Cold Remote Nitrogen Plasma Research Articles

Multilayer coating by plasma polymerization of TMDSO deposited on carbon steel: Synthesis and characterization

Polysiloxane films obtained from a cold remote nitrogen plasma polymerization of 1,1,3,3-tetramethyldisiloxane monomer mixed with oxygen show attractive properties and can be used for many applications. These films can also be modified in-situ by the (nitrogen+oxygen) remote plasma. An increase of the atomic oxygen concentration in the plasma leads to carbon removal and to an enhancement of the cross-linking of the Si–O–Si chains. The uppermost layer tends towards a silica structure while the core of the coating remained unchanged. By successive (deposition/plasma treatment) sequences, it was possible to obtain multilayer coatings which were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red (FTIR) spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and contact angles measurements. The efficiency of such multilayer coatings to protect carbon steel against corrosion in NaCl 0.5M was also investigated from polarization curves and Electrochemical Impedance Spectroscopy (EIS).

Exploring potential of Micro-Raman spectroscopy for correlating graphitic distortion in carbon fibers with stresses in erosive wear studies of PEEK composites

Abstract Cold remote oxygen nitrogen plasma (CRNOP) treatment was used to enhance reactivity of carbon fabric (CF) towards PEEK. The composite with treated fibers exhibited significantly better mechanical properties due to enhanced fiber–matrix adhesion as evidenced from SEM studies. It was of interest to examine the effect of the treatment on erosive wear performance with variation in angle of impingement and under elevated temperatures. The treatment proved successful in imparting wear resistance to the composite as compared to that with untreated CF. Efforts were made to study correlation between mechanical properties and erosive wear behavior at high temperature. Micro-Raman spectroscopy (MRS) was used to analyze the effect CRNOP treatment on CF and also to study stresses introduced during the erosion of CF-PEEK composites at different angles of impingement. Fairly good correlation was observed in wear rate and strain produced on the surfaces of fibers. SEM was used to understand wear mechanisms.

Polymer Functionalization and Thin Film Deposition by Remote Cold Nitrogen Plasma Process

Modification of polymer surfaces by cold plasma processes is attracting a growing interest. Especially, the use of plasma gases such as N2, O2 or air, which are cheap and environmentally safe, is very attractive from an industrial point of view. The lifetime of atomic oxygen being very short, it is very difficult to operate with air or oxygen plasma when wide plasma volume is required. However, it is possible to obtain cold remote nitrogen plasma reaching volume of several m3 due to the long lifetime of atomic nitrogen because of a re-dissociation mechanism. Moreover, the temperature being close to the ambient makes this plasma very attractive for functionalization and/or coating of polymer surfaces. Several applications of this plasma process are presented in this paper. The incorporation of new chemical functions during the treatment of polymers leads to an increase of their adhesion properties. Several industrial applications (painting, sticking, bonding, foaming and thermo-covering) are presented. The ability of this remote plasma to decompose, to polymerize, or to react with a volatile chemical component is described through three examples involving polymer substrates: (i) the deposition of metallic films; (ii) the synthesis of a nitride film combining hardness and elastic behavior; (iii) the synthesis of an organosilicon film showing interesting barrier properties. Adhesion aspects are investigated for all these examples.

Grafting of copolymer styrene maleic anhydride on poly(ethylene terephthalate) film by chemical reaction and by plasma method: Optimization of the grafting reaction using experimental design

This work deals with the chemical grafting of a styrene maleic anhydride copolymer on the surface of a previously hydrolyzed polyethylene terephthalate (PET) film 12 μm thick via covalent bond. Two different ways are studied. The first one involves an activation of the hydrolyzed PET by the triethylamine before the grafting step. In the second one, the copolymer reacts with the 4-dimethylaminopyridine in order to form maleinyl pyridinium salt which reacts with alcohol function of the hydrolyzed PET. Characterization and quantification of the grafting are performed by Fourier transform infrared spectroscopy. Factorial experiment designs are used to optimize the process and to estimate experimental parameters effects. The opportunity to associate the chemical process to a cold remote nitrogen plasma one is also examined.

Remote nitrogen plasma treatment of a polyethylene powderOptimisation of the process by composite experimental designs

A coupling between fluidised bed and far cold remote nitrogen plasma technologies is used to treat a polyethylene powder in order to increase its wettability evaluated from capillarity rising measurements. An optimisation of the process is performed thanks to face-centred central composite experimental designs. It is shown that treatment duration and oxygen rate added to nitrogen are the more influent parameters. Electron spin resonance analyses revealed the presence of a mixture of alkyl and allyl radicals on the treated powder. Reactions leading to the incorporations of new chemical functions on the polyethylene surface are proposed.

Remote nitrogen plasma treatment of a polyethylene powder: Optimisation of the process by composite experimental designs

A coupling between fluidised bed and far cold remote nitrogen plasma technologies is used to treat a polyethylene powder in order to increase its wettability evaluated from capillarity rising measurements. An optimisation of the process is performed thanks to face-centred central composite experimental designs. It is shown that treatment duration and oxygen rate added to nitrogen are the more influent parameters. Electron spin resonance analyses revealed the presence of a mixture of alkyl and allyl radicals on the treated powder. Reactions leading to the incorporations of new chemical functions on the polyethylene surface are proposed.

Characterization of organosilicon films synthesized by N 2-PACVD. Application to fire retardant properties of coated polymers

Organosilicon thin films, obtained from the polymerization of 1,1,3,3-tetramethyldisiloxane monomer pre-mixed with oxygen using a cold remote nitrogen plasma process, are used to improve flame retardant properties of polyamide-6 (PA-6) and polyamide-6 clay nanocomposite (PA-6 nano) substrates. A comparison between virgin PA-6 and coated PA-6 nano shows that the clay addition combined with the coating leads to an efficient fire retardant effect. The limiting oxygen index increases by 130% while, at the same time, the rate of heat release and the total heat evolved decrease by 41% and 33%, respectively. The nanocomposite structure leads to the formation of a silicon and carbonaceous protective layer during the combustion. This layer acts as a barrier limiting heat and mass transfers between the polymer and the flame, and this effect is reinforced by the coating.

Treatment of a polyethylene powder using a Remote Nitrogen Plasma reactor coupled with a fluidized bed: Influence on wettability and flowability

A Far Cold Remote Nitrogen Plasma is used both to fluidize and to treat a polyethylene powder in order to increase its hydrophilic character. The evolution of the wettability of the powder as well as the one of its physical (density, particles size distribution, average diameter, shape factor, and BET surface area) and flow properties (angle of repose, angle of slide, and Hausner index) are determined versus various experimental conditions. It is shown that the plasma treatment efficiency is strongly dependant on the oxygen content of the nitrogen flow and on the velocity of fluidizing gas. Best wettability is obtained by the addition of 0.75% of O2 in the nitrogen plasma gas and with a high gas velocity. It is also evidenced that the flowability of the powder is slightly altered by the plasma treatment.

Surface property modification of a polyethylene powder by coupling fluidized bed and far cold remote nitrogen plasma technologies

AbstractA far cold remote nitrogen (FCRN) plasma, eventually doped with oxygen, was used to modify the surface properties of a polyethylene (PE) powder. The process associates both remote plasma and fluidized bed technologies. Two applications are described. The first one, for increasing the hydrophilic character of PE, only requires a single plasma treatment. The second application involves FCRN plasma polymerization of 1,1,3,3‐tetramethyldisiloxane mixed with oxygen to obtain a hydrophobic film on the powder surface. The wettability evolution of the PE powder was followed by contact angle measurements (Washburn method) versus different experimental parameters. The surface modifications induced by the treatments were studied by XPS. Copyright © 2002 John Wiley & Sons, Ltd.

Elaboration of fire retardant coatings on polyamide-6 using a cold plasma polymerization process

A cold remote nitrogen plasma process is involved to induce the polymerization of the 1.1.3.3-tetramethyldisiloxane (TMDS) monomer mixed with oxygen. Oxygen addition to TMDS promotes the formation of more thermally stable coatings. The fire retardancy performances of polyamide-6 coated with this organosilicon polymer are evaluated using the cone calorimeter and limiting oxygen index test. The deposits are efficient fire retardant coatings: the rate of heat release of coated PA-6 can decrease by approximately 30% in comparison to PA-6.

Thermal stability and flammability studies of coated polymer powders using a plasma fluidized bed process

In this work, the thermal stability of organosilicon coatings, polyamide-6 powders and polyamide-6 clay nanocomposite powders coated with organosilicon are studied. The coatings were obtained from polymerization of 1.1.3.3-tetramethyldisiloxane (TMDS) monomer doped with oxygen using a cold remote nitrogen plasma (CRNP) process. A fluidized bed reactor using CRNP assisted polymerization was used to coat the polymer powders. The effect of oxygen addition to TMDS on the thermal stability was investigated. Oxygen addition to TMDS promotes the formation of more thermally stable coated polymers. In the case of the polyamide-6 clay nanocomposite, the Limiting Oxygen Index values were much improved. This shows that the deposits are effective fire retardant coatings.

Far cold remote nitrogen plasma for surface modification and film deposition

Far cold remote nitrogen plasma for surface modification and film deposition

Far cold remote nitrogen plasma for surface modification and film deposition

Remote nitrogen plasma presents two distinct non-equilibrium thermodynamic zones. The first, called CRNP, is exempt from any electrons or ions. Its main reactive species are nitrogen atoms N( 4S), electronically excited N 2 triplet states and vibrationally excited N 2 in the ground electronic state. The translation temperature of CRNP is close to ambient temperature. The second zone is ionized by a thermal conductive process in the CRNP without any electrical field, and its translation temperature is approx. 600 K. These plasmas, mainly CRNP, are used for: (1) functionalization of polymers, composites and metallic materials for hardening or increasing surface free energy and adhesion properties; and (2) deposition of thin films, such as (i) metal-metal or metal-insulating materials, (ii) polymers with many outstanding and attractive properties, low friction coefficient, good dielectric or barrier properties, and (iii) hard or superhard materials, e.g. (Si, N, O, H) complex with good elastic behaviour, or CNx with carbon atoms in a tetrahedral environment ( β-C 3N 4). Reactors up to 5 m 3, using the CRNP process, are now used in industrial factories.

Cold remote nitrogen plasma effects on pulsed laser deposited CN X films characteristics

Carbon nitride films were deposited by ablation of carbon molecular fragments from a graphite targets on a silicon substrate after few pulses of a localized transversely excited atmospheric pressure CO 2 laser. Deposition media were either a non excited nitrogen flow or cold remote plasma of nitrogen. Fourier transform infrared spectra of the deposited films show a very efficient nitrogen fixation with CN bands characteristic of tetrahedral carbon. The effect of the distance of deposition zone from the discharge is also discussed.

Elaboration and study of an elastic hard Si-based coating obtained at room temperature from a far cold remote nitrogen plasma

The reactivity of a far cold remote nitrogen plasma is used to dissociate SiH 4 in order to deposit, at ambient temperature, an elastic hard coating on various substrates. The deposition rate, independent of the substrate nature, is equal to 75 nm min −1. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses of the film deposited on silicon reveal the presence of covalent Si-N bonds and the incorporation of oxygen and hydrogen. Scanning electron microscopy observations show that the film is a dense layer with a non-columnar structure. The values of hardness and elastic modulus calculated from microindentation experiments are equal to 9 and 34 GPa for a 4 μm thick film deposited on polyvinyl chloride. For such a film, the specific abrasion energy calculated from scratch test is about 1300 N mm −2.

Carbon nitride CN x film deposition assisted by IR laser ablation in a cold remote nitrogen plasma

Thin films of carbon nitride CN x were prepared on a non-heated substrate in the pressure range 100–1000 Pa. Carbon nitride films were deposited by ablation of carbon molecular fragments from a graphite or pyrocarbon target onto a silicon substrate after a few pulses of a localized transversely excited atmospheric pressure (TEA) CO 2 laser. The deposition medium was either a gaseous flow of pure nitrogen or nitrogen—helium mixtures or cold remote plasma of nitrogen (CRNP) or of nitrogen—hydrogen mixtures (CRNPH). Fourier transform IR (FTIR) spectra of the deposited films show a very efficient nitrogen fixation with C-N bands characteristic of tetrahedral carbon. These results are confirmed by Raman spectroscopy. X-ray photoelectron spectroscopy of samples typically shows two peaks in the N 1s core level spectrum (centred at 399.4 and 400.8 eV). The effect of the distance of the deposition zone from the discharge is also discussed. The plasma created around the target is studied by UV—visible optical emission spectroscopy (OES). Gas phase results are correlated with the characteristics of the deposits.

Barrier behavior hindering Zn++ diffusion from cold remote nitrogen plasma-deposited silicon films

Cold remote nitrogen plasma (CRNP) process is used to deposit organosiloxane polymeric films. 1,1,3,3-tetramethyldisiloxane (TMDS) or its mixture with oxygen is used to deposit polymeric layers on a rubber disks at ambient temperature. The deposited films appear to be efficient against chemical agents diffusion from the disks to a distilled water surrounding phase. The barrier efficiency is increased for films deposited from a TMDS/O2 mixture. The extracted quantity of Zn++ after 30 days of immersion in distilled water at ambient temperature is 70% lower in comparison to the uncoated ones. The transfer of Zn++ into a liquid phase for coated disks is also discussed. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 699–705, 1997

Surface modifications of polycarbonate (PC) and polyethylene terephtalate (PET) by cold remote nitrogen plasma (CRNP)

Industrial PC and PET specimens have been treated by CRNP with pure N 2 or with N 2O 2 mixtures in order to modify their adhesion and surface properties. Scanning electron microscopy (SEM), IR ellipsometry, XPS analyses and wettability measurements reveal interesting modifications at the surface of these materials which extent mainly depends on the conditions used during the plasma treatment, a key parameter being the amount of O 2 introduced in the mixture. IR ellipsometry gives evidence of the presence of new functional groups after CRNP exposure at 1270 cm −1 (PC and PET) and in the 1650–1800 cm −1 (PC) or 1700–1750 cm −1 (PET) regions. Assignments to vibrational stretching modes of CO, CN and CO bonds are discussed. XPS also allows identification of new surface groups associated with O and N species but when O 2 is present in the plasma, no N species is present on PC. Moreover, during the XPS analyses, the surface of treated PC is progressively modified by desorption of small oxygenated fragments which presence was induced by the plasma treatment. Wettability of treated PC increases initially very sharply with the duration of the CRNP treatment and then reaches a constant value. Presence of 10% O 2 in the N 2O 2 mixture is detrimental for high wettability and also induces surface roughness as detected by SEM.

Ageing of an organosiloxane deposit in a cold remote nitrogen plasma: XPS investigation

Thin polymeric films are deposited from tetramethyldisiloxane (TMDS or TMDS O 2 mixture) by cold remote nitrogen plasma (CRNP). X-ray photoelectron spectroscopy (XPS) has been used to characterise the deposited films. SiN bonds are detected for films deposited from TMDS. These bonds disappear for films deposited from TMDS O 2 mixture. Moreover the deposited films were subjected to a further ageing in CRNP or CRNP O 2 media. A smooth etching of the deposit and a surface composition change are evidenced. Oxygen addition to CRNP leads to more pronounced modifications of the film composition and morphology.

Characterization of mixed zinc-oxidized zinc thin films deposited by a cold remote nitrogen plasma

A method for the deposition of a zinc-containing film on aluminium and polypropylene substrates by a cold remote nitrogen plasma (CRNP) was described. The reactivity of the CRNP was first used to clean the substrate which had to be metallized; when the substrate was a polymer, this step was also used to increase its wettability. The reactivity of the CRNP was then used to decompose diethylzinc vapour in order to deposit, at ambient temperature, a zinc-containing film with a blue-grey metallic appearance. XPS analyses were performed after transfer to ambient air during about 10 min. An Ar + etching procedure was then used to progressively investigate the inner layers. The evolution of the Zn Auger LMM transition and of the Ols, Cls and Nls photoelectron peaks were studied versus the Ar + etching duration. Under a contamination layer, the amounts of C and N relative to Zn in the coating film were very low while oxidized zinc species have been detected in the film. Oxidation of the Zn deposit may occur either during the process itself or during air exposure before XPS analyses considering the porosity of the film. The nature of the interface with the substrate appears different: with the aluminium substrate, the deposited film was a Zn-ZnO-Zn(OH) 2 mixture with a zinc rate equal to 55%. With the polypropylene substrate, Zn(OH) 2 appeared only on the outer layer. Inside it was a Zn-ZnO mixture.