Advanced Materials Research Vol. 549

Abstract: The orientation of the hydrocarbon chains and functionally important chromophore of copper (II) phthalocyanine (CuPc) derivatives are discussed by spectrum assessment methods in ordered thin films. The attention is focused upon the monolayer and multilayer films of CuPc derivatives that are symmetrically and asymmetrically substituted CuPc biosimulation systems. On the basis of infrared (IR) transmission, polarized IR, reflection–absorption (RA) IR spectroscopy and surface enhancement resonance Raman spectra (SERRS) study, following conclusions are given. The hydrocarbon chains of CuPc in the film are in hexagonal or pseudohexagonal subcell packing, and the CH2 asymmetric vibrational vector is oriented with respect to the substrate surface. The macrocycle of CuPc on the Ag substrate is oriented parallel to the surface, and the RA spectroscopy can distinguish the two CH2 stretching modes of benzene cycle. All these studies and results are useful to provide an insight into the nanostructure of the thin films of other kinds of compounds.

Abstract: UV-curable cationic hybrid adhesives containing TiO2 nanostructures were prepared by using 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate (CE) as UV-curable cationic monomer, triphenylsulfonium hexafluorophosphate salt (PI-432) as photoinitiator and titanium-tetraisopropoxide (TIP) as inorganic precursor. Morphology of the UV-cured hybrid adhesives was characterized by atom force microscopy (AFM). The effect of TIP content on refractive index was studied. The results showed that TiO2 nanostructures, the average diameter of which was 20 nm or so, could be uniformly dispersed in hybrid adhesives in presence of 5 wt% 3-glycidoxypropyltrimethoxysilane (GPTS) coupling agent. And the refractive index of hybrid adhesives could be controllably adjusted from 1.5019 to 1.5449 with the change of TIP content. At the same time, the bonding strength of hybrid adhesives were also improved.

Abstract: In the study, ZM5 Mg alloy was laser melted by dispersion of TiO₂ nanoparticles on its surface. The microstructure of the composite surfaced layer (both the top surface and the cross section) was characterized by optical and scanning electron microscope. A detailed analysis of the composition of the composite layer was carried out by energy dispersive spectroscopy. The microhardness of the composite layer was measured and the wear of the composite surfaced ZM5 was studied. Experimental results showed that composite surface layer consists of TiO₂ particles in grain refined ZM5 matrix, but the nanoparticles was agglomerated. And there was degradation of TiO₂ particles or interfacial reaction at the particle-matrix interface. Microhardness and wear resistance of the composite surfaced zone was improved compared to ZM5 substrate.

Abstract: Cyanate ester resin (CE)/epoxy functionalized polyhedral oligomeric silsesquioxane (POSS-Ep) organic-inorganic hybrids were prepared by casting and curing. The hybrid resin systems were studied by gel time test to evaluate the effect of POSS-Ep on curing reactivity of CE. Impact and flexural strengths of the hybrids were investigated. The thermal properties of the hybrids were studied by thermogravimetric analysis (TGA). TGA results show that CE10 also possesses the best thermal stability. The initial temperature of decomposition (Ti) of CE10 is 426 oC, 44 oC higher than that of the pristine CE.

Abstract: Ba_0.85Ca_0.15Ti_0.9Zr_0.1O₃-xLi₂CO₃ lead-free piezoelectric ceramics (abbreviated as BCZT-xLi) were prepared by conventional solid state reaction method. The microstructure, piezoelectric properties and dielectric properties were studied for BCZT-xLi samples doped with different Li₂CO₃ content(x= 0, 0.05, 0.1 0.2 0.3, 0.4wt. %). The results show that the piezoelectric constant(d₃₃), planar electron mechanical coupling coefficient(k_p) and thickness electron mechanical(k_t) of BCZ-T-xLi ceramics increase firstly and decreases subsequently with increasing of Li⁺ doping amount, the dielectric loss(tanδ) of BCZT-xLi ceramics decreases firstly and then increases at the same time while Li⁺ doping amount increases. But the r-elative permittivity (ε_r) of BCZT-xLi ceramics increases all the time. With the in-creasing of the amount of Li₂CO₃ doped the grain size of BCZT-Li ceramic first increases and then decreases. The BCZT-xLi ceramics display the optimum properties (d₃₃=83, tanδ=0.035, ε_r=2020, k_p=0.41, k_t=0.046) while Li₂CO₃ doped amount is 0.20wt. %.

Abstract: Pressure vessels in high sulfur-containing natural gas purification plants are likely corroded in acid media. Corrosion monitoring and control must be carried out to ensure safety and efficiency of purification system. So corrosion cause and service characters of pressure vessels in the purification plants were analyzed in this paper. The factors which influence pressure vessels corrosion include acid gas load, flow rate, phase state, temperature, heat-stable salts and degradation products. Then adaptability, advantages and disadvantages of the methods such as weight loss hanging slice method, electrochemical monitoring, ultrasonic thickness measurement, etc. were also analyzed in the paper. The results show that current on - line corrosion monitoring methods are hard to be applied in high sulfur-containing natural gas purification plants. Weight loss hanging slice method is an effective approach for pressure vessels corrosion monitoring. The data obtained are reliable and the investment is relatively lower. Based on characteristics of different technology units, corrosion coupon monitoring scheme is established. The research result provides a solid base for ensuring safe operation of high sulfur-containing natural gas purification plants.

Abstract: Polyimide is a typical complex high-molecular polymer of imide monomers which is widely used in the manufacture of parts for aerospace technology. In order to improve the safety of spacecraft, the interaction between continuous wave laser and polyimide is studied. Firstly the Hugoniot parameters for a kind of polyimide made in Shanghai Research Institute of Synthetic Resins are obtained in two-stage light-gas gun driven flyer loading way, and the Grüneisen coefficient is determined with the Huang equation and the shock compression experiment data. Then the interaction between continuous wave laser and polyimide is numerically studied with a smoothed particle hydrodynamics program which compiled by ourselves with the FORTRAN language, the ablation process are obtained.

Abstract: Fe nanoparticles with shell of Ni-P coating layer were successfully synthesized using Ni electroless plating process. Electromagnetic-wave absorption of Ni-P coated Fe nanoparticles has been investigated. In contrast to earlier reported materials, the absorption amplitude of as-prepared samples is found not largely decrease with increasing absorption-layer thickness. A reflection loss (RL) exceeding -20 dB can be obtained for almost the whole frequencies within the 2-18GHz range by choosing an appropriate layer thickness between 0.9 and 6.0mm. The broadest bandwidth (RLu-bands(12-18GHz), is obtained for 1.1mm layer. At the same time, it is worth noticing that in a thin thickness range 0.91-2.0mm, the reflection loss (RL) exceeding -10 dB in the 6-18GHz range is obtained, which covers half of C-bands (4-8GHz), the whole X-bands (8-12GHz) and K_u–bands (12-18GHz).

Abstract: Porous UHMWPE with different characteristics are prepared by hot press molding in Metallographic Sample Mounting. Friction and wear loss of porous UHMWPE samples are studied under different loads and lubricant on an improved tribological tester. The friction coefficient and wear loss of samples with porosity of 5.44% are lower than that of samples with porosity of 10.17%. Thickness of porous layer has little effect on the tribological properties of porous UHMWPE. Contact angle remarkable decreases with increasing porosity of UHMWPE samples. The change of wettability is the primary cause of the improving tribological properties of porous UHMWPE.

Abstract: Highly transparent glasses coated with TiO2 hydrosol and polyethylene glycol (PEG) have been successfully fabricated via ultrasonic nebulization technique. Experimental evidences have indicated that the obtained glass surfaces show excellent non-UV activated superhydrophilic wetting and antifogging performance. These properties are significantly affected by calcination temperature and the optimal value is 600 oC. In this paper, the effect of film thickness and the role of PEG in facilitating the pore formation and interacting with TiO2 are also discussed.