Materials Science Forum Vol. 815

Abstract: The medical Ti-20Mo alloys were fabricated by powder metallurgy. The effects of sintering temperature on the phase, the morphology and the mechanical properties of Ti-Mo alloys were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and mechanical properties test methods. The results showed that after sintering at 1200 °C, the microstructure of Ti-Mo alloys mainly consisted of α phase. The increasing sintering time could promote α→β phase transition, thus the flexural strength and the elastic modulus of Ti-Mo alloys could be controlled. When the sintering temperature was 1300 °C, molybdenum content was 20%, the bending strength and the compressive strength of Ti-20Mo alloy were 1369MPa and 2602MPa respectively, and the elastic modulus was 3.4GPa. It may be concluded that the Ti-20Mo alloys is prospective prostheses materials.

Abstract: A series of novel reddish-orange phosphors Ca₃Y_2-xSm_xWO₉ were synthesized by solid-state method and characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR) and photoluminescence (PL) spectra. The results showed that these phosphors are tetragonal structures. The optimum calcining temperature was 1100°C, and the sintering time was 3h. The results demonstrated that the optimal doping concentration of Sm³⁺ in Ca₃Y₂WO₉ was about 1 mol%. The main emission line was ⁴G_5/2→⁶H_7/2 transition of Sm³⁺ at 593nm, and showed intense reddish-orange.

Abstract: The luminescence properties of green-yellow emitting (Sr_1-xBa_x)_1.95SiO₄:0.05Eu²⁺ (0≤x≤1) phosphors were discussed in this paper. These phosphors were synthesized through the high temperature solid-state reaction technique and characterized by X-ray diffraction. The experimental results indicated that all the major phase of prepared phosphors gradually varied from α-Sr₂SiO₄ (x=0) phase to Ba₂SiO₄ (x=1) phase, and an intermediate phase between the two phases was observed at x=0.5. The excitation spectra (λem λ_em=524 nm) and emission spectra (λex λ_ex=400 nm) showed a broad band character with peak located at 365 nm and range from 579 nm to 508 nm, respectively. With the increase of concentration of barium, the thermal stability of the phosphors increased first when x is less than 0.5, and then it decreased when x surpasses 0.5. In addition, luminescence intensity was enhanced with the barium concentration. Under the 400 nm NUV light excitation the (Sr_1-xBa_x) _1.95SiO₄:0.05Eu²⁺ phosphors have a potential application in white LED.

Abstract: A red-emitting phosphor, Eu³⁺ activated Ca₂Li₂BiV₃O₁₂ was synthesized via combining combustion with solid state method and characterized by X-ray powder diffraction (XRD) and fluorescence spectrophotometer. The influence of synthesis temperature and the concentration of Eu³⁺ ions, on phase composition and luminescent properties of the synthesized samples was investigated systematically. The results showed that the Ca₂Li₂BiV₃O₁₂:Eu³⁺ phosphor with high phase purity and good crystallinity can be obtained by this citric acid - assisted sol combustion-solid state route at the synthesis temperature from 600°C to 700°C. The excitation spectrum of Ca₂Li₂BiV₃O₁₂:Eu³⁺ was composed of a broad band from 200 nm to 385 nm and a number of sharp small peaks extending from 390 nm to 480 nm, and the main peak was at 277 nm. The main emission peak was at 612 nm due to the electric dipole transition of ⁵D₀ → ⁷F₂ of Eu³⁺, which results in a red emitting. The sample prepared at T=680 °C, Eu³⁺ mol%=15 mol% has the highest emission intensity in this work.

Abstract: Using anionic surfactant sodium dodecylsulfate (SDS), cationic surfactant cetyltrimethylammonium bromide (CTAB) and nonionic surfactant polyethylene glycol 20000 (PEG20000) and glyceryl monostearate (monostearin) respectively, Ce-doped Y₃Al₅O₁₂ (YAG:Ce³⁺(6%)) yellow phosphors were prepared by a combination method of high energy ball milling and solid state reaction. The effects of surfactant type on structure, morphology and luminescence properties were investigated by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and fluorescence spectrometer. The results showed that the crystal structure of YAG:Ce³⁺ phosphors were not changed with the introduction of surfactants,but their morphology was greatly influenced. The maximum PL intensity was obtained for the nonionic surfactant PEG20000 due to the more uniform morphology and size as well as more homogeneous distribution of particles. Also, the results demonstrated that surfactant concentration had a vital effect on morphology and fluorescent properties of the phosphors,and the optimum amount of surfactant is 10 wt%.

Abstract: Titanium (Ti) foams used in biomedical application has been attracted scientific and technological interest because of their excellent mechanical properties, superior corrosion resistance and good biocompability. In this article, Ti foam with semi-open cell was prepared using the acicular carbamide as a space holder without any adhesives. The pore structure was characterized by SEM and the mechanical properties were determined by compressive tests. The results show that the porosity is 56.8%, the compressive strength and Young’s modulus are 104.6 MPa and 2.9 GPa, respectively. These results demonstrated that the obtained foam has a great potential as a substitute biomaterial for cortical bone.

Abstract: To improve the properties of silk fibroin film, the silk fibroin/pyrrolidone blend films were prepared by mixing silk fibroin and pyrrolidone solution at different ratios. The structure and mechanical properties of blend films were characterized. X-ray diffraction was used to investigate structure of the SF/PYR films, and the results indicated that the blend films were composed of the β-sheet form. Tensile strength and elongation at break of blend films were measured using an instron tensile tester. The results showed that tensile strength and elongation at break of blend films were high enough for application. Furthermore, the films’ flexibility was significantly improved. The optical clarity of blend film was tested by Microplate system. It can be seen from the results that optical clarity is not stable, but in some particular ratios we also can get high light transmittance blend films. At last, biocompatibility of blend films (the rate of the blend film is 30%) was accessed with L929 cell. The results showed that all types of blend films were able to support cell adhesion and proliferation. In addition, the cellular morphology of the cells cultured on blend films was better than that on silk fibroin films. In view of the mechanical properties and optical clarity, combined with their ability to support L929 proliferation suggests that this blend films will offer new options in many different biomedical applications.

Abstract: The availability of a safety and efficient vehicle for pain relief system remains major challenge. The clinical applications of capsaicin are restricted by lacking a long-term drug delivery system The purpose of the present study is to control the release of topically applied capsaicin from silk fibroin hydrogel, all factors including proportions of silk fibroin, amount of capsaicin and penetration enhancer are studied. The capsaicin release behavior was measured by using x-ray fluorescence spectroscopy (XRF). X-ray diffraction (XRD) was used to investigate structure of the silk fibroin hydrogels. The results indicate that the silk can protect the capsaicin and also all factors involved influence the capsaicin release behavior. The release of the capsaicin may be controlled exactly by changing the factors involved. So the silk fibroin hydrogels make the capsaicin a promising pain relief drug used in clinic in the future.

Abstract: To explore the preparation of novel dental resin composites with enhanced properties, two commercial silica particles with sizes of around 1μm and 40 nm were chosen as inorganic fillers, and firstly surface functionalized by 3-methacryloxypropyltrimethoxysilane (γ-MPS) to incorporate cross-linkable vinyl groups onto the surface of fillers. Then the modified fillers were blended with organic monomers, bisphenolAdiglycidyldimethacrylate (Bis-GMA) and triethylene glycol dimethacrylate (TEGDMA), to fabricate the resin compositeswith a three-roll mixer.Resin composites with various weight percentage of fillers and component ratio of microparticle and nanoparticle were prepared. Surface functionalization of silica particles was characterized by fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA), and mechanical properties degree of conversion, and depth of cure of the resultant resin composites were investigated byuniversal testing machineand FTIR. The results indicated that surface modification of silica particles was successful and the surface organic contents were 3.29% and 4.34%, respectively. Among the studied resin composites, the resin composite with 75 wt.% silica particles (59 wt.% microparticles and 16 wt.% nanoparticles) presented the highest value of depth of cure (5.52 ± 0.07 mm), and optimum mechanical properties such as flexural strength (149.8 ± 3.3 MPa), flexural modulus (13.8 ± 0.06 GPa), compressive strength (340.6 ± 8.3 MPa) and Vicker’smicrohardness (78.26 ± 2.45 HV). The study of dental resin composites fabricated from commercial silica particles with excellent properties might provide a new sight for realizing the preparation of this kind of dental resin composites in an industrial scale.

Abstract: A kind of novel antibacterial denture base powder incorporated with PMMA-modified nanoAg/NaZr₂(PO₄)₃ (CBD-300) was prepared by in-situ suspension polymerization and the flexural properties of denture base resin was investigated. CBD-300 was silanized by 3-methacryloxy propyl trimethoxyl silane (γ-MPS), and then γ-MPS-CBD-300 was grafted with poly (methyl methacrylate) (PMMA) to prepare M-CBD-300 which has a good compatibility with the denture base resin. Denture base powders with different addition of M-CBD-300 were prepared by in-situ suspension polymerization. Thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR) and water contact angle were used to characterize M-CBD-300. The size of denture base powder was observed by optical microscope. Universal testing apparatus and scanning electron microscope (SEM) were used to investigate flexural properties of denture base resin samples. The results showed that the surface of M-CBD-300 was successfully modified by PMMA, and the incorporation of M-CBD-300 leads to increasing of the denture base powder size. The flexural properties of the denture base resin samples prepared with our antibacterial denture base powders were enhanced greatly compared with the blank sample.