Nitride Layer Research Articles

CORROSION RESISTANCE OF BRAKE DISCS AFTER NITRIDING

The article presents the work carried out to create a surface layer, ultimately on cast iron brake discs, by theZeroFlow method using regulated gas nitriding. The presented research is aimed at creating a nitrided layerwith corrosive wear resistance maintained at the stage of brake disc manufacture, waiting for sale of a newvehicle, and even during further exploitation. Examples of nitriding parameters enabling such treatment ofbrake discs made of flake cast iron are presented. The research also includes measurements of the roughnessof the working areas of brake discs before and after nitriding. The properties of the nitrided layers producedare assessed following microscopic observations and microhardness measurements using the Vickers method.The impact of nitrided layers on corrosive wear is also analyzed by observing the behavior of the surfaces ofthe tested discs in a corrosive environment in the so-called “corrosion experiment.”

Conversion of 30 W laser light at 1064 nm to 20 W at 2128 nm and comparison of relative power noise

Abstract All current gravitational wave (GW) observatories operate with Nd:YAG lasers with a wavelength of 1064 nm. The sensitivity of future GW observatories could benefit significantly from changing the laser wavelength to approximately 2 μm combined with exchanging the current room temperature test mass mirrors with cryogenically cooled crystalline silicon test masses with mirror coatings from amorphous silicon and amorphous silicon nitride layers. Laser light of the order of ten watts with a low relative power noise would be required. Here we use a laboratory-built degenerate optical parametric oscillator (OPO) to convert the light from a high-power Nd:YAG laser to 2128 nm. With an input power of 30 W, we achieve an output power of 20 W, which corresponds to an external conversion efficiency of approximately 67%. We find that the relative power noise spectrum marginally increases during the wavelength conversion process. Our result is an important step in the development of low-noise light around 2 μm based on existing low-noise Nd:YAG lasers.

Al-N3 Bridge Site Enabling Interlayer Charge Transfer Boosts the Direct Photosynthesis of Hydrogen Peroxide from Water and Air.

Manipulating the electronic environment of the reactive center to lower the energy barrier of the rate-determining water oxidation step for boosting the direct generation of H2O2 from water, air, and sunlight is fascinating yet remains a grand challenge. Driven by a first-principles screening across a series of metal single atoms in carbon nitride, we report a class of an Al-N3 bridge site enabling interlayer charge transfer in carbon nitride nanotubes (CNNT-Al) for the highly efficient photosynthesis of H2O2 directly from water, oxygen, and sunlight. We demonstrate that the interlayered Al-N3 bridge site in CNNT-Al is able to activate the neighboring surface N atom for promoting the rate-determining step of the two-electron water oxidation to H2O2. It is also able to act as a bridge for enhancing the vertical interlaminar charge transfer due to the hybridization between the 3s and 3p states of the interstitial Al atom and the conduction band of two adjacent carbon nitride layers. Collectively, these factors lead to a highest photocatalytic mass activity of 1410.2 μmol g-1 h-1 (with a photocatalyst concentration of 1 g L-1) for direct photosynthesis of H2O2 out of all CN-based photocatalysts and a 7-fold higher solar-to-chemical conversion efficiency (0.73%) compared to that of the natural photosynthesis of typical plants (∼0.1%). Most importantly, the CNNT-Al-based flow reactor can steadily produce H2O2 for 200 h and be directly used for the on-site degradation of organic dye in water. The CNNT-Al-based flow reactor can also kill a 10 times higher concentration of bacteria in deionized water than that in natural water with 100% efficiency, which makes our design economically appealing for practical water treatment.

ModulatioAn of Hybrid Plasmon Phonon Polaritons Mode in Circular Cylindrical Three-Layer Graphene Waveguide

In this present research article, we have investigated analytically the characteristics of the fundamental mode of hybrid surface plasmon phonon polariton (HSPPhPs) mode in a circular cylindrical three-layer graphene (CTLG) waveguide structure. The dispersion equation of HSPPhPs is derived by using Maxwell’s equations and continuity conditions of tangential components of electric and magnetic fields in cylindrical geometry. The dispersion curve has been illustrated and thoroughly examined in relation to the effects of temperature and chemical potential (μc) of graphene, as well as variations in the thickness of silicon dioxide (SiO2) and hexagonal boron nitride (hBN) layers, and found that in the presence of hBN, the effective mode index exhibits hyperbolic behavior with wave number. Up to the first Reststrahlen band (∼830.57cm⁻¹), it varies slightly with graphene temperature; increasing graphene's (μc) lowers the index, while a thicker hBN layer reduces it, whereas the index increases with SiO₂ layer thickness. Also, we looked at how the CTLG waveguide structure is affected by the electric field distribution, phase speed, and propagation length.

Advances in Room Temperature of Indium Aluminum Nitride InAlN Deposition via Direct Current (DC) Co-Sputtering for Solar Energy Applications

This study presents an innovative method for the synthesis of indium aluminum nitride (InAlN) layers by direct current (DC) co-sputtering at room temperature, with the aim of reducing production costs of optoelectronic devices. Indium and aluminum targets are used, varying the power applied to the aluminum target. The results show that increasing the target power favors the formation of aluminum nitride (AlN), which modifies the chemical composition of the material. The layers obtained present smooth surfaces with a roughness of less than 3 nm, which is beneficial for applications requiring interfaces with low defect density. Regarding the optical properties, it is observed that the optical bandgap varies between 1.8 eV and 2.0 eV, increasing with the target power. Hall effect measurements indicate a decrease in the free carrier concentration and an increase in the resistivity with increasing power. This approach allows for the synthesis of InAlN with properties suitable for optoelectronic applications, solar cells, photocatalysis, and photoelectrocatalysis at low cost.

Analysis of interlayer dependency of MoS2/g-C3N4 heterostructure as an anode material for sodium-ion batteries

In this present work, we explore the effectiveness of layered molybdenum disulfide (2H-MoS2) and graphitic carbon nitride (g-C3N4) heterostructure as anode for Sodium-Ion Batteries (SIBs) by using first principles analysis. To study the anode properties, we varied the interlayer distance between 2H-MoS2/g-C3N4 as 3Å, 6Å, 9Å,12 Å, and 14 Å between MoS2 as substrate and g-C3N4 as top layer. The fundamental properties, such as structural stability and electronic structure were analysed for the respective systems. The adsorption kinetics of Na ion on the g-C3N4 layer were analysed by performing molecular dynamics (MD) simulations to understand the adsorption mechanism better. Our results showed that the interlayer distance of 6 Å with formation energy of −4.31 eV, the theoretical specific capacity value of 765.32 mAhg−1, the average electrode potential is between 0.8 and 1.3 V and the adsorption energy of −2.16 eV is suitable for MoS2/g-C3N4 based anodes for Na ion batteries.

Aluminum-Modified Plasma Nitriding with High Efficiency and Enhanced Performance

Aluminum-modified plasma nitriding was developed in this research by the addition of a few FeAl particles around samples of 42CrMo middle carbon alloy steel during plasma nitriding. The goal of this study was to enhance nitriding efficiency and the combined performance of the steel. The research results show that nitriding efficiency was greatly enhanced, by about 6 times, with the effective hardening layer rising from 224 μm to 1246 μm compared with traditional plasma nitriding at 520 °C/4 h. More importantly, the compound layer increased just a little bit, from 11.64 μm to 14.32 μm, which remarkably reduced the ratio of the compound layer’s thickness to the effective hardening layer’s thickness, thus being quite beneficial to decreasing the brittleness level, making the brittleness level decrease from Level 4 to Level 1. Also, extremely high surface hardness and excellent wear resistance were obtained by aluminum-modified plasma nitriding due to the formation of hard phases of AlN and FeAl in the nitrided layer, with the surface hardness rising from 755 HV0.025 to 1251 HV0.025 and the wear rate reducing from 8.15 × 10−5 g·N−1·m−1 to 4.07 × 10−5 g·N−1·m−1. In other words, compared with traditional plasma nitriding, wear resistance was enhanced by two times after aluminum-modified plasma nitriding. Therefore, this study can provide comprehensive insights into the surface characteristics and combined performance of aluminum-modified plasma nitriding layers.

Nanostructures/TiN layer/Al2O3 layer/TiN substrate configuration-based high-performance refractory metasurface solar absorber

Metasurface solar absorber serves as a kind of important component for green energy devices to convert solar electromagnetic waves into thermal energy. In this work, we design a new solar light absorber configuration that incorporates the titanium nitride substrate, aluminum oxide layer, titanium nitride layer, and the topmost refractory nanostructures. The metasurface absorber based on this configuration can achieve an average spectral absorption of over 91% and a total solar radiation absorption of 91.5% at ultra-wide wavelengths of 300–2500 nm. It is discovered that the excellent performance of the proposed metasurface absorber is attributed to the synergistic effects of surface plasmonic effect and Fabry–Pérot (FP) cavity resonance by comprehensive analysis of the simulated field distributions. Furthermore, the effect of geometrical parameter of the proposed configuration on absorber performance is studied, indicating the proposed configuration possesses a large fabrication tolerance. Moreover, the proposed configuration is not sensitive to the polarization direction and the angle of incident light. It is also found that the use of other refractory metal materials and other shapes as the topmost absorbent nanostructures also have good results with this configuration. This work can offer a universal platform for constructing and guiding the design of refractory metasurface solar absorbers.

Surface modification of high-speed steel (HSS) drills by plasma nitriding and cathodic cage tin deposition

Cutting tools made of high-speed steel have significant economic and technological importance. To enhance their productivity, thermochemical treatments are sought to improve both surface mechanical and tribological properties. Plasma nitriding and thin film deposition are widely employed for this purpose. In this study, modifications were made to M2 high-speed steel drills through plasma nitriding at temperatures of 400°C and 450°C. Cathodic cage TiN plasma deposition was also performed, varying the dwell time at a fixed temperature of 450°C. Characterization techniques included optical microscopy, X-ray diffraction (XRD), Vickers microhardness testing, and scanning electron microscopy (SEM). Performance tests were carried out to evaluate the behavior of the drills in relation to wear when machining AISI 1020 steel. It was observed that longer deposition times promote more uniform and thicker layers, and higher nitriding temperatures result in thicker nitride layers. An increase in hardness was noticeable in all deposition and nitriding treatments, with the nitrided samples exhibiting the highest hardness. During performance tests, the cathodic cage plasma TiN deposition demonstrated greater potential for application in HSS drills, with a treatment lasting 4 h providing the best results.

Charge transfer between layers of polymeric carbon nitride driven by surface grafting phosphotungstic polyanions toward efficient photocatalytic hydrogen evolution

It is a challenging issue to achieve efficient charge transfer between layers for the layered polymer photocatalysts, because the photogenerated carriers would prefer random migration within layers and thus have high reverse recombination rate due to their inherent anisotropy and high exciton binding energy. Herein, an innovative surface grafting strategy is developed to modify the layered polymeric carbon nitride (PCN) making use of phosphotungstic (PWO) polyanions. The surface coupling effect of PWO on PCN effectively improves reduction ability and utility rate of luminous energy through shifting the conduction band (CB) upward and broadening light absorption range to cover near infrared region up to 1000 nm, respectively. In especial, the strong electron-withdrawing effect of surface PWO moieties can reduce layer spacing to shorten electron transfer path and attract the photogenerated electrons transfer from PCN matrix to surface, thus conquering the charge transfer restriction between layers to improve the carrier separation efficiency. As a result, the photocatalytic hydrogen evolution (PHE) performance is dramatically enhanced. The optimal PWO-PCN-1% sample achieves an average PHE rate of 9.6 times that of PCN, stable operation for a total of 28 h on 7 cycles, and an AQY up to 22.3% at 400 nm. This contribution affords a viable modification avenue to overcome the limitation of charge transfer between layers for layered polymer photocatalysts.

Enhanced Energy Storage Properties of Four-Layer Composite Films via Strategic Macrointerface Modulation.

Dielectric capacitors play a crucial role in the field of energy storage; however, the low discharged energy density (Ue) of existing commercial dielectrics limits their future applications. Currently, further improvement in the Ue of dielectrics is constrained by the challenge of simultaneously achieving high permittivity (εr) and high breakdown electric field strength (Eb). To address this issue, we designed a series of four-layer poly(vinylidene fluoride) (PVDF)-based composite films comprising three functional layers: a sodium bismuth titanate (NBT) plus PVDF composite (NBT&PVDF) layer to achieve high εr values and a pure PVDF layer and a boron nitride (BN) plus PVDF composite (BN&PVDF) layer to achieve high Eb values. This design synergistically enhanced the εr and Eb values of the composite films by exploiting low-loss macrointerface polarization via adjustment of the functional layer stacking order, as supported by simulation analyses. Ultimately, the composite film with a topmost layer of pure PVDF, followed by an NBT&PVDF layer, another pure PVDF layer, and a BN&PVDF layer achieved an enhanced Ue value of 26.42 J·cm-3 and excellent efficiency of 80.03% at an ultrahigh Eb value of 770 MV·m-1. This approach offers an innovative pathway for developing advanced energy storage composite dielectrics via macrointerface manipulation.

Machinability Performance of Single Coated and Multicoated Carbide Tools During Turning Ti6Al4V Alloy

AbstractThis paper presents the machinability performance of uncoated, single-coated, and multicoated carbide tools during turning of Grade 5 (Ti6Al4V) Titanium alloy, which is challenging to machine due to its distinctive material properties. Coated tools with single-coated Titanium Aluminium Nitride (TiAlN) and multi-coated layer of Titanium Aluminium Nitride with Aluminium Chromium Nitride (TiAlN + AlCrN) coated inserts were utilized to assess surface roughness (Ra), tool wear rate (R), and chip morphologies under various cutting conditions using dry machining. Analysis of the used tools revealed that coated tools exhibited improved tool life and surface quality compared to uncoated tools across all cutting conditions. Multi-coated tools of TiAlN + AlCrN demonstrated a tool life increase of up to 15% compared to uncoated and single-coated tools, with surface roughness improvements ranging from 30 to 45% depending on cutting speed. Chip morphology analysis indicated an increase in the chip reduction coefficient with higher cutting speeds for all tool types. Coated tools exhibited the lowest chip-reduction coefficient due to the presence of TiAlN and AlCrN coatings, which control the tool chip contact length. Conversely, uncoated chip morphology resulted in larger chip thickness values compared to coated tools, particularly at cutting speeds above 100 m/min, attributed to poor heat dissipation and chemical reactions at the tool chip interface. Energy dispersive X-ray scanning electron microscopy (SEM/EDXS) analysis of worn uncoated inserts revealed a higher tendency towards Titanium adhesion compared to coated tools. The proposed multi-layer coatings of (TiAlN + AlCrN) used for dry machining proved highly beneficial for achieving economic machining objectives and may reduce the need for lubrication when processing Ti6Al4V alloys.

Transient Current Analysis of GaN Neutron Detector Based on the SRIM and TCAD Methods

Utilizing Technology Computer Aided Design (TCAD) software, this study determines the optimal thickness and doping concentration for the intrinsic gallium nitride (GaN) layer in a p-i-n GaN diode to improve detection efficiency and reliability. The study examines energy loss and the transient current response induced by alpha and 3H particles within the GaN p-i-n diode. Additionally, TCAD elucidates the transient current behavior arising from electron-hole pair generation, utilizing the Stopping and Range of Ions in Matter SRIM-2013 linear energy transfer distribution as a guide. The simulations disclose that the tailing effect in the transient current response results from radiation-induced hole accumulation. Elevated applied bias results in increased transient current pulse amplitude, attributed to an extended depletion region that boosts carrier collection. These insights are expected to drive advancements in GaN-based neutron detector technology, essential for advancing nuclear and space science applications in the next generation.

An (AlN/GaN)N D (AlN/GaN)N Photonic Crystal-based Gas Sensor

Over the past few years, more studies have been conducted on the use of photonic crystals (PCs) in the detection field. Particularly fascinating for use as gas sensors are these materials’ outstanding spectrum sensitivity and small design. Using one-dimensional PCs as the theoretical foundation, this work aims to develop and analyze a nanoscale system that can identify the concentration of gases in ambient air and differentiate it from contaminated air. The intended structure is composed of layers of gallium nitride (GaN) and aluminum nitride (AlN) that alternate. In between these layers is a defective layer cavity that is filled with polluted air, which has a refractive index that is quite similar to pure air. The transfer matrix method (TMM) was used to perform numerical results for the proposed sensor. This sensor achieves average sensitivity of 1791 nm/RIU, average quality factor and figure of merit (FoM) of 1833 and 2287, respectively. We therefore think that the suggested detector’s design offers a strong candidate for accurate and efficient detection.

Adhesion-Related Phenomena of Stellite 6 HVOF Sprayed Coating Deposited on Laser-Textured Substrates.

The focus of this research is to examine the feasibility of using laser texturing as a method for surface preparation prior to thermal spraying. The experimental part includes the thermal spraying of a Stellite 6 coating by High Velocity Oxygen Fuel (HVOF) technology on laser-textured substrates. The thermal spraying of this coating was deposited both on conventional substrate material (low carbon steel) and on substrates that had been previously heat treated (nitrided steel). The properties of the coatings were analysed using scanning electron microscopy (SEM), optical microscopy (OM) and Raman spectroscopy. Adhesion was assessed through a tensile adhesion test. The results showed the usability of laser texturing in the case of carbon steel, which was comparable or even better than traditional grit blasting. For nitrided steel, the problem remains with the hardness and brittleness of the nitrided layer, which allows for the propagation of brittle cracks near the interface and thus reduces the adhesion strength.

Epitaxial growth of GaN on β-Ga2O3 via RF plasma nitridation

The lack of suitable p-type dopant for β-Ga2O3 remains a hurdle for vertical power device applications. Epitaxy of GaN on Ga2O3 substrates was demonstrated as an alternative. (–201)-oriented β-Ga2O3 was converted into (0001)-oriented hexagonal GaN via nitrogen plasma in a plasma-assisted molecular beam epitaxy chamber, as verified by XRD and RHEED. The resulting nitridated GaN layers were characterized by TEM, x-ray reflectivity, and AFM to relate the nitridation conditions to crystallinity, layer thickness, and surface roughness. The crystallinity of subsequently grown epitaxial GaN films was quantified via XRD rocking curves and related to the nitridation layer properties across varying nitridation conditions. Specifically, the effect of the grain size and nitridation layer thickness was investigated to determine their role in threading screw dislocation management.

Electrolytic Plasma Nitriding of Medium-Carbon Steel 45 for Performance Enhancement

This article analyzes the effect of electrolytic plasma nitriding on the performance of medium-carbon steel 45 under increased mechanical loads and in aggressive environments. Nitrided samples in carbamide electrolytes, both with and without the addition of ammonium nitrate, were compared to the initial material. SEM with EDX and XRD analysis was used to examine the microstructure and phase composition of nitrided samples. Wear resistance was studied using the ‘ball-on-disk’ method and Vickers microhardness testing, while corrosion resistance was studied using potentiodynamic polarization curves. The study results show that the sample without ammonium nitrate demonstrated better mechanical and corrosion properties due to a more homogeneous and denser nitride layer, approximately 10 µm thick, containing phases FeN and Fe4N. Its wear resistance doubled compared to that of the initial sample. The sample treated in an electrolyte with the addition of ammonium nitrate demonstrated a higher current density (2.8672 × 10−5 A/cm2) and a lower corrosion potential (−0.565 V) compared to the initial sample (i_corr = 1.8971 × 10⁻5 A/cm2, E_corr = −0.480 V) and the sample without ammonium nitrate (i_corr = 1.7315 × 10−5 A/cm2, E_corr = −0.376 V). This is due to the formation of an uneven nitride layer and the presence of microcracks on the surface.

Promising metal-free green heterogeneous catalyst for quinoline synthesis using Brønsted acid functionalized g-C3N4

Rationally designing distinct acidic and basic sites can greatly enhance performance and deepen our understanding of reaction mechanisms. In our current investigation, we studied the utilization of Brønsted acid sites within layered graphitic carbon nitride (g-C3N4) for the first time to enhance the rate of the Friedländer synthesis. The structural and surface analyses confirm the effective integration of -COOH and -SO3H groups into the g-C3N4 lattice. The surface-functionalized g-C3N4-CO-(CH2)3-SO3H exhibits a remarkable acceleration in quinoline formation, surpassing previously mentioned catalysts, and demonstrating notable recyclability under optimized mild reaction conditions. The heightened reaction rate observed over g-C3N4-CO-(CH2)3-SO3H is attributed to its elevated surface acidity. By probing the Friedländer reaction mechanism through surface characterization, examination of reaction intermediates, and investigation of substrate scope, we elucidate the pivotal role of Brønsted acid sites. This study constitutes a comprehensive exploration of metal-free heterogeneous catalysts for the Friedländer reaction, offering a unique contribution to the field.

Bulk acoustic wave—Solidly mounted resonator with a-SiOCN:H as low-Z material

Bulk acoustic wave (BAW) filters have been proven to be of high demand in today's low power RF front-ends for mobile communication devices. Within the launch of 5G applications worldwide, especially in the region of new radio (nr-1) up to 6 GHz, defined frequency bands require filters of wide bandwidths, while simultaneously featuring steep edges and high out-of-band rejection. Due to the coexistence with 4G LTE (long term evolution) wireless standards as well as advanced data transfer concepts such as carrier aggregation, the increasing complexity of antenna systems forces the implementation of highly selective acoustic filters. In contrast to the widely used surface acoustic wave (SAW) technology, BAW filters appear with superior performance for frequencies above 1 GHz. This work describes the fabrication of a BAW-solidly mounted resonator (BAW-SMR) with a tailored material system of a-SiOCN:H as a low impedance (low-Z) material integrated within its acoustic Bragg mirror. A direct comparison to the widely used low-Z material of SiO2 with an acoustic impedance of around 13 MRayl is demonstrated by two equal resonator stacks by replacing only the uppermost low-Z thin film of the acoustic reflector. A single-mask design was chosen with platinum as a bottom electrode to ensure the most equal growth conditions for the piezoelectric aluminum nitride (AlN) layers on both reflectors’ surfaces featuring either the tailored a-SiOCN:H or standard SiO2. The a-SiOCN:H thin films were deposited by plasma-enhanced chemical vapor deposition and the according acoustic impedance was priorly depicted to 7.1 MRayl, which could be exploited to achieve an increase in the effective coupling coefficient beyond 7% as well as a resonator bandwidth of more than 60 MHz.

One-Pot Coating of Ceramic Powders by Exfoliated Boron Nitride Layers with a Dense CO2 Medium and Ultrasound-Aided Mixing

One-Pot Coating of Ceramic Powders by Exfoliated Boron Nitride Layers with a Dense CO₂ Medium and Ultrasound-Aided Mixing