Effect Of Nitrogen Flow Rate Research Articles

Low friction and wear of Nitrogen-doped diamond-like carbon films deposited on NBR with different flows of N2 by DC-MS

Utilizing a diamond-like carbon (DLC) coating on rubber surfaces is an innovative approach to improve the wear resistance and tribological characteristics of rubber. In this paper, a series of N-doped diamond-like thin films (N-DLC) were deposited on the surface of nitrile butadiene rubber (NBR) substrate by varying the flow rate of nitrogen using direct current magnetron sputtering (DC-MS) technology, and the effects of nitrogen flow rate on the surface morphology, structure, surface energy and tribological properties of N-DLC films were systematically investigated. The results show that the friction coefficients of the N-DLC films are all smaller than those of the undoped DLC films, and most importantly, the samples maintain a stable, ultra-low coefficient of friction of about 0.057 and a low wear rate of the order of 10−9 in the tribological tests at a nitrogen flow rate of 3 sccm, exhibiting excellent tribological performance. This is attributed to several key factors: higher hardness, better film-base bonding, lower surface roughness, and lower friction interface adhesion. This recognition provides insight into the preparation of N-DLC films on rubber to achieve low frictional wear.

Study on Slag Splashing Behavior in a 120 t Converter Based on Physical and Mathematical Simulation

The service life of converter linings is crucial for efficiency and emission reduction. Slag splashing performance is essential in steelmaking. This study constructs a physical model based on a specific 120 ton converter using similarity principles. Dimensional analysis is employed to investigate process parameters and fluid properties. The influence of various process parameters on slag splashing performance is analyzed. Mathematical simulations using the volume of fluid method are conducted to quantitatively assess the volume of slag splashing, determine the optimum lance height, and examine the effects of nitrogen flow rate on the impact crater profile, splashing shape, and angle. The results demonstrate that when the fluid viscosity and surface tension meet specific conditions, the lance height in the physical model and the prototype satisfy geometric similarity. However, as no suitable fluid meeting the conditions is found, a corrective relation for the lance height between the physical model and the prototype is established to optimize the process parameters. By adjusting the lance height and bottom gas flow rate, damaged areas can be repaired, while modifying the nitrogen flow rate alters the shape of the slag splashing, resulting in uniform slag splashing.

Effects of Nitrogen Flow Rate on the Performances of Cathodic Arc Deposited TiN Films on 316L Stainless Steels as Bipolar Plates for the Proton‐Exchange Membrane Fuel Cell

The corrosion resistance, interfacial contact resistance (ICR), and hydrophobicity of cathodic arc deposited TiN films on 316L stainless steels at different nitrogen flow rates as bipolar plates (BPs) for the proton‐exchange membrane fuel cell (PEMFC) are investigated. It is shown in the results that the TiN‐coated 316L stainless steel prepared at a moderate nitrogen flow rate (250 sccm) exhibits a low stable corrosion current density of 6.5 × 10−8 A cm−2 in the simulated corrosive cathode environment of PEMFC, and a low ICR of 8.94 mΩ cm−2 at a pressure of 1.38 MPa after corrosion, meanwhile presents a good hydrophobicity before and after corrosion. These results are discussed by considering the probable effects of the nitrogen flow rate on the substrate/coating system based on the microstructural characterization of the substrate/coating interface and the coating, which shows that the interdiffusion will be started in the deposition process and a moderate nitrogen flow rate during the coating process will promote to the broadening of interface region and lead to the formation of a robust and high‐quality coating with fewer defects that can effectively improve the performances of the 316L stainless steel substrate as the BP for PEMFC.

Effects of nitrogen flow rate on the microstructure and mechanical and tribological properties of TiAlN films prepared via reactive magnetron sputtering

In this study, TiAlN ceramic films were fabricated via reactive magnetron sputtering on a Ti6Al4V titanium alloy substrate. The effects of N2 flow rates on the microstructure and mechanical and tribological properties of the films were systematically studied. With increasing N2 flow rate, the films underwent a morphological evolution from a fine columnar structure to a coarse structure with holes and microcracks. In addition, the preferred orientation of the films varied from TiAlN (220) to the (111) plane. However, a high N2 flow rate (≥20sccm) resulted in target poisoning and reduced the deposition rate, which resulted in defects such as cavities and holes on the surface. Moreover, with increasing N2 flow rate, the hardness and elastic modulus first increased and then reduced owing to grain refinement. The films deposited at a N2 flow rate of 16 sccm exhibited the smallest wear width and the lowest wear rate. As the N2 flow rate increased from 12 to 24 sccm, the wear mechanism of the films changed from abrasive and adhesion wear to abrasive wear caused by severe plastic deformation, which was directly related to the microstructural evolution and mechanical properties.

Effect of nitrogen flow rate on the mechanical properties of (V,Mo)N thin films

The objective of this research was to study the effect of nitrogen flow rate on the structure and mechanical properties of (V,Mo)N thin films. Five sets of (V,Mo)N thin films were deposited with different nitrogen flow rates ranging from 1.2 to 6.0 sccm on Si (100) substrate using unbalanced magnetron sputtering. The results showed that the N/metal ratio increased from 0.47 to 0.85 with increasing nitrogen flow rate. The microstructure of the specimen deposited at the lowest nitrogen flow rate (D12) was characterized by transmission electron microscopy, where the microstructure contained three phases, including Mo, VN and (V,Mo)N. The X-ray diffraction patterns also indicated the presence of minor Mo metal phase for the specimens deposited at nitrogen flow rate lower than 2.5 sccm. The texture of the thin films was mostly (200) and switched to random texture at nitrogen flow rate from 4.0 to 6.0 sccm. The lattice constant of the specimens was linearly related to the N/metal ratio. The specimen D12 had the highest hardness 29.3 GPa, which could be due to the existence of Mo metal phase in between (V,Mo)N phase, thereby retarding the crack propagation. By contrast, the hardness of all the other specimens showed slight variation ranging from 23.6 to 26.1 GPa, which may be attributed to the nanograin size (<15 nm) where deformation was controlled by grain boundary-mediated mechanisms. Fracture toughness (Gc) of the thin films was evaluated using internal energy-induced cracking method. The resultant Gc of the specimens, ranging from 16.4 to 30.1 J/m2, linearly increased with increasing N/metal content, suggesting that the MoN bonding may be crucial on increasing fracture toughness of (V,Mo)N thin films. For specimen D12, the higher Gc may be caused by the presence of Mo metal phase that could arrest the crack propagation. The results showed that Gc of the (V,Mo)N thin films was higher than that of VN and TiN thin films, which was consistent with the theoretical predictions.

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.

A new technique of lithium isotope extraction and separation: Flotation complexation extraction

Flotation complexation extraction can effectively extract and separate lithium isotopes. The effects of nitrogen flow rate, bubble size, gas holdup, reaction flow pattern, aeration time, and temperature on the separation process were studied. In addition, the complex relationship and separation mechanism of lithium with 10-hydroxybenzoquinoline were discussed. Results show that nitrogen flow rate and bubble size significantly affected the flotation complexation extraction process. With an appropriate flow rate, we obtained a homogeneous regime pattern containing small and evenly distributed bubbles to achieve better separation efficiency and ensure a smooth extraction process. According to the slope method, lithium and 10-hydroxybenzoquinoline were complexed and extracted at a ratio of 1: 2. Compared with the traditional oscillating extraction, the bubble mass transfer mode in the flotation complexation extraction strengthened the complex extraction process and achieved higher extraction rate and separation efficiency.

Effect of nitrogen flow rate on the microstructure, mechanical and tribological properties of CrAlTiN coatings prepared by arc ion plating

The influence of the nitrogen flow rate on the microstructure, mechanical and tribological properties of the CrAlTiN coatings prepared by arc ion plating technology was systematically investigated. The results showed that the content of N and Ti increased, while the deposition rate and grain size decreased with the nitrogen flow rate from 100 sccm increased to 500 sccm. The toughness and adhesion strength firstly increased and then decreased. The coatings showed a cubic NaCl structure, (111) and (200) crystal planes show competition growth, while high nitrogen flow promoted the growth of (200) plane. The main wear mechanisms of CrAlTiN coating against Si3N4 ball were adhesive and chemical erosion. The coefficient of friction decreased with the increase of nitrogen flow rate, but the wear rate firstly decreased and then increased, the coating prepared by using 500 sccm nitrogen flow appeared to peel off the substrate. In addition, the shear resistance and contact area were reduced due to the adhesive Cr–O, Al–O and Ti–O with a low coefficient of friction and high hardness. Therefore, a low coefficient of friction of the coating was obtained. As a result, the CrAlTiN coating prepared by applying optimal nitrogen flow rate had excellent mechanical and tribological performance.

Hot target magnetron sputtering enhanced by RF-ICP source: Microstructure and functional properties of CrNx coatings

CrNx coatings were deposited at high rates (100–130 nm/min) using hot Cr target magnetron sputtering enhanced by a radio-frequency inductively coupled plasma (RF-ICP) source in an Ar + N2 atmosphere. Besides separation of inert and reactive atmosphere, the RF-ICP source can be an effective tool for ion assistance in case of coating growth and to tailor film parameters. The effects of nitrogen flow rate and substrate bias potential on microstructure and functional properties of the CrNx coatings were investigated. An increase in nitrogen flow rate favored the formation of a looser microstructure of the coatings, while substrate biasing had the opposite effect. The functional properties were strongly dependent on the phase composition of the CrNx coatings. The change in coating microstructure significantly affected hardness, elastic modulus, adhesion, friction coefficients and corrosion resistance. The results indicated that ion assistance can be a key feature for regulating functional properties in the considered type of coating deposition. Cr2N and CrN compound coatings with high hardness (∼20 GPa) and low corrosion current density (icorr ∼ 3–5·10−9 A/cm2) in a 3.5 wt% NaCl solution were obtained by high-rate deposition.

Experimental study on the micro-explosion characteristics of two blended types of droplets under different nitrogen flow rates

Using the single droplet suspension method, the effect of nitrogen flow rate on the micro-explosion characteristics of L/H (low-boiling fuel in high one) and H/L (high-boiling fuel in low one) droplets in the laminar flow regime at 700 °C and atmospheric pressure was studied. The experimental results showed that for B80P20 (80% biodiesel and 20% 1-pentanol by volume) and B20P80 (20% biodiesel and 80% 1-pentanol), the micro-explosion intensity as well as the number of micro-explosions and strong micro-explosions increased first and then decreased with the increase in the nitrogen flow rate. In addition, the change range of B20P80 was always larger than that of B80P20. The micro-explosion intensity of B80M20 (80% biodiesel, 20% methanol) changed a little. However, for B20M80 (20% biodiesel, 80% methanol), it decreased monotonously with nitrogen flow rate. The variation of droplet lifetime was opposite to that of micro-explosion intensity except for B80M20. The micro-explosion delay time and relative micro-explosion delay time increased monotonously with nitrogen flow rate for B80P20, B20P80, and B20M80. As nitrogen flow rate increased, the micro-explosion distribution of B80M20 and B20M80 became more dense, but for B80P20 and B20P80, it became dense first and then sparse. In short, the nitrogen flow rate had a greater impact on H/L droplets than L/H ones, and a greater impact on B20M80 than B20P80. The experimental results provided a reference for further study on the micro-explosion mechanism of different blended types of droplets in different flow regimes.

Fabrication of TiZrNbTaFeN high-entropy alloys coatings by HiPIMS: Effect of nitrogen flow rate on the microstructural development, mechanical and tribological performance, electrical properties and corrosion characteristics

One TiZrNbTaFe and five (TiZrNbTaFe)N high entropy alloy coatings were deposited onto three different substrates using a high power impulse magnetron sputtering (HiPIMS) at different nitrogen gas flow ratios (RN2). The peak current and peak power density values of HiPIMS increased with increasing RN2. The crystalline nitride (TiZrNbTaFe)N coatings were obtained as grown using equal and higher than 10.0% RN2. The higher RN2 can promote a phase transformation from an amorphous state to face-centered cubic (fcc) structure. The fcc structured coatings exhibited a fine columnar microstructure and enhanced crystallinity. The highest hardness and reduced elastic modulus reached 36.2 GPa and 265 GPa, respectively, were found for the 32.0 at.% nitrogen contained (TiZrNbTaFe)N coating primarily due to its high residual stress and secondarily because of the formation of metal-nitride phase and the solid solution strengthening of various elements. The electrochemical properties of coatings in 3.5 wt.% NaCl aqueous solution at room temperature was studied using the potentiodynamic polarization and electrochemical impedance spectroscopy methods. We discovered that the highest corrosion polarization resistance of 3.08 × 106 Ω·cm2 was also obtained for 32.0 at.% nitrogen contained (TiZrNbTaFe)N coatings grown at RN2 of 10.0%. Based on these excellent properties, (TiZrNbTaFe)N high-entropy alloy nitride coating with 32.0 at.% nitrogen content can be used as a promising protective hard coating.

Fabrication of tungsten nitride thin films by superimposed HiPIMS and MF system: Effects of nitrogen flow rate

The high-power impulse magnetron sputtering (HiPIMS) technology starts a new era in the thin film fabrication, which already attracts researchers and industries' interest on its further application in many fields. For improving the low deposition rate of HiPIMS, the superimposition concept by introducing mid-frequency (MF) pulses during the off-time of HiPIMS pulsing was adopted for the fabrication of transition metal nitride hard coatings. Tungsten nitride coating is characterized by its high hardness, good thermal stability and low electrical resistivity. In this study, tungsten nitride coatings were fabricated using five different N2 gas flow rate ratios by a superimposed HiPIMS-MF power system. The W target showed a hysteresis-free behavior during the reactive sputtering process of WNx coating, where x indicated the chemical composition ratio between W and N elements. The peak current and peak power density values of both HiPIMS and MF powers decreased with increasing N2 flow rate ratio. The nitrogen content of WNx coating increased with increasing nitrogen flow rate ratio, whereas the tungsten concentration shows a decreasing tendency. The x value and the nitrogen content of WNx coating increased from 0.05 to 0.60 and from 5.1 to 36.7 at.%, respectively, when the nitrogen flow rate increased from 13 to 37 sccm. The crystalline structure of WNx coatings changed from a pure BCC-W phase to a mixture of BCC-W and FCC β-W2N phases when the x value increased from 0.05 to 0.12. A pure FCC β-W2N phase structure was obtained when the x values of WNx coating reached 0.36, 0.43 and 0.60. The hardness values of WNx coatings were ranging from 26.7 to 31.6 GPa. The WN0.12 coating with a low coefficient of frictions of 0.33, a high hardness of 31.5 GPa and high H/E and H3/E2 ratios were achieved due to the solution hardening and smoother microstructure induced by the substrate bias and the higher energy of superimposed HiPIMS-MF system.

The Effect of Nitrogen Flow Rate on the Loadbearing Capacity from Nano- to Macro-Hardness of Austenitic Stainless Steels Magnetron Sputtering-Coated with Stainless Steel Films

UNS S31603 stainless steel (SS) substrates were covered by reactive magnetron-sputtering with protective SS coatings of the same steel specification. A mechanical characterization study (through nano-, micro- and macro-hardness tests) of samples obtained under two different sputtering conditions and varying the N2 gas flow rate was carried out. This contribution aimed at appraising the effects of varying the nitrogen flow rate on hardness, elastic modulus, and susceptibility to indentation-induced crack formation of the coated SSs. Nitrogen-free samples displayed body-centered cubic (BCC) films with 9.0-9.4 GPa hardness and 203-206 GPa elastic modulus, while their susceptibility to indentation-induced cracking varied between superior and moderated among the two sets of sputtering conditions studied. Samples alloyed with 4-6 N at-% displayed a predominantly face-centered cubic (FCC) structure, 9.4 GPa hardness, 196-218 GPa elastic modulus, and superior resistance to crack formation. Samples with 11.5-22.0 N at-% were fully composed of the FCC structure, displayed 12.4-15.2 GPa hardness, 188-193 GPa elastic modulus, and moderated resistance to indentation-induced crack formation. Samples with 47.0 N at-% displayed FCC compound nitride structure, for which hardness and elastic modulus were 8.1 GPa and 139 GPa, respectively. These samples displayed low resistance to crack formation.

Effects of Nitrogen Flow Rate on the Structural, Morphological and Optical Properties of TaN Thin Films Grown by the DC Magnetron Sputtered Technique

Effects of Nitrogen Flow Rate on the Structural, Morphological and Optical Properties of TaN Thin Films Grown by the DC Magnetron Sputtered Technique

Arc deposition of wear resistant layer TiN on Ti6Al4V using simultaneous feeding of nitrogen and wire

As an admirable surface improvement method, arc surface cladding has been widely used in various fields. The surface properties of titanium alloy were improved by gas tungsten arc cladding. In the process of arc claddings, a certain amount of nitrogen was added in the shielding gas to form the hard phase of TiN in the cladding layer. Titanium alloy surface was cladded with the same process parameters and different nitrogen flow rate. The effects of nitrogen flow rate on the microstructure and mechanical performance of the cladding layer were studied through an optical microscope, scanning electron microscope (SEM), X-ray diffraction (XRD), Vickers hardness and friction wear testing machine. The results show that the increase of the nitrogen flow rate not only changes the shape of the arc but also forms a large number of TiN hard phases in the cladding layer. With the increase of the nitrogen flow rate, the number of TiN hard phases in the cladding layer increases gradually, which improves the mechanical property of the cladding layer. The Vickers hardness of the cladding layer is much larger than 600 HV and the friction coefficient is 0.419 when the nitrogen rate is 2 L/min.

Effects of nitrogen flow rate on the morphology and composition of AlGaN nanowires grown by plasma-assisted molecular beam epitaxy

Nitrogen flow rate is one of the important growth parameters for the growth of group-III nitride nanowires in plasma-assisted molecular beam epitaxy. However, nitrogen flow rate has received less attention compared to the group-III metal fluxes since its effects are not as prominent as that of the metal fluxes. In this study, we investigated the effects of nitrogen flow rate on the morphology and composition of AlGaN nanowires. Reducing the nitrogen flow rate improved the structural uniformity and increased the Al composition. We present a composition change model and show that excess nitrogen suppresses Ga desorption by recombining the Ga atoms, thereby causing a change in the composition of AlGaN. It was confirmed that the influence of the nitrogen flow rate on the Al composition varied with the growth temperature. These results provide insights into the role of nitrogen flow rate on the growth of AlGaN nanowires and suggest that more sophisticated growth control is possible by considering the nitrogen flow rate.

Effect of nitrogen flow rate on the mechanical properties of CVD-deposited SiCN thin films

Silicon carbonitride (SiCN) thin films were deposited on p-Si (100) substrates with different \(\hbox {N}_{2}\) flow rates using SiC and \(\hbox {Si}_{3}\hbox {N}_{4}\) powder precursors by chemical vapour deposition. To investigate the structural, vibrational and mechanical properties, the SiCN thin films were characterized by atomic force microscopy, Raman spectroscopy, X-ray diffraction (XRD), Fourier transform infrared and nanoindentation techniques. The XRD results reveal nanocrystals embedded with amorphous networks in the SiCN thin films. An increase in the \(I_{\mathrm{D}}/I_{\mathrm{G}}\) ratio with an increase in the \(\hbox {N}_{2}\) flow rate indicated the increase of \(\hbox {sp}^{3}\) bonds in the SiCN thin film. The hardness (H), Young’s modulus (E), plasticity index (H / E) and \((H^{3}/E^{2})\) increase with an increase in the \(\hbox {N}_{2}\) flow rate.

Optimal parameter(s) for the synthesis of nitrogen-vacancy (NV) centres in polycrystalline diamonds at low pressure

Nitrogen-vacancy (NV) centres in diamonds are emerging quantum materials having applications in quantum computing and magnetic field sensing. The ability to synthesize polycrystalline diamond films from chemical vapour deposition technique offers a possibility to grow cheap diamonds with NV centres over large areas. Till date, extensive studies have not been carried out to understand the influence of nitrogen flow rate on the formation of NV centres in polycrystalline diamonds. In this study, we investigate the effect of nitrogen flow rate on the morphology, optical, and electrical properties of polycrystalline diamonds deposited at low pressure. Several samples were prepared in different nitrogen flow regimes using the microwave plasma chemical vapour deposition (MPCVD) technique. The films were characterized using Raman spectroscopy and scanning electron microscopy (SEM). The I–V characteristics of the samples were measured using a point contact method at room temperature. Results obtained showed the formation of both neutral and negatively charged NV centres at an optimum nitrogen flow rate of 10 sccm. An increase in nitrogen flow rate led to a decrease in the electrical resistivity of the films. Furthermore, nitrogen flow rates greater than 20 sccm results to a decrease in the reflectance spectra of samples and a depreciation in the crystalline quality of films. This study is important in benchmarking an optimal parameter space for the growth of nitrogen doped polycrystalline diamonds suitable for sensing applications.

Improving the oxygen barrier properties of PET polymer by radio frequency plasma-polymerized SiOxNy thin film

Plasma-polymerized silicon oxynitride (SiOxNy) oxygen barrier thin film was deposited on polyethylene terephthalate substrate by plasma enhanced chemical vapor deposition at low temperature. The deposition reactor utilizes capacitively coupled plasma operating at radio frequency (13.56 MHz). Nitrogen incorporation during the polymerization leads to a SiOxNy dense film with low defects which assists to improve the oxygen barrier properties. The gas mixture of tetraethyl orthosilicate as organosilicon precursor with oxygen and nitrogen gases was used to deposit the transparent polymerized SiOxNy thin films. The effects of nitrogen flow rate on deposition rate, refractive index, surface morphology, surface wettability, chemical structure and binding composition and oxygen permeability of the barrier films were investigated. Moreover, the plasma parameters were monitored by optical emission spectroscopy. SiOxNy oxygen barrier films showed 89–91% transparency. Under the optimal deposition conditions the minimum oxygen permeability of 0.08cm3/cm2day bar was obtained.

The effect of nitrogen flow rate on Acrawax C decomposition and its removal during sintering of Alumix 431D grade powder

ABSTRACTAlumix 431D pre-alloyed powder (ECKA Granules GmbH) containing 1.5 mass% of Acrawax C was used to study the effect of nitrogen flow rate on delubrication and sintering evolution. Mass loss of compacts during heating was controlled by the TG method using a STA Netzsch apparatus coupled with a mass spectrometer. The latter was used to identify the volatile lubricant’s decomposition products. Macro- and microstructural observations of sintered compacts were also performed. The results documented a strong influence of nitrogen flow rate on delubrication and thus on the sintering behaviour of examined powder. High nitrogen flow rate is required to produce the desired sintered compacts. In contrast, at low nitrogen velocity, the lubricant removal is not complete, which leads to the formation of carbonaceous residuals in the form of soot, which in turn significantly impedes densification and deteriorates the sintered products.