Formation of hard tungsten boride layer by spark plasma sintering boriding

Metal borides are attractive candidates for high-temperature, wear resistance, and corrosion resistance applications. Tungsten borides (WB and W2B5) are known to have high hardness values, chemical inertness, and electronic conductivity, and have potential industrial applications as abrasive, corrosion-resistant and electrode materials, which are exposed to exacting environments. In this work, boride layers are formed on the surface of W samples using a pack boriding method with the assistant of the spark plasma sintering technique. The process was performed in the temperature range 1000-1400 °C with a holding time of 30 min. The microstructure, microhardness, and fracture toughness of the tungsten boride layer are investigated by optical microscopy, X-ray diffraction and microhardness indentations. Results showed that the boride layer, composed of WB, have thickness in the range ~35-112 μm. The WB layers are found to have a preferred orientation in the (200) direction, which is reflected by a distinct columnar growth observed in the optical micrographs of polished cross-sections of SPS samples