Effect Of N2 Flow Rate Research Articles

Microstructure evolution and mechanical behavior of magnetron sputtering AlN–Al nanostructured composite film

In this paper, a series of AlN–Al nanocomposite films are prepared by reactive magnetron sputtering. The effects of N2 flow rate on the microstructure and mechanical properties of the films are studied. The formation and evolution mechanism of the nanocomposite structure are revealed. The results show that with the decrease of N2 flow rate, the microstructure goes through three stages: pure AlN, amorphous Al surrounded nanocrystalline AlN and AlN nanoparticle reinforced Al matrix composite. Benefiting from the good wettability of Al on AlN ceramics, the film deposited at 6 sccm N2 flow rate forms a nanocomposite structure of about 8 nm AlN grains wrapped by 1–2 nm amorphous Al. The hardness of the films increases first and then decreases with the decrease of N2 flow rate, ranging from 4 GPa to 25 GPa. The toughness of the films is analyzed by the ratio of H/E, H3/E2, the normalized plastic depth (δH) and the morphology of large load indentation. The results show that the toughness of the nanocomposite film obtained at 6 sccm N2 flow rate is significantly improved while maintaining the hardness equivalent to that of pure AlN film. The improvement in toughness comes from the microcracks initiated in AlN hindered by the surrounding Al phase.

Effect of N2 flow rate on the crystallization and electrical performance of AlN films prepared by medium frequency magnetron sputtering

Aluminum nitride film is used as the insulator in semiconductor devices, and the low leakage current density plays an important role in their performance and reliability. In this work, a system of aluminum nitride films was fabricated by medium frequency magnetron sputtering on the P (100) Si and their composition, crystalline phase, surface topography as well as electrical properties were investigated. N2 flow rate manipulates the sputtering mode and therefore becomes an effective way to modulate the deposition rate, composition and crystallization behavior of the AlN films. The films deposited at 10.0 sccm exhibits excellent leakage current density of 6.08 × 10−7 A/cm2 at 1MV/cm, which indicates that the film is a promising candidate for insulator applications. At low electric field (E < 0.3 MV/cm), the leakage current is dominated by ohmic behavior, while for high electric field, the leakage current is controlled by Poole–Frenkel mechanism.

Microstructure, mechanical properties, and corrosion resistance of TiSiN coating prepared by FCVA technique with different N2 flow rates

TiSiN coatings have attracted extensive attention due to excellent performance in cutting tools, Marine engineering equipment and ship critical components. However, due to the many microparticles and micropores on the coating surface prepared by traditional PVD techniques, the performance of the coatings, especially corrosion resistance, is seriously affected. Therefore, the preparation of high quality TiSiN coatings is very important for the industrial applications. In this study, high-quality TiSiN coatings were prepared by FCVA technique. The effect of N2 flow rate on microstructure, mechanical properties and corrosion resistance of TiSiN coating was investigated. The results showed that all TiSiN coatings presented smooth and compact microstructure without cracks. Meanwhile, TiSiN coatings had a nanocomposite structure of amorphous Si3N4 encapsulated TiN crystallites and possessed a preferred orientation of TiN (200) plane. With the increase of N2 flow rate, the grain size and hardness increased first and then decreased. When N2 flow rate is 20 sccm, the hardness of TiSiN coating reached the maximum owing to the fine grain strengthening effect. Moreover, TiSiN coating deposited N2 flow rate of 40 sccm had the best corrosion resistance, with the highest charge transfer resistance and pore resistance, which was primarily related to the best surface quality.

Effect of Nitrogen Flow Rate on Microstructure and Optical Properties of Ta2O5 Coatings

Ta2O5 coatings were prepared on highly transparent quartz glass and silicon wafer substrates using RF magnetron sputtering technology. Different flow rates (10%, 15%, and 20%) of N2 were introduced during the sputtering process while keeping the total sputtering gas flow rate constant at 40 sccm. The effects of N2 flow rate on the phase structure, micro-morphology, elemental composition, and optical properties of Ta2O5 coatings were investigated. The coatings were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), electron energy spectroscopy (EDS), and spectrophotometry. The results show that the phase composition of the coating is an amorphous structure when the sputtering gases are pure argon and nitrogen-argon mixed gases, respectively. The coating after the passage of N2 is mainly composed of Ta, N, and O, which confirms that the deposited coating is a composite coating of Ta oxide and nitride. The EDS spectrum indicates that the ratio of O to Ta atoms in the composite coating is greater than the stoichiometric value of 2.5. It may be related to the deposition rate of Ta atoms during the preparation process. The optical properties show that the average transmittance of the composite coating is greater than 75% and the maximum light transmission is 78.03%. The transmittance in the visible range of Ta2O5 coatings prepared under nitrogen-argon mixed gas sputtering conditions is greater than that of those prepared under pure argon sputtering conditions. Finally, the coatings optical direct band gap Edg and indirect band gap Eig are obtained.

Study on the Electrical, Structural, Chemical and Optical Properties of PVD Ta(N) Films Deposited with Different N2 Flow Rates

By reactive DC magnetron sputtering from a pure Ta target onto silicon substrates, Ta(N) films were prepared with different N2 flow rates of 0, 12, 17, 25, 38, and 58 sccm. The effects of N2 flow rate on the electrical properties, crystal structure, elemental composition, and optical properties of Ta(N) were studied. These properties were characterized by the four-probe method, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and spectroscopic ellipsometry (SE). Results show that the deposition rate decreases with an increase of N2 flows. Furthermore, as resistivity increases, the crystal size decreases, the crystal structure transitions from β-Ta to TaN(111), and finally becomes the N-rich phase Ta3N5(130, 040). Studying the optical properties, it is found that there are differences in the refractive index (n) and extinction coefficient (k) of Ta(N) with different thicknesses and different N2 flow rates, depending on the crystal size and crystal phase structure.

Atmospheric pressure plasma jet treatment enhances the effect of Alloy Primer on the bond strength between polymethyl methacrylate and stainless steels: application for retention of magnetic attachment to resin denture base

Magnetic attachment system is used to embed in polymethyl methacrylate (PMMA) resin denture base to improve denture stability. However, dislodgement of magnetic attachments from denture base is a major clinical problem. This study is to evaluate the bond strength between PMMA and stainless steel using metal primer and atmospheric pressure plasma jet (APPJ) treatment. Stainless steel discs were treated with Single Bond Universal Adhesive; Palfique Universal Bond; Alloy Primer; heat treatment with Alloy Primer; and 10-s, 20-s, and 30-s APPJ treatment with Alloy Primer. The shear bond strength between PMMA and surface-treated stainless steel was measured using universal testing machine. The effects of N2 flow rate (60, 50, 40, 30 SLM), thermal cycling, and air quenching on shear bond strength were also investigated. The surface of each disc was examined using X-ray photoelectron spectroscopy and a goniometer. Finally, the temperature of plasma with various N2 flow rates was measured and the optical emission spectra of the plasma were measured using spectrometer. Alloy Primer produced the highest bond strength. APPJ treatment was effective at enhancing bond strength by cleaning the surface of contaminants. Moreover, APPJ treatment with air quenching increased surface O2-/OH- and Fe2O3/FeOOH ratios, reducing the negative influence of thermal cycling on bond strength. Alloy Primer with 20 s of APPJ treatment with a 50-SLM N2 flow rate and air quenching was the most effective at increasing bond strength.

Effect of N2 flow rate on kinetic investigation of lignin pyrolysis

Fast pyrolysis of lignin can obtain valuable products such as bio-oil, bio-chemical, syngas, and biochar. In this study, two types of lignin known as brown solid from the byproduct of cellulosic ethanol fermentation and commercial dealkaline lignin from the papermaking process were used for pyrolysis in a 3-L batch reactor at 300–450 °C. The product composition in the liquid and gas phases were analyzed by using gas chromatography-mass spectrometry/Flame-ionization detector/thermal conductivity detector (GC-MS/FID/TCD). Increasing the N2 flow rate to 150 mL/min was sufficient to increase the production of bio-oil/bio-organics up to 15% for brown solid pyrolysis. In contrast, the biochemical production during dealkaline lignin pyrolysis was not sensitive to the change of the N2 flow rate. The amount of biochar produced in the pyrolysis (~60%) slightly changed at various pyrolysis temperature and gas flow rate, which could be due to the relatively low pyrolysis temperature that was insufficient to decompose the lignin. The GC-MS analysis also revealed that C7–C8 compounds, which represented the phenolic compounds, were the most abundant in the liquid products. Kinetic models of the pyrolysis were established based on the thermogravimetric analysis.

Effect of N2 Flow Rate on Structure and Corrosion Resistance of AlCrN Coatings Prepared by Multi-Arc Ion Plating

Effect of N2 Flow Rate on Structure and Corrosion Resistance of AlCrN Coatings Prepared by Multi-Arc Ion Plating

Effect of N2 flow rate on structural and infrared properties of multi-layer AlCrN/Cr/AlCrN coatings deposited by cathodic arc ion plating for low emissivity applications

The effect of N2 flow rate on structural, composition, deposition rate, electrical and infrared properties of the multi-layer AlCrN/Cr/AlCrN tandem coatings have been studied. The coatings were designed and prepared by a cathodic arc ion plating system at various N2 flow rates for low emissivity applications. The results showed that the thickness of AlCrN layers decreased continuously with increasing N2 flow rate. Structure and elemental composition of the deposited coatings strongly depended on N2 flow rate. X-ray diffraction analysis showed that for 10–80 sccm, the coatings exhibited a single (fcc) phase, for 120–160 sccm, an amorphous phase was obtained. The phase formation has been confirmed by transmission electron microscopy diffraction patterns. As for electrical resistivity, the AlCrN layers turned from conductive, semiconductive, to dielectric behavior. In practice for low emissivity applications, the deposited multi-layer coatings exhibited emissivity values among 0.0748–0.1193, which rose with increased N2 flow rate. Among all the phases, the coating with an amorphous AlCrN layer (160 sccm) presented an outstanding thermal stability and had an emissivity of 0.1194 even after annealing at 800 °C for 10 h in air. It was observed that the amorphous AlCrN layer effectively controlled the inward diffusion of O and the outward diffusion of Cr, Al and Ni from substrate, which rendered this multi-layer coating a potential material for low emissivity applications at high temperature.

Effect of N2 flow rate on electromagnetic interference shielding effectiveness of TiNx films

TiNx films with different nitrogen contents were fabricated using direct current reactive magnetron sputtering. Influence of N2 flow rate on the resistivity and electromagnetic interference (EMI) shielding effectiveness (SE) of TiNx films was studied. The EMI SE of TiNx films was found to be related with the resistivity. With the rise of N2 flow rate, the resistivity of TiNx films increased, while the EMI SE decreased. When the N2 flow rate was 1 sccm, the EMI SE of TiNx films was over 20 dB with the thickness of 1.47 µm, which was much smaller than the thickness of the presently known EMI-shielding materials. The results indicated that TiNx films could be applied as ultrathin thickness, lightweight, and design flexibility shielding materials.

Extraction of Metal Arsenic from Waste Sodium Arsenate by Roasting with Charcoal Powder

The current paper explored the directly reductive decomposition of waste sodium arsenate by roasting it with charcoal powder to volatilize less toxic As0 and to simultaneously obtain sodium salts with potential commercial value, serving the purpose of developing a more sustainable route to deal with the environmental issues faced by the antimony production industry in China. The process was firstly evaluated by thermogravimetric (TG) analysis and thermochemical calculations. The effects of N2 flow rate, roasting temperature, dosage of charcoal powder, and roasting time were then investigated. The results showed that the arsenic extraction could reach 99.84% under optimal conditions. The roasting residue, containing arsenic as low as 0.0598%, was a promising source for the production of Na2CO3 as expected. In addition, X-ray diffraction (XRD), scanning electron micrograph (SEM), and X-ray photoelectron spectroscopy (XPS) were conducted to reveal the roasting mechanism and formation of metal arsenic was thereby confirmed.

Multi-phase structured hydrogenated amorphous silicon carbon nitride thin films grown by plasma enhanced chemical vapour deposition

In this work, hydrogenated amorphous silicon carbon nitride (a-SiCN:H) films were grown by plasma-enhanced chemical vapour deposition (PECVD) process using SiH4, CH4 and N2 gas discharge. The effects of N2 flow-rate on the structure, optical as well as photoluminescence properties were investigated. AES depth profile and FTIR spectroscopy analysis were used to probe the distribution of elemental composition and the bonding configuration within the film structure respectively. As a complement, Raman analysis were done to investigate the presence and properties of the amorphous carbon phases within the films. The films grown on both c-Si and glass substrates were multiphase in structure with dominant component of a-SiCN:H, a-SiC:H and a-CN:H phases. Optical spectrophotometer measurements indicated that the band gap energy was dependent on the dominant phase present in the film structure and the overlapping of the tail states within the band gap, contributed to the low ETauc values of the films. The origin of the most dominant PL emission from the films was shown to be contributed by radiative transition and recombination within the band tails of the sp2-C clusters within the film structure.

Effect of N2 flow rate on the microstructure and electrochemical behavior of TaNx films deposited by modulated pulsed power magnetron sputtering

Modulated pulsed power magnetron sputtering (MPPMS) technology offers the possibility to grow high performance coatings compared to the ones developed by conventional dc magnetron sputtering. The high degree of ionization of sputtered particles developed during MPPMS can be usefully utilized to precisely tailor the properties of the growing films. One of the main advantages of such a high metal ion flux is related to the densification of the coatings due to enhance ion bombardment towards the growing film. The development of extremely dense and low-defect microstructure coatings can have a positive effect on the corrosion resistance of tantalum nitride (TaNx) films.In this study, TaNx thin films have been deposited by MPPMS in a closed field unbalanced magnetron sputtering system. Structure, surface morphology, hardness and corrosion resistance of the developed coatings have been analyzed as a function of different N2-to-Ar ratios (0, 0.25, 0.625, 1). X-ray diffraction and scanning electron microscopy analysis reveal high dependence of the grown crystal phases and the microstructure on N2-to-Ar ratio. The hardness of the TaNx coatings increases when increasing N2-to-Ar ratio up to a maximum value of 25GPa (N2-to-Ar ratio of 0.625). The corrosion behavior was investigated using electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry. EIS measurements registered at different immersion times show high impedance values (in the order of 10MΩcm2) and corrosion resistance enhancement with time, indicating the formation of a passive protective oxide layer on the top of their surfaces. TaNx film grown at 0.25N2-to-Ar ratio exhibits the highest corrosion resistance of 103.53MΩcm2 and low porosity of 1.63×10−3 and is characterized by columnar-free microstructure.

Pyrolysis Process Optimization for SU8-Derived Carbon Structures

For the last 15 years, the Carbon-MEMS (C-MEMS) process has gained widespread interest due to its low cost, reliability and simplicity for the fabrication of 2-D or 3-D carbon structures. Briefly, one step photolithography is used to pattern the structures onto a photosensitive layer and the patterned structures are then converted to carbon using thermochemical decomposition (also known as Pyrolysis). During pyrolysis, an organic material is heated in an inert atmosphere to temperatures higher than 800°C. This step is as important as photolithography to fabricate 3-D carbon structures because it defines the physico-chemical properties of the resulting carbon structures (e.g., electrical conductivity, thermal conductivity, reactivity, and mechanical stiffness, among others). Several parameters of the pyrolysis process can be adjusted in order to fine-tune the properties of the carbon structures. For example, a flow of Nitrogen (N2), Argon (Ar), or even a mixture of gases like N2 and Hydrogen (H2) is commonly used to create an inert atmosphere, with each gas yielding carbon structures with different properties. Other critical parameters are the gas flowrate, final temperature, and heating and cooling ramps. Therefore, optimization of these process parameters is of utmost importance for the carbon structures to meet the requirements of the application at hand. Sometimes, although pyrolysis parameters have been optimized, a very small amount of Oxygen (O2) can invade the pyrolysis chamber, rendering the structures unusable. The source of O2 may be a defect in the pyrolysis chamber or the sample itself (we found that the aging effect of the polymeric sample being pyrolyzed can significantly affect the result of the pyrolysis step). We discuss here about the effect of N2 flowrate, sample aging, final temperature and temperature ramps on carbon yield, and report a few guidelines for the operation of a newly installed pyrolysis system. In this work, samples for pyrolysis consisted on SU-8-based nanofibers electrospun atop 3-D SU-8 walls through electromechanical spinning (EMS). We found that the required N2 flow volume (per minute) is equal to, or a little more than, the tube volume. If a reasonably higher flowrate is required to properly pyrolyze the polymeric structure, then O2 is accessing the pyrolysis chamber through the exhaust tube or through a defect in the chamber itself. We employed an N2 flowrate 1.5 times the volume of the tube at the beginning of the process (for at least 15minutes) to ensure that the atmosphere within the pyrolysis chamber is inert and reduced the flow to slightly more than the volume of the tube for the rest of the process. We often obtain carbon structures even at lower N2 flow than the volume of the tube. However the average pore size is bigger in that case. We made a comparative study of average pore size at different flowrates. For the aging effect study we noticed that small structures are less affected with time than bigger structures. Finally, we optimized the pyrolysis process parameters for SU8 derived carbon structures and compared them with those of an existing, already-optimized facility.

Effect of N2 flow rate on the properties of N doped TiO2 films deposited by DC coupled RF magnetron sputtering

N doped TiO2 films were deposited on glass substrates at room temperature using DC coupled RF magnetron sputtering with a TiO2 ceramic target. The influences of N2 flow rate on the deposition rate, crystal structure, chemical composition and band gap of the deposited films were investigated by Optical profiler, X-ray diffraction, X-ray photoelectron spectroscope and ultraviolet-visible spectrophotometer. The film growth rate gradually decreased with increasing N2 flow rate. As N2 flow rate increased, the crystallization of the films deteriorated, and the films tended to form amorphous structure. XPS analysis revealed that N dopant atoms were added at the substitutional sites into TiO2 lattice structure. FE-SEM results showed that the grain size of the film decreased and the crystallinity degraded as N2 flow rate increases. In addition, N doping caused an obvious red shift in the optical absorption edge.

Effect of Nitrogen Flow Rate on Structure and Adhesion Strength of Magnetron Sputtered Ti-Si-N Nanocomposite Films

Ti-Si-N nanocomposite films were prepared by co-sputtering Ti and Si targets in Ar/N2 gas atmosphere. The effect of N2 flow rate on the structure, adhesion strength and friction coefficient of the deposited films was studied by using X-ray diffraction, atom force microscope, field emission scanning electron microscopy and multi-functional tester for material surface properties. The Ti-Si-N films had a fine, smooth and compact structure with TiN nanograins embedded in an amorphous Si3N4 matrix. The nanocomposite films exhibited (200), (111), (220) and (222) reflections with a dominant orientation of the (200) reflection. When the N2 flow rate increased, the film structure was refined. It was found that both interfacial adhesion strength and friction coefficient depended on the N2 flow rate, and the best values were exhibited by the nanocomposite film produced at N2 flow rate of 15 sccm, perhaps contributed to a finer and smoother structure of this deposited film. Keywords: Ti-Si-N, Sputtering, Nanocomposite film, Microstructure, Adhesion strength, Friction coefficient

Selective dry etching of TiN nanostructures over SiO2 nanotrenches using a Cl2/Ar/N2 inductively coupled plasma

An inductively coupled plasma etch process for the fabrication of TiN nanostructures over nanotopography is presented. Using a Cl2/Ar/N2 plasma, a selectivity of 50 is achieved over SiO2. The effect of N2 flow rate on the etch rates and the nonvolatile residues on TiN sidewalls is investigated. As N2 flow rate is increased up to 50 sccm, a change in the deposition of the nonvolatile residues on TiN sidewalls is observed. The current density–voltage characterizations of TiN devices fabricated with TiN nanostructure sidewalls are presented. The measured current densities of two different samples etched with low and high N2 flow rate, respectively, demonstrated the presence after cleaning of an insulating layer deposited on the sidewalls for low N2 flow rate only.

Effect of N2 flow rate on microstructure and mechanical properties of PVD CrNx coatings for tribological application in seawater

The CrNx coatings were deposited on 316L stainless steel and silicon (100) wafer by multi-arc ion plating with different N2 flow rates. Composition, microstructures and mechanical properties of the as-deposited CrNx coatings were systematically investigated by X-ray photoelectron spectrometry (XPS), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), nano-indentation and scratch tester. The friction and wear properties of CrNx coatings were investigated by a ball-on-disk tribometer in artificial seawater. The results showed that the coatings transformed from a mixture of Cr+Cr2N to single-phase Cr2N, and then Cr2N+CrN to pure CrN phase with the increase of N2 flow rate. The coatings were all dense except for the one deposited at 200sccm, which clearly exhibited a typical columnar structure. With the increase of N2 flow rate, the friction coefficients first decreased to 0.196 at 100sccm then slightly increased to 0.215 at 200sccm in seawater. However, the depth of wear track and wear rate were lowest at 125sccm, which could be attributed to the denser structure related to better corrosion resistance consisting of Cr2N and CrN phases.

Effect of N&lt;sub&gt;2&lt;/sub&gt; Flow Rate on Structure and Mechanical Properties of CrN Coatings Prepared by Closed Field Unbalanced Magnetron Sputtering

CrN coatings were deposited by Closed Filed Unbalanced Magnetron Sputtering (CFUMS). The effect of N2 flow rate on composition, phase components, morphologies and mechanical properties of CrN coatings were studied. The results show that the deposition rate of CrN coatings declined with the increase of nitrogen flow percentage in a Ar/N2 mixture atmosphere. When the nitrogen flow percentage reached 50% or more, the Cr and N atomic ratio of CrN coatings is close to 1:1. The phase in coatings was the coexistence of Cr, Cr2N and CrN, but the crystal preferred orientation changed significantly with the different N2 flow rates. The columnar crystal CrN coating with low N2 flow rate was denser. The hardness and adhension of CrN coatings have no direct relationship with N2 flow rate.

Stability Studies on Nitrogen Doped p-ZnO (NZO) Thin Films Grown by Reactive Magnetron Sputtering

Nitrogen doped ZnO (NZO) thin films, at different N2 flow rates have been deposited on glass substrates by pulsed DC reactive magnetron sputtering technique. The effect of N2 flow rate (1.0 sccm - 3.0 sccm) on the structural, optical, electrical and chemical state of N has been studied. With the effect of N2 flow rate: the crystallinity of the films decreased, tensile stress is developed, optical transmittance decreased (80% to 60%), conductivity decreased till 1.5 sccm and films were n-type conducting. At 2.0 sccm and 2.5 sccm of N2 flow rates, NZO thin films showed p-type conductivity. The changes in the magnitude and type of conductivity have a direct relation with the changes observed in N-chemical state in ZnO lattice. p- NZO thin films are electrically unstable; this instability has been explained based on the changes occurred in the N chemical states, resulting from the stress release in NZO lattice.