Advanced Materials Research Vols. 287-290

Abstract: With the reaction between titanium (Ti) sponge, high purity aluminum (Al) and TiC/Al inter-alloy, non-consumable arc melting technique has been successfully used in situ synthesize Ti matrix composites of Ti-25Al and Ti-25Al-1.5C. The composites oxidized at 900°C for 5~60h in static air. The influences of carbon content to oxidation kinetics of composites were analyzed. The surface morphologies and cross-section microstructures of the oxidation scales were examined by scanning electron microscope (SEM) with energy dispersive spectrometer (EDS). The results show that the isothermal oxidation kinetic curves of composites mainly follow parabolic rate law. The surface oxides of two materials are mainly columnar TiO₂, while the grain size of Ti-25Al-1.5C is smaller than that of Ti-25Al. The cross-section microstructure of the oxidation scales of Ti-25Al are layered constructions which grow in alternating way. The oxides of Ti-25Al-1.5C are mainly around the carbide particles, the oxidation resistance of which is stronger than Ti-25Al when oxidized for long time.

Abstract: Using microwave-assisted solid-state method, a series of zinc oxide-modified mesoporous SBA-15 materials were synthesized. The desulphurization test with a gas mixture containing 0.1 vol % hydrogen sulfide was carried out on these materials. Chemicals before and after the desulphurization test were analyzed using nitrogen adsorption, XRD, EDS, TEM, ICP and other standard methods. The results suggest that zinc oxide modification can accelerate the transformation from a mesoporous to a zeolite phase. The different zinc loading results in different zinc-phase dispersions on the materials.

Abstract: Nano-silica sol with average particle size of 20-30nm has been prepared by the hydrolyzation method of elemental silicon powder with addition of MD-01. The influencing factors of nano-particle size growth such as reaction time, reaction temperature, dosages of sodium hydroxide and additive MD-01 were investigated in this paper, and the forming process of nano-silicon dioxide was also analysed.

Abstract: Barium carbonate (BaCO₃) crystals with different morphologies were synthesized using BaCl₂·2H₂O by a carbonation method in water/ionic liquids (ILs) mixed solvents. The as-prepared products were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the results indicated that the types of ILs and the mole ratio of water to ILs played important roles in determining the morphologies of the products. The analysis of the XRD pattern showed that ILs had an influence on the crystallinity of BaCO₃. When the mole ratio of water to ILs increased, the size of BaCO₃ crystals increased and the morphology gradually changed from spherical to oval and rod-like. A microemulsion model was employed to explain this mechanism.

Abstract: Stabilization effect of sodium phosphate on crystalline phase and crystal shape of hemihydrate calcium sulfate whiskers was investigated. Morphology, thermal stability and phase composition of stabilized hemihydrate calcium sulfate whiskers were characterized by means of SEM, DSC-TG and XRD respectively. Results indicated that crystalline shape of hemihydrate calcium sulfate whiskers could be invariable in two hours at 100 °C with addition of 0.10 wt % sodium phosphate for 20 min. Meanwhile sodium phosphate had a good effect on whiskers morphology stabilization.

Abstract: Graphene oxide was prepared through Hummers' method，then different reduced graphenes were prepared via reduction of graphene oxide with hydrazine hydrate for 1h、12h and 24h. X-ray photoelectron spectroscopy (XPS) was used for the characterization of graphene oxide and the reduced graphenes. The variation of the contents of carbon in carbon and oxygen functional groups and chemical compositions of graphene oxides were investigated through analysis the content of different carbon atoms in different reduced graphenes. The results showed that the reduction reaction was very fast in the first 1 h, the content of total oxygen bonded carbon atoms decreased from 83.6% to 22.1%, and then after the reduction rate became very slow. After 12h, the content of total oxygen bonded carbon atom is 19.56%, only 2.54% lower than that of 1h’s. At the same time, C-N was introduced in the graphene oxides; this increased the stereo-hindrance for hydrazine hydrate attacking the C-Oxygen groups, thus reduced the reduction rate. After reduction for 24h, there still exists 16.4% oxygen bonded carbon atoms and the total conversion ratio of graphene approaches 70%.

Abstract: In order to study the comparison of material design, structure design and integrated design about the porous material, a concurrent topology optimization design model associating materials and structures with periodical microstructures is presented. The sensitivity formulae of hierarchy optimization are given based on the integrated design model and related numerical experiments were carried out. The applicability of hierarchy optimization is discussed and their advantage and disadvantage are analyzed through numerical examples which provide some useful opinions about the porous material design.

Abstract: Ground calcium carbonate (GCC) is usually of smooth/flat surface and pointed edges angles which have disadvantageous effects on the mechanical properties of composite polymer materials filled with the powder. Nanometer calcium carbonate reactants would deposit, nucleate and grow on surface of ground calcium carbonate with micron grain size by adjusting suitable technical parameters in Ca(OH)₂–H₂O–CO₂ system. Compared with the uncoated powder, composite ground calcium carbonate (CGCC) is of rough surface, blunt edges, larger specific surface area, larger in whiteness. In this paper, we reported the successful preparation of CGCC particles, and found GCC/Ca(OH)₂ weight ratio was the key parameter. Some technological parameters were mainly analyzed for the coating process. Furthermore, We also prepared nanosized calcium carbonate coating GCC at higher temperature (40 °C) using additives. Filling tests showed that a rough surface of the CGCC enhanced contact opportunities and improved the interface between polymer and CGCC blended with polypropylene (PP).

Abstract: Icosahedral quasicrystalline phase (I-phase) formed in a number of Ti-based alloys, and that the I-phase was well ordered and thermodynamically stable in the Ti-based alloy. Further, studies on the physical/chemical properties have received much attention. It was important from scientific and technological point to study the preparation and hydrogen storage property of the alloys. Recently we have prepared single I-phase Ti₄₅Zr₃₅Ni₁₇Cu₃ powder and investigated their hydrogen storage property. Here, we reviewed the research results and proposed the research of Ti/Zr-based I-phase as hydrogen storage material.

Abstract: Based on the actual conditions during industrial production, this paper proposes an improvement method and solution to the typical grinding process model and derives a mathematical model of grinding process that’s suitable for industrial production. Sampling analysis and laboratory experiments of the production process were conducted, the derived model was tested, and the results show that particle size distribution curve obtained from the improved model is similar to the actual product, which means that the improved model can be applied to simulate industrial grinding process.