Nitrogen Gas Flow Rate Research Articles

Preparation and characterization of nanostructured TiCrN thin films deposited from Ti-Cr mosaic target by reactive DC magnetron sputtering

In this research work, nanostructured thin films of TiCrN have been deposited on Si by reactive DC magnetron sputtering from a mosaic Ti-Cr target. The effects of nitrogen gas flow rates on the structure of the as-deposited TiCrN thin films were examined. The crystal structure, microstructure, surface morphology, thickness, and composition were characterized by GI-XRD, FE-SEM and EDS technique, respectively. The results revealed that the thin films were formed as a (Ti, Cr)N solid solution. The as-deposited thin films showed a nanocrystalline structure of TiCrN with the crystal sizes less than 45 nm. The lattice constants were in the range of 4.144 to 4.181 Å. The thickness of the TiCrN films decreased from 379 to 276 nm with increasing of the nitrogen gas flow rates. The nitrogen content of the as-deposited films was increased with increasing of the nitrogen gas flow rates, while the titanium and chromium content in the films were decreased. Finally, the TiCrN thin films showed compact columnar and dense morphology as a result of various the nitrogen gas flow rate.

The effect of torrefaction on the thermo‐kinetics of thermally processed black pine

AbstractThis paper investigates the kinetic behaviour of thermal decomposition of pre‐treated pine needles. The model‐free methods of Flynn‐Wall‐Ozawa (FWO), Kissinger‐Akahira‐Sunose (KAS), and Kissinger, are used to determine the kinetic parameters of the processed pine needles. For a comparative analysis, the kinetic characteristic of the pre‐treated pine needles is equated to the thermal decomposition of the raw pine needles. For torrefaction of the raw substrate, some changes related to the design have been made to the furnace. The raw material has been thermally pre‐treated at a temperature of 523 K for 5 minutes. The volumetric rate of nitrogen during the torrefaction process is 42 L · min−1, while the purge flow rate of nitrogen gas is 0.2 L · min−1 for the thermogravimetric analysis. The temperature range for the thermal degradation of the torrefied pine needles is 308 K‐873 K. The activation energies determined by the FWO and the KAS methods are 157.08 kJ · mol−1 and 160.54 kJ · mol−1, respectively, whereas it is 137 kJ · mol−1 by the Kissinger method. The activation energy computed by the FWO and the KAS schemes for the raw material is found to be 1.3% less than that of the processed pine needles. The aromaticity of the thermally processed pine needles is increased by 13.61%. Thermal immunity or stability due to the increasing fraction of lignin causes the activation energy and frequency factor of the pre‐treated pine needles to slightly elevate. The redistribution of the pyrolysis stages has been observed for the torrefied pine needle sample, the temperature scale at a constant heating rate increases slightly by 0.34% during the char formation.

Thermal degradation characteristics, kinetics, thermodynamic, and reaction mechanism analysis of pistachio shell pyrolysis for its bioenergy potential

The research work aims to estimate the bioenergy potential of pistachio shell and study its degradation kinetics which is necessary for the efficient design and optimization of thermochemical processes for bioenergy generation. Initial characterizations (proximate, ultimate, higher heating value, and compositional analysis), kinetic study, and thermodynamic analysis accompanied by reaction mechanism are investigated. Physicochemical characterization results confirmed high volatile matter (~ 79.8 wt%) and high heating value (16.85 MJ/kg) of pistachio shell. Thermogravimetric analysis (TGA) is performed at four different heating rates of 10, 20, 30, and 40 °C/min under nitrogen gas flow rate from ambient temperature to 900 °C. TGA results show the three-stage pyrolysis reaction which involves removal of moisture and light volatiles, degradation of cellulose and hemicellulose, and decomposition of lignin. The result also reveals that maximum degradation occurred in the temperature range of 200–400 °C. For calculating the kinetic (activation energy and pre-exponential factor) and thermodynamic parameters (enthalpy, entropy, and Gibbs free energy), different iso-conversional models, i.e. Flynn-wall-Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), Starink, and Friedman, are employed which gives the average value of activation energy as 168.86, 165.80, 166.29, and 190.10 kJ/mol, respectively and the pre-exponential factor values lie in the range of 107-1021 s−1. The average values of Gibbs free energy calculated for FWO, KAS, Starink, and Friedman methods are 182.09, 182.15, 182.13, and 181.42 kJ/mol, respectively. Criado method and Z plot are showing complex reaction mechanism. The results of kinetics and thermodynamic study reveal pistachio shell is an efficient biomass for bioenergy production.

Comparative study of oxidizing ambient infused with varying nitrogen flow rates for fabrication of ternary nitrided AlZrO based MOS capacitor

High dielectric constant nitrided aluminum zirconium oxide films were successfully fabricated on silicon substrate via an oxidation process infused with different nitrogen gas flow rates at 800°C. The presence of nitrogen piling up at the interface could control the thickness of interfacial layer formation. An increase in the nitrogen gas flow rate might be effective in controlling the overall thickness of the films, yet the nitrogen piling up at the interface impeded the diffusion of oxygen to the interface. Consequently, the interface quality was affected, leading to degradation in the interface-state density. In addition, the generation of oxygen vacancies in the films, as well as the presence of nitrogen at the interstitial sites, would create a lattice polarization, which decreased the k values. Corresponding effects were also discussed in corroboration with energy band gap, effective oxide charges, and slow trap density, as well as interface-state density calculated from capacitance and conductance methods.

Modulation of the cutoff wavelength in the spectra for solar selective absorbing coating based on high-entropy films

This paper demonstrates an intrinsic modulation of the cutoff wavelength in the spectra for solar selective absorbing coating based on high-entropy films. The (NiCuCrFeSi)N ((NCCFS)N) films were deposited by a magnetron sputtering system. Rutherford backscattering spectroscopy analysis confirms the uniform composition and good homogeneity of these high-entropy films. The real and imaginary parts of the permittivity for the (NCCFS)N material are calculated on the basis of the reflectance spectral fitting results. A redshift cutoff wavelength of the reflectance spectrum with increasing nitrogen gas flow rate exists because of the different levels of dispersion when changing nitrogen content. To realize significant solar absorption, the film surface was reconstituted to match its impedance with air by designing a pyramid nanostructure metasurface. Compared with the absorptance of the as-deposited films, the designed metasurface obtains a significant improvement in solar absorption with the absorptance increasing from 0.74 to 0.99. The metasurfaces also show low mid-infrared emissions with thermal emittance that can be as low as 0.06. These results demonstrate a new idea in the design of solar selective absorbing surface with controllable absorptance and low infrared emission for high-efficiency photo-thermal conversion.

Thermal pyrolysis of empty fruit bunch (EFB) in a vertical fixed-bed reactor

In the production of crude palm oil, huge quantities of solid biomass waste is generated such as empty fruit bunch (EFB), palm fronds and palm–pressed fibre (PPF). This inevitably resulted in the environmental pollution due to its natural conversion to methane. In this study, thermal pyrolysis of EFB was conducted using a fixed bed reactor. The factors such as nitrogen gas flowrate and holding time that affect the distribution of pyrolysis product yields were being investigated by evaluating the percentage product yields. It was determined that at nitrogen gas flowrate of 300 cm3/min and 30 mins holding time, the maximum bio-oil yield of 46.20 % was attained with gas and char yield of 21.79 % and 32.01 % respectively. The existence of functional groups in bio-oil was analyzed by Fourier Transfrom Infra-Red (FTIR) spectroscopy. It was identified that the bio-oil has several functional groups such as hydroxyl (OH), ketone/aldehyde (C=O) and ester (O-C=O) groups. The dynamic viscoscity of bio-oil was analyzed by Brookfield viscometer. It showed that the viscosity of bio-oil decreased with increasing temperature from 25-50 °C.

An acidic-groups detection method and its application to analysis of Chinese humic acid samples.

The method of non-aqueous conductivity titration (NACT) of organic weak acids was applied to quickly and accurately determine the phenolic-hydroxyl and carboxyl-groups contents in humic acid. By varying the pH of the humic-acid sample, the concentration of the titrant, and the nitrogen-gas flow rate, the optimal titration conditions were determined to be a sample pH of 4, titrant concentration of 0.05 mol/L, and nitrogen-gas flow rate of 80 mL/min. Applying the detection method to p-hydroxybenzoic acid showed that its phenolic-hydroxyl content was 758.82±111.76 cmol/kg and carboxyl content was 744.44±51.11 cmol/kg. The theoretical phenolic-hydroxyl and carboxyl-groups contents of the p-hydroxybenzoic acid were 723.96 cmol/kg respectively, indicating that the method can accurately quantify the carboxyl and phenolic-hydroxyl groups in the sample. The NACT was used to measure the phenolic-hydroxyl and carboxyl-groups contents in humic acid quickly and accurately. In addition, 29 humic acid samples from 8 provinces of China covering the main humic-acid producing areas were collected and analyzed for acidic-groups content using the reported method.

Effects of substrate temperature and reactive gas flow rate on the crystalline ceramic phases formation and tribological properties of W–Ti–Co–C–N thin films produced by co-sputtering

The present study investigates the deposition condition of W–Ti–Co–C–N thin films made by magnetron co-sputtering. The central composite design of experiments was applied for analyzing the effect of substrate temperature (X1) and nitrogen gas flow rate (X2) on the mechanical properties. Nanoindentation, sliding wear test (ball-on-disk method), scanning electron microscopy, atomic force microscopy, and X-ray diffraction techniques were employed to evaluate the tribological properties and microstructure of the thin films. The optimum values of variables were found to be in the range of 500 °C < X1 and 6.5 < X2 < 9 sccm, giving a high hardness of 36.5 GPa, while the friction coefficient and wear rate have the lowest amount of 0.10 and 4 × 10−8 mm3/N.m, respectively.

Effect of preparation method and B-side metal type on the physicochemical properties of LaBO3 perovskite catalyst and its catalytic behaviour in the biomass pyrolysis

Although perovskites are extensively investigated in many areas, studies using perovskites as catalysts for biomass pyrolysis are still quite limited. While various transition metals can be inserted into perovskites to form different perovskites, it is critical to investigate the effects of various transition metallic substituents on the characterization of catalysts. This work involves the evaluation of nine perovskite-type catalysts in terms of their effectiveness and suitability for pyrolysis of date stone biomass. LaCoO3, LaMnO3 and LaNiO3 perovskite catalysts were prepared by sol-gel, hydrothermal and microwave methods and characterized by X-ray powder diffraction, scanning electron microscopy and surface area measurement. Pyrolysis of date stones has been performed in tubular reactor at 520 °C with 100 °C/min and a nitrogen gas flow rate of 100 cm3/min. The influences of catalyst preparation method on catalytic cracking of pyrolysis vapours in terms of bio-oil yields were examined. Additionally, the effect of B metal in ABO3 perovskite structure on catalyst character and pyrolysis yields were examined in detail. According to results, highest bio-oil yield was achieved as 23.4% with LaMnO3 catalyst synthesized with sol-gel method. All perovskite-type catalysts have reduced the bio-oil yield and improved the water and gaseous yield as expected. This study paves the way for developing more challenging perovskite catalysts for the renewable energy sources.

Investigation on the Threading Dislocations Formed by Lattice Misfits during Initial Stage of Sublimation Growth of 4H-SiC

We investigated the relation between the nucleation of dislocations and the lattice misfits by nitrogen concentration difference between seed and grown crystal during the initial stage of growth. 4H-SiC single crystals were grown with various nitrogen gas flow rates introduced into the crystal growing chamber under the same temperature and pressure to minimize the effect of thermal stress on the nucleation of dislocations. The nitrogen atomic concentrations of grown crystals depended on the introduced nitrogen gas ratios and they highly increased at the very early stage of growth. The generation of new threading dislocations at the interface also was affected by the nitrogen atomic concentrations differences between seed and grown crystals. Very few generated threading dislocations were observed in low nitrogen atomic concentration samples, however nucleation of threading dislocations at the interface were found in high nitrogen atomic concentrations samples. At initial stages of PVT growth process, the generation of threading dislocations induced by lattice misfits originated from nitrogen concentration difference between seed and grown crystals were investigated and found the appropriate nitrogen gas flow rates and profile at the heating and depressurized stage.

Catalytic Pyrolysis of Palm Empty Fruit Bunch over Activated Natural Dolomite Catalyst: Product Distribution and Product Analysis

In this study, an activated natural dolomite catalyst is used as catalyst for the palm empty fruit bunches (PEFB) pyrolysis to produce bio-oil. The research was conducted in fixed bed reactors operating in batches by varying several parameters, which are temperature (400-600°C) and nitrogen gas flow rate (100-300 mL.min-1). The results show that the catalytic pyrolysis process using an activated natural dolomite catalyst obtains a maximum liquid yield of 35.87% when using a 500°C catalytic pyrolysis temperature and the rate of nitrogen gas is 100 cm3/minute, while the yield of gas and solids is 53.12% and 11.76%, respectively. The use of the dolomite activation catalyst influences the product distribution of pyrolysis and the bio-oil chemical compounds.

Microstructure and Mechanical Properties of ZrCuSiN Coatings Deposited by a Single Alloy Target

Recently, research has been conducted on nanocomposite thin films containing new additive elements in ZrN. In this paper, a method for depositing ZrCuSiN nanocomposite coatings using a ZrCuSi single target is presented. The ZrCuSi target that was used to easily deposit a ZrCuSiN coating in a mixed gas atmosphere (Ar + N2) was produced by a simple arc melting method (casting process). The effect of the nitrogen content was investigated by depositing a ZrCuSiN coating using alloy targets at various nitrogen gas flow rates (2, 4, 6, and 8 sccm). X-ray diffraction analysis of the ZrCuSiN coatings revealed a ZrN structure with a preferable orientation (200). As the nitrogen flow rate increased, the formation of o-Zr3N4 was dominant in the ZrN formation. A nitrogen gas flow rate of 4 sccm produced a coating with optimal ZrN and a-Si3N4 coordination and maximum hardness (41 GPa). Reciprocal friction tests of all coatings and uncoated carburized SCM415 steel in a 5W30 lubrication atmosphere demonstrated that the 4 sccm coating had the lowest friction coefficient (0.002). Therefore, our method has the potential to be an alternative surface coating technique for materials used in automotive engine parts and various other wear protection applications.

Optimization and characterization of bio-oil from fast pyrolysis of Pearl Millet and Sida cordifolia L. by using response surface methodology

The objective of this study was to optimize experimental parameters to obtain the maximum bio-oil yield (BOY) from fast pyrolysis of Pearl Millet (PM) and Sida cordifolia L. (Sida) by using response surface methodology (RSM) based on the central composite design (CCD). Important fast pyrolysis process parameters such as particle size (PS), reaction temperature (T), and nitrogen gas flowrate (NGF) were optimized. The most influential factor of each experimental design response was identified and an empirical model was derived in terms of factors through ANOVA. The second-order polynomial equation for the BOY was developed to correlate the parameters. The cubic and quadratic models fit the data of PM and Sida the best, respectively. The maximum BOY of 48.27 and 48.00% for PM and Sida respectively were obtained at the optimum parameters of PS of 1.5 mm, T of 400 °C, and NGF of 200 mL min−1 for both biomasses. GC–MS analysis of the optimized bio-oil samples from PM and Sida indicated the presence of many important chemical compounds such as acids, alcohols, aldehydes, aromatics, ketones, phenols, and others. Therefore, PM and Sida can be used as feedstocks for fuels and chemicals production through fast pyrolysis.

Thermal Cracking of Karanja de-oiled seed cake on Pyrolysis Reactor for producing Bio-oil with focus on its application in diesel Engine

A thermal cracking experiment was conducted on Karanja seed (de-oiled) cake at to determine its potential to be an automotive fuel. Experiment was conducted on a fluidised bed type Pyrolysis reactor. The production parameter such as particle size of de-oiled seed and temperature on the oil yield were studied. Fluidization was achieved with the help of Nitrogen gas that is why Nitrogen gas flow rate was also considered as production parameter. For the study purpose a particular particle size range were used. Similarly the Temperature and Flow rate of Nitrogen range were selected from the initial run data of experiment. After investigating the test data the optimized parameter were found for 65.56 wt % of bio oil. The temperature was 500°C and the particle size was in the range of 0.50-0.99 mm at sweep gas flow rate about 8 LPM for the optimized condition. The pyrolysis oil obtained after condensation can be used as fuel. And by some up-gradation technique like trans-esterification process, bio oil can be made suitable for the today’s engine technology. Non condensable gases were consisting of Hydrogen, Methane, Carbon Dioxide, Carbon Monoxide, Oxygen and Nitrogen as major fractions.

Influence of Nitrogen Content on Persistent Photoconductivity in Zinc Oxynitride Thin Film Transistors

In this work, the influence of anion composition on the photoresponse characteristics of zinc oxynitride thin film transistors is investigated and compared directly to conventional In-Ga-Zn-O TFTs. Increasing the ratio of N to (N+O) led to higher field effect mobility and improved subthreshold swing. The subgap density of states extracted by monochromatic photonic capacitance-voltage measurement indicated that the nitrogen-related defect states, such as nitrogen vacancies, increased with increasing nitrogen gas flow rate. Furthermore, the photoconductivity mechanism of ZnON TFTs is discussed in detail.

Effect of Material and Process Variables on Characteristics of Nitridation-Induced Self-Formed Aluminum Matrix Composites-Part 2: Effect of Nitrogen Flow Rates and Processing Temperatures.

The nitridation-induced self-formed aluminum matrix composite (NISFAC) process is based on the nitridation reaction, which can be significantly influenced by the characteristics of the starting materials (e.g., the chemical composition of the aluminum powder and the type, size, and volume fraction of the ceramic reinforcement) and the processing variables (e.g., process temperature and time, and flow rate of nitrogen gas). Since these variables do not independently affect the nitridation behavior, a systematic study is necessary to examine the combined effect of these variables upon nitridation. In this second part of our two-part report, we examine the effect of nitrogen flow rates and processing temperatures upon the degree of nitridation which, in turn, determines the amount of exothermic reaction and the amount of molten Al in the nitridation-induced self-formed aluminum matrix composite (NISFAC) process. When either the nitrogen flow rate or the set temperature was too low, high-quality composites were not obtained because the level of nitridation was insufficient to fill the powder voids with molten Al. Hence, since the filling of the voids in the powder bed by molten Al is essential to the NISFAC process, the conditions should be optimized by manipulating the nitrogen flow rate and processing temperature.

Study on the Microstructure and Friction Characteristics of ZrN Coatings Containing Cu and Si

To improve the mechanical properties of coatings used in cutting tools and automotive parts, ZrCuSiN coatings were deposited in an argon-nitrogen gas mixture using magnetron sputtering at various nitrogen gas flow rates. The structural properties of the fabricated ZrCuSiN coatings were investigated using the friction coefficient, wear coefficient, coating hardness, and elastic modulus via nano indentation and ball-on-disk friction testing. The surface morphology of the coatings was analyzed using scanning electron microscopy (SEM). The structural characterization results show a typical face-centered cubic ZrN structure with peaks in the (111) and (200) directions. The highest hardness was obtained for coatings deposited at a nitrogen gas flow rate of 5 sccm, and the coefficient of friction was lowest at a nitrogen gas flow rate of 3 sccm. It was found that the high hardness of the coating causes wearing of the counterpart. In contrast, a 3 sccm coating with stable hardness and coefficient of friction was found to be the most optimal.

Properties of titanium oxynitride films deposited on glass substrate by reactive high-power pulsed magnetron sputtering

Titanium oxynitride (TiON) films were prepared without additional heating by reactive high-power pulsed magnetron sputtering at a total pressure of 0.7 Pa, changing the gas flow rates of nitrogen and oxygen. The composition and the chemical bonding in the films prepared on the glasses were obtained by X-ray photoelectron spectroscopy. The titanium content gradually decreased from about 50% corresponding to TiN to about 30% corresponding to TiO2 with the increase in oxygen flow rate (FO2), whereas the oxygen content drastically increased with the slight increase in FO2. In X-ray diffraction results, the variation from the pattern of (200) texture to amorphous structure with increasing FO2 was observed. The film hardness gradually decreased from 22 to about 9 GPa with the increase in FO2, whereas the transmittance for the light with wavelengths longer than 400 nm and the electrical resistivity markedly increased with FO2.

Preparation and characterization of nanostructured titanium oxynitride films for the application in self-cleaning and photoelectrochemical water splitting

Titanium oxynitride (TiOxNy) films capped with 10 nm titanium oxide (TiO2) layer were prepared using reactive direct current magnetron sputtering from pure Ti target. Part of the samples was annealed. Energy dispersive analysis of X-ray revealed that all the samples contain nitrogen and the incorporation of nitrogen into the oxynitrides is not linear. Phase investigation by X-ray diffraction showed structural variation with changing oxygen and nitrogen gas flow rates as well as annealing. Anatase, brookite, rutile and titanium nitride were detected individually or mixed in the as-prepared and annealed samples. The optical properties were found to be controlled by a structure and chemical composition. Transmittance and reflectance measurements were carried out by a high performance double beam ultraviolet-visible-near infrared spectrophotometer. Based on that, the energy band gap, refractive index and extinction coefficient were derived. The obvious difference between the dark and light currents indicated the validity of the TiO2/TiOxNy bilayer samples to act as photoanodes. All the annealed samples have photoelectrochemical water splitting response better than the as-prepared samples. The as-prepared TiO2/TiOxNy bilayer films were hydrophobic (contact angels, 81° - 93°) and their contact angles were independent from the nitrogen content. The annealed samples have lower contact angles than the as-prepared samples. The wettability of the as-prepared and annealed samples was changed from hydrophobic to more hydrophilic with increasing illumination time. These results are of important interest for the self-cleaning surfaces.

Fast pyrolysis of oil palm empty fruit bunch in an auger reactor: bio-oil composition and characteristics

Fast pyrolysis of oil palm empty fruit bunch (EFB) has been conducted in an auger reactor to produce bio-oil. The reactor was a continuous feeding auger reactor heated by gas-fired external heater. The experiments were conducted under different operating temperatures ranging from 400 °C to 650 °C, different nitrogen flow rates ranging from 1 to 4 L/min, and various feeding rates ranging from 2 to 8 kg/h. The maximum yield of bio-oil from EFB was 58.67 % obtained at temperature of 500 °C with feeding rate of 8 kg/h under 1 L/min of nitrogen gas flow rate. The average moisture content of bio-oil was varied between 30 and 40 % and the bio-oil produced at 500 °C provided the maximum HHV of 27.38 MJ/kg, respectively. The Fourier-transform infrared spectroscopy (FT-IR) and gas chromatography-mass spectrometry (GC-MS) spectra shows bio-oil contains high phenolic compounds. This paper explains the fast pyrolysis of empty fruit bunch using auger reactor to enhance the bio-oil yield and characteristics.