increase of the surface hardness from 350 HV0.05 in the initial state to more than 600 HV0.05. The modified surface areas were characterized by means of optical microscopy, scanning electron microscopy, and EDXS. Oscillating and cavitation erosion wear tests were carried out. For reinforcement of component surfaces with complex shape, a two-step laser deposition process and a technology for predeposition of diboride layers with defined thickness is required. The applicability of vacuum plasma spraying for predeposition is discussed.