Advanced Materials Research Vols. 239-242

Abstract: This study investigated the applicability of TiO₂/Au (or TiO₂/Ag) composite particles, which probably have the plasmon resonance effect, on FTO-glass substrate of the working electrode of a DSSC. The dry particle coating technique was utilized to coat the surfaces of TiO₂ particle with nano-sized Au (or Ag) powder particles. A layer of TiO₂/Au (or TiO₂/Ag) composite particles was deposited on the FTO-glass substrate of the working electrode, and it was then sintered in a high-temperature furnace. The working electrode covered with a TiO₂/Au (or TiO₂/Ag) thin film was kept immersed in a solution of N-719 (Ruthenium) dye for 12 h. Finally, the DSSC was assembled, and the short-circuit photocurrent; the open-circuit photovoltage, and the power conversion efficiency η of DSSC were measured using a home-made I-V measurement system. This study also examined the effects of the mass ratio of TiO₂ to Au (or Ag) and the duration of dry coating on the η of the DSSC. If the duration of dry coating is adequate, the η of the DSSC with TiO₂/Au (or TiO₂/Ag) composite particles increased with increase in the percentage of Au (or Ag) in the composite particles. Most importantly, this study shows that the power conversion efficiency η of the DSSC with a film of TiO₂/Au (or TiO₂/Ag) on the working electrode always exceeds that of the conventional DSSC due to presence of the Schottky barrier, which is probably created in the TiO₂/Au (or TiO₂/Ag) composite particle.

Abstract: To decrease the interdiffusion, CrON interlayer as a diffusion barrier was introduced into the interface of NiCrAlY overlayer and DSM11 substrate. The microstructure and effect of the diffusion barrier were investigated. It was found that the as-deposited CrON diffusion barrier was comprised of Cr₂O₃ and CrN. During thermal treatment (including vacuum heat treatment and thermal exposure), the diffusion barrier was first transformed to Al₂O₃ and Cr₂N, then to Al₂O₃ dominant interlayer, and porous mixed-oxides including TiO₂ and NiCr₂O₄ spinels were detected in the interdiffusion zone between the diffusion barrier and the substrate. The presence of α- Al₂O₃ in the diffusion barrier was the main reason for suppressing the interdiffusion. The interfacial reaction mechanism in the diffusion barrier was discussed by elemental diffusion and chemical reaction thermodynamics.

Abstract: Conversion coatings on commercial brass were prepared with lanthanum salt (La(NO₃)₃) and benzotriazole (BTAH) as reagents. A “Critical La(NO₃)₃ content” and “Critical BTAH content” were both observed, at which the coatings prepared performs the highest protectiveness.The results showed that La(NO₃)₃ and BTAH had an excellent synergism effect on the corrosion inhibition of brass. A remarkable enhancement of the brass’s corrosion protection was obtained by the formation of conversion coatings consisted of Cu₂O, La₂O₃, Cu(I)BTA and La-complex, which acted as a barrier avoiding the release of metal ions and inhibited the diffusion of the oxygen.

Abstract: With an average diameter of 148-285 nm and a conductivity of 2.38E^-2- 5.88 E^-2S/cm, Nanoscaled polyaniline (PANI) were synthesized based on template-free method in the presence of dicarboxylic acids dopants (e.g., D-tartaric acid, Succinic acid, maleic acid and fumaric acid). Furthermore, the trans-cis isomerization of butenedioic acid plays an important role in the formation of nanostructures from plane-like to nanofibers, and PANI-MA has larger diameter, higher crystallinity and conductivity than PANI-FA.

Abstract: Bamboo kraft pulp with Kappa number of 25.6 was sampled, and oxygen delignification was applied to bleach these bamboo pulp samples. By investigating yield, Kappa number, viscosity, brightness of pulp, and delignification selectivity, it has been proven that caustic soda dosage and reaction temperature were major factors for oxygen delignification. The optimal conditions for oxygen delignification were proposed as follows: alkali dosage of 3.5% on o.d. pulp-mass, reaction temperature of 85°C, oxygen pressure of 0.6 MPa, and temperature retention time of 80 min. Two stages of oxygen delignification were used and no washing between the two was required. It was found that delignification efficiency and selectivity to lignin-removal were improved significantly. In addition, adding hydroquinone compounds during oxygen delignification can improve the qualities greatly such as higher viscosity and better selectivity of delignification.

Abstract: Ni-Cr films were electrodeposited from a nickel sulfate, chromium chloride and chromium sulfate bath. To avoid the poor adhesion and bad surface morphology of the secondary-co-deposition of Ni-Cr alloy films, H₂O and DMF (volume ratio as 1:1) is used as solvent. Along with the alloy films growing thick, their surface apertures become larger correspondingly, which causes the hardness and corrosion resistance of the films becoming poor. For comparison, nanocrystalline Ni-Cr films with TiO₂ nanoparticles were obtained on the same condition. TiO₂ nanoparticles have an average size of 40 nm. The corrosion resistance of the Ni-Cr composite coatings were comparatively evaluated by salt spray test. It is found that the incorporation of TiO₂ particles enhances the microhardness and corrosion resistance of the coatings. The reason is that the nano-TiO₂ particles in the deposit effectively reduce the size of Ni and Cr crystals through grain refinement-strengthening and dispersion-strengthening effect. The observation results of scanning electron microscopy (SEM) indicated that the Ni-Cr films without dispersions of TiO₂ nanoparticles exhibited numerous large and deep crackles, however, the crackles of nano-TiO₂ Ni-Cr film distinctly became less.

Abstract: In-mold coating (IMC) of plastic parts is a promising coating process in automotive and consumer products industry. An IMC material, such as carbon black suspension, can potentially be used as a top coat or paint. IMC is performed by injecting a reactive liquid polymer onto a part’s surface in the end of the forming process while the part is still in the mold. The coating material flows under high pressure by compressing the part’s surface, which causes a microchannel of 75-125 micron thickness. The IMC flow, particularly in a microchannel, tends to cause the slip boundary at the channel wall. This research work aims to (i) study rheological properties of carbon black suspended in acrylic resin in both macro- and micro-scale, (ii) study slipping at the wall in the microchannel, and (iii) determine significant factors affecting the slip flow of the carbon black suspension. A custom-built microslit rheometer was developed to conduct experiments to serve these purposes. By analyzing the viscosity data, a slip parameter called slip length could be determined. Statistical design of experiments was then applied to determine the effect of three factors including channel gap, operating temperature, and carbon black content on the slip boundary conditions of the microflow. The results showed that these three factors significantly affected the slip length of the flow of carbon black suspension.

Abstract: In this study, the comprehensive performance of AZ80 magnesium alloy was improved by solution treatment and multi-step ageing treatment. The effects of different thermal processing parameters on the microstructure and mechanical properties of AZ80 magnesium alloy were studied. The experimental results show that the optimal process of solution treatment for AZ80 alloy is heated at 420°C for 5h, which the β phase dissolve thoroughly into the α substrate. After first-stage ageing treatment, the hardness of samples varied as the ageing temperature, and had higher hardeness at temprature 180°C. While in the second-stage ageing treatment, the sample got the ageing peak value at 210°C for 10h. After two-stage treatment, the grains of AZ80 magnesium alloy became homogeneous and fine, and the second phase distributes along the grain boundary and plays an important role of dispersion strengthening. Above all, the optimal heat treatment process of AZ80 magnesium is solution treated at 420°C for 5h, as well as ageing at 180°C, 4h and 210°C, 10h.

Abstract: Zinc zeolite-Ce/ TiO₂ antibacterial material was prepared through immersion method with anatase nano- TiO₂ power as main raw materials, zinc zeolite as carrier and cerium ions as doping ions. Its antibacterial function was evaluated by detecting the inhibition zone, the light-catalyzed effect of pure TiO₂ antibacterial material was contrasted with zinc zeolite-Ce/ TiO₂ antibacterial material by using ultraviolet spectrum. The results showed that zinc zeolite-Ce/ TiO₂ antibacterial material had strong bacteriostasis to escherichia coli. It performed best when the diameter of inhibition zone reached to 34.64 mm under the condition of the ratio of nano-TiO₂ to cerous nitrate was 40:1, the reacting time was half an hour, the maturing temperature was 300°Cand pH value was equal to 3.

Abstract: P-type hydrogenated amorphous silicon films were deposited on float glass substrates by plasma enhanced chemical vapor deposition (PECVD). The effect of B doping concentration on the properties of the films was studied. The structure of the films was investigated by X-ray diffraction (XRD). The transmittance of the films was measured using an UV–Vis–NIR spectrophotometer in the wavelength range 200–2600nm.The film thickness was fitted by NKD-7000W optical thin film analysis system. The optical band gap of the films was obtained by the Tauc method. The conductivity of the films was tested by Electrometer Keithley 6517B. The results show that the optical band gap of the films changes from 1.93 eV to 1.65eV with the increase of B doping concentration, the highest conductivity of the film doped with 1.86% B₂H₆ is 7.82 × 10^-4S/cm.