Synthesis and formation mechanisms of nanocomposite WC–MgO powders by high-energy reactive milling

• Published in: Journal of alloys and compounds Vol. 478; no. 1; pp. 615 - 619
• Main Authors: Wu, C.X., Zhu, S.G., Ma, J., Zhang, M.L.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 10.06.2009; Elsevier
• Subjects: Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Formation mechanism; High-energy ball milling; Materials science; Materials synthesis; materials processing; Milling energy map; Physics; WC–MgO; Milling energy map; WC–MgO; Formation mechanism; High-energy ball milling; Planetary mill; Ball mill; Magnesium oxide; Self propagating high temperature synthesis; XRD; High temperature; WC―MgO; Tungsten oxide; Transmission electron microscopy; Nanocomposites; Heat of formation
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2008.11.100

The nanocomposite WC–MgO powders were prepared at room temperature by reactive milling of low-cost WO 3, Mg and graphite powders under argon gas atmosphere in a planetary ball milling. Powder samples were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The milling energy was calculated using a collision model and the milling energy maps were attained. The effects of milling parameters (including milling speed, ball-to-powder weight ratio and milling time) on the formation mechanism have been illuminated by the obtained milling energy maps. Results show that WC–MgO can be formed via Self-propagation High-temperature Synthesis (SHS) when the effective extensive factor E b is above 38.24 kJ g −1 s −1, and it also can be formed from gradual reaction when E b is between 22.12 kJ g −1 s −1 and 38.24 kJ g −1 s −1. As the energy map demonstrates, the total energy E t required for fabricating WC–MgO through SHS ranges from 25.61 × 10 6 kJ g −1 to 61.82 × 10 6 kJ g −1, while more than 112.83 × 10 6 kJ g −1 is necessary for gradual reaction one. These milling energy maps are proposed as a tool for better understanding of the synthesis and formation of WC–MgO by high-energy reactive milling.