Materials Science Forum Vols. 675-677

Abstract: Micron, sub-micron and nanometer sized MgO•Al2O3 ultra-fine powders were prepared by gel precipitation, solid-phase synthesis, sol-gel and flame throwing pyrogenation methods. XRD analysis showed that all of the ultra-fine powder is pure with the single MgO•Al2O3 spinel phase. The powder size was measured by laser granularity analyzer and the average size is 1780, 505 and 60 nm with a quite uniform distribution of particle size. MgO•Al2O3 spinel powder with different granularity were sprayed into molten low carbon steel in MgO crucible and MoSi2 furnace at 1873 K. Quantitative microscopic examination showed that big particle inclusions reduce and small particle inclusions increase, as a result, the average size reduce. Data comparison from spraying powders with different size showed that spraying MgO•Al2O3 of nanometer tends to cause more small inclusions in molten steel. The sprayed steel samples were rolled and heat treated for the mechanical properties tests, which showed spraying nanometer MgO•Al2O3 is the best way to improve mechanical property of steel.

Abstract: New types of conducting composites using andalusite as an inorganic substrate and polyaniline as the conducting phase were prepared. The composites exhibited conductivities in the 0.14-2.08 S/cm range, depending on the amount of polyaniline. The thermal stability of andalusite/polyaniline composites were studied by thermogravimetric analysis. The resulting composites were also characterized by using FTIR spectroscopy and scanning electron microscopy.

Abstract: We demonstrated the fabrication of the flower-like silver nanoplate micro-assemblies in high yields by a facile hydrothermal method. This novel nanostructure was synthesized in the presence of poly (vinyl pyrrolidone) (PVP) and ascorbic acid (AsA) at 150 °C for 10 h. The microassemblies with average size of 1~2 μm are consisted of several uniform nanoplates and show face centered cubic structure. The effects of the concentration of reactants, molar ratio of silver nitrate to ascorbic acid on the formation of the flower-like silver micro-assemblies were also presented.

Abstract: The composite magnetic nanoparticles of coated SiO nano film with about 8 nm size can be dispersed in various liquid media, widely known as magnetic fluids or ferrofluids with both magnetic and liquid properties. In this paper, a bio-medicine coating technology on surface of magnetic nanoparticles and the optimum fabrication condition and the magnetism of composed bio-nanoparticles are investigated. Through observation of micro-structure of the bio-nanopaticles on coating surface, and evaluation of magnetic property and safety to apply to biomaterials, we know the bio-medicine coated on surface of magnetic nanoparticles is suitable of bio-solutions into surface of biomaterials.

Abstract: MnAlC nanoparticles were synthesized by plasma arc-discharge method. Heat treatment of these nanoparticles at temperature from 400 to 600 °C resulted in the formation of the ferromagnetic τ-phase. Most of the nanoparticles had nearly spherical shape, smooth surface and core/shell structure. The shells of the nanoparticles mainly consisted of Al2O3 and a small amount of Mn oxides. Though the saturation magnetization of MnAlC nanoparticles was lower than that of bulk samples due to the effect of nonmagnetic phases (β, γ2 and Mn3AlC) and the oxide shell, the highest coercivity, up to 5.6 kOe in the MnAlC magnets, was achieved when annealed at 500 °C for 30 min.

Abstract: Electrorheological (ER) fluids are regarded as smart materials with potential for application in various industries because of the controllable viscosity, the reversibly and fast response. In this paper, core-shell structured Ni/Ti/Urea nanoparticles, as an ER material, were prepared by a sol-gel method. TEM, XRD and FT-IR spectra demonstrated that the Ni nanoparticles have been homogeneously coated with a 2 nm thick layer of TiO2 containing polar groups. The polar groups were caused by the introduction of urea. The ER effect of the fluids of Ni/Ti/Urea particles in silicone oil was investigated under a DC electric field. It is found that the ER fluids of the urea-doped Ni/TiO2/Urea particles have a high ER activity, which is 10 times that of the particles containing no urea. The polar groups in the particles are the intrinsic reasons for the enhancement of electrorheological effect.

Abstract: The conservation of historic stone sculptures and buildings is a focus of research. But there are no completely satisfying protective materials until now. In this paper, a conservative film of apatite has been prepared on the surface-modified marble stone by using a solution of CaCl2 and (NH4)2HPO4 as the precursor through a biomimetic method. The prepared material was characterized by some instruments. Its performances were also evaluated by its ability to consolidate, resist soil and acid. The obtained results indicate that the conservative effects are satisfying and the biomimetic synthesis should represent a new prospective in stone conservation.

Abstract: A β-NaCaPO4 containing borate glass ceramic is prepared. Two kinds of porous scaffolds are constructed by sintering glass particles in the size of 300~400μm and binding glass particles in the size of 200~300μm using 5 wt% sodium silicate solution respectively. The reaction of the scaffolds in the SBF solution, the bioactivity and biodegradation of the scaffolds are characterized by weight loss analysis, XRD, and SEM. The same is done to the 45S5 scaffolds as comparison. The results show that the borate glass ceramic scaffolds have better biodegradation and bioactivity. The final weight loss of the sintering scaffolds and the binding scaffolds are 50.71% and 70.68% respectively, which indicates that the high temperature during the course of the sintering has great influence on the bioactivity of the borate glass ceramic scaffolds. The XRD indicates that the hydroxylapatite has formed on the both kinds of the scaffolds, and the hydroxylapatite on the binding scaffolds has higher degree of crystallinity. The residual glass phase of the glass ceramics contributes to a quick apatite formation on the scaffolds due to its high solubility in SBF solution, while the β-NaCaPO4 crystal phase leads to a slower apatite formation which guarantees an improved mechanical stability of the scaffold. This combined reaction mechanism enables the biodegradation rate of the scaffolds to match with the growth rate of tissues, which makes the scaffolds a good potential prospect in the field of tissue engineering.

Abstract: A series of natural materials used for oil absorption based on corn stalks have been prepared by acylation grafting with propionic anhydride in a solvent-free system at 100 and 140 °C for 2-6 h. It is found that the oil (benzene) sorption capacity of the grafted corn stalks is about 8.5- 12.6g/g (in 15 minutes), and the grafted material is significantly more hydrophobic than the raw corn stalks. The grafted corn stalk float on the surface of water, as the oil, can be easily to be removed when the application is completed. Fourier infrared (FT-IR) analysis is used to confirm the chemical reaction which takes place between corn stalks and propionic anhydride. Scanning electron microscope (SEM) analysis is used to determine the structure of the grafted corn stalk material.

Abstract: The aim of this work was to study the ability of NIR spectroscopy to determine holocellulose and alpha-cellulose contents in triploid clones of Populus tomentosa. For this purpose 90 trees with five families in different planting density grown in Shandong were analyzed. Calibration models were developed from wet chemical and NIR data using partial least squares (PLS) regression. High coefficients of determination (R2) and low root mean square errors of cross-validation (RMSECV) were obtained for holocellulose (R2 = 0.7805, RMSECV =0.652) and alpha-cellulose (R2 = 0.8702, RMSECV = 0.548) from wood meal. Prediction produced high correlation coefficients between laboratory and predicted values for holocellulose and alpha-cellulose contents, which R2 values are 0.7467 and 0.8505, and RMSEP are 0.993 and 0.553, respectively. This study showed that NIR analysis can be reliably used to predict holocellulose and alpha-cellulose contents in triploid clones of Populus tomentosa.