Abstract(s) :

(Anglais) The mechanical alloying method allows obtaining tungsten carbide by carburization of tungsten trioxide. The parameters that have a determining role on the reaction kinetics are the temperature and the pressure. The milling installation must maintain a low pressure by removing carbon dioxide released during carburizing reaction. Tests were carried out in a planetary balls mill, equipped with bowls lined with tungsten carbide and filled with tungsten carbide balls of 10- and 12-mm diameter. Two levels of filling of the jars, 150 g and 200 g of balls were also tested. The balls/milled powder ratio was kept at 10:1. To monitor the carburizing reaction, samples were taken every 3 hours of milling and investigated by X-ray diffraction to determine the phases in presence. The morphology of the particles was studied by scanning electron microscopy and the particle size was investigated by laser granulometry. The energy developed during a ball impact was determined via a simplified computational modeling and depends on the mass of balls and on the speed of balls reach during the milling process. To determine the effect of various milling parameters on the temperature during a milling cycle, a temperature-monitoring device was created and installed on the milling bowl. The values obtained demonstrate that the diameter of the balls and the filling degree of the bowl have an important role in the evolution of the temperature during milling. The complete transformation of oxide into tungsten carbide takes place after 75 hours of milling using 12 mm diameter balls.

• (Anglais) milling parameters
• (Anglais) mechanical alloying
• (Anglais) direct carburization
• (Anglais) tungsten carbide