Variation Of Phase Composition Research Articles

Enabling Invar to Ti6Al4V transitions through copper in functionally graded laser powder bed fused components

This study examines the microstructural evolution, elemental distribution, phase composition, and hardness variations in multi-material samples fabricated using Laser Powder Bed Fusion (LPBF) with Invar and Ti6Al4V with compositional gradients mediated by copper. A range of compositional transitions from Invar to Ti6Al4V with different copper fractions are reported. Defects such as gas and keyhole pores were detected in well-deep keyhole mode areas, while lack of fusion defects were observed in samples with pure Cu interlayers due to poor wettability and processing parameter variations. Crack formation between interlayer gradient zones and Invar regions was linked to FeNi and CuNi intermetallic phases. Intermetallic compounds (e.g., FeNi, CuNi, TiFe, TiNi) significantly influenced the microstructure and mechanical performance. Vickers hardness testing shows varying hardness across different builds, with the highest hardness being observed in the gradient zone enabled by pure copper (approximately 620 HV). This study also underscores the need for tailored component design linking build processing parameters and compositional transitions in multi-material LPBF to achieve desired properties and component structural behaviour.

Investigations on porous silicon nitride ceramics prepared by the gel-casting method

Abstract Due to their special structure and many excellent properties, porous Si3N4 ceramics have a wide range of potential applications as a new structural and functional integrated material. In the present study, porous Si3N4 ceramics with excellent bending properties and satisfactory porosity were prepared by the gel-casting method. The variations in porosity, bending strength, fracture morphology and phase composition of the porous Si3N4 ceramics with different weight fractions of La2O3–MgO sintering additive were investigated. The results showed that the density of porous Si3N4 ceramics increased linearly with the increase of sintering additive content. When the content of sintering additive increased from 2.5 wt.% to 10 wt.%, the porosity of porous ceramics decreased from 30 % to 10 %. With the increase of sintering additive content, the bending strength of the samples first increased and then decreased. When the sintering additive content was 5.0 wt.%, the average bending strength of the samples reached a maximum of 240.88 MPa, and scanning electron microscopy and X-ray diffractometry results showed that β-Si3N4 particles with well-developed pores and a maximum aspect ratio of 5.8 were formed in the porous silicon nitride ceramics. This study provides a reference for the preparation of porous Si3N4 ceramics with good bending properties and porosity.

Transmission Electron Microscopic and X-ray Diffraction Based Study of Crystallographic Bibliography Demonstrated on Silver, Copper and Titanium Nanocrystals: State of the Art Statical Review

This statistical review compares the crystallographic structures of functional nanocrystals composed of silver (Ag), copper (Cu) and titanium (Ti) using transmission electron microscopy (TEM) and X-ray diffraction (XRD) analyses. TEM provides high-resolution imaging to directly visualize individual nanoparticles' size, internal shape and crystallinity. Statistical analysis quantifies variations in lattice parameters, crystal structure, size distributions, phase compositions, lattice strains, preferred orientation and lattice volume of these three crystalline nanomaterials. The review highlights the complementary roles of TEM and XRD in comprehensive Ag, Cu and Ti nanocrystalline materials characterization. The crystallographic functional parameters of Ag were 2θ= 38.1° (111), 44.3° (200) and 64.4° (220); for Cu crystal 43.3° (111), 50.4° (200), 74.1° (220), 89.9° (311) and 95.1° (222) and 35.1° (100), 38.4° (002), 40.2° (101), 53.0° (102), 63.0° (103), 70.7° (110), 76.2° (112), 82.3° (201) demonstrated for Ti nanocrystals. The crystallographic predominant plane or Miller indices were also revealed by selected area electron diffraction (SAED) on TEM. The FCC structure of Ag and Cu is shown in larger lattice volumes compared to the HCP structure of Ti and prefer oriented. The degree of crystallinity of Ti, Cu and Ag nanocrystalline materials was observed at 90.0%, 98.0% and 100.0% respectively. This quantitative comparison provides valuable insights into the structural property relationships in these nanocrystals, enabling rational design strategies for optimizing their performance in various functional applications.

High-temperature resistance performance of silica aerogel composites through fiber reinforcement

Aiming to meet the fireproof requirements for bridges, three fiber/silica aerogel composites were fabricated using basalt fiber, a composite of basalt fiber and high silica glass fiber, and high silica glass fiber as the matrix. The dimensional, structural, mechanical, and thermal insulation stability of these composites under high-temperature heating ranging from 800 °C to 1000 °C were systematically studied. Upon high-temperature heating, the fracture and deformation basalt fiber occurred, leading to the breakage of the fiber skeleton and the aerogel integrity. This resulted in significant densification and a consequent decrease in porosity in the heated basalt fiber/aerogel composite and basalt fiber-high silica glass fiber/silica aerogel composite. Crystallization of basalt fiber began after heating to 800 °C and fully completed at 1000 °C. Besides, part of the high silica glass fiber in the basalt fiber-high silica glass fiber/silica aerogel composite crystallized at 900 °C and 1000 °C. These variations in micro-macro structures and phase compositions led to a substantial degradation of mechanical property and thermal insulation performance in the composites containing basalt fiber. In sharp contrast, the fiber skeleton and aerogel integrity remained relatively stable under high-temperature heating, enabling a synergistic thermal insulation effect of fiber and aerogel. The integrated fiber skeleton reduced the radiative thermal conductivity of the aerogel, while the unbroken aerogel protected the fiber from crystallization. Consequently, the mechanical property and thermal insulation performance of the high silica glass fiber/silica aerogel composite remained stable after high-temperature heating. The ultimate tensile strength and thermal conductivity of the pristine and 1000 °C-heated high silica glass fiber/silica aerogel composite were 0.74 MPa and 0.53 MPa, 0.0213 W/(m·K), and 0.0279 W/(m·K), respectively. This novel composite, exhibiting low thermal conductivity, high strength, excellent thermal stability, is expected to be a desirable candidate for bridge fireproof applications.

Ultra-corrosion-resistant aluminum alloys achieved by femtosecond laser complete remediation of microarc oxidation defects

Microarc oxidation (MAO) is a widely employed technology for the corrosion protection of metal surfaces due to the formation of thick-layer ceramic substances. However, its practical effectiveness is strictly limited by the inevitable concomitant generation of numerous microscale pores/cracks on the oxidation surface to directly expose the substrate materials. As concerning this problem, we here introduced a novel method of the femtosecond laser irradiation to completely eliminate the above MAO defects on aluminum alloys, which consequently modulates the passivation layer into the dense and the superhydrophobic. Meanwhile, with the deep insights into the phase composition variations of the oxide layer, we can find that the laser treatments enable the development of both γ-Al2O3 and α-Al2O3 nanocrystallines with embedment in the amorphous substances to significantly improve the chemical stability of materials. Such laser modifications eventually result in the ultra-corrosion-resistant surface of aluminum alloys, with the measured corrosion current density of 1.46 × 10-13 A/cm2 as well as the impedance value over 112 GΩ∙cm2, about two orders of magnitude enhancement in the anticorrosion compared to the initial MAO sample.

Study of biphasic calcium phosphate (BCP) ceramics of tilapia fish bones by age

Biphasic calcium phosphate (BCP), consisting of bioceramics such as HAp + β-TCP and Ca10(PO4)6(OH)2 + Ca3(PO4)2, is a popular choice for optimizing performance due to its superior biological reabsorption and osseointegration. In this study, BCP was produced by calcining the bones of tilapia fish (Oreochromis niloticus) reared in net cages and slaughtered at an age ranging from 15 to 420 days. The bones were cleaned and dried, calcined at 900 °C for 8 h, and then subjected to high-energy grinding for 3 h to produce BCP powders. After the calcination process, the crystalline phase’s hydroxyapatite (HAp) and/or beta-tricalcium phosphate (β-TCP) were present in the composition of the bioceramic. The age-dependent variation in phase composition was confirmed by complementary vibrational spectroscopy techniques, revealing characteristic peaks and bands of the bioceramic. This variation was marked by an increase in HAp phase and a decrease in β-TCP phase. Thermogravimetric Analysis (TGA) and Differential Thermal Analysis (DTA) from 25 to 1400 °C showed the characteristic mass losses of the material, with a greater loss observed for younger fish, indicating the complete removal of organic components at temperatures above 600 °C. Comparison of the results obtained by X-Ray Diffraction (XRD) and Rietveld refinement with Raman spectroscopy showed excellent agreement. These results showed that with temperature and environment control and adequate fish feeding, it is possible to achieve the desired amounts of each phase by choosing the ideal age of the fish. This bioceramic enables precise measurement of HAp and β-TCP concentrations and Ca/P molar ratio, suitable for medical orthopedics and dentistry.

Compressibility effects on cavity dynamics and shock waves in high-speed water entry

The importance of high-speed water entry is acknowledged within the defense industry. This study numerically investigates the water entry of a high-speed rectangle projectile, focusing on cavity dynamics and shock wave generation. A computational model is employed to accurately simulate the intricate fluid dynamics of compressible multiphase flows. This model integrates a dual-phase flow algorithm with a thermally sensitive Tait equation of state for the liquid phase. The primary focus lies in understanding the effects of fluid compressibility on cavity evolution and shock wave propagation across different Froude numbers. The findings reveal that compressibility induces changes in cavity formation size, leading to significant variations in phase composition within the cavity. Furthermore, compressibility enhances the air cushion effect upon surface impact, resulting in delayed water entry and concurrent reduction in projectile drag. Moreover, a prognostic model is proposed, correlating shock pressure with propagation distance, thereby validating theoretical hypotheses advanced by Lee et al. [J. Fluid Struct., 11, 819–844 (1997)].

Microstructure and Impact Toughness of Laser-Arc Hybrid Welded Joint of Medium-Thick TC4 Titanium Alloy

This study delves into the impact toughness of medium-thick (12 mm thick) titanium alloy joints crafted through a multi-layer, multi-pass welding technique that blends laser-arc (MIG) hybrid welding technology. Microstructural scrutiny, employing optical microscopy, SEM and TEM, unveils a consistent composition across weld passes, with prevailing α/α′ phases interspersed with some β phase, resulting in basket-weave structures primarily dominated by acicular α′ martensite. However, upper regions exhibit Widmanstatten microstructures, potentially undermining joint toughness. Hardness testing indicates higher values in cosmetic layers (~420 HV) compared to backing layers and bending tests manifest superior toughness in lower joint regions, attributed to smaller grain sizes induced by repetitive welding thermal cycles. Impact toughness assessment unveils diminished values in the weld metal (WM) compared to the heat-affected zone (HAZ) and base material (BM), amounting to 91.3% of the base metal’s absorption energy. This decrement is ascribed to heightened porosity in upper regions and variations in grain size and phase composition due to multi-layer, multi-pass welding. Microstructural analysis proximal to failure sites suggests one mechanism wherein crack propagation is impeded by the β phase at acute crack angles. In essence, this study not only underscores the practicality of laser-MIG hybrid welding for medium-thick TC4 alloy plates but also underscores the reliability of joint mechanical properties.

Investigation of sensing performances of thick-film resistors sintered on fluorophlogopite glass-ceramic substrates

Strain gauges made of thick-film resistors (TFRs) offer a promising solution for monitoring the structural health of civil engineering projects, owing to their exceptional durability and stability. To address the issue of strain mismatch between alumina substrates and concrete materials, fluorophlogopite glass-ceramic (FGC), which has a low elastic modulus and good machinability, was utilized as a substrate for thick-film resistors. Compatibility between resistor pastes and substrates should be considered, as the substrate can significantly impact the performance of thick-film resistors. TFRs with varying concentrations of RuO2 were screen printed and fired at different temperatures on both FGC and 96% Al2O3 (as a control) substrates. The sheet resistivity, temperature coefficient of resistance (TCR), and gauge factor (GF) of TFRs were evaluated. The strain sensing performances of TFRs on FGC evaluated under compressive loading. The results indicate that TFRs on FGC substrates exhibit higher hot TCRs, lower sheet resistivities, and lower gauge factors than those on Al2O3 substrates under typical firing conditions of 850°C for 10 minutes. As the concentration of RuO2 increases, the differences in properties between TFRs on the two substrates become less pronounced. Microstructural analyses of the interface between the resistor layer and substrate indicate that changes in properties of TFRs on FGC substrates are primarily attributed to variations in RuO2 concentration and glass phase composition, which result from interactions between the resistor layer and FGC substrate. The interaction between the FGC substrate and the resistor layer can be significantly alleviated by lowering the firing temperature from 850°C to 750°C, resulting in TFRs on FGC substrates with properties comparable to those on alumina substrates. The TFRs on FGC exhibit favorable sensitivity, linearity, repeatability, and hysteresis within the input compression strain range of 0–3043με, thus showcasing significant potential for application in structural health monitoring (SHM) in civil engineering.

Ordered Phase Distribution of Quasi‐2D Perovskites Controlled by a Supramolecular Approach Enables Efficient Blue Light‐Emitting Diodes

AbstractQuasi‐2D perovskites demonstrate exceptional luminescent properties, mainly attributed to heightened radiative recombination facilitated by the energy transfer process among spontaneous quantum‐well structures featuring varied n‐value distributions. However, the rapid crystallization process often induces uncontrolled variations in phase composition, characterized by distinct “n” values, leading to suboptimal energy transfer efficiency. In this study, an innovative supramolecular strategy utilizing cryptand is introduced as an additive to regulate the phase distribution within quasi‐2D perovskite films. Cryptand effectively inhibited the aggregation of PEA+ and the formation of unsaturated Pb‐X coordination compounds, thereby suppressing the generation of low‐“n” phases. This intervention resulted in a continuous series of ordered intermediate phases with higher “n” values. The graded electronic structure facilitated efficient energy transfer from low‐“n” to high‐“n” phases, promoting effective radiation recombination. As a result, the optimized PeLEDs emitting at 490 nm demonstrated a remarkable external quantum efficiency (EQE) enhancement to 10.16%, compared to the reference device with an EQE of 2.33%. The device also exhibited impressive spectral and operational stability. The findings establish a viable strategy for precise phase distribution regulation in quasi‐2D perovskites, offering great potential for high‐performance blue PeLEDs.

Microstructural Control of a Multi‐Phase PH Steel Printed with Laser Powder Bed Fusion

AbstractThe established approach to materials design for additive manufacturing (AM) consists of attempting to reproduce the uniform structures and properties of conventionally processed materials. While this certainly helped facilitate material certification and the rapid introduction of AM technologies in several industries, the opportunity to exploit unique features of specific AM processes to generate spatially varying microstructures–and hence novel materials, remains largely untapped. This work presents a method for manufacturing materials through laser powder bed fusion (LPBF), in which control over the spatial variation in phase composition and mechanical properties is achieved. This technique is demonstrated using 17‐4 precipitation‐hardened stainless steel (17‐4PH), by controlling spatial modulation of energy densities during printing. This results in local control of ferrite/martensite volume fractions, allowing the fabrication of metal/metal architected composites with hard/brittle regions interspersed with soft/tough regions. Local variations of ~20% in tensile strength and ~150% in elongation are achieved, with a spatial resolution of ~100 microns. The approach is general and robust, fully compatible with commercially available LPBF equipment, and applicable to virtually any multi‐phase alloy system. This work shifts the paradigm from attempting to print components with uniform properties to manufacturing alloys with controlled spatial property gradients.

Understanding secondary phase inclusion and composition variations in the microstructure design of n-type Bi 2Te 3 alloys via selective dissolution of KCl

Understanding secondary phase inclusion and composition variations in the microstructure design of n-type Bi ₂Te ₃ alloys via selective dissolution of KCl

Comprehensive analysis of the effective and intra-particle diffusion of weakly retained compounds in silica hydrophilic interaction liquid chromatography columns

A detailed analysis of intra-particle volumes and layer thicknesses and their effect on the diffusion of solutes in hydrophilic interaction liquid chromatography (HILIC) was made. Pycnometric measurements and the retention volume of deuterated mobile phase constituents (water and acetonitrile) were used to estimate the void volume inside the column, including not only the volume of the mobile phase but also part of the enriched water solvent acting as the stationary phase in HILIC. The mobile phase (hold-up) volume accessible to non-retained components was estimated using a homologous series approach. The joint analysis of the different approaches indicated the formation of enriched water layers on the hydrophobic silica mesopore walls with a thickness varying significantly with mobile phase composition. The maximal thickness of the enriched water layers, which corresponded to the minimum void volume accessible to unretained solutes, marked a transition in the retention behavior of the studied analytes. Discrepancies between deuterated solvent measurements and pycnometry were explained by the existence of an irreplaceable water layer adsorbed on the silica surface. Regarding the diffusion behavior in HILIC, peak parking experiments were used to interpret the influence of the acetonitrile content on the effective diffusion coefficient Deff. A systematic decrease in Deff and molecular diffusion Dm was observed with decreasing acetonitrile concentration, primarily attributed to variations in mobile phase viscosity. Notably, Deff/Dm remained nearly unaffected by variations in mobile phase composition. Finally, the effective medium theory was used to make a comprehensive analysis of Dpart/Dm to study the contribution to band broadening when the solute resides in the mesopores. The obtained data unveiled a curvature with a minimum corresponding to conditions of maximum water-layer thickness and retention. For the weakly retained compounds (k’ < 0.5) the Dpart/Dm-values were found to be relatively high (order of 0.35-0.5), which directly reflects the high γsDs/Dm-values that were observed (order 0.35-7).

Wetting mechanisms in the mass transfer process of CuSi3 droplets on the TC4 and 304SS multi-metal system controlled by the hybrid shielding gas atmosphere

To explore the synergistic wettability of the Ti-Cu-Fe multi-metal system, the wetting behaviors of CuSi3 droplets on the TC4 and 304SS plates during the cold metal transfer welding process in various gas atmospheres were studied in this work. The effects of Ti, Fe, Si, C, and O on the spreading dynamics of liquid Cu were analyzed in detail. The results reveal that the CO2 + Ar hybrid gas shielding atmosphere significantly affects the interfacial mass transfer. The sufficient interfacial reaction and increased element diffusion promoted the formation of Ti2Cu/TiCu multiphase microstructure at the Cu/Ti interface instead of a continuous Ti2Cu layer, and a thicker and loose Fe (s, s) layer was formed at the Cu/Fe interface. The variations of surface phase composition and the generation of inward flow weakened the wettability of CuSi3/TC4 and CuSi3/304SS systems. The dissolution of Si and surface adsorption of O decreased the σlv of liquid Cu, whereas Ti and Fe had the opposite effect. When the shielding gas changed from pure Ar to CO2 + Ar hybrid gas, the potential spreading model of the CuSi3/TC4 system changed from reaction-limited to diffusion-limited, and the wetting activation energy increased from 46 kJ/mol to 57 kJ/mol. Removing oxide film, forming Ti2Cu and diffusion of Ti controlled the wetting. Whereas for the CuSi3/304SS system, the potential spreading model changed from diffusion-limited to a molecular dynamics model. Removing oxide film, diffusion of Fe and interfacial adsorption were the dominant factors for wetting.

Mechanisms of cadmium adsorption by ramie nano-biochar with different aged treatments

Biochar (BC) has proven to be very effective against the remediation of cadmium contamination. However, aged treatment is inevitable and variations in the adsorption mechanism caused by ageing remain unclear. In this study, different treatments (i.e., photo-aged (nano-PBC) and chemical treatment (nano-NBC)) were used on the nano-BC. The nano-BC as well as the two aged nano-BCs were characterized separately to examine their surface morphology, functional groups, and variations in phase composition. The aged nano-BCs exhibited larger specific surface area and mesopore volume. The nano-NBC produced more surface functional groups (i.e., carboxyl groups, lactone groups, and phenolic hydroxyl groups) compared to the nano-BC and nano-PBC. In addition, the study revealed the effect of aged treatment on the adsorption mechanism of the nano-BCs by adsorption kinetic model and adsorption isotherm model, respectively. The fitted consequences revealed that the adsorption of Cd by the three nano-BCs was consistent with the pseudo-second order kinetic model and the Langmuir adsorption isotherm model. The aged nano-BCs have higher Cd adsorption capacity, which was more effective for the nano-NBC. In addition, different adsorption conditions (i.e., pH, ionic strength, coexisting cations, and initial nano-BCs addition concentration) were performed to explore the optimal adsorption capacity. The results showed the optimal adsorption efficiency of 93.24 % was achieved for nano-NBC at pH 7, a background solution of 0.001 M Na+, and an initial nano-BC addition concentration of 50 mg L−1. The different aged treatments did not significantly affect the adsorption mechanism of the nano-BCs, but changed the chemisorption mode and enhanced the physical adsorption (pore size filling and hydrogen bonding). Namely, aged treatment significantly enhanced the adsorption capacity of the nano-BCs on Cd.

Synthesis, characterization, and photocatalytic hydrogen evolution performance of neodymium iron composites: Influence of annealing temperature

Hydrogen is a highly sought-after and versatile energy carrier, as well as a crucial chemical with widespread applications. It can be produced from water through photocatalysis using sunlight or through electrolysis powered by solar or wind energy. However, the design of efficient photocatalytic systems for hydrogen production remains a significant challenge, necessitating the development of novel photocatalysts. In this study, we successfully synthesized neodymium iron composites with a platelet-like nanostructure using a sol–gel technique, followed by heat treatment at different annealing temperatures ranging from 750 to 900 °C. The analysis using Rietveld Refinements revealed the formation of a composite consisting of NdOCl/Fe2O3/NdFeO3. To investigate the effects of phase composition variations caused by different annealing temperatures, we applied various characterization techniques to explore the optical absorption properties, band structure, and photocatalytic hydrogen evolution ability. Among the samples, the one obtained at 800 °C exhibited the highest photocatalytic hydrogen evolution activity. It demonstrated a measured rate of 12.79 µmol/g/h when methanol was used as the sacrificial agent and 18.99 µmol/g/h when triethanolamine (TEOA) was applied as the sacrificial agent. To provide insight into the observed differential photocatalytic activity, we propose a possible mechanism based on the separation of photogenerated charge carriers through varied interfacial heterojunctions resulting from the phase composition change in each sample.

STUDY OF THE INFLUENCE OF VARIATIONS IN THE PHASE COMPOSITION ON THE DIELECTRIC PROPERTIES OF FERROELECTRIC CaTiO&lt;sub&gt;3&lt;/sub&gt; CERAMICS DOPED WITH Y&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;

The study of the relationship between the effect of phase composition variation on the dielectric characteristics of ferroelectric ceramics is one of the most important fundamental questions, the answer to which will allow us to determine the potential of using ferroelectrics in microelectronic applications and the creation of alternative energy sources (solid oxide fuel cells). The purpose of this study is to explore the effect of the Y2O3 dopant on the phase formation processes and the properties of the synthesized ferroelectric ceramics of calcium titanate, as well as to establish the connection between the influence of the formation of impurity phases on the change in the dielectric properties of ceramics. According to the data of X-ray phase analysis, it was found that the addition of Y2O3 with a concentration above 0.15 M leads to the formation of an orthorhombic CaY2O4 phase in the ceramic structure, the weight contribution of which increases with the dopant concentration growth. An analysis of the dependence of the specific electrical conductivity (σDC) with varying dopant concentration showed that the maximum value of σDC is achieved at dopant concentrations of 0.05 M, which leads to structural ordering due to the effect of adding yttrium oxide acting as a stabilizer, as well as the formation of impurity donor conductivity in the structure. An analysis of the dependence of the specific electrical conductivity (σDC) from dopant concentration was carried out. It has been established that the maximum value of σDC is achieved at a dopant concentration of 0.05 M. This is explained by structural ordering due to the addition of a stabilizer – yttrium oxide, as well as the formation of impurity donor conductivity in the synthesized sample. At the same time, the established dependences of the change in dielectric characteristics are in good agreement with the change in the phase composition, and an increase in the concentration of charge carriers due to the introduction of a donor impurity in the form of Y3+ leads to the appearance of volume-charge polarization in ceramics.

Microstructural evolution during H2 corrosion of Al2O3–SiO2 based refractory aggregates

Hydrogen-based direct reducing iron production (H-DRI) has caused more and more attention in metallurgical industry owing to the near-zero carbon emission. However, the strong reducibility of H2 at elevated temperature can possibly cause serious corrosion to the lining refractories of furnaces. In this study, four types of Al2O3–SiO2 based aggregates (brown corundum, bauxite, mullite and quartz) with various SiO2/Al2O3 mass ratios were utilized for the H2 corrosion test at 1673 K with a soaking time of 8 h. Based on the analysis of weight-loss ratios, phase-composition variation and reduction thermodynamics, the microstructure evolution during H2 corrosion was investigated in detail. The results indicates that the SiO2 impurity of brown corundum was partly reduced by H2 which led to the formation of rod-like or flaky intergranular grains. For bauxite, a porous structure was produced by the accumulation of rod-like or elongated grains owing to the significant reduction of intergranular silicon compounds. Nevertheless, due to the high sintering activity between the Al2O3 products from the reduction of mullite, a high densification structure was realized to effectively prevent the further H2 penetration, hence, mullite inversely obtained the better H2 corrosion resistance than bauxite in spite of its higher S/A ratio. The accumulation of SiO and H2O gases due to the high reduction rate of SiO2 led to the formation of a great deal of SiO2 fiber on the surface of quartz aggregates. The [O] provided by the phase-transformation from α-quartz to cristobalite could be partially captured by the H2 for the reduction, which caused the deterioration of corrosion. With this study, we aim to provide theoretical assistance for the refractory selection applied in hydrogen metallurgy.

Effect of heat treatment on the microstructure and corrosion resistance of 316L stainless steel fabricated by hybrid in-situ rolled wire-arc additive manufacturing

The effect of heat treatment on the microstructure and corrosion resistance of 316L stainless steel fabricated using the hybrid in-situ rolled wire-arc additive manufacturing (HRAM) technique was studied. The results showed that the as-built sample was composed of dendritic δ-ferrite and irregular austenite grains. With increasing annealing temperature (650–1200 °C), the corrosion resistance of HRAM 316L steel in a proton exchange membrane fuel cell environment showed a complex change trend of constant-increase-decrease-increase, attributing to the coupling effects of the variation in phase composition, grain characteristics, and texture. Particularly, after annealing at 1050 °C, the δ-ferrite transformed into the σ-phase with higher contents of Cr and Mo, which promoted the formation and stabilization of the passivation film in the steel, thereby resulting in superior corrosion resistance.

ANALYTICAL METHOD DEVELOPMENT AND VALIDATION FOR SIMULTANEOUS ESTIMATION OF DIPHENHYDRAMINE AND NAPROXEN IN PHARMACEUTICAL DOSAGE FORMS

The aim of the present work is to develop a new simple sensitive accurate and economical analytical method and validation for the Simultaneous estimation of Diphenhydramine and Naproxen in pure and pharmaceutical Tablet dosage form by using RP-HPLC and validate the developed method in accordance with ICH guidelines for the intended analytical application i.e., to apply the proposed method for analysis of the drug in its dosage form. And also to apply the developed method for the simultaneous estimation of Diphenhydramine and Naproxen in pure and pharmaceutical tablet dosage form. System (waters 2690 usa), Pump (Analytical HPLC isocratic pump, gradient pump), Detector (waters 996 diode array detector), Software (empower 2 software), Column (Kromosil (250×4.6mm, 5μ) ODS C-18 RP-column), Injector (Rheodyne injector with 20μ capacity), Electronic balance (SHIMADZU electronic balance), Sonicator (Analytical Technologies Limited- Ultrasonic cleaner). Diphenhydramine &amp; Naproxen peaks in the chromatogram passed the system suitability criteria %RSD of peak areas of Diphenhydramine &amp; Naproxen was not more than 2.0% for variation in mobile phase composition. The newly developed RP-HPLC method for determination of Diphenhydramine &amp; Naproxen in tablet dosage forms is specific, precise, accurate and rapid. The proposed method can be conveniently adopted for routine quality control analysis.