Papers by Author: Dun Qiang Tan

Abstract: To study the ignition-proof behavior in the spray deposited magnesium alloy with nitrogen as atomizing gas, SEM and XRD were employed to study the morphology and elements profile of nitride film formed on the Mg-5Ca alloy melt in different conditions, and the ignition proof principle was also analyzed preliminarily. The results indicated that under ordinary nitrogen (99.5%), a layer of smooth and continuous nitride film was formed on the surface of Mg-5Ca alloy after sintered at 740°C for 2 hours, and with the increasing of temperature and holding time, small cracks and cavities appeared locally on the surface film. The surface film was mainly composed of CaO、MgO、Ca₃N₂ and Mg₃N₂.The profile analysis of the nitride film indicated that Ca element collected on the surface of the nitride film, and a multiple film was formed which filled the loose and holes of single film, avoided the burning of Mg alloy during spray forming process.

Abstract: By detecting microstructures and properties of Cu-W composites, effects of powder composition, sintering temperature and compacting pressure on sintered billets were studied, and sintering mechanism of Cu-W powders was discussed. Effective rules of process parameters have been preliminarily obtained: Sintered billets of Cu-40W and Cu-50W had a low density when compacted at 200MPa, sintered below the melting point of copper, and density, hardness enlarged with sintering temperature increasing; Hardness, density, electrical conductivity of Cu-40W enlarged with compacting pressure when compacted above 600MPa, sintered at 1100°C; But when compacted at 800MPa, sintered at 1100°C, Cu-40W sintered billets had a density of 11.37g/cm3, relative density of 99.6%, closed to the theoretical value.