Bingwen Zhou

Study on preparation and properties of carbon nanotubes/hollow glass microspheres/epoxy syntactic foam

Abstract Hollow glass microspheres (HGMs)/epoxy syntactic foam reinforced by multiwalled carbon nanotubes (MWCNTs) was prepared in this study. The effect of MWCNTs on the density, mechanical properties and water absorption of HGMs/epoxy syntactic foam was investigated. Because of the low density and low content of MWCNTs, the density of HGMs/epoxy syntactic foam does not change much with adding MWCNTs. In addition, the compression strength of HGMs/epoxy is enhanced by 17–25% when adding 0.3 wt% MWCNTs. The fracture surfaces of specimens were examined with scanning electron microscopy (SEM), and results indicated that the bridging effect of MWCNTs is the reinforcement mechanism. Analyzing the water absorption testing results, it is concluded that MWCNTs may decrease the water absorption content due to the hydrophobicity. Bigger inorganic ions in salt water could prevent the water diffusion, which results in a decrease of water absorption. In addition, the water absorption rate decreases with the extension of testing time.

Effects of alloying and deformation on microstructures and properties of Cu–Mg–Te–Y alloys

Abstract New copper alloys with high mechanical properties and high electrical conductivity were prepared, and the effects of addition of minor Mg and Y elements on microstructures and properties were studied. The high tensile strength of above 510 MPa, high elongation of 11% and high electrical conductivity of over 63% IACS can be simultaneously obtained in Cu–0.47Mg–0.20Te–0.04Y alloy after deforming and annealing treatment. Effects of purification together with the grain refining by Y and solid-solution strengthening by Mg are appropriate for enhancing mechanical properties and electrical conductivity of the copper alloys.

Effects of rolling and annealing on microstructures and properties of Cu–Mg–Te–Y alloy

Abstract Microstructures and element distributions of the as-cast, hot-rolled and cold-rolled Cu–Mg–Te–Y alloys were studied. Effects of rolling process and annealing temperature on the properties of the Cu–Mg–Te–Y alloys were correspondingly investigated. The results indicate that the Mg element is homogeneously distributed in the matrix and the fragmentized Cu2Te phase is dispersed in the matrix after hot rolling. Then, the Cu2Te phase is further stretched to strip shape after the cold rolling process. The microstructures of the cold-rolled alloy keep unchanged for the sample annealed below 390 °C for 1 h. However, after annealing at 550 °C for 1 h, the copper alloy with fibrous microstructures formed during the cold rolling process recrystallizes, leading to an obvious drop of hardening effect and an increase of electrical conductivity. The Cu–Mg–Te–Y alloy with better comprehensive properties is obtained by annealing at 360–390 °C.

Effect of ultrasonication on the properties of multi-walled carbon nanotubes/ hollow glass microspheres/epoxy syntactic foam

Multi-walled carbon nanotubes (MWCNTs) reinforced hollow glass microspheres (HGMs)/epoxy syntactic foam was fabricated. The effects of ultrasonication on the density, compression strength, and water absorption properties were studied. Better dispersed MWCNTs can be obtained after ultrasonication treatment, but an increasing viscosity will lead to a larger amount of voids during syntactic foam preparation especially when the content of HGMs is more than 70 vol%. The existing voids will decrease the density of epoxy syntactic foam. However, the ultrasonication does not change the compression strength much. Ultrasonication treatment will decrease the water absorption content due to the better dispersion and hydrophobic properties of MWCNTs. But a significant increase of water absorption content occurs when HGMs is more than 70 vol%, which is attributed to the higher viscosity and larger amount of voids.

Numerical Simulation of Zr-based Bulk Metallic Glass During Continuous Casting Solidification Process

A numerical simulation method was used to analyze the solidification process of Zr-based bulk metallic glass (BMG) during the horizontal continuous casting (HCC) process. The large-scale general-purpose finite element analysis software ANSYS was adopted to develop a temperature field model. The variation of temperature field in the specific area at different time was studied. Its accuracy was verified by the experimental results of Zr48Cu36Ag8Al8 bulk metallic glass continuous casting solidification process. The effects of casting parameters include intermittent casting procedure (drawing and stopping), casting speed, pouring temperature and cooling rate. The results show that the optimum casting speed range is 1-2 mm/s, pouring temperature is 1223 K and cooling rate of 10 mm rod casting is 5 L/min respectively. A fully Zr-based bulk metallic glass whose diameter is 10 mm and length has no limitation has been successfully fabricated.