Al2O3–WC synthesis by high-energy reactive milling

✍ Scribed by Eliria M.J.A. Pallone; Diego R. Martin; Roberto Tomasi; Walter J. Botta Filho

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 418 KB
• Volume: 464
• Category: Article
• ISSN: 0921-5093
• DOI: 10.1016/j.msea.2007.02.101

✦ Synopsis

Like most carbide-based composites, the two main characteristics of alumina-tungsten carbide (Al 2 O 3 -WC) composites are high hardness and high wear resistance. These features confer the composites important engineering applications, in particular when they are used as cutting tools. The present research involved a study of Al 2 O 3 -WC nanometric powders obtained through reactive milling. In this process, high-energy milling promotes the reaction in a mixture of reactive powders. The material was milled in a high-energy SPEX 8000 Mixer/Mill, using WO 3 , Al and C precursor powders. The highly exothermic self-propagating high-temperature synthesis (SHS) type reaction was self-sustained, producing a temperature peak that was detected by a thermocouple attached to the external surface of the vessel. Using stoichiometric proportions of the reagents to reduce the WO 3 and to obtain WC, and adding Al 2 O 3 as diluent, the SHS reaction occurred up to a limit of 0.8 mols of diluent, forming not only alumina but also a W 2 C mixture with little WC. To obtain only WC it was required the addition of more than 0.8 mols of C, which indicates that the reaction may have occurred through a gaseous phase reaction mechanism.