Nano-Y2O3 and nano-CeO2 of different weight ratio mixed with deionizing water were doped into MoO2 powder by liquid-solid doping method. The diameter 1.80 and 0.18 mm alloy wires of Mo-0.3Y, Mo-0.3Ce, and Mo-0.15Y-0.1...Nano-Y2O3 and nano-CeO2 of different weight ratio mixed with deionizing water were doped into MoO2 powder by liquid-solid doping method. The diameter 1.80 and 0.18 mm alloy wires of Mo-0.3Y, Mo-0.3Ce, and Mo-0.15Y-0.15Ce were prepared through reduction, iso- static pressing, sintering, and drawing. Tensile properties, second phase microstructure and fracture surface appear- ance of wires were analyzed. The better refining effect for Mo alloy powder can be gotten after two kinds of nano- particle oxide doped into MoO2 than only one doped. Nano-Y2O3 and nano-CeO2 have different influences on sintering process. For nano-CeO2, the constraining effect of grain growth focuses on the initial sintering stage, nano- Y2O3 plays refining grains roles in the later densification stage. Nano-Y2O3 is undistorted and keeps intact in the process of drawing; and nano-CeO2 is elongated and bro- ken into parts in the drawing direction. The strengthening effect of nano-Y2O3 and nano-CeO2 keeps the finer grains and superior tensile properties for Mo-0.15Y-0.15Ce wire.展开更多
At three critical temperatures which were obtained by thermo-gravimetry-differential thermal analysis–differential scanning calorimetry（TG/DTG/DSC）curves of lanthanum nitrate crystal, the air thermal decomposition ...At three critical temperatures which were obtained by thermo-gravimetry-differential thermal analysis–differential scanning calorimetry（TG/DTG/DSC）curves of lanthanum nitrate crystal, the air thermal decomposition experiments and solid–liquid spray doping simulation procedures of lanthanum nitrate crystal were carried out, and their products were analyzed by X-ray diffraction（XRD）. Meanwhile, the spray doping processing of Mo O2–50 wt% La（NO3）3composite powder was undergone with lanthanum nitrate solution as the dopant,and doped Mo O2powder was analyzed by XRD. The results demonstrate that during the traditional solid–liquid spray doping processing, lanthanum nitrate, in the form of either crystal or aqueous solution, would be converted into La（NO3）3á4H2O by the dehydration reaction, rather than be decomposed to La2O3and NO or NO2. Therefore, it is inferred that the oxynitride gas produced from the process is attributed to the decomposition of residual HNO3in lanthanum nitrate crystal. The source of HNO3is supported by the chemical composition of lanthanum nitrate crystal.展开更多
基金financially supported by the National Tungsten and Molybdenum Value-added Utilization Tech-nology Industry Development(No.2012BAE06B02)Shanxi Province Science and Technology Innovation Plan(No.2012KTCQ01-08)
文摘Nano-Y2O3 and nano-CeO2 of different weight ratio mixed with deionizing water were doped into MoO2 powder by liquid-solid doping method. The diameter 1.80 and 0.18 mm alloy wires of Mo-0.3Y, Mo-0.3Ce, and Mo-0.15Y-0.15Ce were prepared through reduction, iso- static pressing, sintering, and drawing. Tensile properties, second phase microstructure and fracture surface appear- ance of wires were analyzed. The better refining effect for Mo alloy powder can be gotten after two kinds of nano- particle oxide doped into MoO2 than only one doped. Nano-Y2O3 and nano-CeO2 have different influences on sintering process. For nano-CeO2, the constraining effect of grain growth focuses on the initial sintering stage, nano- Y2O3 plays refining grains roles in the later densification stage. Nano-Y2O3 is undistorted and keeps intact in the process of drawing; and nano-CeO2 is elongated and bro- ken into parts in the drawing direction. The strengthening effect of nano-Y2O3 and nano-CeO2 keeps the finer grains and superior tensile properties for Mo-0.15Y-0.15Ce wire.
基金financially supported by the National Science and Technology Support Program of China (No. 2012BAE06B02)
文摘At three critical temperatures which were obtained by thermo-gravimetry-differential thermal analysis–differential scanning calorimetry（TG/DTG/DSC）curves of lanthanum nitrate crystal, the air thermal decomposition experiments and solid–liquid spray doping simulation procedures of lanthanum nitrate crystal were carried out, and their products were analyzed by X-ray diffraction（XRD）. Meanwhile, the spray doping processing of Mo O2–50 wt% La（NO3）3composite powder was undergone with lanthanum nitrate solution as the dopant,and doped Mo O2powder was analyzed by XRD. The results demonstrate that during the traditional solid–liquid spray doping processing, lanthanum nitrate, in the form of either crystal or aqueous solution, would be converted into La（NO3）3á4H2O by the dehydration reaction, rather than be decomposed to La2O3and NO or NO2. Therefore, it is inferred that the oxynitride gas produced from the process is attributed to the decomposition of residual HNO3in lanthanum nitrate crystal. The source of HNO3is supported by the chemical composition of lanthanum nitrate crystal.
