Advanced Materials Research Vols. 287-290

Abstract: Hydroxyapatite (HA) is a frequently used bioactive coating material. However, when HA coating is soaked in the simulated body fluid (SBF), it is usually detached from substrate material due to its high dissolution rate in the solution. Recently, it is found that Fluorapatite (FA) has a better anti-dissolution ability than HA. In this study, Fluorapatite was mixed with TiO₂ powder (either Anatase phase (A) or Rutile phase (R)) as a coating material precursor, and then be deposited on Ti-6Al-4V substrate to form the coating layer by using Nd-YAG laser cladding process. After soaking in SBF for various days, it is observed that dense ball-like apatite grew faster on the surface of the FA+R coating layer than that on the surface of the FA+A specimens. The corresponding Ca/P ratios of FA+R specimens also dropped faster than FA+A ones.

Abstract: Based on the design principle of high reflective (HR) membrane of multilayer medium. The HR membrane appropriate for the chemical oxygen-iodine laser (COIL) with Si/SiO2 as high low refractive index materials, was designed on the silicon substrate, using TFCale3.4 simulation design software. We get the reflectivity of COIL over 99.999% at the output wavelength of 1315nm, above 99.2% at the harmonic of 632.8 nm in theory. The thermal deformation of Si-based reflector under the irradiation of Gaussian beam are calculated, using heat conduction equations and axial thermal deformation formula.

Abstract: The effects of the polyhedral oligomeric silsequioxanes (POSS) in stacked poly(methyl methacrylate) (PMMA) film samples were investigated in two different film thicknesses, ~50 and ~660 nm. The types of the POSS include methacryl-, octaisobutyl-, and octasilane-POSS. The glass transition temperature (T_g) and isothermal physical aging was depressed by the reduction of film thickness. Among POSS molecules used in this work, methacryl-POSS was the greatest effect in both T_g and relaxation enthalpy (DH_Relax) due to the physical aging. The Kohlrausch-Williams-Watts (KWW) relaxation function was used to further understand the effect of POSS and film thickness on the physical aging.

Abstract: Poly (vinyl) chloride (PVC)-based proton conducting polymer electrolytes have been prepared by solution cast technique. The effect of addition of ethylene carbonate (EC) as the plasticizer on the structural property of the prepared proton conducting polymer electrolyte system was investigated by X-Ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) while its effect on electrical property was investigated by Impedance Spectroscopy (IS). With addition of plasticizer, the crystalline nature of the polymer was found to be disrupted as revealed by X-Ray diffraction. FTIR showed interactions between Cl^- and H⁺ which was accounted by shifts in the bands of Cl^-. Ionic conductivity was found to be 3.06 x 10 ^-5 S cm^-1 at room temperature (300 K) for the films containing 95 wt. % (PVC -NH₄CF₃SO₃) –5 wt. % EC.

Abstract: Lanthanum hexaboride films were deposited on SiO₂ substrates in a vacuum chamber by D.C. magnetron sputtering from Lanthanum hexaboride pellet target. The films deposited with the same parameters besides the argon pressure. XRD, AFM and style profiler were used to characterize the properties of the deposited films. Surface of the films was compactive and smooth. Density of the film increased with the argon pressure. Roughness of the films decreased firstly and increased after with increasing of the argon pressure. Structure of the films was studied by the XRD. Results of the XRD showed that the dominant crystal face was (100) face. The crystallinity decreased with the increased argon pressure. Deposition rate of the film increased first and decreased last, and the value was lager than other at the argon pressure of 1.5Pa.

Abstract: The laser-induced thermoelectric voltage was observed for the first time in praseodymium doped LaMnO₃ thin film grown on LaAlO3 single crystal vicinal cut substrates by pulsed laser deposition. The experimental data for La_0.5Pr_0.5MnO₃ showed a good liner relation between the voltage and the laser energy. The result suggested that the anisotropic Seebeck effect were responsible for the voltage signals in colossal magnetoresistance manganites thin film.

Abstract: Adaptive genetic algorithm (AGA) is wildly used nowadays for its features such as global searching, fast convergence speed and so on. But it will be difficult to build its fitness function or constraint equation some times. On the contrast, ADAMS is a dynamic analysis software based on the theory Computational Dynamics of Multibody Systems, it is good at physical model analysis. In order to make full use of both advantages, this paper is aim at combination of AGA with ADAMS. What is more, some improved methods are used in AGA. The optimal design of car hood mechanism shows that the use of improved adaptive genetic algorithm (IAGA) based on ADAMS is feasible. Form the result of simulation; it is easy to see that IAGA have better optimal precision and fast convergence speed compared with AGA.

Abstract: Two-dimensional (2D) regular and random cell models composed of circular cells are developed to simulate the microstructure of polymer foams. Two-parameter Mooney-Rivlin strain energy potential model is employed to characterize the hyperelasticity of the solid of which the foams are made. Finite element method is used to simulate the large deformation of the foams. Numerical results show that the strain rate sensitivity of the polymer foam is weak as rate independent constitutive model is introduced to describe the mechanical performance of cell material. ‘X’-, ‘I’-, and ‘V’-shaped bands are observed in regular foam models at a low, high and moderate impact velocities, respectively; whereas ‘I”-shaped modes appear in random cell models at a high impact velocity only.

Abstract: The effect of deposition parameters such as sputtering power, nitrogen flow rate and thickness of TaN_x on the optical performance and chemical durability of composite Tantalum nitride /Ag/ tantalum nitride (TaN_x/Ag/TaN_x) films was investigated. When the configuration of composite film was TaN_x (60nm)/Ag (12nm)/TaN_x (60nm) accompanying with the sputtering power 120W and the nitrogen flow rate 50sccm, the visible light transmittance of composite film could reach up to 80% at the wavelength of 550nm and the emissivity was 0.087. In addition, the chemical durability of the coatings was evaluated and the results indicated that the low-e coating presented very good chemical durability.

Abstract: Two new kinds of Ni-based and Fe-based alloy power have been developed. Both kinds of power have been successfully coated by laser cladding on the surface of stainless steel as strengthening layers. The morphology and microstructure of these coatings have been analyzed by SEM and XRD, the mircohardness, wear and corrosion resistance of Ni-based and Fe-based laser cladding coatings have been measured respectively. The analysis reveals that both coatings with smooth and successive surfaces and homogeneous morphology have been obtained under the proper laser processing parameters; besides, Ni-based and Fe-based coatings have fine, well-proportioned and dense microstructure, and better joints with the substrates, respectively. So the results indicate that Ni-based and Fe-based alloys can supersede the cobalt-based alloys in the certain conditions.