Advanced Materials Research Vols. 199-200

Abstract: Microring resonator based on Si₃N₄ waveguides was fabricated by using CMOS compatible processes with 1 µm wide waveguides and 200 µm in radius. The optical characteristic of the resonator was measured with a Q factor up to 20,000 and a free spectrum range (FSR) of 1 nm. The structure was further packaged to be a sensor for liquid sensing. Finally, the sensor was applied to detect concentrations of glucose solutions with sensitivity of 1.78×10^-5 refractive index unit (RIU), which proves its functionality and feasible application as high sensitivity chemical sensor.

Abstract: The objective of this research is to propose a practical model to predict the in-process surface roughness during the turning process by using the cutting force ratio. The proposed in-process surface roughness model is developed based on the experimentally obtain result by employing the exponential function with six factors of the cutting speed, the feed rate, the rank angle the tool nose radius, the depth of cut, and the cutting force ratio. The multiple regression analysis is utilized to calculate the regression coefficients with the use of the least square method. The prediction accuracy of the in-process surface roughness model has been verified to monitor the in-process predicted surface roughness at 95% confident level. All those parameters have their own characteristics to the arithmetic surface roughness and the surface roughness. It has been proved by the cutting tests that the proposed and developed in-process surface roughness model can be used to predict the in-process surface roughness by utilizing the cutting force ratio with the highly acceptable prediction accuracy.

Abstract: Sulfate reducing bacteria (SRB) were most common bacteria involved in microbiologically influenced corrosion (MIC). In this paper, the influences of surface free energy and electrochemical polarization on sulfate reducing bacteria (SRB) attachment were investigated. Microbial adhesive to hydrocarbons experiment and zeta potential test showed that SRB were relative hydrophobic and were negative charged. SRB showed affinity to substratum with higher water contact angle and its biofilm formation led to alterations in the hydrophocibity of the substratum surface. The mild steel was used to systematically examine the effect of electrochemical polarization on SRB attachment. At -800mV (vs.SCE), the sessile number was similar to those without polarization. At -950mV and -1000mV, the polarization promoted SRB attachment. At -1100mV and -1200mV, the adhered cell number decreased sharply compared to those at -1000mV. SRB attachment was inhibited, at an applied potential of -1300mV. These results indicated that the infuence of negative polarization on SRB attachment was dependent on applied potential.

Abstract: The alicyclic dianhydrides 1,2,3,4-cyclobutanetrtracarboxylic dianhydride was polymerized with four kinds of fluorinated aromatic diamine, 1,4-bis(4-amino-2-trifluoromethyl phenoxy)diphenyl, 1,4-bis(4-amino-2-trifluoromethylphenoxy) diphenyl ether, 2,2-bis[4-(4- aminophenoxy)phenyl]hexafluoropropane and 2,2-bis[4-(4-amino-2-trifluoromethylphenoxy) phenyl]sulfone respectively, via a two-step polycondensation procedure to prepare four series of fluorinated polyimides(PIs). The PI films exhibited high optical transparency in the visible light region(400-700nm) with the transmittance higher than 80% at 450nm. Especially, the PI-III containing four CF3 group showed the best optical transparency with the transmittance higher than 84.61%. And the PI films showed little absorption at the optocommunication wavelengths of 1.30µm and 1.55µm. In addition, these PIs were soluble in amide-type solvent, even in less polar solvent. The effect of internal linkage group of fluorinated diamine on the solubility of PIs was similar.

Abstract: The corrosion behavior of graphite-like carbon (GLC) coating in sea water was studied and yttrium and cerium were doped into it by using mosaic in the target of magnetron sputtering process to improve its corrosion resistance. The result shows that the GLC coating characterizes typical underfilm electrochemical corrosion in sea water. Yttrium added in chromium interlayer or yttrium and cerium added in the surface layer of the GLC coating can apparently improve the microstructure result in significantly decrease the corrosive current density. As the modifications of Y in interlayer and Y, Ce and Ta in top layer are composed together to form complex GLC coating, the wear resistance and the antifriction is dramatically improved, the corrosive current density is only one-twenty fourth of that of the commercial C/Cr GLC coating.

Abstract: This paper describes a curved-layer additive manufacturing technology that has the potential to print plastic components with integral conductive polymer electronic circuits. Researchers at AUT University in New Zealand and the National University of Singapore have developed a novel Fused Deposition Modeling (FDM) process in which the layers of material that make up the part are deposited as curved layers instead of the conventional flat layers. This technology opens up possibilities of building curved plastic parts that have conductive electronic tracks and components printed as an integral part of the plastic component, thereby eliminating printed circuit boards and wiring. It is not possible to do this with existing flat-layer additive manufacturing technologies as the continuity of a circuit could be interrupted between the layers. With curved-layer fused deposition modeling (CLFDM) this problem is removed as continuous filaments in 3 dimensions can be produced, allowing for continuous conductive circuits.

Abstract: Based on the high temperature compression simulation experiments, the mechanical behavior of Ti-6AI-2Zr-1Mo-1V alloy were studied over the range of temperature from 850°C to 1100°C , strain rate from 0.01 to 10s^-1. The results show that the flow stress reduces with temperature increasing at the constant strain rate and increases rapidly with strain rate increasing at the constant temperature. The stress index n and deformation activation energy Q is respectively 7.0874 and 610.463 kJ/mol at 850-950°C . While at 950-1100°C , n is 4.7324 and Q is 238.030 kJ/mol. From the obtained processing map, it is found that two unstable regions present at the lower temperature or higher strain rate and two optimum regions in hot deformation process. The unstable zones are 850-950°C , 0.001-0.008s^-1 of strain rate, and 940-1030°C , 2-10s^-1 of strain rate respectively. In the optimum zone with the temperature range of 1060-1100°C , strain rate of 0.05-0.65s^-1, and the peak efficiency of power dissipation of about 0.42; while in the other zone with the deformation temperature 890-940°C , strain rate of 0.06-0.18s^-1, and the peak efficiency of power dissipation of about 0.33.

Abstract: In a larger-power CNC milling machine, the milling stability of CNC small size tool which is less than φ 25 diameters is restricted under a certain degree. Authors studied CNC milling chatter stability by the experiment and simulation; they had researched those influences of tool’s diameter, suspended length and craft of manufacturing system on chatter stability domain. Researches show that the larger diameter and shorter suspended length of the tool can improve the stability of milling, and also can improve critical axial cutting depth. The lobes of chatter stability domain can forecast effectively critical axial cutting depth and relevant to milling speed, can better mining machine cutting potential.

Abstract: The chitosan derivatives(S-CTS and RS-CTS) were prepared and the application of the derivatives in surface activation process for Ni electroless plating was exploited. S-CTS was prepared by shiff-base reaction of CTS with salicylic aldehyde and RS-CTS was prepared by reduction reaction of S-CTS with KBH4. The results of FT-IR spectroscopic characterization showing the formation of C＝N in S-CTS and C－N in RS-CTS indicated that the above reactions occurred in the supposed route. The thermal properties of the derivatives were studied by Thermogravimetry-Differential thermal analysis (TG-DTA) methods. It is suggested that the thermal stabilities of CTS derivatives were better than that of CTS. Furthermore, RS-CTS is capable of forming even films on ABS surface and adsorbing adequate Ni nano-catalysts for follow-up electroless plating. Optic tight and dense plating layers were finally obtained. It is showed that RS-CTS could be applied as a biopolymer film in activation process for electroless plating.

Abstract: A mathematical model to predict oxygen, carbon dioxide, and water vapour exchanges in non-perforated and micro-perforated thin films in modified atmosphere packaging system has successfully been proposed. Validation of the mathematical model was found to yield good prediction for gas exchanges in the mass of the produce after comparison with the experimental results of modified atmosphere packaging for Lycopersicon esculentum fruit.