Advanced Materials Research Vols. 690-693

Abstract: A preliminary study on the micro-structure of a special sericite-jade material has been carried out by using the XRD and SEM methods. By XRD analysis, the 2M₁ type sericite is identified as the main mineral composition of the white-colored, yellow-colored and green-colored jade. Quartz, as the secondary mineral, is also common in the green-colored jade. However, the dominant mineral composition of the black-colored jade is chlorite. SEM analysis reveals both the micro-morphology of the jade-forming minerals and the micro-structure of the mineral aggregates are various, which have significant relationships with the Guangning jade quality. Minuscular mineral grains and compact micro-structure make jade materials exquisite. Conversely, large mineral grains and the loose micro-structure make jade materials more rougher.

Abstract: In this paper, it can be seen that the optimum mixture ratio of graphite to other contents (graphite: H₂SO₄: H₂O₂: HClO₄) is 10(g):28(ml):1(ml):5(ml), which obtained the best expansion volu_{Subscript text}me (191ml/g). The Fe₃O₄-expanded graphite composite material was prepared by FeCl₃ solution of ethylene glycol with heating reaction in reactor. The graphite sheets within EG were nanoscales, four iron oxide nanoparticles were dispersed between holes of expanded graphite sheets. Evidently, the graphite nanosheets wrapped in the four iron oxide particles can be observed. It is clearly that the magnetic adsorption properties of particles are strength on EG/Fe₃O₄. In addition, the EG/Fe₃O₄ composite obtained by this process has a product (magnetite), which is proved of XRD characteristic peaks.

Abstract: Ag⁄N co–doped TiO₂ nanotube arrays (TNTs) were prepared by anodic oxidation, a certain amount of Ag deposited on the surface of TNTs by photodeposition and annealing post-treatment. The doped TNTs were characterized by field-emission scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV–vis diffusion reflection spectroscopy (UV–vis DRS). The photocatalytic activities of the prepared TiO₂ were evaluated by degrading rhodamine B (RhB) under visible light irradiation (≤ 420 nm). The photocatalytic degradation efficiency of the Ag/N-TNTs obtained for the degradation of RhB are 0.32 times, 0.6 times and 1.86 times higher than that of TNTs, N–TNTs, AgTNTs, respectively.

Abstract: To successfully prepare drug delivery system, nanoparticles (NPs) with simple and effective method avoiding use of potentially toxic solvent and components, 5-fluorouracil (5-Fu) was chosen as a model low molecular weight chemotherapeutic drug and 5-Fu- loaded NPs were prepared with the lecithin emulsified method following the alginate solidification and chitosan aggregation. Prescription was optimized by orthogonal experiment. The resultant 5-Fu NPs had a spherical structure with a diameter about 200 nm. The encapsulation efficiency of 5-Fu NPs is 55.36 ± 1.10%. The loading capacity is 4.22 ± 0.14%.

Abstract: A modified electrospinning setup with two-grounded-frame collector is proposed to fabricate aligned fiber arrays and fiber ropes. In this setup, two frames are placed under the spinneret, with the outer frame rotated with an electromotor and the inner frame hold still in a horizontal direction. Aligned nanofiber arrays can be collected rapidly on the inner frame. Influence of included angle and motor rotating speed on the arrays is discussed. In addition, through rotating one side of the inner frame, twisted fiber ropes with diameter 30~40 μm and length of 12 cm are obtained. Mechanical properties of the individual nanofiber ropes are also measured and discussed.

Abstract: Wetting agent plays one of the most important roles in matrix designing of vitrified bond tools. In this paper, we studied the impact of wetting agents, resin liquid, sodium silicate and dextrin liquid, in different types and amount on the formability and bending strength of abrasive tools. It shows that tools using resin liquid as moistening agent by adding 4wt%～5wt% of the amount of bond and diamond to forming materials has the best performance in formability and bending strength of green and finished abrasive segment.

Abstract: Three kinds of Al2O3 ceramics matrix composites, such as Al2O3-TiB2, Al2O3-SiC and Al2O3-TiC, were prepared by two steps, which were synthesis of the composites by thermal explosion under a pressure of 20MPa and hot pressing of the composites at 1700°C under a pressure of 32MPa respectively. The preparation process, the composition and the microstructure of the composites were investigated in detail. The Gibbs free energy and the adiabatic temperature (Tad) of three exothermic synthesis reactions were calculated. Disc-shaped and elongated TiB2 grains were synthesized in the Al2O3-TiB2 composite. Some whiskers and platelet grains were synthesized in the Al2O3-SiC composite. Nano-particles were synthesized in the Al2O3-TiC composite and distributed both within the Al2O3 matrix grains and along the grain boundaries.

Abstract: With the addition of ZrSi₂, the highly densified ZrB₂-based ceramics were fabricated by hot pressing. The relative density increased with increasing the volume fraction of ZrSi₂^­ and sintering temperature; the Vickers hardness increased with increasing the sintering temperature, but decreased with increasing the volume fraction of ZrSi₂^­.

Abstract: Domains and size effect of Curie temperature in BaTiO₃ nanoceramics has been studied in this paper. We have calculated Coulomb interaction in a single domain of multi-domains BaTiO₃ grain, and obtained Curie temperature at various grain size. The results show that along with the grain size decreases, the change of Coulomb interaction depends on type of domains. 90 degree domains cause Coulomb interaction increase and Curie temperature moves to high temperature; 180 degree domains make Coulomb interaction weak and Curie temperature moves to low temperature. The results are compared with experimental data.

Abstract: A new comprehensive evaluation method for grindability of ceramic materials is advanced. The mechanical property parameters of ceramic materials are selected as influencing factors for grindability, the interval sample matrices are established, the interval grey relational coefficient matrices are calculated and the factors weights determined by the eigenvectors. The important degree sequence of influencing factors and comprehensive evaluation value of grindability for ceramic materials are obtained. Seven typical engineering ceramic materials are analyzed using the method, the objective and comprehensive results are gained.