Spark Plasma Sintering of Molybdenum Silicides Synthesized from Oxide Precursors

ABSTRACT This work investigated the spark plasma sintering behavior of mechanochemically synthesized molybdenum silicide (MS) powders. Nanosized MS powders were obtained via a mechanochemical synthesis process applied to the initial MoO3-SiO2-Mg powder batches. Various characterization techniques such as X-ray diffraction (XRD), particle size analysis (PSA), Fourier-transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM) were performed to reveal the compositional and morphological properties of the homemade MS powders. The increasing sintering temperature up to 1600 oC enhanced the sinterability of the MS samples. In addition to the XRD and SEM/EDS analyses, the samples sintered at different temperatures were also characterized in terms of Archimedes’tdensity, microhardness, and fracture toughness properties. The MS sample sintered at the temperature of 1600 oC demonstrated a relative density of 93.7 %, a Vickers microhardness of 14.9 GPa, and a fracture toughness of 3.54 MPa√m. The wear rate decreased significantly with increasing sintering temperature from 3.60×10-5 mm3/Nm (1500 oC) to 1.77×10-5 mm3/Nm (1600 oC). Lastly, thermal gravimetry analyses (TGA) were conducted to observe the oxidation behavior of the sintered samples. The oxidation resistance of MS samples improved with increasing sintering temperatures.