Rf Plasma Technique Research Articles

Bivariate analysis of the hydrophobic textiles obtained by plasma treatment

This paper presents aspects concerning the bivariate analysis of the textiles surfaces treated by RF plasma technologies (Ar RF plasma and SF6 RF plasma) to obtain the hydrophobic effect. Besides this, it was studied the remnant or temporary hydrophobic effect obtained by polytetrafluoroethylene (PTFE) thin-film by physical vapor deposition (PVD) technique and SF6 RF plasma technique. In this paper, there are presented the bivariate analysis of the parameters and characterization of hydrophobic textile samples (cotton 100% with mass 401 g/m2) by investigation of the water contact angle using the device VCA OPTIMA and resistance to surface wetting by James Heal spray tester. The morphological modification of the textile was evaluated by scanning electron microscope with magnification x8000. Following these investigations there has been observed that the treatment with polytetrafluoroethylene is even more harmful to the environment, offering a hydrophobic effect resistant in time, for approximative 101 days, and the treatment by SF6 RF plasma confer a temporary effect for 24 hours.

Study of self-masking nanostructuring of boron doped diamond films by RF plasma etching

The surface nanostructuring of boron doped diamond (BDD) can further enhance its unique properties e.g. in electrochemical sensing, photoelectrochemical cells, field emission devices and various kinds of sensors. Here we present an investigation of plasmatic nanostructuring of BDD films without use of a time-consuming masking process. RF plasma technique was used to etch surface nanostructures with dimensions ranging from tenths to hundreds of nm in width and height. The size and shape of achieved diamond nanostructures were influenced only by applied etching parameters. We have found that the etched carbon is re-deposited in an amorphous form creating a mask and this self-masking process is responsible for the final shape of obtained structures.Therefore, this technique is effectively controllable by changing plasma power, gas type and pressure which influence the energy of incident ions and thus the sputtering yield and re-deposition of masking material. Utilization of various gas types, pressures and RF powers revealed the physical type of etching to be dominant over the chemical at both high and low energy ions. The nanostructured surfaces were then observed and characterized by SEM and Raman spectroscopy to investigate the nanostructures dimensions and to confirm the remaining diamond quality.

Tribo-mechanical and electrochemical properties of plasma nitriding titanium

Titanium nitrides have good tribo-mechanical and biomedical properties. They are employed to harden and protect cutting and sliding surfaces for industrial purpose and as a non-toxic outer-surface for bio-medical applications. In this study, pure titanium was nitrided using RF plasma technique. The microstructural, mechanical, tribological, electrochemical and biomedical properties of nitrided titanium were investigated. The X-ray diffraction demonstrates the formation of ε-Ti2N and the cubic δ-TiN phases after plasma nitriding. The microhardness of the nitride samples increases as the plasma-processing power increases up to 1300HV0.1. That represents approximately 7-fold increment in the microhardness in comparison with the untreated titanium. High nitriding rate of 0.17μm2/s was recorded for the sample that was treated at 650W. The wear and corrosion resistance are improved after plasma nitriding. Moreover, the friction coefficient is reduced from nearly 0.75 for the untreated titanium to 0.25 for the nitride one. An enhancement in the biocompatibility of the nitrided titanium has been achieved. The number of grown mesenchymal stem cells was higher for nitrided substrates compared to that of the untreated titanium. The improved tribo-mechanical and electrochemical performance of the nitrided titanium can be attributed to the formation of super-hard titanium nitrided phases.

Synthesis of SiC powder by RF plasma technique

Continuous synthesis of SiC nanoparticles by RF thermal plasma method has been studied. Precursor mixtures comprised commercial silica powder and various types of carbon source including graphite, char, carbon black as well as the carbonaceous residue of tire pyrolyses. The obtained SiC consisted of nanosized particles that were crystallized mainly in β phase with traces of α. The conversion rate of the silica precursor to SiC varied between 60% and 73% depending on the type of carbonaceous material and on the carbon excess. The main obstacle to achieve higher conversion is the rapid cooling of reactive species that can also be attributed to formation of nanosized particles.

Application of Double Gate Ion Sensitive Field Effect Transistor for Detection of Fluid Flow Rate in Micro-Channel

In this work a micro flow sensor, using a double gate Ion Sensitive Field Effect Transistor (ISFET) and two metal electrodes, for fluid flow rate measurement in micro-channels were fabricated and demonstrated. By the channel fabrication the molds were patterned reversely on a silicon wafer using Deep Reactive Ion Etcher (DRIE). The double gate ISFET and two metal electrodes were placed on the mold in the distance 15 millimeters. The channels were formed using polydimethylsiloxane (PDMS) from the mold with the width 1000 and 2000 micrometer and the depth of 250 micrometer. After removing PDMS from the mold the channel was bonded with glass substrate by RF plasma technique. By the verification of flow sensors working range water and one mole of sodium nitrate solution were alternated in flow channel. The fluid flow rate were compared with the flow rate from weighing. It found from the comparison that the high deviation was found at low flow rate. Furthermore, the deviation depends also on the dimension of the flow channel.

Duplex treatment of AISI 304 austenitic stainless steel using rf nitriding and dc reactive magnetron sputtering of titanium

In this work, duplex treatment has been carried out using radio frequency (rf) plasma nitriding process and direct current (dc) magnetron sputtering of titanium. Nitriding of AISI 304 stainless steel, using rf plasma technique, created a thick modified layer of approximately 20 μm for short plasma processing time of 10 min. After nitriding process, a thin titanium nitride film has been deposited using dc magnetron sputtering of titanium for different nitrogen/argon gas pressure ratios. The treated samples were characterized via glow discharge optical spectroscopy, X-ray diffractometry, scanning electron microscopy, profile meter and Vickers microhardness tester. The elemental composition, thickness and microhardness values of the duplex treated layers are found to be gas composition dependent. The data shows that the microhardness of the duplex treated layer increases to 1.42 fold relative to the associate value of the nitrided one. Moreover, high deposition rate of 110 nm/min is obtained.

Surface modification of several carbon-based materials: comparison between CF 4 rf plasma and direct F 2-gas fluorination routes

Due to their extreme reactivity, fluorine and fluorinated gases may be used to modify the surface properties of numerous materials. In the following, the surface fluorination of some carbon-based compounds (graphite, graphitised carbon fibres, carbon blacks and elastomers) using CF 4 rf plasma technique and direct F 2-gas fluorination is proposed. From XPS studies, the different types of C F bonding obtained in the materials after treatment have been correlated either to the physico-chemical characteristics of the pristine material or to the experimental parameters of the fluorination. Reaction mechanisms are proposed.

Influence of Plasma Functionalization of Poly(propylene) with Acrylic Acid on the Nucleation of CaCO3

AbstractSummary: Poly(propylene) surfaces were modified by polymerization of acrylic acid using an RF plasma technique. Whereas a stable and reproducible hydrophilicity is obtained even after short treatment times, the thickness of the deposited layer, and thus the concentration of COOH functional groups per substrate surface area, increases with plasma exposure time. The modified‐poly(propylene) samples were exposed to aqueous solutions supersaturated with respect to CaCO3. Even though the polymer surfaces show a significant affinity for the adsorption of Ca2+ ions, the density of nucleation sites for calcite is reduced in comparison to untreated poly(propylene). This result can be explained by the special conditions in porous (“gelatinous”) growth media and high disorder provided by the plasma‐polymerized layers.AFM surface profile of a poly(propylene) surface (*) and film segments of plasma‐polymerized acrylic acid (**).imageAFM surface profile of a poly(propylene) surface (*) and film segments of plasma‐polymerized acrylic acid (**).

Formation and properties of a carbonitrided layer in 304 stainless steel using different radio frequency plasma powers

Radio frequency (rf) inductively coupled plasma was used for carbonitriding the surface of AISI-304 austenitic stainless steel (ASS) samples at different input plasma powers (300–650 W). The morphology and the microstructure of the treated surfaces of carbonitrided austenitic stainless steel samples (CNASS) were examined by optical microscopy (OM) and scanning electron microscopy (SEM). The surface hardness of the treated surfaces as well as the microhardness profile of the samples was measured. X-Ray diffraction was employed to investigate the structure of product phases as a result of carbonitriding process. The results indicate that by using the rf plasma technique, we can greatly improve the tribomechanical properties of these materials. The high rate of carbonitriding (1 μm 2/s) and the high hardness of CNASS (1375 Hv, 0.1) at plasma input power 550 W have been interpreted in terms of nitrogen and carbon concentration gradients, and microcracks formed in the surface during the plasma process in the compound layer.

Friction and wear properties in dry, water- and oil-lubricated DLC against alumina and DLC against steel contacts

Diamond-like carbon (DLC) films can be divided into two major categories according to their hydrogen content. These categories have similarities in tribological performance, but the films also behave in a different manner in different tribological conditions. The results of amorphous hydrogenated carbon films (a-C:H) and hydrogen-free hard carbon films (a-C) are reported in this study. The a-C:H films were deposited using the radio frequency (rf) plasma technique, and the hydrogen-free hard carbon films using pulsed vacuum arc. The coatings were characterized and investigated with respect to their tribological performance in dry (50% RH), water-lubricated and oil-lubricated slow sliding conditions (0.004 m s −1). The a-C and a-C:H films had a low friction coefficient in dry sliding conditions (0.15 to 0.22), which was further decreased by 10–40% under boundary lubrication. The a-C:H(Ti) films exhibited good self-lubricating properties (0.10) in dry sliding conditions and the a-C films had the lowest friction coefficient in water- (0.03) and oil-lubricated (0.08) conditions. The hydrogen-free hard carbon films showed excellent wear resistance in dry, water- and oil-lubricated conditions, but hydrogenated a-C:H films suffered from severe wear in aqueous conditions. The performance of a-C:H films could be improved by titanium alloying. In dry sliding conditions, the tribolayer formation of DLC films influenced the friction and wear performance, but in oil-lubricated conditions boundary lubrication layers were formed, which governed the tribological mechanisms in the contact.

Morphology Studies of Oxide Films Deposited by Rf Plasma Technique

AbstractRecently, an energetic film growth technique was developed. In this process, an RF (radio frequency) plasma was ignited in an ambient atmospheric environment. An aqueous solution was excited into mist, which was then fed into the plasma reactor. After vaporization, films were formed on substrates outside the plasma. As a by-product, small amount of powders were collected in the plasma reactor. Films studied were indium-tin oxide (ITO), aluminum oxide (Al2O3), and lanthanum strontium manganite oxides (LaSrMnO). Films and powders were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX, EDS), and Ultraviolet-Visible (UV-Vis) transmission measurements. Morphology of a film surface was dependent on deposition conditions, such as chemical composition of the precursor materials, precursor feeding rate, and/or substrate temperature.

Crystalline and Electrical Properties of ITO Semiconductive Films deposited by Atmospheric RF Plasma Technique

AbstractIndium tin oxide (ITO) semiconductive films were deposited by an atmospheric RF plasma technique. Indium-to-tin (In:Sn) ratios varied from 10:0 to 0:10. A small amount of antimony was doped into some ITO samples for comparative studies. Substrate materials were soda-lime-silicate (SLS) float glass and fused silica glass. Structural, electrical, and optical properties were dependent on the In:Sn ratio, precursor material feeding rate, oxygen feeding rate, and other deposition conditions.

Novel low temperature RF plasma annealing using NH 3 − 2 gas mixture

A novel low temperature (350°C) RF plasma technique using a NH3−N2 gas mixture was used to anneal bipolar structures. Vertical pnp transistors made with high energy ion implantation and possessing poor electrical characteristics have been dramatically improved after 30min annealing with this new technique. The value of the ideality factor of the base current which was about 1.4 before annealing approached the ideal value of 1.0 after 30min annealing.

Low Temperature RF Plasma Annealing Using A NH3-N2 Gas Mixture

Techniques such as plasma etching, electron-beam lithography, X-ray lithography, ion etching, sputtering and ion implantation are used to Increase the density of Integration of semiconductor devices. All these techniques introduce undesirable radiation damage into the processed device. Annealing techniques are used to reduce or remove completely the radiation induced defects. The conventional postmetallization low temperature (400–450 °C) annealing using Forming gas (10% H2-90% N2) does not anneal all the charge pentres in many device structures. We have employed a novel low temperature (350°C) rf plasma technique using a NH3-N2 gas mixture to anneal bipolar structures. Vertical pnp transistors made with high energy ion implantation and having poor electrical characteristics have been dramatically improved after 30 min annealing with this new technique. The value of the ideality factor of the base current which was about 1.4 before annealing approached the ideal value of 1.0 after 30 min annealing. Optical emission spectroscopy of the NH3-N2 glow discharge shows the presence of NH radicals, atomic hydrogen and nitrogen ion molecules during the plasma annealing. The atomic hydrogen passivates electrically active defects in the oxide and at the Si/SiO2 interface. A nitridation process occurs at the surface of the top BPSG layer, where a thin silicon nitride film is formed and plays the role of a capping layer which inhibits saturation phenomena. Angle-resolved XPS and ellipsometry have been used to analyze the surface of a silicon wafer exposed to this plasma annealing process. A qualitative model is also proposed to explain the mechanisms involved in this novel NH3-N2 rf plasma annealing process.

Preparation of SiC Powders from SiO<sub>2</sub> Powders by RF-Plasma Technique

Preparation of SiC powder from SiO2-CH4 mixtures by RF-plasma method was investigated. The reaction product consisted of β-SiC, free carbon, Si and SiO2. The maximum yield of SiC formation was obtained for the moler ratio [CH4]/[SiO2]≈3. Addition of H2 to the reaction system suppressed the formation of free carbon, but increased the amounts of SiO2 and Si. The crystallite size of β-SiC was in the range of 10-30nm irrespective of the reaction conditions.

Plasma Nitriding of Stainless Steel using Continuous and Pulsed RF Glow Discharge

A novel radio frequency (rf) plasma technique for nitriding engineering steels is described whichproduces a surface layer of exceptional hardness in extremely short nitriding times. The sample does not form part of the primary electrical circuit, as is the case, with de plasma methods, and the temperature at the metal surface is controlled by a variable pulsed mode operation of the inductively coupled nitrogen plasma. The rate of nitriding is compared to those obrained by conventional ammonia nitriding and by de plasma methods. The rapid rates of layer growth observed with the rf plasma are discussed in terms of an interstitial–vacancy coupled diffusion model. The results demonstrate the feasibility of a rapid and flexible process for nitriding all grades of engineering steels.

The growth of amorphous and graphitic carbon layers under ion bombardment in an rf plasma

Methods of preparing C-films from energetic C-ions and from ion impact bombardment of hydrocarbon species are reviewed. It is shown that amorphous C-deposits resulting from impact damage can have dielectric properties and be exceptionally hard. The rf plasma technique used to grow a-C-films on a negatively biased target is described and the effects of temperature rise on structural change is followed using differential scanning calomimetry. The as-grown films contain absorbed hydrogen which produces compressive stress and is released to form gas bubbles at 400°C.

Construction and application of solid-lubricant plain bearings : N. A. Spitsin and G. M. Paptsoy, Russian Eng. J., 50 (9) (1970) 16–20; 4 figs., 1 table, 5 refs. (Transl. by P.E.R.A. of Gt. Britain of Vestn. Mashinostr., 50 (9) (1970) 16–20.)

Diamond-like carbon (DLC) films can be divided into two major categories according to their hydrogen content. These categories have similarities in tribological performance, but the films also behave in a different manner in different tribological conditions. The results of amorphous hydrogenated carbon films (a-C:H) and hydrogen-free hard carbon films (a-C) are reported in this study. The a-C:H films were deposited using the radio frequency (rf) plasma technique, and the hydrogen-free hard carbon films using pulsed vacuum arc. The coatings were characterized and investigated with respect to their tribological performance in dry (50% RH), water-lubricated and oil-lubricated slow sliding conditions (0.004 m s−1). The a-C and a-C:H films had a low friction coefficient in dry sliding conditions (0.15 to 0.22), which was further decreased by 10–40% under boundary lubrication. The a-C:H(Ti) films exhibited good self-lubricating properties (0.10) in dry sliding conditions and the a-C films had the lowest friction coefficient in water- (0.03) and oil-lubricated (0.08) conditions. The hydrogen-free hard carbon films showed excellent wear resistance in dry, water- and oil-lubricated conditions, but hydrogenated a-C:H films suffered from severe wear in aqueous conditions. The performance of a-C:H films could be improved by titanium alloying. In dry sliding conditions, the tribolayer formation of DLC films influenced the friction and wear performance, but in oil-lubricated conditions boundary lubrication layers were formed, which governed the tribological mechanisms in the contact.