In this study, the influence of pulling velocity on temperature field, fluid field and grain structure of a unidirectionally solidified superalloy DZ417G cylindrical casting was investigated by using a 3D cellular automaton finite element (CAFE) model within commercial software CALCOSOFT. The predictions show that temperature distribution in the casting is well in accordance with the experiment result. The solidification front and fluid field are sensitive to changes in pulling velocity. And the pulling velocity should be controlled less than 0.5 mm/s in our experiment so as to effectively decrease the grain number and mean grain deviation.
A macro-scale ProCAST and a meso-scale Cellular Automaton Finite Element model (CAFE) are used to simulate the grain selection during solidification with different simulation conditions. To improve the efficiency of the spiral grain selector, the effects of spiral geometries, boundary conditions and nucleation parameters on the grain selection are investigated. Simulation results reveal that the spiral geometries affect the height where the single crystal occurs in the spiral selector when volume nucleation is neglected. The average orientation deviation and grain number is relatively insensitive to volume nucleation and thermal boundary conditions around grain selector, and the thermal boundary conditions in the top of grain selector being of lesser importance.
Pt/CeO2/multi-walled carbon nanotubes (Pt/CeO2/MWCNTs) catalysts have been synthesized by microwave-assisted polyol process at different microwave power values. The obtained samples have been characterized by physical examinations and electrochemical measurements. The effects of different microwave power on performance of Pt/CeO2/MWCNTs have been mainly investigated. The results of physical examinations show that Pt nanoparticles have a narrow size and Pt nanoparticles and CeO2 units are highly dispersed on the surface of MWCNTs. The results of electrochemical measurements present that Pt/CeO2/MWCNTs catalysts by microwave-assisSubscript textted polyol process have higher catalytic activity and stability than Pt/MWCNTs catalyst by the same procedure. When the value of microwave power is 70%, the Pt/CeO2/MWCNTs catalyst has the smallest particle size and exhibits the highest activity and stability of methanol electrooxidation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.