Advanced Materials Research Vols. 160-162

Abstract: A stabilized laser is essential for optical fiber communication network. One of the passive technique for stabilization of central wavelength of laser is based on the application of fiber Bragg gratings. Due to the positive coefficient of thermal expansion of optical fiber, the Bragg gratings within the fiber written by excimer laser gives about 0.01nm/oC shift on the central wavelength respect to the ambient temperature which leads serious problem in the communication network. Since both the temperature and tension force are linearly proportional to the central wavelength of fiber Bragg gratings. A feasible approach to derive the wavelength stabilization is to decrease the tension force of fiber Bragg gratings respect to the increase of ambient temperature. In this paper, a Kovar substrate with negative coefficient of thermal expansion is used to decrease the tension force while the environmental temperature increases. The experimental results show that the coefficient of thermal expansion of the Kovar substrate is negative and linearly proportional to the temperature. Thus, this Kovar substrate differing from the constant negative coefficient of thermal expansion ceramic substrate induces about 0.0085nm/C on the fiber Bragg gratings, which shows the well application of this Kovar for athermalization of the fiber Bragg gratings in optical communication system.

Abstract: Ni-Fe-P coatings were deposited on ferritic stainless steel by means of electroless method. The oxidation behavior of the steel with these coatings were investigated at 800°C in air. The mass gain of the steel with Ni-Fe-P coatings deposited from solutions with different mass ratios of FeSO4 to NiSO4 decreased with increasing mass ratio. For the steel with Ni-Fe-P coating deposited in the solution with 0.25 of the mass ratio, the mass gain increased with the increase in oxidation time. While the mass gain of the steel with coatings deposited in solution with 0.5 and 0.75 of the mass ratio, respectively, became stable after 10-h oxidation. Compared with Ni-P, The Ni-Fe-P coatings improved the spallation resistance of the surface oxide scale. The oxide scale formed the bare steel consisted of Cr2O3 with TiO2 and (Mn,Cr)3O4 spinel. However, the oxide scale thermally grown on the steel with Ni-Fe-P coatings was composed of NiO, (Ni,Fe)3O4 spinel and Cr2O3.

Abstract: A Microscopic Study on Local Strain Rate Sensitivity of Polypropylene Syntactic Foam with Microballoons

Abstract: The behavior of the ammonia (NH3) oxidation was by selective catalytic oxidation (SCO) over a nanosized Pt-Rh composite catalyst in a tubular fixed-bed flow quartz reactor (TFBR) at temperatures between 423 and 673 K. The catalysts surface properties were characterized using UV-Vis and TEM. The experimental results show high activities for NH3 removal was achieved during catalytic oxidation over the Pt-Rh catalyst at 673 K with an oxygen content of 4%. N2 was the main product in the NH3-SCO process over the nanosized Pt-Rh composite catalyst. These results also verify that the Pt-Rh metals on catalyst surfaces, resulting in the formation of the remarkable catalytically active sites at the metal-support interface in the reduction of NH3 in this process. In addition, the nanosized Pt-Rh composite-induced cytotoxicity testing was mainly applied to the human lung MRC-5 cell line and the percentage of cell survival was determined by MTS analysis in vitro. For nanosized Pt-Rh composite, only minor cytotoxicity was observed when human lung cells were exposed.

Abstract: Since the growing interest in the manufacture and environmental applications of composites consisting of CuO and CeO2 nanoparticles. This work describes the CuO/CeO2 nanoparticle materials were synthesized by coprecipitation approach with aqueous solutions of copper nitrate and cerium nitrate. The nanocomposite particles were characterized by HRTEM, with a particle size around nanoscale particle sizes (~10 nm) with high dispersion phenomena. Further, cell cytotoxicity and the percentage cell survival was determined by using 3-(4,5-dimethylthiazol-2-yl)-5(3-carboxymethoxyphenol)-2-(4-sulfophenyl)-2H-tetrazoli um (MTS) assay on human fetal lung tissue cell (MRC-5). The experimental results show that the CuO/CeO2 nanoparticle materials only minor cause cytotoxicity effect in cultured human cells.

Abstract: A low-cost acid leaching process is studied in this paper to prepare solar-grade polysilicon. The effects of process conditions (grain size, acid species and concentration, leaching time and temperature) are discussed. The further optimized conditions by orthogonal experiments are given in this paper. Optimal operating conditions are suggested: 75μm of grain size, 80 min of leaching time, 0.28 mol/l of concentration of HF, 80 C of leaching temperature. The removal efficiency of impurity reaches 98.41%. Analysis by ICP-AES and SEM illustrates acid leaching appears to be a potential primary process for solar-grade Si purification. .

Abstract: Hydroxylapatite(HAP) nano-whiskers are prepared by reaction-precipitation in the submerged circulative impinging stream reactor(SCISR), with (NH4)2HPO4 and Ca(NO3)2 as the reagents; and the products are characterized by X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectroscopy, Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). The results TEM measured indicate that the product prepared under typical operation conditions is average-sized 15nm and 50-70nm long. Multiply repeated experiments illustrates that, because of the excellent performance of the reactor, the preparation process can be easily controlled to yield nano rod/whisker hydroxylapatite with very narrow size distribution.

Abstract: A novel idea to prepare Polymethacrylimide (PMI) foam is presented in this paper, in which PMI foam was prepared by two steps, the butyl methacrylate (BMA)/methacrylamide (MAM) copolymer was formed using solution polymerization through free radical copolymerization, and then PMI foam was produced through the BMA/MAM copolymer foaming. Mechanism of polymerization reactions was analyzed. The BMA/MAM copolymer and PMI foam were investigated by Fourier transform infrared spectroscopy. It showed disappearance of the primary amide and appearance of the formation of PMI foam, which was in accordance with the mechanism of polymerization reactions. The polarizing micrograph showed PMI foam was highly transparent and closed cell. Differential scanning calorimetry and thermogravimetric analysis results showed PMI foam had excellent thermal stability below ~255°C because of the presence of the imide ring.

Abstract: Colloid mill or high-speed shearing mechanical is used in traditional preparation technology of SBS modified asphalt for the dispersion of SBS in matrix asphalt, which leads to the high equipment cost in production of SBS modified asphalt. The fractions oil of FCC slurry oil distillation with a high content of aromatics is a good swelling agent of SBS. The FCC distillation residual (FR) with high softening point can resolve the problem that penetration increased when the addition of swelling agent increased. SBS is pre-swelled by the heavier fractions from FCC slurry oil, and then it will be dispersed in the vacuum residuum (VR) by simple mechanical stirring to prepare SBS modified asphalt due to the perfect swelling effects in this work. The influences of different materials, distillation yield and ratio of FR to VR on the performance of SBS modified asphalt have been investigated. Fluorescence microscopy was applied to observe the different disperse images of SBS modified asphalt prepared by simple mechanical stirring and high speed shearing. The results indicated that the novel method can be used to prepare SBS modified asphalt with good performance and storage stability.

Abstract: Based on the characteristics of SBS modified asphalt (SBSMA) and crumb rubber modified asphalt (CRMA), crumb rubber and SBS composites modified asphalt (CR/SBSCMA) technology is proposed combine the advantages of crumb rubber and SBS. The preparation technology and production process factors have been discussed in this work. Moreover, the performance comparison results of three modified asphalts confirms that CR/SBSCMA could achieve good high and low temperature performance with low content of SBS and crumb rubber. Furthermore, the separation behavior of CR/SBSCMA has been analyzed, the experimental results indicate that the separation behavior of CR/SBSCMA is caused by the sinkage of rubber particles as well as CRMA. However, the softening point difference of CR/SBSCMA after separation test is smaller greatly than CRMA due to the prevention of SBS particles.