Papers by Keyword: Surface Modification

Abstract: This paper adopts wet method to prepare serpentine particles on the planetary ball mill, executes lipophilic degree tests and friction and wear tests of these particles. The results showed that: 1) as the modification agent, the optimum dosage of oleic acid is when the volume ratio of oleic acid and serpentine particles is 2, and the optimum time of milling (modification) is 24h. 2) 4012 maritime lubricating oil with serpentine particles has obvious anti-wear and friction effect, and the optimum dosage range of serpentine particles is 0.9%-1.0%. According to the outcomes of metallurgical microscope observation and electron microprobe analysis, a conclusion can be drawn: during the process of friction and wear, serpentine particles brought on physical or chemical reactions with the surface of test samples, create a layer of protective film, thus this kind of lubricating oil has filling function to the furrow of friction pair surface, so as to decrease the surface roughness, decrease the degree of friction and wear.

Abstract: As a biofilm carrier for wastewater treatment, PAN-based carbon fiber (CF) was usually modified with different ways. The double modification treatment composed of surface oxidation and maleic anhydride (MA) graft was used in current research and it’s regarded to be a favorable surface treatment for CF carrier. The consequent CF surface morphology and natures were then characterized by laser confocal microscopy (LCM), X-ray photoelectron spectroscopy (XPS) and the degree of moisture. In addition, biocompatibility of CF was discussed through immobilization behavior of microorganisms. The results indicated that the immobilization ability of microorganisms will be improved if the CF surface is modified to better hydrophilicity by producing oxygen-based functionalities. Furthermore, the configurations and the adhesion forms of cells were affected by the properties of CF surface.

Abstract: Zeolite as a cheap mineral material in industry used in catalytic and environment protection, long time has passed for research on zeolite modification, synthesis and application. In the paper, several modifications for zeolite have been reviewed in detail such as the skeleton element modification, skeleton element modification and zeolite crystals surface modification, modified zeolite properties and application. The shortcomings of the modification methods were pointed out, development and zeolite modification suggestions in the future were put forward.

Abstract: Aramid fiber (AF) was treated by NaOH solution of various concentrations with supersonic vibration at room temperature. The density of NaOH solution was the main parameter. Elongation at break and break strength were tested. The chemical composition of AF was characterized by elemental analysis. The surface of AF was examined by scanning electronic microscopy (SEM). It was shown that elongation at break of treated AF was not decreased, and break strength was a little increased, first increases and then decreases as the concentration of NaOH solution raising. It was also found that the surface of AF after modified was a little rougher. Low concentration of NaOH solution was fit to modify AF.

Abstract: Ni-Ti alloys have been investigated for applying to various surgical procedures. However, little is known about the toxicity of Ni-elements and the actual conditions of surface modification of Ni-Ti alloy for preventing the toxicity of Ni. In this study, the corrosion resistance of Ni-Ti alloys was improved through making TiO2 thin film by conducting in air oxidation and reactive sputtering. These thin films were characterized using FE-SEM, XRD, XPS and AFM. And judging from the polarization curves obtained by electro-chemical measurement in quasi-living body environment, corrosion resistance of Ni-Ti super elastic alloy was evaluated. From these considerations, some trials for establishing a method for TiO2 thin film formation on the surface of Ni-Ti alloy were conducted from the view point of improving biocompatibility.

Abstract: Silica nanospheres with good dispersibility in oily solvents were prepared using a facile in-situ surface-modification route. The microstructure of resultant surface-capped silica nanospheres was analyzed with a transmission electron microscope. The tribological behavior of the silica nanospheres as additive in engine oil SE 15W/40 was evaluated using a four-ball machine; and the morphology and composition of the worn steel surfaces were analyzed using a scanning electron microscope equipped with an energy dispersive X-ray analysis attachment. It was found that organic modifier hexamethyldisilazane (HMDS) was combined with nano-SiO2 by covalent bonds, resulting in varied surface properties and improved dispersibility of the nanoparticles in many organic mediums. Besides, oil-soluble silica nanospheres as additive in the engine oil had excellent friction-reducing and antiwear abilities, showing promising application prospect.

Abstract: Electrical discharge machining (EDM) technique has been widely used in modern metal working industry for producing complex cavities in dies and moulds, which are otherwise difficult to create by conventional machining. The process has the advantage of being able to machine hardened tool steels. However, its low machining efficiency and poor surface finish restricted its further applications. To address these problems, one relatively new technique used to improve the efficiency and surface finish is EDM in the presence of powder suspended in the dielectric fluid. Powder mixed electric discharge machining (PMEDM) is one of the recent innovations for the enhancement of capabilities of EDM process. In PMEDM, the electrically conductive powder is mixed in the dielectric fluid of EDM, which reduces the insulating strength of the dielectric fluid and increases the spark gap between the tool and workpiece. As a result, the process becomes more stable, thereby, improving the material removal rate (MRR) and surface finish. Moreover, the surface develops high resistance to corrosion and abrasion. This paper presents the current research trends on dry, near dry EDM and review on research carried out in the area of PMEDM.

Abstract: Partially amorphous iron-based coatings were produced onto aluminium using a powder flame-spraying process with a commercially available feedstock powder (Nanosteel SHS-7170) obtained from the Nanosteel Company Inc.. Several coating properties such as the microstructure, porosity, phase content, micro-hardness, and wear resistance were evaluated in the as-sprayed condition. As shown by the results obtained, the powder flame iron-based coatings perform relatively well in term of wear resistance in comparison with similar coatings produced using other expensive thermal spray techniques. Furthermore, this study shows that all the coating properties (microstructure, porosity, phase content, hardness and wear performance) depend strongly on the flame spraying parameters used. Finally, this paper demonstrates clearly that the flame-spray process may be used to produce amorphous iron-based coatings having a good wear resistance, and that this process appears to be a suitable inexpensive alternative to plasma or HVOF processes based on the present results.

Abstract: A nanocrystalline surface layer is produced in Co plate by surface mechanical attrition treatment (SMAT). The characterization of microstructure and composition indicates that elements of Fe, Cr diffuse from hardened steel balls into the surface layer during SMAT. The diffusion phenomenon results in the composition deviation in the surface layer, leading to higher value of saturation magnetization (M_s) for nanocrystalline Co surface layer in comparison with its coarse-grained counterpart.

Abstract: Under mild conditions, trihydridosilanes interact with a variety of clean, hydrogenated and fresh metal and metalloid surfaces, including titanium, silicon and gold. In contrast, monohydridosilanes appear to have minimal interaction. All classes of hydridosilanes have minimal interaction with anhydrous oxide surfaces. Preliminary results suggest that surface modification with trihydridosilanes may provide a route for generating self-assembled monolayers on metal substrates. The synthesis of new trihydridosilanes is described. Contact angle, FTIR and XPS data for modified surfaces are provided.