Papers by Author: Chun Yong Liang

Abstract: Based on the analysis of primal process and structure of gray iron brake pad failing early, hydrodynamic software Flow-3D was used to simulate the defect distribution and temperature fields of different improved technology schemes. According to simulation results, the merits and faults of all schemes were investigated and the feasible casting system was determined. The results showed that uniform temperature distribution could be achieved and potential defects mainly distributed in gate riser or nonworking surface when adopting the casting system with single ingate, which gave brake pad better service performance.

Abstract: Carbon nanotubes (CNTs) over hydroxyapatite (HA) as catalyst carrier were synthesized successfully using transition metal by chemical vapor deposition (CVD). The influences of catalyst types on the synthesis of CNTs were investigated when using Fe, Co and Ni as transition metal catalyst respectively. The results showed that CNTs synthesized by Fe catalyst normally possess more ideal morphology and higher crystallinity than those by the other two. But the yield rates of CNTs synthesized by CVD were in the order of Ni>Fe>Co. On the basis of this, HA matrix composites reinforced by CNTs in-situ were prepared and their mechanical properties were studied preliminarily. This study supplies valuable information for controlling the property of CNTs/HA composite by the selection of catalyst.

Abstract: The paper studied various morphologies of the quasicrystal phase in Mg-Zn-Y alloys caused by different cooling rates. The cooling rates were reached through five kinds of cooling media. The cooling curves were monitored by multichannel data acquisition cards. A further heat treatment was made to study quasicrystal growth behavior. The results showed that, with the decrease of cooling rate, the quasicrystal morphology changed and its size became larger. Moreover, a planar quasicrystal morphology evolution schematic diagram during quasicrystal growth process was observed for the first time.

Abstract: During casting process design, CAD/CAE technology can play important role to avoid macroscopic irregularity, internal defect and assure casting performance. Based on the casting process analysis and gating system design, the numerical simulation of gray iron butterfly valve was done by hydrodynamic software Flow-3D to obtain its optimal process scheme. According to the simulation results including flow field, temperature field and defect distribution, the merits and faults of designed schemes were investigated and then the feasible gating system was proposed. The results showed that, compared with top or intermediate casting, when adopting bottom casting, steady flow of molten metal and reasonable temperature distribution could be achieved. And workpiece defects mainly distributed in riser. The predicted results are in good agreement with practical ones.