Papers by Author: Tie Yong Zuo

Abstract: China is the largest primary magnesium producer in the world, because of nearly 80% of the global market share. In the present paper, an approach of life cycle assessment (LCA) was applied to build an inventory of air emissions and to analyze the environmental impact of the global warming potential (GWP) and the acidification potential (AP) related to the production of AZ91D magnesium alloy. A summary of environmental impacts of primary magnesium and primary aluminum production with various studies was made to show the influence of uncertainties on the impacts. The results showed that the cumulative GWP and the acidification potential (AP) of AZ91D Mg-alloy are 33.4 t CO₂ eq/t ingot and 139 kg SO₂ eq/t ingot, with the range of 29.5-36.3 t CO₂ eq/t ingot and 104-152 kg SO₂ eq/t ingot, respectively. The GWP and AP of primary magnesium account for 90% and 77% of the cumulative environmental impact of AZ91D Mg-alloy. Under the grand background of advancing the development strategy of energy-saving and emission-reducing, China magnesium smelting and manufacture industry has made rapid progress in the structure optimization, energy efficiency improvement, and environment protection. The calculated data show that the improvement measures, e.g. reduction of dolomite consumption and energy consumption, in Chinese Pidgeon process led to 23% decrease of the GWP for the primary magnesium production in 2009 compared with 2005. The global warming reduction potential for 1 ton AZ91D alloy ingots produced in China was estimated of substituting HFC-134a for SF₆ as a cover gas.

Abstract: A systematic investigation of the fabrication process, microstructure and treatment technology of the Rare earth oxide doped Mo cermet (REO-Mo in brief) on the secondary electron emission (SEE) mainly has been performed. The REO-Mo samples were fabricated by liquid-liquid, Liquid-Solid and Liquid-Liquid doping method and subsequently by the Spark Plasma Sintering (SPS) techniques. It was found that the uniform mixing of REO with Mo would have considerable benefit for enhancement of SEE coefficient (δ). Annealing the cathode in hydrogen (called as the pre-activation treatment) could greatly improve the SEE performance by removing the absorbed water and oxygen at the cathode surface which might cause the oxidation of molybdenum during cathode high temperature operation. It is found that the activation temperature of REO-Mo cathode annealed in hydrogen could decrease to 1000oC, about 300oC lower than that of the cathode without pre-activation treatment, which is favorable for the practical application.

Abstract: We have systemically studied the effect of the erbium on the microstructure and the mechanical properties in the 5xxx series aluminum alloys by using optical microscope, transmission electron microscope (TEM) and by tensile testing. The results demonstrate that the tensile strength increased quickly at the beginning of small contents of 0.1%Er both in the hot and cold rolled states, then slowly increased with increasing the contents of Er until 0.4%, at which the best balance of the strength and ductility (438MPa and 9.6%) were obtained. Microstructure observation in the hot rolled state was indicated that the grain structure in the Er free Al-5Mg alloy revealed fully recrystallized grain structure, while in the Al-5Mg containing Er was demonstrated deformation structure, indicating the Er addition delayed the recrystallization behavior by the formation of the precipitation of the Al3Er, which confirmed by means of the X-ray diffraction analysis. Furthermore in the TEM microstructure observation the precipitation of Al3Er was distributed both in the grain interior and subgrain or grain boundaries, which could be pinning the subgrain or grain boundary migration and dislocation movement as well. Consequently the beginning of the recrystallization temperature in the Al-5Mg containing Er was elevated about 50°C than in Al-5Mg without Er. This could be explained that the strength increased without the deterioration of the ductility was attributed to the microstructure refinement by the Er addition.