W – TiB₂ Composite Material for Electro-spark Deposition

The W – TiB₂ composite materials were prepared by spark plasma sintering at INM Gliwice, Poland and by solar powder metallurgy at Plataforma Solar de Almeria (PSA), Spain. Composites were prepared by sintering of green compacts of W powder with 60 vol.% of TiB₂ powder. During the spark plasma sintering the sintering temperature was 1800 °C, pressure of 22kN, time of 300 s and heating rate of 1.67 °C/s. In solar furnace the sintering temperature was 1820 °C, pressure less, time 600 s and heating rate of 2.33 °C/s. The resulting composites prepared by spark plasma sintering possess 95 - 97 % of theoretical density. The composites prepared in solar furnace have porosity of 49%. Both composites are brittle and prone to cracking. The following phases were observed by EDS and XRD analyses: After solar sintering only W and TiB₂ phases were observed. After spark plasma sintering WB and TiB₂ phases were observed. The reason is different method of preparation. Finally it was proved experimentally that both composites can be successfully used as electrodes for electro spark deposition of hard wear resistant layers on metallic substrates. (paper)