Microstructural Evolution of the Rail Steels Manufactured by Hanyang Iron Works.

The microstructural evolution of the rail steels manufactured by Hanyang Iron Works was investigated through optical microscopy (OM), scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD). The OM and SEM images reveal that the microstructures are ferrite with a small amount of pearlite in the rail steel 1904, reticular ferrite and pearlite in the rail steels 1911 and 1921, and full pearlite in the rail steels 1917 and 1919, respectively. The EBSD results show that the rail steel 1904 holds the smallest average grain diameter owing to the pearlite with small size. Moreover, the average grain diameter of the pearlite cluster decreases in the rail steels manufactured after 1908, except for 1921, when it was on the verge of bankruptcy. The rail steels 1917 and 1919 exhibit a higher proportion of low angle grain boundaries and local misorientation with angles lower than 1°. Besides, the grain boundary misorientation holds a lower proportion in the range of 40~50° in the rail steels 1917 and 1919.

Numerical Simulation Study on Flow and Heat Transfer of the Tungsten Crucible CVD Reactor.

In order to investigate the optimization of the performance and structure of a tungsten crucible CVD reactor, the CFD simulation method was used in this paper to simulate the internal flow of the tungsten crucible CVD reactor. The velocity distribution and temperature distribution in the reactor were obtained. The simulation results show that the axial and radial heat convection will occur between the susceptor and the outer wall surface, but the axial heat convection is more intense. Moreover, it was found that the temperature distribution in the CVD reactor was more uniform and reasonable when the upper gas inlet was applied, which was beneficial to the reduction and deposition processes of tungsten. The molar ratio of H2 to WF6 has a great influence on the deposition rate of tungsten, and excess H2 is not conducive to the deposition of tungsten. Thermal radiation has a great influence on the temperature distribution of CVD reactors. It cannot be neglected.

Carbon Fiber Reinforced Multi-Phase Epoxy Syntactic Foam (CFR-Epoxy-Hardener/HGMS/Aerogel-R-Hollow Epoxy Macrosphere(AR-HEMS)).

Because the aerogel has ultra-low density and good impact resistance, the aerogel material, epoxy-hardener system, and expandable polystyrene beads (EPS) were used to prepare the lightweight aerogel reinforced hollow epoxy macro-spheres (AR-HEMS). The multi-phase epoxy syntactic foam (ESF) was manufactured with the epoxy-hardener system, HGMS (EP-hardener-HGMS), and AR-HEMS by "the compression modeling method." In this experiment, in order to enhance the strength of the ESF, some different kinds of the carbon fiber (CF) were added into the EP-hardener-HGMS system (CFR-EP). The influence of the volume stacking fraction, inner diameter, and layer of the AR-HEMS and the content and type of the CF in the EP-HGMS (CFR-EP) system on the compressive strength of the ESF were studied. Weighing the two factors of the density and compressive strength, the ESF reinforced by 1.5 wt% CF with 90% AR-HEMS has the better performance. This kind of the ESF has 0.428 g/cm3 nd 20.76 Mpa, which could be applied in 2076 m deep sea.