Increase In Activation Energy Research Articles

The effect of functionalized hydroxyapatite on the thermal degradation behaviour and flammability of polyoxymethylene copolymer

In this work, the effect of functionalized hydroxyapatite (HAp-g-PEG) on the thermal degradation behaviour and flammability of polyoxymethylene copolymer (POM_C) was investigated. Organic–inorganic hybrid additive, obtained by grafting of poly(ethylene glycol) on HAp surface using 1,6-hexamethylene diisocyanate as a linker, has been incorporated into POM matrix through an extrusion process. TG analyses show that the incorporation of HAp-g-PEG into POM_C leads to the significant improvement in the thermal stability of the polymer matrix. This is an important finding as POM, being an engineering polymer, suffers from a relatively low thermal stability that limits processing options to develop advanced composite materials. Based on TG results kinetic parameters of the thermal degradation process using Friedman isoconversional method and nonlinear regression method have been calculated; an increase in activation energy of POM degradation process after incorporation of HAp-g-PEG has been found. Thermoanalytical analyses (TG-FTIR/MS) show that incorporation of HAp-g-PEG has no significant effect on the composition of the thermal degradation products. Flammability investigations showed small effect of HAp-g-PEG 600 on the burning time and rate, however, there was a significant reduction in the amount of dripping during the material’s burning process.

Impact of exponential form of internal heat generation on water-based ternary hybrid nanofluid flow by capitalizing non-Fourier heat flux model

The flow of fluids containing nanoparticles is important in industrial applications, particularly in nuclear reactors and nuclear system cooling to enhance energy efficiency. In connection to this, the convective boundary layer flow of ternary hybrid nanofluid (water-based graphene-CNT-Silver) flow over a curved stretching sheet with activation energy is investigated in this article. In addition, the non-Fourier heat flux model is taken into account. The use of similarity variables transforms the existing partial differential equations into an ordinary differential equation, which is then numerically solved using the Runge-Kutta-Fehlberg fourth and fifth order (RKF-45) method combined with a shooting approach. The set of graphical results for the significant parameters on thermal, concentration, and velocity profiles is explored. Results reveal that the heat transport in ternary hybrid nanoliquid rises as the thermophoresis and Brownian motion parameters rise. The Biot number influences the thermal profile positively, whereas the increasing Schmidt number and Stefan blowing parameter values reduce mass transport. The curvature parameter has positive impact on skin friction and mass transport rate but negative impact on heat transport rate. The concentration profile rises with increased activation energy parameter, but declines with increased chemical reaction rate parameter.

Gamma irradiation-induced changes in the structural, optical, electrical and radiation shielding properties of lithium borate glasses

Lithium borate glass with the chemical composition 25Li2O–75B2O3 (LBO) was prepared using the melt quenching technique. The changes in their structural, optical and electrical parameters due to gamma irradiation were investigated and its radiation shielding ability was discussed. The as-prepared glasses were transparent, colourless and inclusion free. The glasses were irradiated for 20, 40, 60, 80 and 100 kGy using a60Co gamma source having a dose rate of 2.906 kGy/h. As the radiation dose increases colour centres were formed in the LBO glass, for higher dosages the glasses turned black. The theoretical structural parameters such as density, optical basicity, ionicity, boron-boron separation, bond density, molar volume and oxygen packing density were calculated. The structural changes were carried out using x-ray diffraction confirming the amorphous nature even after a high dose of gamma irradiation. Gamma irradiation induces the formation of BO4. The bandgap decreases from 3.72 to 3.64 eV with an increase in the dose of gamma irradiation. The dielectric spectroscopy and A.C. conductivity mechanism of the glasses were analyzed. The activation energy of the glasses was calculated before and after gamma irradiation using the Arrhenius plot. High doses of gamma irradiation resulted in an increase in activation energy of LBO glasses which increases from 0.12 eV to 0.42 eV at 100 kHz frequency. The radiation shielding ability of the prepared glass samples was estimated using theoretical simulations by Phy-X/PSD software.

Post‐deposition annealing and interfacial atomic layer deposition buffer layers of Sb2Se3/CdS stacks for reduced interface recombination and increased open‐circuit voltages

AbstractCurrently, Sb2Se3 thin films receive considerable research interest as a solar cell absorber material. When completed into a device stack, the major bottleneck for further device improvement is the open‐circuit voltage, which is the focus of the work presented here. Polycrystalline thin‐film Sb2Se3 absorbers and solar cells are prepared in substrate configuration and the dominant recombination path is studied using photoluminescence spectroscopy and temperature‐dependent current–voltage characteristics. It is found that a post‐deposition annealing after the CdS buffer layer deposition can effectively remove interface recombination since the activation energy of the dominant recombination path becomes equal to the bandgap of the Sb2Se3 absorber. The increased activation energy is accompanied by an increased photoluminescence yield, that is, reduced non‐radiative recombination. Finished Sb2Se3 solar cell devices reach open‐circuit voltages as high as 485 mV. Contrarily, the short‐circuit current density of these devices is limiting the efficiency after the post‐deposition annealing. It is shown that atomic layer‐deposited intermediate buffer layers such as TiO2 or Sb2S3 can pave the way for overcoming this limitation.

Pyrolysis of sewage sludge under conditions relevant to applied smouldering combustion

Pyrolysis of sewage sludge under conditions relevant to applied smouldering combustion was carried out in this study to investigate the influences of gas flow rate, oxidative atmosphere, and inert porous medium involvement on the properties of products. The experiments were carried out at 300–600 °C under atmospheres of N2, 5% O2/95% N2, 10% O2/90% N2, and 15% O2/85% N2, with Darcy flow rates of 1.0 and 3.5 cm/s, respectively, with dried sewage sludge loaded individually or as a mixture with sand. As a result, both the increment of gas flow rate and involvement of sand leaded to lower yields of char and higher yields of bio-oil and gas under N2 at temperature of ≤500 °C, due to the enhanced efficiency of pyrolysis reaction and gas transportation. However, when temperature increased to 600 °C, the influencing trends on product distributions changed due to the mechanisms of secondary cracking reaction and volatile-char interaction. The involvement of oxygen in fraction of ≤15 vol% at temperatures of 400–500 °C would lead to the intense decreasing yields of char and bio-oil, and increasing yield of the gaseous (dominated by CO2 and CO), due to the involved oxidation reaction during pyrolysis. Both increment of temperature and oxygen fraction would lead to the delay of ignition and the increase of activation energy of the produced char, except for that of char produced at 400 °C under 5% O2/95% N2, whose calculated activation energy was lower and volatile content was higher compared to that of char produced from pyrolysis at 400 °C under N2. The bio-oil from pyrolysis under N2 was dominated by aliphatic acids, phenols, steroids, amides, and indoles, etc., and the involvement of partial oxidation would lead to the weakened formation of aromatics, phenols, and S/Cl/F-containing compounds in bio-oil.

Crystallization behaviors and kinetic of argon oxygen decarburization slag via various SiO2 content: Conditions for obtaining amorphous state

The crystallization behaviors and morphology of industrial AOD slag with various SiO2 levels were studied. The time-temperature-transformation (TTT) and continuous-cooling- transformation (CCT) diagrams of argon oxygen decarburization (AOD) slag were obtained using confocal laser scanning microscopy (CLSM). The results show that the main crystalline phases evolved from dicalcium silicate, merwinite, and bredigite to an amorphous state when the dosage of SiO2 increased to 15 wt% in the quenching slag. Crystallization behaviors of AOD slag follow the Johnson-Mehl-Avrami (JMA) crystallization kinetic model. The Avrami exponent and the activation energy increase to 2.382 and 83.68 kJ/mol, respectively in the 15 wt% SiO2 samples. Thus, the crystal size shrinks, and the crystallization capacity of slag decreases. The critical cooling rate reaches the minimum value of 2052.5±34 °C/min in the 15 wt% SiO2 samples. This research showed that AOD slag modified by SiO2 can enhance the potential of preparing supplementary cementitious materials for added-value applications.

Effect of ZrO2 addition on the structure and the crystallization delay in lithium disilicate based glasses

Lithium disilicate (LD) glasses in system (99-X)(1Li2O:2SiO2)-(1K2O)-XZrO2 (X ​= ​0, 1 and 2 ​mol %) have been synthesized by melt quenching technique and converted into glass-ceramics by three and four-stage heat treatment schedules. The sequence of phase formation in glass-ceramics with ZrO2 addition has been discussed. The activation energy of crystallization increases with the addition of ZrO2. Rietveld refinement and micro structural analysis show an increase in the amorphous content with the addition of ZrO2. 29Si MAS-NMR, Raman and XPS spectroscopy studies for the glasses reveal that the ZrO2 addition to LD based glasses causes network polymerization and changes the role of network modifying Li+ and K+ species into charge compensators. The increased connectivity of [ZrO6]2- units in the glass network restricts the mobility of Q2 [Si2O6]4-, Q3 [Si4O10]4- and Q4 [SiO2] units, which leads to an increase in activation energies of crystallization and hampers the devitrification ability of glasses.

Theoretical analysis of the MHD flow of a tangent hyperbolic hybrid nanofluid over a stretching sheet with convective conditions: A nonlinear thermal radiation case

The objective of this research is to examine the two-dimensional flow of a non-Newtonian water-based hybrid nanofluid containing silver and alumina nanoparticles over a stretching surface with convective conditions. The flow is considered to be steady, laminar and incompressible. The mathematical modeling of the flow analysis is considered in the form of partial differential equations which are then transformed into ordinary differential equations by mean of suitable similarity transformations. The present problem is solved with the help of semi-analytical technique called HAM. Convergence of HAM is shown with the help of Figure. The impacts of embedded parameters like magnetic parameter, Joule heating, activation energy and nonlinear thermal radiation on the flow profiles are displayed with the help of Figures and Tables. Our results showed that the greater magnetic parameter reduced the velocity profile, while a reverse impact magnetic parameter is found against temperature profile, skin frication and heat transfer rate of the hybrid nanofluid. Concentration profiles of the hybrid nanofluid flow are augmented with the increasing activation energy while reduced against chemical reaction parameter. Sherwood number has shown increasing behavior due to larger value of Schmidt number and decreasing on larger value of temperature relative parameter.

Understanding the reactivity of magnesium powder subjected to various aging conditions

Metal fuels are emerging as one of the promising alternatives to fossil fuels by providing considerable heat energy without CO2 generation. In particular, magnesium (Mg) is utilized in rocket propellants, fuel cells, and energy storage systems by virtue of its high reactivity, great energy density, and low cost. While its performance degradation when exposed to both short-term and prolonged storage conditions is expected, the clear aging characteristics have not been explained in the past. Two products of hygrothermal aging process of Mg are identified as Mg(OH)2 and MgO, where Mg(OH)2 decomposes at a relatively low temperature for accelerating the oxidation process while MgO tends to desensitize the reactivity of Mg by the surface oxidation of particles. Here, a decreased on-set reaction temperature or enhanced reactivity is observed on relatively short-term aged samples, which is attributed to the formation of Mg(OH)2. For accelerated aging conditions beyond 25 weeks, the oxide film covers the entire particle surface, and thus only the core oxidation could occur, which results in an increase of activation energy. This observation is contrary to the decreased reactivity of metal fuels subjected to aging in general. Moreover, the reactivity based on the stoichiometry is examined by varying the amount of oxygen supplied. The activation energy for long-term aging periods tended to increase under oxygen-rich condition, which can be ascribed to the reaction between Mg(OH)2 and O2. Also, the effects of the generation or the decomposition of various intermediates of the oxidation process can be included. Thus, the present study identified the peculiar enhancement of reactivity of Mg subjected to hygrothermal aging and further clarified the roles of surface and core oxidations as they both affect the reactivity under the oxygen enrichment conditions.

Enhanced scintillation performance of β-Ga2O3 single crystals by Al3+ doping and its physical mechanism

β-Ga2O3 is a potential fast semiconductor scintillator with no significant self-absorption and excellent stability. However, the relatively low light yield of β-Ga2O3 at room temperature limits its practical application. In order to improve its scintillation performance, Al3+ doped β-Ga2O3 single crystals are investigated. By doping 5%Al3+ (atomic concentration), the light yield of β-Ga2O3 is increased from 4394 to 6816 ph/MeV. The increased light yield may be attributed to the decreased free electron concentration and inhibition of Auger nonradiative recombination. The thermal quenching effect can also be moderated by the increase in the thermal activation energy induced by Al3+ doping. The results indicate that Al3+ doping is an effective method to increase the light yield of β-Ga2O3.

Binary Ligand‐Mediated Photochromic Tuning of Lanthanide‐Doped Upconversion Nanoparticle Conjugates

AbstractThe ability to tune photochromic features of nanoparticle (NP)‐ligand conjugates can vastly extend the utility of dynamic materials in the fields of drug delivery, bioimaging, and data storage. Herein, the photochromic tuning of lanthanide‐doped upconversion nanoparticle (UCNP)‐spiropyran (SP) conjugates through a binary ligand strategy is reported. It is found that the content of SP ligand on the surface of UCNPs can be rationally controlled by an SP‐to‐oleate ligand exchange reaction, allowing for regulating the steric congestion in the ligand layer. A highly congested SP layer not only leads to an ultralong lifetime for the purple open‐ring state but also results in improved red fluorescence under UV excitation. The enhancement in steric congestion further enables increased activation energy for the ring‐opening reaction for the bound SP ligand, permitting the generation of high‐resolution self‐erasing patterns in a UCNP‐SP conjugate‐doped polydimethylsiloxane film by local irradiation with either UV or near‐infrared light. The findings provide new insights into the optical tuning of nanoconjugates by controlling the conformational dynamics of their mixed ligand layers.

Implication of operation time on low-temperature catalytic oxidation of chloroaromatic organics over VOx/TiO2 catalysts: Deactivation mechanism analysis

Three commercial granular catalysts were collected according to their operation time (fresh, two years, and three years, denoted as Cata-1, Cata-2, and Cata-3, respectively). The catalytic efficiency and CO2/CO/HCl selectivity of 1,2-dichlorobenzene (1,2-DCB) catalytic oxidation were investigated at low temperature (150–200 °C). The Cata-1 showed excellent catalytic activities with high conversion efficiency (CE, 76.12–85.94%), CO2/CO selectivity (77.56–82.47%), and HCl selectivity (63.74–72.54%). The irreversible deactivation distinctly reduced the catalytic activities of Cata-2 and Cata-3, caused the decrease of catalytic reaction rate (k) and increase of apparent activation energy (Ea) from Cata-1 (1.59–2.18 s−1, 11.01 kJ/mol) to Cata-2 (0.12–0.38 s−1, 34.44 kJ/mol) and Cata-3 (0.007–0.125 s−1, 92.70 kJ/mol), respectively. Based on the abundant characteristic results and their correlation coefficient (R2) with 1/Ea, the S-poisoning was assigned as the major deactivation factor, while the implication factors also included alkali metals, heavy metals, HCl, fly ash, and the deposition substances formed with them. The deactivation pathways contained destroying surface porous structures and Brønsted acid sites, inhibiting the redox cycle of VOx, competing for surface reactive oxygen species, and blocking surface active sites. Based on these, two improvement suggestions were proposed to (1) develop new catalysts by reducing VOx content and introducing a second active component (eg., WOx, MoOx, CeOx, etc.); (2) develop new reactivated technologies. The former can impair the S-poisoning and improve the resistance for other implication factors and the redox ability of catalyst, and the latter was aim to sweep foreign residues, restore, or introduce surface reactive oxygen and available acid sites. The results provided essential basics for further improvement of granular catalyst and benefited the synergistic emission control of chloroaromatic organics and NOx from MSWI.

Research on chemical resistance characteristics of water-immersed coal with different metamorphic degrees

In order to reduce the risk of spontaneous combustion of coal left after long-term flooding in the goaf of the mine, in this paper, the inhibitory properties of different inhibitors on two kinds of water-immersed coals with different metamorphic degrees were studied in depth. The experiment selected Pingzhuang brown coal and Shaqu coking coal as research objects. The raw coal and water-immersed coal samples were compared and analyzed by thermogravimetric experiment method and Fourier transform infrared spectroscopy experiment method. The study showed that the activation temperature of brown coal and coking coal decreased by 7.91 and 2.25 °C respectively, and the activation energy decreased by 43.18 kJ/mol and 20.58 kJ/mol respectively. The natural tendency of coal was enhanced after water immersion, and water immersion had a greater impact on low-metamorphic brown coal. After adding four kinds of inhibitors, MgCl2, TEMPO, TPPI and PA to the two water-immersed coals, it was found that TPPI could significantly reduce the heat release rate of water-immersed brown coal, and the reduction value was 10.49 W/mg. The dry cracking temperature of water-immersed brown coal increased by 11.75 °C, and PA greatly increased the combustion activation energy of water-immersed coking coal by 25.77 kJ/mol. Meanwhile, it was found from the microscopic active groups that TTPI increased the content of water-immersed brown coal ether bonds by 4.84%. The absorption peak intensity of oxygen-containing functional groups such as C=O was significantly weakened. Similarly, PA also produced a large number of stable ethers in water-immersed coking coal, whose content increased by 5.21%, and the hydroxyl content decreased most significantly. The decomposition of TPPI into phosphoric acid after heating can inhibit the growth of active groups such as a large number of oxygen-containing functional groups in the water-immersed brown coal, thereby reducing the risk of spontaneous combustion. As a metal chelator, PA can reduce the catalytic effect of metal ions in water-immersed coking coal with fewer active groups, and inhibit coal spontaneous combustion by generating stable metal complexes to increase activation energy. This indicated that TTPI had the best inhibitory effect on water-immersed brown coal, while PA was more suitable for water-immersed coking coal.

Key Peculiarities of the Pyrolysis Behavior of Different Rank Coals, and Characterization of the Pyrolysis Products

The chemical composition, structural and plastometric properties of typical different-ranked coals from Mongolia deposits were studied. The non-isothermal iso-conversion Ozawa-Flynn-Wall method was used to assess kinetic parameters and to differentiate decomposition steps. Key peculiarities of the pyrolysis kinetics of brown and bituminous coals were revealed and discussed in terms of the composition and plastometric properties of coals. Brown coal was shown to undergo three decomposition steps with ever increasing activation energy as temperature increased because of the decomposition of thermally more and more stable molecular fragments. The pyrolysis of bituminous coals occurred in four steps, the activation energy having an extreme mode of temperature dependence. An important new finding was that the temperature range of the second, major pyrolysis step well corresponded to that between the softening and resolidification temperatures according to Gieseler plastometry, so that the decomposition of bituminous coals at the second step proceeded in a fluid-like medium, moreover, with constant activation energy. The yield and composition of the pyrolysis products obtained under isothermal conditions were also characterized depending on coal rank and temperature, and the ways for qualified utiliza tions were offered.

Effect of aluminum oxide on the structure and conduction behaviors of silver borate glasses

ABSTRACT. The current study focuses on glass preparation and characterization in the glass system of chemical formula xAl2O3 (35-x) Ag2O.65B2O3 (0≤x≤35 mol%), where Ag2O is replaced with Al2O3. To examine a wide range of both structure and morphology of the prepared glasses, nuclear magnetic resonance (NMR) of 27Al nuclei, X-ray diffraction (XRD) spectroscopy, and transmission electron microscopy (TEM) are used. In Al2O3-rich glass, the well-formed AlO6, AlO5, and AlO4 structural groups are the well-formed units. In samples of (20 and 30 mol % Al2O3), tetrahedral AlO4 and traces from AlO6 units could be detected. At lower concentrations of Al2O3 (10 mol%), the dominant forming unit is only AlO4 groups containing non-bridging oxygen bonds (NBO). The XRD spectra confirm the amorphous nature of the glasses of Al2O3 ˂20 mol% while glasses of higher Al2O3 concentrations contain crystalline Ag2Al2B2O7 formed due to the higher oxygen packaging of the mixed AlO5 and AlO4 compared with that of glasses containing only AlO4 species only. The morphology of crystalline units is confirmed from TEM to differ from that of an amorphous composition. The increase of activation energy and the hardness number of the glasses led to an increase in the durability of the investigated glasses.
 
 KEY WORDS: Aluminum borate glass, NMR, Coordination of aluminum atom, Conductivity, Crystallization process
 Bull. Chem. Soc. Ethiop. 2022, 36(3), 597-606. 
 DOI: https://dx.doi.org/10.4314/bcse.v36i3.9

Dynamics of slip phenomenon in micropolar nanofluid flowing over a stretchable disk with Arrhenius activation energy

An incompressible, laminar, and electrically conducting micropolar nanofluid flowing above a stretchable disk is examined. The surface is located in the plane [Formula: see text] and the axi-symmetric flow occupies its space in the region [Formula: see text]. The activation energy is considered in concentration equation of the flow model. The uniform temperature and nanofluid volume fraction are assumed at the surface. The approach of similarity transformations is utilized to normalize the governing flow equations. The resulting system is then solved using Runge-Kutta-Fehlberg (RKF-45) solver to obtain the graphical and numerical results of various dimensionless physical variables. It is scrutinized that the porosity parameter is important in the reduction of radial velocity. The microrotation curves are enhanced magnitude wise due to enhancement in the vortex viscosity parameter. It is also perceived that the concentration field is enhanced against the increasing activation energy parameter. Temperature is augmented by increasing the thermophoresis and Brownian movement parameters while the heat transport rate is reduced by the larger thermophoresis and Brownian movement parameters. Concentration field is reduced by the larger Brownian movement parameter while enhanced against the higher thermophoresis parameter.

RETRACTED ARTICLE: Solar energy optimization in solar-HVAC using Sutterby hybrid nanofluid with Smoluchowski temperature conditions: a solar thermal application

In solar heating, ventilation, and air conditioning (HVAC), communications are designed to create new 3D mathematical models that address the flow of rotating Sutterby hybrid nanofluids exposed to slippery and expandable seats. The heat transmission investigation included effects such as copper and graphene oxide nanoparticles, as well as thermal radiative fluxing. The activation energy effect was used to investigate mass transfer with fluid concentration. The boundary constraints utilized were Maxwell speed and Smoluchowksi temperature slippage. With the utilization of fitting changes, partial differential equations (PDEs) for impetus, energy, and concentricity can be decreased to ordinary differential equations (ODEs). To address dimensionless ODEs, MATLAB’s Keller box numerical technique was employed. Graphene oxide Copper/engine oil (GO-Cu/EO) is taken into consideration to address the performance analysis of the current study. Physical attributes, for example, surface drag coefficient, heat move, and mass exchange are mathematically processed and shown as tables and figures when numerous diverse factors are varied. The temperature field is enhanced by an increase in the volume fraction of copper and graphene oxide nanoparticles, while the mass fraction field is enhanced by an increase in activation energy.

Improved thermal stability and direct hexagonal transition accompanied by metal-insulator transition in Arsenic substituted Ge2Sb2Te5

Amorphous chalcogenides, particularly Ge2Sb2Te5 (GST) based alloys, are well known for their non-volatile phase-change random access memory applications (PCRAM). In this work, the phase change properties of Ge2Sb2−xAsxTe5 (x = 0, 0.5, 1.0, 2.0) thin films deposited by thermal evaporation are reported. The As substituted samples crystallize at higher temperatures compared to parent GST. During the phase change for x > 1.0, a direct transition from amorphous to the stable hexagonal structure has been observed. A distinct two-step transition in Sb rich samples and a single step transition for As rich samples are observed in R-T measurements with a high contrast in electrical resistivity. The transition is becoming sharper and sharper with increasing As substitution. A composition-dependent Metal-Insulator Transition (MIT) is also observed in these samples. Compared to GST, As substituted samples show an increase in crystallization temperature and activation energy for crystallization. For GST, the 10-year data retention temperature is 67 °C, and with complete As substitution, it increases to 169 °C, with a significant rise of 102 °C in the data retention temperature. High thermal stability, sharp transition and increased data retention of As substituted Ge-Sb-Te suggest that they are promising candidates for PCRAM applications.

Effect of hot compression on the microstructure evolution of aluminium bronze alloy

This work aims to study the flow behaviour, phase transformation, and microstructure evolution of aluminium bronze (Cu–9Al–4Fe) alloy. The hot compression behaviour of aluminium bronze were studied using simulator isothermal hot compression tests investigated at strain rates of 0.01–10 s−1 and temperature of 500–800 °C. According to the construction of constitutive equation and three-dimensional hot processing maps, the activation energy was 275.64 kJ/mol. The precipitated fine κⅣ particles during hot compression inhibit grain growth; the coarse κⅡ particles promote dynamic recrystallization through the mechanism of particle-stimulated nucleation (PSN). The formation of deformation twins under the influence of the fine κⅣ particles and high-density annealing twins are formed by stacking fault energy (SFE). Phase transformation by hot compression of the material at 500–800 °C, where the structure consists of the α phase and (α + γ2) eutectoid structure to α + β phase, is important for the increase in the power dissipation factor. Adiabatic shear leads to wedge-shaped cracks at 500 °C and 600 °C, 10 s−1, which pass through the (α + γ2) eutectoid structure and α phase interface with coarse-phase particles. The discontinuous dynamic recrystallization (DDRX) mechanism is the dominant DRX mechanism for aluminium bronze, in which DDRX, characterized by grain boundary bulging, was activated. The strengthening mechanism of aluminium bronze includes dispersion strengthening, twin strengthening, and grain refining strengthening during hot deformation, which leads to the increased activation energy of aluminium bronze alloy.

The effect of SiN x film for H plasma implantation in p-GaN/AlGaN/GaN high electron mobility transistors

A thin SiN x film was deposited on the p-GaN layer before H plasma implantation, which cause four orders of magnitude reduction in gate reverse leakage current. The OFF-state breakdown voltage increases by 89%. It displays a more stable dynamic performance. It is believed that the decrease of gate leakage current is attributed to the increase of trap activation energies in the p-GaN layer, It is concluded that improved dynamic characteristics are owing to the fact that the SiN x film blocks the excessive H plasma into the AlGaN barrier layer and reduces the implantation damage in AlGaN barrier layer.