Papers by Keyword: Surface Modification

Abstract: This study investigated the use of nanoscale bilayers assembly for hydrophilic surface modification on stainless steel plate. This study first performed nanoscale bilayers assembly method, with the addition of top layer coatings for durability purposes, to modify the surface structure and thereby the hydrophilicity of the surface at 15, 17, 20, 23, and 25 bilayers. The relationship between the number of bilayers and the resulting contact angle was then empirically established. Results showed 17 bilayers to be the optimal number of bilayers among the samples tested, resulting in the smallest contact angle of 11° (compared to 70° on unmodified surface), corresponding to the highest surface wettability and hydrophilicity. From 0 to 17 bilayers, the contact angle seems to decrease linearly with the number of bilayers. Beyond 17 bilayers, at 20, 23, 25, and 30 bilayers, the samples showed no significant improvements in contact angle or hydrophilicity.

Abstract: This study investigated the use of nanoscale bilayers assembly film for hydrophilic surface modification on stainless steel plates and observed its effects on the evaporation of acetone and ethanol on the plates. This study first established the nanoscale bilayers assembly technique, and then performed hydrophilic surface modification on stainless steel plates by changing the surface structure, producing different contact angles. The relationship between the number of bilayers (10, 20, and 30) and the resulting contact angle was empirically determined; results indicated that 20-bilayer modification yielded the best result, reducing the contact angle from 70° (unmodified surface) to 12°. Beyond 20 bilayers, at 30 bilayers, the samples show no significant changes or improvements to contact angle or hydrophilicity. Results from evaporation time tests showed that, compared to the evaporation time of ethanol and acetone on unmodified flat stainless steel surface, this decreased contact angle can improve the evaporation time by 100%, clearly indicating that hydrophilic surface modifications causes significant improvement in evaporation.

Abstract: Using ring friction testing machine and metallographic and SEM on three formula of carbon fiber reinforced PFFE composite materials (CFRP) and stainless steel under water lubrication tribological properties were studied, and analyses the influence of load, grinding time on friction coefficient and wear quantity. It was found that CFRP with carbon-fiber content of 15% mass fraction and the high temperature nitride treated OCr17Ni14Cu4Nb got a friction coefficient of 0.0ll under 200N load, sliding speed of 5 m/s , which is the lowest one between all of the similar materials in domestic reporting.15 min before testing, the friction coefficient decreased with the increase of load. After 15 min, the friction coefficient basically was stabilized at around 0.011-0.014, Main wear mechanism of the CFRP material containing carbon fiber is fatigue wear, the higher the carbon fiber content, the lower the friction coefficient; the applied load increases from100N to 250N, the wear quantity increases with load decrease, starting from250 N wear increases with load increase.

Abstract: In this work the microstructure and microhardness distribution of modified layers 40Cr (AISI 5140) alloy steel after nitriding by electrolytic plasma have been under research. It is shown that as a result of electrolytic plasma nitriding it becomes possible to increase the surface microhardness of the steel.

Abstract: In this study, polystyrene (PS) nanocomposites with TiO₂ and surface-modified TiO₂ nanoparticles were prepared by compression molding method. TiO₂ nanoparticles were modified by 3-(methacryloxy) propyl trimethoxysilane (MPS). The resulting nanocomposite thick films were compared with pure polystyrene. It was found that MPS-modified TiO₂ nanoparticles were better dispersed in PS matrix due to their hydrophobic characteristics. The addition of small amount of TiO₂ nanoparticles could greatly decrease the optical bandgap of PS from 4.0 eV in pure PS to less than 3.0 eV in PS-TiO₂ nanocomposite. The effects of surface modification and UVC irradiation on the physical properties and the degradation of nanocomposites were investigated.

Abstract: In the present study, a surface layer of TiC-CNT hybrid compositecoating has been developed on low alloy steel (LAS) by using powder preplacement and tungsten inert gas (TIG) torch melting techniques.The weighed powder mixture with the content of 1.0 mg per millimeter square area and containing TiC-4wt. % CNT particles was preplaced on LAS surfaces using a suitable binder and then melted under the TIG arc with an operating current of 100 A and energy input of 1440 J/mm. The microstructural and microhardness characteristics of the processed composites coating were analyzed using SEM, EDXand Vickers microhardness testers. Under the melting condition used in this investigation, the arc completely dissolved the composite powder mixture that resolidifiedinto a melt track with radial marks and smooth surfaces. Themelt cross sections were hemispherical in shape and produced 1 mm deep hard coating layer which were free from porosity and cracks. SEM micrographs TiC-CNT hybrid coated surface glazed at 100A consists of fineprecipitated TiC in form globular and cubic dendrites and this is the reason for hardness increment to an average of three times greater than that of substrate value. The result obtained indicated that TIG arc melting process is applicable to generate resolidified layer of precipitated TiC microstructure with uniformly distribution in the coating region.

Abstract: The modified PFA via silica nanoparticle insertion was studied under different experimental conditions. In the key step, thermal and mechanical properties variations of the material (thermal stability, vitrification) were closely correlated with the type of the silica nanoparticles employed. To reach the results, thermal analytical experiment were conducted such as TGA or DMTA. Moreover, the silica nanoparticles surface modifications were highlighted from TGA and FTIR. Their morphology and dispersion into the polymer were shown by TEM measurements.

Abstract: The ozone oxidation can easily produce peroxides with free radicals for the surface modification on biomaterials. This process would be highly efficient and without toxicity. In this research, naringin, a HMG-CoA reductase inhibitor which can promote bone formation, was immobilize onto chitosan film by using the ozone activation process. At first, chitosan films were treated by the ozone activation to produce peroxides for the following immobilization of naringin. The amounts of peroxides produced by ozone treatment were quantified by the iodide assay. The immobilized naringin were identified with UV and FTIR. The results indicated successful immobilization of naringin. The concentration of crosslinkers was also optimized in this study. From SEM images, the surface topography of chitosan film was not changed after the immobilization process. The FTIR spectra indicated the difference in amine bonds of chitosan, revealing that there would be the chemical reaction between chitosan and crosslinkers. In the in vitro delivery, the chitosan substrate with immobilized naringin was immersed in PBS and the released amount of naringin was measured by UV every two days. It was found that the immobilized naringin was slowly released in two weeks, where the naringin concentration was successfully controlled by this delivery process. The results of cell culture showed that cell activity, attachment and proliferation were promoted with immobilized naringin without any cytotoxicity. The early osteoblastic differentiation, ALPase expression, was also enhanced. The results in this research demonstrated the successful immobilization of naringin onto chitosan substrates. With the slow delivery of naringin, the naringin-chitosan substrate was highly osteoconductive without cytoxicity.

Abstract: This study investigates the use of nanoscale bilayers assembly film for hydrophilic modification on stainless steel plate and observed its effect on the plates evaporation behavior in acetone. This study first establishes the technique of nanoscale bilayers assembly, then performs surface hydrophilic modification on stainless steel plate by changing the surface structure, which produces different contact angles. The relationship between layers (0, 5, 10, 15 bilayers) of surface modified and the contact angle is empirically determined, and results show that, similar to findings stated in the literature [, after surface modification the contact angle decreases from 70° (layer 0) to 24° (layers 15); in addition, the results from this study have demonstrated a certain level of technical capability. This study was investigated the evaporation test in a modified surface , also is the first time reported in previous literature. Evaporation tests show that under the best contact angle evaporation rate can be increased by 50%, indicating the high potential of surface hydrophilic modification on stainless steel plate for improving evaporation behavior.

Abstract: In this article, we report the surface modification results of Parylene C Film by solution of sodium naphthalene complex and its application. In this work, the function group and the crystal structure of the film were characterized separately with Attenuated Total Reflection Fourier transformation infrared spectroscopy (ATR-FTIR) and X-ray diffraction (XRD).The result of test shows that the bond of carbon (C) and chlorine (Cl) is damaged; The crystalline of the film reduces, and the NaCl crystal exist on the film surface. The surface energy of the film is increased from 28.64mJ/m² to 41.48mJ/m², and the shearing tension of modified film was reached over 212.8kPa.The generalized analysis result indicated that nucleophilic reagent destructs the C-Cl bond on the benzene ring, the chlorine (Cl) atom on the benzene ring and the sodium ion in modified reagent forms the sodium chloride which adheres to the film surface.