Showing 4 results for Carbothermic Reduction
N. Setoudeh, A. Saidi, A. Shafyei and N.j. Welham,
Volume 27, Issue 2 (1-2009)
Abstract
Kh. Biralvand, M.h. Abbasi, A. Saidi,
Volume 31, Issue 1 (6-2012)
Abstract
Carbothermic reduction of Molybdenite in the presence of Magnesium oxide was thermodynamically studied. The stability diagrams for MoS2-MgO and MoS2-MgO-C Systems was prepared. The reduction of MoS2 with Carbon in the presence of Magnesium oxide proceeded through the direct oxidation of MoS2 by MgO to form intermediate molybdenum oxidized Species, MoO2 and MgMoO4. The results showed that the gaseous phase is mainly composed of CO. Stability diagrams for Mo-O-C (Reduction of MoO2 with carbon) and Mo-Mg-C-S-O (Reduction of MgMoO4 with carbon) were also investigated. The results showed that the Reduction of oxidized species leads to the formation of Mo, Mo2C, MoC or MgO products.
K. Sheybani, M.h. Abbasi, M. Shamanian ,
Volume 33, Issue 2 (3-2015)
Abstract
in this research, the kinetics of carbothermic reduction of molybdenite in the presence of sodium carbonate was studied. For this purpose, mixed powder of molybdenite, graphite, and sodium carbonate with 1:4:2 mole ratio was investigated using simultaneous thermal analysis (STA) at the heating rates of 10, 15 and 20 0C /min. The results of thermal analysis were evaluated through Friedman, Kissinger, Ozawa and Coats-Redfern methods. The activation energy of reduction reaction was determined 220 kj/mole, and it was found that the reaction was chemically controlled. To study the reaction mechanism, the mixed powder was heated to 400, 800 and 1100 0C in argon atmosphere at the heating rate of 10 0C/min. X- Ray diffraction
of the reaction products and thermodynamic analysis at these temperatures indicated that carbothermic reduction of molybdenite in the presence of sodium carbonate would advance through the formation of intermediate phases, Na2MoO4 and MoO2
A. Amiri Moghaddam, M. Kalantar,
Volume 36, Issue 1 (6-2017)
Abstract
The aim of this investigation is obtaining WC-Co composite powder from WO3 and Co3O4 by in-situ and carbothermic reduction method using activated carbon as a reducing agent. In this study, cobalt and tungsten oxide powders with 17% carbon (30% more than stoichiometric value) were mixed by ball-milling under atmosphere of argon for 20 hours. Differential Thermal Analysis (DTA) and Thermal Gravimetric Analysis (TGA) results on powder mixture show complete reducing of oxides at 1050°C and forming cobalt carbide and tungsten carbide. Compact samples underwent carbothermic reduction at 1050 °C for different times of 1, 2 and 4 hours with protective layer of alumina and carbon powder mixture with ratio of 1:1. Based on X-Ray Diffraction (XRD) analyses, the best holding time in furnace is 4 hours, in which tungsten reduction and carbonization is completed. XRD evaluation of reduced compacted samples in three conditions of atmosphere protective layer of alumina and carbon powder mixture with ratio of 1:1, protective foil of refractory steel and argon, shows that unreduced oxides and extra phases are present in argon atmosphere and protective foil of steel but not in alumina and carbon mixture layer. The measurement results of physical and mechanical properties on the sintered composite sample in heating rate of 5 °C /min to temperature 1500 °C and the holding time of 2 hours under a shielding layer of alumina and carbon shows obtaining the optimal properties (Pr=80%, KIC=8.1 MPa , MHV=15.67GPa) comparable to that of advanced and costly methods.
