Papers by Keyword: Surface Structure

Abstract: nfluential degree of different surface structures on stable output power of diesel engines under continuing work condition was evaluated, and relatively comprehensive reference optimizing micro-geometric morphology structure on cylinder liner surface was provided, through performing friction and wear experiments of cylinder liner and piston ring with three kinds of different surface structures: honing textured surface, no textured surface, and crater-grooved surface on an Optimal SRV IV oscillating friction and wear tester respectively, and analyzing effects of different surface structures on vibration of friction coefficient with power spectrum density. Results show that crater-grooved surface structure has smaller vibration value of friction coefficient under low loads and fluid lubrication state, while roughness determines vibration of friction coefficient under high loads and boundary lubrication state.

Abstract: Carbon fibers with different surface structure are obtained by changing the level of anodization, and have the carbon fiber and epoxy resin processed into carbon fiber-resin matrix composite. Relationship between chemical structure of carbon fiber and moisture absorption property of composite in hot and humid environment is studied. The experiments show that the surface activity of carbon fiber increase significantly after anodization treatment, and there are a large amount of increase for oxygen-containing functional groups in fiber surface, in particular to OH which increase from 17.92% to 33.25%. The moisture absorption mechanism differs in varied conditions of heat and humidity, and temperature is an important factor affecting composites hygroscopic property. The higher the carbon surface activity is, the bigger the equilibrium absorbent moisture would be, and the increase of which would cause an obvious decline in inter-level shear strength (ILSS) value of carbon fiber-epoxy composites.

Abstract: The effect of HF concentration on the surface structure of porous silicon (PS) was carefully investigated by the AFM characterization. The results showed that no pores were present on PS surface which was prepared under the higher concentration of HF (10%). However, the pores were gradually visible with the HF concentration reduction. The main pores diameter was about 100 nm, when the concentration is 5.71%. The data of surface roughness and the main height distribution of the “hill” both showed an increase with the reduction of concentration, from 6.39 nm increase to 16.9 nm and from 30 nm increase to 90 nm, respectively, which implied that the pores were better exposed under the lower HF concentration.

Abstract: Two methods are adopted to remove wetting agents on surface of the quartz fiber, one is heat treatment, and the other is the combination of organic solvent and heat treatment. By comparing the changes of weight loss rate of quartz fiber before and after surface treatment, analyzing variation of morphology and composition of surface in SEM and XPS approaches, we conclude that the combination of organic solvent and heat treatment is superior to the pure thermal treatment in dealing with surface of quartz fiber. In heating process, different heating rates are used, the results show that: the lower the heating rate is, the greater the mechanical strength of the quartz fiber losses.

Abstract: In this study, the surface structure of a self-cleaning, superhydrophobic leaf was examined using electron microscopy and optical methods, and its wetting properties were measured using a contact angle goniometer. Using the micro/nanostructural surface features of this leaf as a blueprint, an inexpensive surface structuring technique was developed by modifying the surface of nanocrystalline nickel to create a template. These templates were then pressed into softened polyethylene at elevated temperatures and pressures, thereby transferring the structured surface to the polymer samples. All templates and pressed polymers were characterized in the same manner as the leaves. This method increased the wetting angle for polyethylene from 96° to 151° and reduced the tilt angle from 38° to <5°.

Abstract: The influences of inner layer′s (spacer yarn′s) pattern, surface structure of fabric, thickness, and spacer yarn′s diameter on compression resistance of warp knitted spacer fabric were investigated in the study. The compression tests involving 10 samples were carried out by TexLab Precision Instruments CT250 based on Chinese standard FZ/T01051.2-1998. The results show that inner layer′s pattern and surface structure affect the compression resistance of spacer fabric by changing the inclination angle of spacer yarn, the closer spacer yarn keep vertical, the better compression resistance of fabric. The laws of force exerted on spacer yarn followed by fabric′s thickness differ according to compression rate, the compression resistance increases as the thickness increases when the deformation of fabric is small (less than 4.90%), but decreases when the deformation is large enough (more than 19.20%). The diameter of spacer yarn has apparent effect on compression resistance, and the fabric with finer spacer yarns has lower compression resistance.

Abstract: Using microwave-assisted solid-state method, a series of zinc oxide-modified mesoporous SBA-15 materials were synthesized. The desulphurization test with a gas mixture containing 0.1 vol % hydrogen sulfide was carried out on these materials. Chemicals before and after the desulphurization test were analyzed using nitrogen adsorption, XRD, EDS, TEM, ICP and other standard methods. The results suggest that zinc oxide modification can accelerate the transformation from a mesoporous to a zeolite phase. The different zinc loading results in different zinc-phase dispersions on the materials.

Abstract: Microneedles have broad applications in biomedical and neural measurements, drug-delivery systems, and microbiological sample analysis. Blood compatibility is required when microneedle is used in blood related field. We proposed a method to improve the blood clotting feature of silicon microneedle by silver coating. We fabricated the silicon microneedle with and without silver coating by wet etching and metal sputtering and implemented the clotting test. The clotting test results indicated that silver coating plays more important role to improve the blood compatibility of silicon microneedle than surface structure.

Abstract: MgCl₂/alcohol complex treated with various Al-alkyl in preparing Ziegler-Natta catalyst and its precursors for polymerization of ethylene have been studied by XPS, SEM, and EDS. With different treatments, their different morphology and various structures were discussed in details. As a result, Al-alkyl treatment for MgCl₂/alcohol complex plays a dominant role in dispersing active titanium on surface of catalyst. The proper species and concentration of Al-alkyl were confirmed to have high performance in dispersing titanium species in treatment of MgCl₂/ alcohol complex. With lower concentration of TEA treatment, Ti distribution in catalyst was even with surface and body Ti/Mg ratio 0.04 and 0.03 respectively. In comparison, with higher concentration of TEA treatment, more Ti would be loaded on surface of catalyst. Ti distribution became to be uneven to form clubbed crystals on the surface. EDS results showed that Ti/Mg ratio was up to 6.2 on the clubbed crystals.

Abstract: In this paper, a novel method for the modeling and characterization of surface structures is presented. The method is based on the nonparametric statistical modeling of the surface structure, represented as a two dimensional field. Using a sample of a surface structure in question, the model reproduces the structure of the surface and estimates the corresponding machining parameters. The applicability of the method is demonstrated on the modeling and characterization of the functional surfaces generated by intentionally invoked chatter during the milling process. Based on the model of the generated surface structures, the corresponding diameter of the toroidal cutter and spindle speed are estimated using the surface structure data as the input for the model.