Papers by Keyword: Plasma Deposition

Abstract: Thermal depositions are very wide spread in the industry of coating techniques. The materials used as coatings for several applications must have the ability to produce a stable, slow-growing surface coating, in order to provide good service behavior. This paper presents a method to increase the wear resistance of steering pump cam, strongly stressed having premature wear effects. The method that the authors use is atmospheric plasma deposition with Ni-Cr-Fe and Ni-Cr-B-Fe powders on steel substrate. It was investigated the morphology and physico-mechanical properties (scratch and micro-indentation analysis). Results showed a comparison between those two coatings with the metallic substrate. It has been found that the deposited coatings have an adherent, dense and uniform layer with a typically molten morphology. By increasing the coefficient of friction we can obtain higher wear resistance and recommend the optimum solution for further researches.

Abstract: In this research, zinc oxide (ZnO) films were prepared by thermal evaporation method at temperature between 400-600°C for 60 min. Then, ZnO films were deposited by nitrogen cold plasma technique. The power, frequency and voltage of plasma generated at 100 W, 50 KHz and 5 KV, respectively. These films were deposited by plasma deposition for 15-60 min. The aim of this research is to study the effect of nitrogen plasma on the crystalline structure and optical properties of ZnO film. Crystalline structure, elemental compositions, morphological and optical properties were characterized by using X-ray diffraction (XRD), energy dispersive x-ray spectroscopy (EDS), scanning electron microscopy (SEM) and UV-VIS spectrophotometer, respectively. It was found that the ZnO films preparation via thermal evaporation method at temperature of 500°C showed the highest crystalline with hexagonal structure. After plasma deposition for 15, 30 and 60 min, ZnO films were amorphous. Optical transmittance values decreased and the optical band gap decreased from 3.14 to 3.06 eV with increasing in the plasma time.

Abstract: Plasma polymerized diglyme (pp-diglyme) is a promising class of biomedical materials due to hydrophilic features when deposited under excitation by RF low power. In order to reach this goal this paper deals with plasma polymerization of diethylene-glycoldimethyl-ether (diglyme here after) by RF-excited plasmas under power ranging from 5 to 20 W and pressure of 6.6 Pa. Films were deposited on glass and aqueous polyurethane dispersion substrates (PUD). For the values of RF used in this paper, film thickness varied from 51 nm to 64 nm. Such films were deposited on flexible biocompatible polyurethane that is not resistant to acids and bases as plasma polymerized diglyme. The recovering of these materials with pp-diglyme films let them with a resistant biocompatible feature that is appropriate for use in aggressive environments. The contact angle measurements show the variation from 56° to 64° for a surface energy which varies from 68 mJ/m² to 59 mJ/m², respectively. The FTIR data show that the main functional groups in the polymeric film structure are C-H (3000 cm^-1 to 2900 cm^-1), C-O-C and C-O (1200 cm^-1 to 900 cm^-1) similar to the polyethylene oxide (PEO) structure. The refractive index results show a variation from 1.58 to 1.63.

Abstract: In this study, We immobilized hydrogel material onto expanded polytetrafluoroethylene (ePTFE) film and used as an functional biomaterial. The material is a film containing titanium oxide onto polymer sheet. The hydrogel film is hydrophilic, bacterial inactivated and bio-compatible. In order to improve the ePTFE film biocompatibility, the cold plasma or γ-ray technology was used with acetic acid as monomer to deposit onto ePTFE film and then (N-isopropylacrylamide) was grafted onto the surface by radiation photo-grafting. The characteristics of the material surface were evaluated with X-ray photoelectron spectroscopy (XPS), FTIR and water contact angle. It was found that the contact angle of water on the untreated ePTFE significantly decrease from125° to 72° after ePTFE film being treated with acetic acid plasma deposition procedure. Due to the hydrophilicity of poly (N-isopropylacrylamide), so the contact angle of water on the ePTFE-g-NIPAAm almost approached to 0°. This thermal sensitive ePTFE hydrogels can be applied to artificial guiding tube and wound dressing material.

Abstract: This work aims to obtain plasma thin film composites with hydrophobic/hydrophilic alternated regions, which are useful for the production of miniaturized mixers. These regions were acquired by two different strategies: either the codeposition of TEOS and HFE plasma thin films or the exposition of TEOS plasma films to ultraviolet radiation (UVA and UVC). These films were characterized by several chemical and physical techniques. The refractive indexes vary from 1.4 to 1.7; infrared and photoelectron spectroscopy detect Si-O-Si and CH_n species. Silicone-like structures with high or low number of amorphous carbon microparticles and with fluorinated organic clusters were produced. Cluster dimensions were in the 1-5 mm range and they are made of graphite or COF (carbon/oxygen/fluorine) compounds. Scanning electron and optical microscopy showed rough surfaces. Water contact angles were 90º; however, for TEOS films that value changed after 6 hr of UVC exposure. Moreover, after UV exposure, organic polar compounds could be adsorbed in those films and water was not. The passive mixer performance was simulated using the FemLab 3.2^® program and was tested with 20 nm thick films on a silicon wafer, showing the capacity of these films to be used in such devices.

Abstract: The aim of this work was production of tetraethoxysilane (TEOS) plasma polymerized thin films and optimization of their physical-chemical characteristic for sensor development. The films were analyzed using several techniques. It was possible to produce composites (graphite clusters imbibed by silicon oxide film) made from only one reactant (TEOS). Deposition rate can vary significantly, reaching a maximum of 30 nm/min; cluster formation and their size widely depending on deposition parameters. The film surface was hydrophobic but can be wetted by organic compounds, probably due to carbon radicals. These films are good candidates for sensor development.

Abstract: This work describes the production and characterization of a selective membrane useful for electronic devices. The membrane was a composite made by a thin film of plasma-polymerized HFE (methyl nonafluoro(iso)butyl ether) immersed in plasma-polymerized HMDS (hexamethyldisilazane) film, a third phase being 5 µm starch particles included in this matrix. The film was deposited on silicon substrates and its physical, chemical and adsorption characteristics were determined. Infrared and x-ray photoelectron spectroscopy analyses showed fluorine and carboxyl groups on the bulk and the surface, respectively. SEM results indicate the film is conformal even if starch is present. Optical microscopy analysis showed good resistance toward acid and base solutions. Quartz crystal microbalance indicated adsorption of polar organic compounds on ppm range. This thin film is environment-friendly and can be used as a protective layer or in electronic devices due to adsorption of volatile organic compounds.

Abstract: Functionalized plasma polymer thin films were obtained in a dielectric barrier discharge at atmospheric pressure in an atmosphere of N2 and C2H4. The coatings were hydrophilic, adherent, chemically stable and presented a surface concentration of NH2 suitable for further biomolecule conjugation. Covalent grafting of a linking arm (glutaric anhydride) and subsequent conjugation of fibronectin, a protein of the extracellular matrix, were successful. Finally, endothelial cell adhesion experiments were performed directly on the functionalized thin films as well as on the conjugated coatings. Effects on cell adhesion were observed as a function of the plasma thin film deposition parameters.

Abstract: Up to the fourth moment distributions of carbide nanocrystallites, produced by duplex treatments of surface nanocrystallization and pulsed plasma electrolytic carburizing on AISI316 stainless steel, were investigated to high precision by means of figure analysis. A skewness and kurtosis study of the Gaussian distribution has been made, and the effect of an applied voltage has been determined. It is found that the use of higher applied voltages is more suitable for achieving lower sizes of carbide nanocrystallites. The surface roughness of treated samples was measured and it has been observed that there is an optimum level of applied voltage for surface roughness increase (difference between two measured data).

Abstract: Expanded polytetrafluoroethylene (ePTFE) is a bioinert material. It has the superior properties of thermal and chemical stabilities, low surface energy and high resistivity, so it was applied in many biomedical fields. In order to improve the ePTFE film biocompatibility, the cold plasma technology was used with acetic acid as monomer to deposit onto ePTFE film and then (N-isopropylacrylamide) was grafted onto the surface by photo-grafting. The characteristics of the material surface were evaluated with X-ray photoelectron spectroscopy (XPS), FTIR and water contact angle. It was found that the contact angle of water on the untreated ePTFE significantly decrease from125° to 72° after ePTFE film being treated with acetic acid plasma deposition procedure. Due to the hydrophilicity of poly(N-isopropylacrylamide), so the contact angle of water on the ePTFE-g-NIPAAm almost approached to 0°. And we obtained the thermal-sensitive ePTFE hydrogels.