Surface Engineering

Abstract: Steel castings with a ceramic reinforced surface layer have been prepared by a casting process combined with self-propagation high-temperature synthesis (SHS). Two material systems, Fe-Ti-C-Al and Al-Fe2O3, were selected in this paper to prepare the steel castings with a ceramic reinforced surface layer. During the process, high temperature steel melt was poured into a sand mould in which SHS performs were cast. The performs were ignited by the high temperature steel melt. As a result, an SHS reaction happened and ceramic reinforcements were synthesized inside the mould. After the penetration of the molten steel and the scattering of the ceramic reinforcement, a steel casting with an in-situ ceramic reinforced surface layer was obtained.

Abstract: In this paper, by measurement of zeta potential and particle size the surface modification of Cu nanoparticles in water was investigated at different pH values and different concentration of sodium dodecylbenzenesulfonate (SDBS) dispersant. The results show that the absolute value of zeta potential has very corresponding relation with particle size, and that the higher the absolute value of zeta potential and the smaller of the particle size are, the better dispersion and stability of copper nano-suspensions system is. It is also found that SDBS can significantly affect the value of zeta potential and particle size by electrostatic repulsions, which lead to the enhancement of the stability of the Cu suspensions, and the optimizing concentration for SDBS in 0.1% copper nano-suspensions is 0.07%, which have the best disperse results.

Abstract: The Cu-coated nano SiC composite particles were prepared by heterogeneous nucleation method. For the heterogeneous nucleation process, the dispered nano SiC particles and the active Cu2O precipitation were both prefabricated. The composite particles were characterized by means of XRD, SEM, EDS, TEM and ED analysis technics. It is found that Cu layers are coated on the nano SiC particles, which are continuous and dense, and partly oxidized to Cu2O, and the oxidation rate can be reduced by improving experimental processes. The investigation on reaction mechanism shows the disproportionating reaction speed of Cu+ can be controlled by adjusting the pH value of reaction solution, which makes the degree of supersaturation of Cu crystallites accord with the conditions of heterogeneous nucleation.

Abstract: A novel discotic triphenylene derivative bearing one triphenylene discogen as core and three cyano-biphenyl moieties was synthesized and its thermal behavior was studied using polarizing optical microscope, differential scanning calorimeter and X-ray diffraction. It was found that this molecule containing [decylene?] spacers showed nematic phase. After being mixed with methyl methacrylate (MMA), the discogen showed nematic phase at the mesophase temperature range (64~85 °C) and oriented spontaneously in the mixture after annealing for 2 hours in the mixture. The orientation can be stabilized by the polymerization of MMA. The orientation can be fixed by the polymerization of MMA. It was treated directly on glass substrate, which surface did not treat by polyimide film and confirmed the orientation was proved by X-ray diffraction. This offers If the alignment of the discotic molecules can be freely controlled and fixed, a useful mean to produce new area of optically anisotropic film will be produced with this material.

Abstract: The unitary thermal insulation fiber materials can not satisfy rigorous high temperature environment usually. New inorganic coatings were prepared by adding SiO2 aerogels super-insulation powder into high temperature adhesive. Aerogels are high dispersive solid materials which consist of colloid particles or high polymer molecule and have continuous random network structure filling with gaseous dispersive medium. The coatings with super insulation function were made by means of adding thermal-proof materials to the coatings. The microstructure of light porous power and the states of coatings on the surface of fiber paper under different state were observed by scanning electron microscope (SEM). The insulated effect of the composite materials was tested by considering thermal conductivity. On the basis of this, the coatings on the surface of fiber paper were optimized according to the material thermal-insulation performance and the materials that could be satisfactory to the service conditions were made in the end. The results show that silica aerogels powder is dispersed equably in high temperature adhesive. The new inorganic coatings possess themselves of good thermal-insulation effect and can be used as insulated space-layers. The insulation ability of fiber paper is improved obviously.

Abstract: This paper reported a novel method to measure photoinduced acid generation in polymer films, which were widely used in microlithography. The method employed Rhodamine B (RB) as acid sensor due to its changes in color and uv-vis absorbency in acidic condition. The property of Rhodamine B was examined in hydrochloric and trifluoromethyl sulfonic acids, and the standard working curves in thin polymer film were set up, which indicated the relationship of acid concentration and Rhodamine B’s relative peak absorption ("ABS). In this case, the difference in absorbency could reflect the different amounts of acid generated. According to these standard working curves, we can calculate the efficiency of photoacid generator (PAG). This method has advantage over existing method in measuring the efficiency of photoacid generator in solution, because it eliminated the influence of solvents.

Abstract: To solve the gelatin gum arabic electronic ink microcapsules’ problems of thin shells, easy to break and poor mechanical properties, the above microcapsule was coated by urea-formaldehyde polymer and double shell microcapsule was got. The surface morphology of double shell microcapsules was observed by Metallurgical Microscopy, the dispersion particle size of microcapsules was measured by Laser Particle Size Analyzer, the microcapsules’ hermetization property was tested by UV-Vis spectrophotometer, and the mechanical intensity of microcapsule was measured by Microcomputer Control Omnipotence Test Machine (MCOTM). It was found that the microcapsule prepared by this method showed regular shape and increased size. Additionally, both the hermetization property and mechanic intensity of the microcapsules were improved.

Abstract: Vertical deposition technique to fabricate thin film solid artificial opals is becoming widely used. In present work, we report on solvent modification and its effect on the arrangement of colloidal crystals. Micrometer-sized periodic stripe patterns of colloidal crystal were formed from the aqueous ethanol mixture solvents containing higher concentration of ethanol.

Abstract: To prepare the nano-scale silver carboxylate emulsions and investigate their applications in the preparation of nano-scale silver films, the silver citrate emulsion was synthesized through the reaction of silver nitrate with sodium citrate in the presence of polyvinylpyrrolidone (PVP) as a surface modification agent in water. The emulsion was coated onto the surface of the PET substrate to form a thin latex layer of silver citrate. And this was followed by drying at about 100 °C. Then, the silver citrate thin film was deoxidized by aqueous ascorbic acid. Finally, a translucent silver thin film was formed on the surface of the PET substrate. Properties of the silver citrate emulsion and the silver film on the PET were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), laser particle size analysis, scanning electron microscopy (SEM), thermogravimetry(TG) ,UV-visible absorption spectroscopy, atomic force microscopy(AFM) and digital multimeter analysis. It was found that the silver citrate particle surface-modified by PVP has a nano-rod structure and homogeneous size distribution. The nano-rod was about 20 nm in diameter and 200 nm in length. For the UV-visible absorption spectrum of the thin film exhibited an absorption peak at 430 nm, the silver thin film prepared on the surface of the PET substrate was a typical nano-scale sliver film. Measurements of the sliver thin film at room temperature indicated that the silver film was electrically conductive, and the surface resistance was 2.42 k5/cm.

Abstract: Surface modification is a process in which Si-CH3 groups of trimethylchlorosilane (TMCS) replace -OH groups on the inner surface of SiO2 aerogels, so the surface property of aerogels has shown hydrophobic performance which could be changed back to hydrophilic by 450 heat treatment. This aerogels with surface property controlled are prepared via sol-gel process with polyethoxydisiloxanes (E-40) used as precursor, and have typical porous structures dried at ambient pressure: high porosity (above 90 %), super specific surface area (about 1000 m2/g), low bulk density (down to 3.03 kg/m3) and average pore size is about 20 nm. This paper presents adsorption mechanisms in aerogels and illustrates that the adsorption capacity of aerogels is three or four times as much as that of activated carbon fiber (ACF) and granule of activated carbon (GAC). So SiO2 aerogels are potentially important to be used as absorbents being quite efficient to adsorb toxic substances.