Investigation on the Simultaneous Reduction and Carburization of Mixture Powder of Tungsten and Nickel Oxides by Pure CO: II=DTA and the Effect of C Precipitation

Tungsten carbides are used to fabricate hard faced cutting tools. The uniformly distributednickel and tungsten containing phases may be acquired through chemical synthesis methodswhich usually destined oxide phases needed to be reduced and in this case along withcarburization. In the present study the thermodynamics of thermochemical method ofsimultaneous reduction and carburization of W-Ni oxide has been studied thoroughly by pureCO gaseous agent. TGA, DSC, Fact-sage software data base and XRD analysis have beenemployed to understand the mechanism of process. The extensive study on the results arepresented which showed the sequence of the reactions as NiO + CO → Ni + CO2 , WO3 + CO →WO2 + CO2, WO2 + CO → W + CO2, W + 2CO→ WC + CO2, 2CO→ C + CO2 , WO2 + C → W+ CO2 and W + C → WC. C precipitation through Boudouard reaction promoted reduction ofWO2 to W and also W carburization to WC, through C solid agent, instead of CO gaseous phase.DTA graph assisted to illustrate the real mechanism of thermochemical process to be as NiO + WO3 → Ni+ WO3-x → Ni + WO2 → Ni + WC.

Keywords:

Simultaneous Reduction and Carburization , CO Agent , TGA , DTA , C Precipitation