The microstructure of a laser-melted Fe-4% C-10% Sn alloy has been studied.A non-crystalline phase was found in the upper part of the laser-melted zone:At the bottom of the melted zone,however,the microcrystalline zon...The microstructure of a laser-melted Fe-4% C-10% Sn alloy has been studied.A non-crystalline phase was found in the upper part of the laser-melted zone:At the bottom of the melted zone,however,the microcrystalline zone which consists of α-Fe and a bet phase was observed.Fine twinning martensite exists in the other area of the melted zone.展开更多
研究了合金成分、烧结气氛对Fe Mo Mn Sn Ce C系合金的力学性能与烧结温度的影响以及在烧结合金中的作用机理。结果表明 :适量的Mn、Sn、混合稀土和氨燃烧氮基保护气氛均可加速该系合金的烧结进程 ,降低其烧结温度 ,改善其力学性能 ,而...研究了合金成分、烧结气氛对Fe Mo Mn Sn Ce C系合金的力学性能与烧结温度的影响以及在烧结合金中的作用机理。结果表明 :适量的Mn、Sn、混合稀土和氨燃烧氮基保护气氛均可加速该系合金的烧结进程 ,降低其烧结温度 ,改善其力学性能 ,而且具有协同、叠加强化效果。其强化作用主要体现在稀土元素的脱氧保碳、变质夹杂物、细化晶粒 ,Mn、Sn元素的固溶强化以及氨燃烧氮基保护气氛对烧结热效率、合金表层脱碳状况、烧结活化能的改善等方面。该系合金在氨燃烧氮基保护气氛中的合适烧结温度范围为 10 2 5～ 10 75℃ ,比Fe Mo Ni C系合金的烧结温度降低了 12 0～ 180℃。展开更多
CO adsorption microcalorimetry was employed in the study of γ-Al-2O-3-supported Pt, Pt-Sn and Pt-Fe catalysts. The results indicated that the initial differential heat of CO adsorption of the Pt/γ-Al-2O-3 catalyst w...CO adsorption microcalorimetry was employed in the study of γ-Al-2O-3-supported Pt, Pt-Sn and Pt-Fe catalysts. The results indicated that the initial differential heat of CO adsorption of the Pt/γ-Al-2O-3 catalyst was 125 kJ/mol. As CO coverage increased, the differential heat of adsorption decreased. At higher coverages, the differential heat of adsorption decreased significantly. 60% of the differential heat of CO adsorption on the Pt/γ-Al-2O-3 catalyst was higher than 100 kJ/mol. No significant effect on the initial differential heat was found after adding Sn and Fe to the Pt/γ-Al-2O-3 catalyst. The amount of strong CO adsorption sites decreased, while the portion of CO adsorption sites with differential heat of 60110 kJ/mol increased after increasing the Sn or Fe content. This indicates that the surface adsorption energy was changed by adding Sn or Fe to Pt/γ-Al-2O-3. The distribution of differential heat of CO adsorption on the Pt-Sn（C）/γ-Al-2O-3 catalyst was broad and homogeneous. Comparison of the dehydrogenation performance of C-4 alkanes with the number of CO adsorption sites with differential heat of 60110 kJ/mol showed a good correlation. These results indicate that the surface Pt centers with differential heats of 60110 kJ/mol for CO adsorption possess superior activity for the dehydrogenation of alkanes.展开更多
文摘The microstructure of a laser-melted Fe-4% C-10% Sn alloy has been studied.A non-crystalline phase was found in the upper part of the laser-melted zone:At the bottom of the melted zone,however,the microcrystalline zone which consists of α-Fe and a bet phase was observed.Fine twinning martensite exists in the other area of the melted zone.
文摘研究了合金成分、烧结气氛对Fe Mo Mn Sn Ce C系合金的力学性能与烧结温度的影响以及在烧结合金中的作用机理。结果表明 :适量的Mn、Sn、混合稀土和氨燃烧氮基保护气氛均可加速该系合金的烧结进程 ,降低其烧结温度 ,改善其力学性能 ,而且具有协同、叠加强化效果。其强化作用主要体现在稀土元素的脱氧保碳、变质夹杂物、细化晶粒 ,Mn、Sn元素的固溶强化以及氨燃烧氮基保护气氛对烧结热效率、合金表层脱碳状况、烧结活化能的改善等方面。该系合金在氨燃烧氮基保护气氛中的合适烧结温度范围为 10 2 5～ 10 75℃ ,比Fe Mo Ni C系合金的烧结温度降低了 12 0～ 180℃。
文摘CO adsorption microcalorimetry was employed in the study of γ-Al-2O-3-supported Pt, Pt-Sn and Pt-Fe catalysts. The results indicated that the initial differential heat of CO adsorption of the Pt/γ-Al-2O-3 catalyst was 125 kJ/mol. As CO coverage increased, the differential heat of adsorption decreased. At higher coverages, the differential heat of adsorption decreased significantly. 60% of the differential heat of CO adsorption on the Pt/γ-Al-2O-3 catalyst was higher than 100 kJ/mol. No significant effect on the initial differential heat was found after adding Sn and Fe to the Pt/γ-Al-2O-3 catalyst. The amount of strong CO adsorption sites decreased, while the portion of CO adsorption sites with differential heat of 60110 kJ/mol increased after increasing the Sn or Fe content. This indicates that the surface adsorption energy was changed by adding Sn or Fe to Pt/γ-Al-2O-3. The distribution of differential heat of CO adsorption on the Pt-Sn（C）/γ-Al-2O-3 catalyst was broad and homogeneous. Comparison of the dehydrogenation performance of C-4 alkanes with the number of CO adsorption sites with differential heat of 60110 kJ/mol showed a good correlation. These results indicate that the surface Pt centers with differential heats of 60110 kJ/mol for CO adsorption possess superior activity for the dehydrogenation of alkanes.
