Preparation of multi-phase composite of tungsten carbide, tungsten boride and carbon by arc plasma melting: characterization of melt-cast product

Abstract Arc plasma melting of WC+B 4 C followed by an in situ furnace cooling produced a multi-phase composite consisting of tungsten carbide, tungsten boride and carbon. The melt-cast product was prepared in six different compositions by varying the boron carbide content (within 1–15 wt%) at the charge stage. XRD, SAED and XPS characterizations of the product showed the major phases to constitute of W 2 B, WB, W 2 B 5 (WB 2 ), WC, W 2 C and C. Carbon was found to exist in three different forms, such as graphite, diamond / DLC and nanocrystalline diamond (C–C sp 3 coordination). FESEM, TEM and BET studies revealed the surface morphology, microstructure and non-porous nature of the composites respectively. From micro Raman spectra it was evident that W 2 C and all tungsten boride phases were non-Raman active with 514 nm radiation (Ar + laser). Preliminary mechanical characterization of the polished composite samples (in solid forms) showed the hardness to increase with increase in B 4 C content (range: 1–10 wt%). An extraordinary hardness of 3835±80 VHN with corresponding Young’s modulus of 695±33 GPa was observed for the typical composition of WC+10 wt% B 4 C. However, the hardness showed decreased value for 15 wt% B 4 C added sample.