Increase In Nitrogen Flow Rate Research Articles

Synthesis and characterisation of self-lubricating tungsten nitride thin films as protective machine tool coatings

ABSTRACT WN thin films were synthesised on silicon (100) substrate by varying the nitrogen flow rate (NFR) at a substrate temperature of 300°C for the initial 15 min using RF magnetron sputtering. With the increase in NFR from 1.58, 5.29 and 10 sccm (standard cubic centimetres per minute), the FCC β-W2N phase was converted to mixed phases of FCC β-W2N and hexagonal δ-WN, and further to amorphous phases. Likewise, XPS results indicated the presence of W-N phases. In addition, structural and morphological studies confirmed the presence of dense films at 1.58 sccm of NFR with a thickness of 430 nm and a surface roughness of 0.99 ± 0.16 nm. Moreover, the film with β-W2N phase (at 1.58 sccm of N2 flow) exhibited high hardness and elastic modulus values of 28.36 ± 2.57 GPa and 149.72 ± 8.04 GPa, and better scratch resistance with average coefficient of friction (COF) value of 0.303, making it best suitable for hard coating applications.

Microstructural and Electrical Resistivity of TiN Electrode Films Prepared by Direct Current (DC) Reactive Magnetron Sputtering

In this study, the crystal structure as well as electron transport of TiN thin films were evaluated. We used DC reactive magnetron sputtering to deposit a thin layer of polycrystalline titanium nitride (TiN) on a Si (100) substrate starting from elemental Ti in a nitrogen atmosphere. The influence of nitrogen flow rate on the crystal structure, surface morphology, and electron transport of TiN were investigated systematically. It was found that the preferred orientation and conductivity of TiN thin films exhibit strong nitrogen flow rate dependence. The preferred orientation changed from (111) to (200) initially and then changed back to (111) as the nitrogen flow rate increases. However, an increase in the (200) phase leads to higher conductivity and lower surface roughness. At the optimized deposition conditions, ultra-thin (around 30 nm) TiN thin films with a low resistivity of 101.8 μC·cm and a surface roughness of less than or equal to 0.51 nm were obtained. These superior performances, along with low running costs, suggest that TiN thin films have great potential for use as electrodes in microelectronic devices.

The Influence of Nitrogen Flow Rate on the Structure and Properties of Mo-Hf-Y-Si-B-N Coatings

This work is devoted to the production of Mo-Hf-Y-Si-B-N coatings using magnetron sputtering with varying N2 flow rate; the analysis of magnetron discharge plasma; and the investigation of the structure, and optical, mechanical, and tribological characteristics, as well as crack resistance and oxidation resistance, of the coatings. The results show that Mo-Hf-Y-Si-B-N coatings were characterized by a dense, homogeneous structure. The non-reactive coatings had a maximum growth rate of 270 nm/min. An increase in the flow rate of N2 from 0 to 37.5 sccm led to a decrease in the growth rate by 5.4 times. Mo-Hf-Y-Si-B-N coatings were X-ray amorphous. In non-reactive coatings, the presence of Mo-Si and Mo-B bonds was revealed. The introduction of nitrogen contributed to the formation of an additional Si-N bond, an increase in the proportion of which led to an increase in transmittance. The Mo-Hf-Y-Si-B coating was characterized by a hardness value of 14 GPa. The maximum hardness of 16 GPa was observed in coatings obtained at nitrogen flow rates of 12.5 and 25.0 sccm. A further increase in the consumption of N2 to 37.5 sccm led to a decrease in hardness by 38%. The coating obtained at a flow rate of 25 sccm N2 was characterized by maximum elastic recovery of 57%, elastic strain to failure of 0.098, and resistance to plastic deformation of 0.157 GPa. An increase in nitrogen flow rate from 0 to 12.5 sccm contributed to a decrease in the wear rate of coatings under sliding friction conditions by 40%. The non-reactive Mo-Hf-Y-Si-B coating had the best oxidation resistance at 1000 °C.

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.

Influence of magnetron sputtering process parameters on low-temperature electrical transport characteristics of zirconium oxynitride thin films

In order to determine the influence of process parameters including nitrogen and oxygen flow rate on the structure and electrical transport characteristics of zirconium oxynitride(ZrOxNy) thin films, the ZrOxNy films were prepared on sapphire substrates by RF reactive magnetron sputtering deposition technology. The crystal orientation and morphology of ZrOxNy films prepared at different nitrogen and oxygen flow rate were characterized by XRD and SEM, respectively. The electric transport behavior of ZrOxNy films at 300K to 3K was measured by PPMS. The results show that the insulativity of ZrN films is enhanced with the increase of nitrogen flow rate in sputtering atmosphere. With the increase of oxygen flow rate in sputtering atmosphere, the insulativity of ZrOxNy film is enhanced.

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.

Corrosion and friction resistance of TiVCrZrWNx high entropy ceramics coatings prepared by magnetron sputtering

High entropy alloy coatings have attracted much attention because of their high hardness, low-level fault energy, and chemical stability. Nevertheless, this type of coating would inevitably suffer from wear, corrosion, aging, and so on. Hence, a novel coating with corrosion and friction resistance would be constructed for broadening its application scenarios. In this work, TiVCrZrWNx high entropy ceramics coatings were prepared by reactive magnetron sputtering. The microstructure, mechanical properties, friction, and corrosion resistance of the coatings deposited at different nitrogen flow rates have been studied. The microstructure of TiVCrZrWNx coatings is strongly dependent on the nitrogen flow rate and forms a stable FCC structure when the nitrogen flow rate reaches 24 sccm. The pure TiVCrZrW coating is 15.65 GPa, with the increase of nitrogen flow rate (24 sccm), the coating hardness reaches 21.27 GPa. The corrosion resistance of the coatings also increases continuously. According to the results of the impedance spectrum and polarization curve, the charge transfer resistance value of the coating gradually increases with the content of nitrogen, the current density rapidly decreases to a minimum as the potential increases. In terms of tribological behavior, the formation of V2O5 during the sliding in seawater could significantly reduce the coefficient of friction from 0.603 to 0.383. Therefore, TiVCrZrWNx HECs coatings simultaneously possess high hardness, toughness, and excellent resistance to friction and corrosion, which is expected to provide a new and reliable method for the research field of coatings in the maritime field.

Investigation of (CrAlTiNbV)Nx high-entropy nitride coatings via tailoring nitrogen flow rate for anti-wear applications in aviation lubricant

(CrAlTiNbV)Nx high-entropy nitride coatings are deposited via tuning nitrogen flow rates, and evaluating their influence on the microstructure, mechanical and tribological properties of the coatings. All deposited coatings exhibit columnar growth morphology and own a single face-center-cubic structure. As the nitrogen flow rate increases, the preferred orientation of the coating gradually transfers from (111) to (200) and (220), and then changes back to (111) with the nitrogen flow rate continues to increase. The S-38 sample possesses the optimal plastic deformation resistance and adhesion strength. Friction and wear results show that the (CrAlTiNbV)Nx coating deposited at nitrogen flow rate of 38 sccm owns the best tribological properties with a friction coefficient of 0.096 and wear rate of 1.8 × 10−7 mm3/(N·m) in 4050# aviation oil.

Effect of nitrogen flow rate on the properties of nitrogen-doped Cu<sub>2</sub>O

Cuprous oxide (Cu₂O) has the potential applications in photovoltaic and photocatalytic fields. Nitrogen-doping in Cu₂O can improve the conductivity by increasing hole concentration. However, the chemical states of nitrogen in nitrogen-doped Cu₂O have not been studied thoroughly.A series of nitrogen-doped Cu₂O samples are prepared by increasing nitrogen flow rates and simultaneously keeping the sputtering pressure and other parameters unchanged. The samples are characterized by X-ray diffraction (XRD), step instrument, scanning electron microscope (SEM), energy dispersive spectrometer, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), spectrophotometer and Hall effect et al. The results of Hall effect measurement show that nitrogen-doping can increase the hole concentration by one order of magnitude. The band gap width decreases with the increase of nitrogen flow rate. The nitrogen in Cu₂O is in three forms: β-N (nitrogen atom), α-N₂(molecular nitrogen, —N=N—)and γ-N₂(molecular nitrogen, N≡N). With the increase of nitrogen gas flow rate, the peak of binding energy of β-N increases while that of α-N₂ decreases. The sample prepared at the nitrogen flow rate of 2.0 sccm has the minimum resistivity among all samples.

Effect of N2 shielding gas flow rate on microstructure and weld surface corrosion resistance of high nitrogen steel by laser-arc hybrid welding

In order to investigate the microstructure of welded joint and corrosion resistance of the weld surface of high nitrogen steel, a laser-arc hybrid welding process was used for welding high nitrogen steel in this paper. The Ar + CO2 mixed gas was used as the shielding gas above the weldment, N2 was used as the shielding gas under the weldment. The microstructure of welded joint and corrosion resistance of the weld surface of high nitrogen steel were studied by changing the flow rate of N2. The results showed that all of the welded joints have an excellent macroscopic appearance, weld nitrogen content increases with increasing N2 flow, the microstructure of welded joints are austenite and a small amount of delta-ferrite, the higher the nitrogen flow, the tinier the dendrite of ferrite is. Compared with the weld arc zone, the dendrite of ferrite of the weld laser zone is finer. As the nitrogen flow rate increases, the pitting potential of L1–L4 increase, and the corrosion resistance become better. Nitrogen pores appear in the weld of the L5 group, and a large number of pitting pits appears around the nitrogen pores, which significantly reduce the corrosion resistance. The corrosion resistance of the weld arc zone is not affected by nitrogen flow, the dendrites of ferrite in the weld arc zone are peeled from the crystal structure. Compared with the surface of the weld laser zone, the corrosion resistance of the weld arc zone is worse.

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.

Temperature effect on the mechanical characteristics of niobium nitride thin films

The mechanical, physical, chemical and tribological properties of niobium nitride thin films are making them suitable for a wide range of applications such as protective coatings, microelectronics and so on. The paper has two main goals: (a) the deposition of niobium nitride thin films by direct current magnetron sputtering on silicon Si (100) substrates and (b) the highlighting of temperature influence on their mechanical properties. The films were deposited at different nitrogen flow rates ranged between 0 and 2.2 cm3 min−1. The deposition time and temperature, argon flow rate, discharge current, pressure and the distance between the substrate and the target were kept constant. The so-obtained coatings were further investigated by atomic force microscopy analyses to determine their topographical and mechanical properties namely the hardness and the modulus of elasticity. The tests were performed at temperatures between 20 °C and 100 °C while the relative humidity was kept constant. The results pointed out that both the modulus of elasticity and the nanohardness of the films decreased with the increase in testing temperature. The increase in nitrogen flow rate up to 1.65 cm3min−1 went hand in hand with the increase in both mechanical properties.

Variation of structure and band gap for N doped Cu2O films deposited with ceramic target

With ceramic target, N doped Cu2O films were deposited by Radio-Frequency magnetron sputtering. The structural, optical and electrical properties were studied. Along with the increase of nitrogen flow rate, the preferred orientation of Cu2O films varied from (111) plane to (200) plane. In addition, may be due to the inhibition of oxygen vacancy by using Cu2O target, an obvious optical band gap narrowing was observed. Hall results indicated that the resistivity decreased sharply with the increase of carrier concentration. And the lowest value 2.1 Ωcm was obtained when the nitrogen flow rate was increased to 20 sccm. However, due to the defects which induced by N doping, the hall mobility is decreased slightly. X-ray photoelectron spectra results further demonstrated the formation of Cu2O films without other phases.

Morphology Evolution Of ZnO Thin Films Deposited By Nitrogen Mediated Crystallization Method

We study the surface morphology of ZnO thin films deposited by nitrogen mediated crystallization method utilizing atomic force microscopy as a function of nitrogen flow rates. Initially, the surface morphology of ZnO thin film deposited without nitrogen exhibits a bumpy surface with spiky grains where the skewness and kurtosis values were found to be 0.48 and 4.80, respectively. By addition of small amount of nitrogen, the skewness and kurtosis values of the films significantly decrease associated with a flatter topography. Further increase in nitrogen flow rate to 16 sccm has roughened the surface shown mainly by the increase in kurtosis value to be 3.30. These results indicate that the addition of small amount of nitrogen during deposition process has enhanced the adatoms migration on the surface resulting in a superior film with a larger grain size. Two-dimensional power spectral density analysis reveals that all the films have self-affine fractal geometry with total fractal values in the range of 2.14 to above 3.00.

Comparative investigation of Si-C-N Films prepared by plasma enhanced chemical vapour deposition and magnetron sputtering

This paper reports on the results of comparative investigations of Si-C-N films prepared by using both plasma enhanced chemical vapor deposition (PECVD) and DC magnetron sputtering (MS) at different nitrogen flow rates (FN2). The films were characterized by an atomic force microscope, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, nanoindentation and photoluminescence spectroscopy. All the deposited films were X-ray amorphous. For the PECVD films, nanohardness (H) and elastic module (E) increase with FN2, which can be assigned to decreasing the hydrogen content. On the contrary, for the films, deposited by magnetron sputtering, the values of H and E decrease, when FN2 increases. The latter is supposed to be due to decreasing a number of strong Si-C bonds and to increasing a number of weak SiN and CN bonds. The surface roughness of two types of the films is smaller compared to that of silicon substrates. An increase in nitrogen flow rate causes the smoothing of the film surfaces. The PECVD films deposited at high FN2 exhibit bright photoemission with the main peak at ∼440nm. The intensity of this peak increases with increasing nitrogen content.

Properties of large-sized porous Si3N4 ceramic tubes fabricated by carbothermal reduction of diatomite preforms

Abstract Si 3 N 4 ceramics with high porosity, complex shape and large dimension could be fabricated by carbothermal reduction of diatomite preforms. Take the fabrication of large tubular porous Si 3 N 4 ceramics as an example, the flow type and flow rate of nitrogen during sintering has little effect on the overall performance of the tubes, while impacts greatly on the composition, porosity and flexural strength at different locations of the tubes. When the nitrogen flow rate is in the range of 0.2–1.0 L/min, the tubes have a porosity of 73.7–79.6% and a flexural strength of 10.5–13.2 MPa when fabricated by conventional sintering, while possess a porosity of 73.2–81.3% and a flexural strength of 8.6–14.7 MPa when fabricated by directional sintering. As the nitrogen flow rate increases, the composition, porosity and flexural strength at different locations of the tubes fabricated by conventional sintering tend to be uniform, while the gradient of composition, porosity and flexural strength of the tubes fabricated by directional sintering becomes more obvious.

Influences of nitrogen flow rate on the structures and properties of Ti and N co-doped diamond-like carbon films deposited by arc ion plating

In this paper, Ti–C–N nanocomposite films are deposited under different nitrogen flow rates by pulsed bias arc ion plating using Ti and graphite targets in the Ar/N2 mixture gas. The surface morphologies, compositions, microstructures, and mechanical properties of the Ti–C–N films are investigated systematically by field emission scanning electron microscopy (FE-SEM), x-ray photoelectron spectroscopy (XPS), grazing incident x-ray diffraction (GIXRD), Raman spectra, and nano-indentation. The results show that the nanocrystalline Ti(C,N) phase precipitates in the film from GIXRD and XPS analysis, and Raman spectra prove the presence of diamond-like carbon, indicating the formation of nanocomposite film with microstructures comprising nanocrystalline Ti(C,N) phase embedded into a diamond-like matrix. The nitrogen flow rate has a significant effect on the composition, structure, and properties of the film. The nano-hardness and elastic modulus first increase and then decrease as nitrogen flow rate increases, reaching a maximum of 34.3 GPa and 383.2 GPa, at a nitrogen flow rate of 90 sccm, respectively.

Effect of nitrogen flow rate on the properties of TiN film deposited by e beam evaporation technique

In this work, titanium nitride (TiN) films have been deposited by e beam evaporation technique on Si/SiO2 (100) substrates at room temperature. The influence of nitrogen flow rate (N2=0, 4, 6, 8 and 10sccm (standard cubic centimeter per minute)) on the structural, morphological and electrical properties of the TiN films has been studied. The deposited TiN films have been characterized using X-ray diffraction (XRD), XPS (X-ray photoelectron spectroscopy), FESEM (Field emission scanning electron microscopy) and four-point probe resistivity measurement techniques. XRD patterns reveal FCC symmetry of the film with (111) preferred orientations for Ti film (N2=0sccm) and (200) preferred orientations for TiN film (N2=4, 6, 8 and 10sccm), respectively. The lattice parameters for TiN films are found to increase from 4.237Å to 4.239Å with the increase in nitrogen flow rate. The presence of different phases such as TiN, TiON and TiO2 were confirmed by XPS analysis. The FESEM images of the TiN films showed a smooth morphology with columnar grain structures. The grain size of the TiN films was found to increase as the nitrogen flow rate was increased from 4 to 10sccm. The electrical resistivity measurement showed that the resistivity of the film decreased from 333μΩcm to 111μΩcm on increasing nitrogen flow rate from 4 to10sccm.

Microstructure, mechanical and tribological properties of TiCN nanocomposite films deposited by DC magnetron sputtering

TiCN nanocomposite films are prepared by direct current magnetron sputtering from Ti C combined target under different nitrogen flow rates. The composition, morphology and microstructure of the nanocomposite films are characterized by X-ray photoelectron spectroscopy, Raman spectroscopy, scanning electron microscopy, X-ray diffraction and transmission electron microscopy. Hardness and tribological properties are tested by nanoindentation measurement and ball-on-disk tribometer, respectively. With the increase of nitrogen flow ranging from 0 to 30 sccm at a work pressure of 0.3 Pa, both crystallinity and sp 2 carbon content in the TiCN films increase. In addition, the ratio of TiN to Ti(C, N) increases as the nitrogen flow rate increases. The friction coefficient and wear rate could be greatly reduced due to the increase of sp 2 carbon and better toughness in the composite films. TiCN nanocomposite film with high hardness and good wear resistance is obtained under a nitrogen flow rate of 30 sccm.

Model of reactive sputtering process in deposition of TiAlN coating

A model of the reactive sputtering process in deposition of TiAlN coating based on the influence of negatively substrate bias (-Vb) on coating composition and deposition rate at various nitrogen flow rate has been developed. TiAlN coatings were deposited by using DC magnetron sputtering. The coating composition and deposition rate were obtained by using SEM/EDX analysis. The results showed that the increase of -Vb decreased the critical nitrogen flow rate (fN2c). The increase of coating composition at nitrogen flow rate lower than fN2c with an increase in -Vb was due to increase of ion flux to the substrate while the decrease of deposition rate was due to coating densification. However, the verification data of coating composition was lower than that of model prediction due to the heterogeneous reaction between sputtered metallic particles and reactive gas at the substrate surface. The experimental results showed that the nitrogen content of unbiased substrate was consistently lower than that of biased substrate and increased with an increase in nitrogen flow rate while the deposition rate was decreased.