Influence of Surface Modification on Tribo-Performance of Hybrid Glass/PTFE Fabric Composite with Phenolic Resin Binder

The fabric/phenolic composites with the pure and silanized hybrid glass/PTFE fabric were prepared by dip-coating of the hybrid glass/PTFE fabrics in a phenolic resin. The friction and wear performances of the resulting fabric composites were evaluated using pin-on-disc wear tester. The composition change of the glass fabric in hybrid glass/PTFE fabric after silanization was analyzed by FTIR spectroscopy. The morphologies of the composite structures and the worn surfaces of the composites were analyzed by means of scanning electron microscopy (SEM). The results show that the fabric/phenolic composite with the β-aminoethyltrimethoxylsilane silanized hybrid glass/PTFE fabric can obtain the highest load-carrying capacity and the best wear-resistance, followed by the composite with γ-glycidoxypropyltrimethoxysilane silanized hybrid glass/PTFE fabric. Chemical reactions have achieved as the hybrid glass/PTFE fabric was silanized with β-aminoethyltrimethoxyl silane or γ-glycidoxypropyltrimethoxy silane, which contribute to strengthen the bonding strength between the fabric and the adhesive and hence to improve the tribological properties of the hybrid glass/PTFE fabric composites.     

Comparing internal stress in diamond-like carbon films with different structure

Diamond-like carbon (DLC) films with different structures were deposited on Si (100) and stainless steel substrates in a hybrid deposition system with Ar and CH₄ as the feedstocks. The effects of the bias voltage, Ti-interlayer, Ti functional gradient layer and Ti-doping on the internal stress in DLC films were investigated. The results show that the internal stress in DLC films arises from both the intrinsic stress generated during the film growth and the thermal stress generated due to the mismatching of the thermal expansion coefficient between the DLC films and the substrate materials. The intrinsic stress can be released through doping titanium element at the expense of reducing the sp³/sp² ratio. The thermal stress in DLC films can be decreased through introducing Ti-interlayer or Ti functional gradient layer. Noticeably, DLC films with very low internal stress deposited on stainless steel can be obtained through the combination of Ti-doping and Ti functional gradient layer.     

Reliable synthesis of bismuth nanoparticles for heavy metal detection

A reliable and facile pathway is described here for preparing high-quality bismuth nanoparticles. Combined with hydrothermal method and confined growing effect of polymer, bismuth nanoparticles with uniform size and shape were obtained with remarkable productivity. The nanoparticles is proved to be pure Rhombohedral structure Bi crystals with R-3m space group and the diameter of the nanoparticles is about 80 nm with a quite narrow particle size distribution. Those bismuth nanoparticles were predicted to grow from a rolling process by sheet-like Bi nanocrystal intermediates. The obtained bismuth nanoparticles were used to prepare modified electrode for the detection of Cd²⁺ and Pb²⁺ in water solution by stripping analysis. Compared with naked glassy carbon electrodes, the modified electrode showed two obvious responses at −0.85 V and −0.62 V, corresponding to the reduction process of Pb²⁺ and Cd²⁺ and this well-resolved stripping response can be observed when the concentration is as low as 10 μg/L, indicating potential application in electroanalysis for environmental inspection.     

Effect of thermal activation on the tribological behaviours of serpentine ultrafine powders as an additive in liquid paraffin

The influence of thermal activation temperature on the tribological properties of surface-coated serpentine ultrafine powders as liquid paraffin additives was studied. It is found that the serpentine powders suspended in liquid paraffin present excellent tribological properties. Thermal activations in a temperature range from 300 to 600 °C increase the film forming ability and tribofilm completeness of the serpentine, keep the layer structure and accordingly further improve the tribological properties. However, the layer structure is destroyed and hard phases appear after thermal activated at or higher than 850 °C, as results in the aggravation of friction and wear.     

Tribological properties of nanocarbon obtained by the electrodischarge method

A new electrodischarge method for obtaining of nanocarbon materials by treatment of organic liquids is proposed. Efficient modes of electrodischarge techniques for obtaining of new promising carbon powders comprising diamond-like nanoparticles, nanotubes, and nanofibers are determined. The tribological properties of these powders are studied. It is shown that the application of nanocarbon powders in the contact area of the surface friction makes it possible to reduce the wear and to enhance the operation factors.     

Preparation and characterization of Si3N4/SBR nanocomposites with high performance

In this work, native silicon nitride (Si₃N₄) nanoparticles were modified by macromolecular coupling agent (LMPB-g-MAH) which was designed and synthesized according to the chain structure of styrene butadiene rubber (SBR), and Si₃N₄/SBR nanocomposites were prepared by two-segment mixing process. The structure and surface properties of modified Si₃N₄ nanoparticles were characterized by Transmission Electron Microscope (TEM), Fourier Transform Infrared Spectroscopy (FTIR), size distribution analyzer, and contact angle measuring instrument. The effect of different dosage of nano-Si₃N₄ on Si₃N₄/SBR nanocomposites was also systematically studied. It can be got that LMPB-g-MAH can effectively inhibit the agglomeration and improve the hydrophobic property of Si₃N₄ nanoparticles. It also can be found that modified Si₃N₄ nanoparticles brings well physical and dynamic mechanical properties, aging resistance, oil resistance, wear resistance, and low rolling resistance to SBR, especially, when the dosage is 0.5–1.5 phr, the best overall performance of Si₃N₄/SBR nanocomposites can be achieved.     

Preparation,characterization and properties of Cr-incorporated DLC films on magnesium alloy

Cr-incorporated diamond-like carbon (Cr-DLC) films were deposited on AZ31 magnesium alloy as protective coatings by a hybrid beams deposition system, which consists of a DC magnetron sputtering of Cr target (99.99%) and a linear ion source (LIS) supplied with CH₄ precursor gas. The Cr concentration (from 2.34 to 31.5 at.%) in the films was controlled by varying the flow ratio of Ar/CH₄. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to investigate the microstructure and composition of Cr-DLC films systematically. An electrochemical system and a ball-on-disk tribotester were applied to test the corrosion and tribological properties of the film on the AZ31 substrate, respectively. At low Cr doping (2.34 at.%), the film mainly exhibited the feature of amorphous carbon, while at high doping (31.5 at.%), chromium carbide crystalline phase occurred in the amorphous carbon matrix of the film. In this study, all the prepared Cr-DLC films showed higher adhesion to AZ31 than the DLC film. Especially for the film with low Cr doping (2.34 at.%), it owned the lowest internal stress and the highest adhesion to substrate among all the films. Furthermore, this film could also improve the wear resistance of magnesium alloy effectively. But, none of the films could improve the corrosion resistance of the magnesium alloy in 3.5 wt.% NaCl solution due to the existence of through-thickness defects in the films.     

Carbon/carbon nanocomposites as counter electrodes for platinum free dye-sensitized solar cells

In this work, carbonaceous materials and their combinations with each other were used as counter electrodes for efficient dye-sensitized solar cells (DSSCs). A small amount of TiO₂ paste was also incorporated in each electrocatalyst to increase the adhesion between the carbon material and the conductive glass substrate. The dispersion of carbonaceous materials in composite films was characterized by transmission electron microscopy (TEM). Electrocatalytic characteristics of carbon/carbon catalysts are systematically investigated by electrochemical techniques, such as cyclic voltammetry and chronoamperometry. Solar cells assembled with carbon/carbon composite counter electrodes were characterized by photocurrent–voltage characteristic and electrochemical impedance spectroscopy measurements. The results indicate that under optimal conditions, the solar cell assembled with carbon/carbon composite counter electrode containing activated carbon, multi-walled carbon nanotube and graphene, shows power conversion efficiency of 10.73%. This photovoltaic performance is comparable with 11.20% for the platinum-based dye-sensitized solar cell. The results exhibit that carbonaceous material is an encouraging alternative for low-cost DSSCs.     

Synthesis and fluorescent properties of Eu and Tb complexes with a series of new diamide ligands

A series of new diamide ligands were introduced into the complexes of Eu(NO₃)₃ and Tb(NO₃)₃ so as to improve the fluorescent properties. The fluorescent properties of the resulting complexes were investigated. It was found that the complexes subject to the excitation of UV light showed characteristic emission of europium and terbium ions, in particular, the Tb complexes had very much intense fluorescence.