Pressure Bar Research Articles

Metallurgical investigation of leakage observed in welded interface of Pilot pressure distributor of liquid stage for aerospace application

Pilot Pressure Distributor (PPD) system is used in liquid fuel stage of launch vehicles for the pressurized flow of liquid propellant. The PPD system is fabricated out of AISI304L austenitic stainless steel. The system consisted of adaptor and plumbing lines is welded together using Gas Tungsten arc welding technique. The distributor system is subjected to hydro test at 120 bar pressure and then post- harnessing command line leak check is carried out after the hydro test. During the leak test at 60 bar with snoop solution, a frothing leak is observed at PPD distributor weld joint. A pressure drop of 6 bar was also observed over a duration of 10 min. The leaked PPD distributor was dismantled from the assembly and subjected to detailed metallurgical investigation to identify the root cause of leakage. The metallographic analysis revealed leakage in PPD distributor attributed to the lack of fusion in the weld joint.

Hierarchical clinoptilolite zeolite-template carbon for highly selective separation of CO2 and CH4

BackgroundSeparating CO2 from natural gas before it is released into the atmosphere is a significant challenge in the present times due to its greenhouse effect. MethodsIn this study, a series of zeolite-template carbons (ZTCs) had been synthesized from acetylene as a carbon source using clinoptilolite as a template, through hydrofluoric acid etching and potassium hydroxide (KOH) activation processes. Significant findingsThe deposition of carbon on the zeolite-template was confirmed with different characterization techniques and their CO2 adsorption capacity and selectively toward methane (CH4) was evaluated at 25 °C, over a 1‒10 bar pressure range. The CO2/CH4 selectivity of the adsorbents was optimized with various synthesis parameters including chemical vapor deposition (CVD) reaction time, acetylene flow rate as well as activation temperature and KOH to carbon (KOH:C) mixing ratio. According to the findings, medium SBET (334.06 m2 g‒1), high Vtot (0.71 cm3 g‒1), high Vmeso (0.68 cm3 g‒1) and a large Dave (8.55 nm) of the ZTC-120–12.5–800–3 adsorbent (CVD reaction time of 120 min and acetylene flow rate of 12.5 cc min−1 as well as activation temperature of 800 °C and KOH:C ratio of 3:1) results in the highest CO2 capacity of 4.81 mmol g‒1 at 25 °C and 10 bar. Moreover, regarding the optimization goal of this study, the highest CO2/CH4 separation at 25 °C and 10 bar is the result of a long CVD reaction time (180 min), a high KOH:C ratio (4:1), a low acetylene flow rate (50 cc min‒1), and a low activation temperature (700 °C). In this regard, ZTC-180–50–700–4 showed the highest CO2/CH4 (15:85) selectivity of 13.35 with a high SBET (549.31 m2 g‒1), Vtot (0.718 cm3 g‒1), Vmicro/meso (15.6014), Vmeso (0.6211 cm3 g‒1) and a medium Dave (5.22 nm). The amine-functionalization of this sample increases the quadrupole moment between CO2 and nitrogen groups, and not only was the F-ZTC-180–50–700–4 sample's CO2 adsorption capacity increased by nearly 41% (4.11 mmol g‒1) compared to the ZTC-180–50–700–4 (2.91 mmol g‒1), but it also showed 58% higher CO2/CH4 selectivity (21.12). Based on the selectivity results of the functionalized ZTCs, their potential use in the separation of CO2 over CH4 at high pressures is demonstrated.

Porous carbon from natural rubber for CO2 adsorption

Porous carbon plays an important role as an adsorbent in carbon dioxide (CO2) capture and is considered an important CO2 mitigation strategy. In this work, porous carbon was developed from natural rubber (NR), and the natural rubber derived-activated carbon (NRAC) was obtained by chemical activation using potassium hydroxide (KOH) and sodium hydroxide (NaOH) with a ratio ranging from 1:1 to 1:4 (NRAC: activator). Results indicate that the specific surface area, total pore volume, and basicity increased linearly with the adjustment to a greater NRAC: activator mass ratio. In addition, the results show that NaOH is more effective than KOH at enhancing the physicochemical features of NRAC. NRAC-NaOH-4 exhibited the highest surface area (1,670 m2/g), highest pore volume (1.01 cm3/g), and strong basic density (23,650 μmol/g). On the other hand, NRAC-KOH-4 showed a surface area of 1,118 m2/g, a pore volume of 0.64 cm3/g, and the highest strong basic density of 24,320 μmol/g. Notably, NRAC-NaOH-4 exhibited the highest CO2 uptake, up to 2.98 mmol/g at under 1 bar of pressure at 25 °C. These findings suggest that NR can be utilised for devising high porosity material as adsorbents for CO2 and can be highly beneficial to society.

Study of the Variation of Fuel Pressure to Improve Spraying and the Range of the Injection Jet

The current study is focused on how varying injection pressure in the fuel supply system of multi-point injection systems can improve fuel atomization and injection jet range. The aim is to achieve a more efficient mix dosage, thus improving combustion and reducing exhaust emissions. In addition, it is intended to develop a characterization of the injection actuators, specifically the injectors, through a series of tests in which the injector pressure, engine speed and injection pulse are modified. To carry out these tests, a heuristic testing technique, like the empirical approach, was implemented, and a mobile device was used to capture the spray frames of the injectors. These data were then used to generate a correlation model between injection and spray angles, considering 0.5 bar pressure variation intervals within the established ranges. This approach made it possible to visualize and record the behavior of the spray in the injector, including the spray angle, the injected fuel flow rate and the working pressure during the operation process. Following the guidelines established in the proposed methodology, a significant result was obtained by varying the pressure at 5 bar and with an injection pulse of 2 ms. In this case, a flow reduction of 66 mL of the injected fluid was achieved, which corresponds to a significant reduction in fuel consumption. Additionally, a spray angle of 10.48° was observed with optimized atomization. These results were verified on vehicles with similar injection systems by testing on the GT-600-PRO injection test bench. In summary, this study shows that by varying the injection pressure and optimizing other parameters, it is possible to achieve a significant reduction in fuel consumption and improve fuel atomization in multipoint injection systems. These findings have a significant impact on the Ecuadorian vehicle fleet and provide a scientific approach to improving fuel efficiency and performance.

Simulation of temperature swing adsorption process to purify hydrogen for fuel cell uses by SAPO34 as adsorbent

To purify hydrogen gas from synthesis gas using a adsorption process, SAPO 34 adsorbent was used. Due to the strong adsorption of carbon dioxide in this adsorbent, it is not possible to recover the adsorbent by reducing the pressure alone, and it is necessary to use thermal operations for recovery. For this purpose, a temperature swing adsorption (TSA) process is used to increase the purity of hydrogen for use in fuel cells. To investigate the optimum operational conditions, various temperatures and different pressures of input gas were investigated to compare the purity and recovery of adsorption process. The TSA process was simulated for pressures of 11, 22 and 33 bars and the recovery percentage of each process was calculated. According to the results obtained, the recovery value at 33 bars is better than the other two pressures, but due to the fact that operational and initial costs increase at high pressures; 22 bar pressure was chosen to present the remaining results. In this work, the total amount of material and the molar rate are also reported. The average purity of the components in the product and waste outlet streams has also been presented. Accordingly, the average molar fraction of hydrogen in the product outlet stream is 99.96% in the temperature increase stage, 99.94% and in the stream used for temperature reduction is 99.96%.

Development of coke model for thermal cracking of hydrocarbon fuels under supercritical conditions and its experimental validation

Coke prediction and its judicious mitigation for thermal cracking of fuels is an essential aspect of regenerative cooling in hypersonic vehicles. The present study performs a numerical investigation of coke prediction for the thermal cracking reactions of hydrocarbon fuels under supercritical conditions. Numerical simulation is performed to obtain the concentration profiles of coking precursors along the length of the reactor. Product distribution and transport properties are estimated using the shear stress transport k-ώ turbulence model. A predictive coke model is developed by considering operating conditions, feed density, and coke precursors concentration. The model is validated with literature-reported experimental data for different hydrocarbons. The model predicted coke value lies within ± 25 % of the experimental coke for a temperature range of 550 °C to 700 °C and a pressure range of 35–55 bar. The suitability of the Coke model is also examined by conducting experiments in an electrically heated flow reactor with n-heptane. At 650 °C and 40 bar pressure, the experimentally obtained coking rate (0.6 mg/min) shows a good agreement with the model-predicted coking rate (0.7 mg/min).

Sorption of Carbon Dioxide and Nitrogen on Porous Hyper-Cross-Linked Aromatic Polymers: Effect of Textural Properties, Composition, and Electrostatic Interactions.

Porous hyper-cross-linked aromatic polymers are one of the emerging classes of porous organic polymers with the potential for industrial application. Four different porous polymeric materials have been prepared using different precursors (indole, pyrene, carbazole, and naphthalene), and the composition and textural properties were analyzed. The materials were characterized in detail using different physicochemical techniques like scanning electron microscopy, transmission electron microscopy, nitrogen adsorption at 77 K, Fourier transform infrared spectroscopy, X-ray diffraction, etc. The effect of textural properties and nitrogen species on carbon dioxide and nitrogen adsorption capacities and selectivity was studied and discussed. The carbon dioxide and nitrogen adsorption capacities were measured using a volumetric gas adsorption system. The adsorption data were fitted into different adsorption models, and the ideal absorbed solution theory was used to calculate adsorption selectivity. Among the studied samples, POP-4 shows the highest carbon dioxide and nitrogen adsorption capacities. While POP-1 shows maximum CO2/N2 selectivity of 78.0 at 298 K and 1 bar pressure. It is observed that ultra-micropores, which are present in the prepared materials but not measured during conventional surface area measurement via nitrogen adsorption at 77 K, play a very important role in carbon dioxide adsorption capacity and determining the carbon dioxide selectivity over nitrogen. Surface nitrogen also increases the CO2 selectivity in the dual mode by increasing carbon dioxide adsorption via the acid-base interaction as well as by decreasing nitrogen adsorption due to N-N repulsion.

Preparation of Cu-BTC MOF extrudates for CH4 separation from CH4/N2 gas mixture

Metal-Organic Frameworks (MOF) are promising materials for gas separation and storage. The shaping of MOFs is an essential step for their practical industrial application. In this work, Cu-BTC MOF extrudates (B-5, B-10, and B-15) were prepared by using 5, 10, and 15 wt% of carboxymethyl cellulose as a binder and well characterized by powder X-ray diffraction (PXRD), N2 adsorption-desorption at 77 K, FTIR, TGA, and Scanning Electron Microscopy (SEM). The equilibrium adsorption isotherms of CH4 and N2 with Cu-BTC extrudates were measured at 298, 313, and 328 K and up to 10 bar pressure and compared with zeolite 13X and 5A. The isotherm data of both adsorbates were fitted in Dual Site Langmuir equations, and adsorption selectivity of methane over nitrogen was predicted using Ideal Adsorbed Solution Theory (IAST) method for 20:80, 30:70, and 50:50 (mol%/mol%) CH4/N2 feed gas mixtures representing nitrogen bearing coal bed methane. The CH4/N2 selectivity of Cu-BTC extrudates B-5, B-10, and B-15 was higher than commercial zeolite 13X and 5A. For example, for the 20:80 CH4/N2 feed mixture, the CH4/N2 selectivity of Cu-BTC extrudates B-5, B-10, and B-15 was 3.21, 3.24, and 3.25, respectively, which are about 38 & 34% higher than zeolite 13X and 5A which makes them potential adsorbent for further dynamic studies for the said separation application.

Interaction and dragging of 2,4-D molecules in SPC/E water by (6,5) carbon nanotubes at ambient pressure

We present a computer simulation study of the herbicide 2,4-dichlorophenoxyacetic acid, interacting with a single-walled (6,5) carbon nanotube in water. Our study was conducted at 1 bar of pressure, and the temperature varied from 280 to 370 K. Pair correlation functions, coordination number, water hydrogen bonding, density, static dielectric constant, and interaction energy between the nanotube and acid molecules, were determined. Mean square displacement and self-diffusion were also obtained. Our results showed that the herbicide molecules and the nanotube form a complex. Pair correlation functions revealed that acid molecules are most likely found at a distance of 7.4 Å from the nanotube and are located within 20 Å of it. Water hydrogen bonding and dielectric behavior of the mixture were similar to those of pure water. The mean square displacement revealed an incipient plateau located between two regions of linear behavior, which might be related to the frequent coming and going of 2,4-D molecules around the nanotube. The diffusion coefficient of 2,4-D was higher than that of the nanotube. Our results show a trend similar to that revealed in experiments on the capture of 2,4-D herbicide by (6,5) carbon nanotubes, indicating that the interaction parameters here used, produce a reasonable description of the calculated properties. As a general conclusion, our data support the idea that using carbon nanotubes in domestic devices for the dragging and removal of 2,4-D herbicide from water might be feasible.

COLD PRESSED PURE ALUMINUM POWDERS SINTERING WITH ULTRA HIGH FREQUENCY INDUCTION

Metals both have good mechanical and electrical qualities, besides, they are also created as light as possible by using recent manufacturing techniques. In that scope, this study aims to use an ultra-high frequency sintering technique to sinter aluminum powders of 15 µm in size. A mold and 30 bar pressure were used to compress the powders before sintering. For the sintering temperature optimization, 3 experiments were conducted in the induction system at 600°C, 650°C, and 700°C temperatures. Sintering conditions were determined at different time intervals of 3 minutes, 5 minutes, and 10 minutes to find an optimum value for sintering time. Finally, furnace sintering was used for 1 hour at these temperatures. With 2 different sintering, 3 different temperatures, and 3 different time parameters, size, density, porosity, and hardness values were obtained. Obtained results were compared among themselves.

Tuning the hydride stability of the TiVNb-based alloys by equimolar Cr/Al addition

Body-centered multi-principal element alloys (BCC-MPEAs) based only on hydride-forming elements have low equilibrium plateau pressures during reaction with hydrogen and, consequently, high decomposition temperatures due to the high thermodynamic stability of related hydrides. In this work, we present a strategy to decrease the stability of the final hydrides formed in the BCC TiVNb alloy by simultaneous addition of two non-hydride forming elements, Cr and Al. The (TiVNb)100-x(CrAl)x alloys with x = 10, 20, 30, and 40 at.% crystallize as major BCC solid solutions with dendritic microstructures. Pressure-Composition-Temperature diagrams revealed that the combined addition of Cr and Al thermodynamically destabilizes the dihydride formation for x = 10 and 20 at.%. For higher Cr/Al contents the destabilization is too large to form stable hydrides under maximum 100 bar pressure. The absorption/desorption plateau pressure at room temperature for (TiVNb)80(CrAl)20 alloy are 9 and 0.6 bar, respectively, enabling a reversible capacity of about 0.8 H/M (1.4 wt%) at ambient conditions. The present results provide important insights into the effects of simultaneous Cr and Al additions in BCC-MPEAs and shed light on the design of new alloys with hydrogen absorption and desorption ability at ambient conditions.

Effective parameters on the combustion performance of coated aluminum hydride nanoparticles: A molecular dynamics study

In this study, the combustion of coated aluminum hydride nanoparticles (NPs) was investigated using molecular dynamics (MD) simulation. The relationship between the type of atomic coating, initial temperature, and initial pressure (IP), and the thermal and combustion behavior of aluminum hydride NPs was explored. The results indicate that the ethanol atomic coating exhibited better combustion performance compared to the octyl sebacate, HTPB, and diethyl ether atomic coatings. As a result, the maximum radial distribution function (RDF) of oxygen and aluminum in the ethanol-coated structure increased to 3.81 W/m2 and 2.33, respectively, after 1 ns. Studying the effect of initial temperature, increasing it from 1000 to 1500 K, led to an increase in heat flux (HF) and maximum RDF from 3.88 W/m2 and 1.55–7.39 W/m2 and 2.84, respectively. This suggests that increasing the initial temperature improved the thermal behavior of the structures. Finally, increasing the IP from 0 to 5 bar resulted in a decrease in HF and maximum RDF from 3.28 W/m2 and 1.38–3.10 W/m2 and 1.20, respectively. Consequently, increasing the IP had no positive effects on the combustion process of the structure, and it operated more effectively at 1 bar pressure. These findings are expected to significantly enhance the thermal and combustion behavior of diverse atomic structures, which will be important given the growing usage of NPs in several sectors of industry and technology.

The computational study of initial temperature/pressure and atomic doping effects on the growth of crack in graphene nanostructure: Molecular dynamics approach

Graphene is a two-dimensional material with excellent mechanical, electrical, and thermal properties made up of single layers of carbon atoms. Despite the fact that graphene is an emerging material, nowadays graphene has become the leader of the nano field, and with the discovery of its various properties, a tremendous transformation is taking place in nano science. In this study, the molecular dynamics method was used to examine the mechanical characteristics of graphene nanosheets. To achieve this, zig-zag and armchair-shaped graphene nanosheet samples were first simulated. In the second step of this research, by adding boron and nitrogen impurities inside the nanosheet structure, the growth of cracks in these structures was studied, and the effect of factors, such as temperature, pressure, and adding impurity atoms, such as nitrogen and boron were evaluated. In graphene nanosheets with zig-zag and armchair structures, the results demonstrate that the greatest fracture lengths were 28.91 Å and 23.6 Å, respectively. The crack length increased from 23.60 Å to 30.68 Å by increasing the temperature from 300 to 400 K. From 0 bar to 1 bar of pressure, the crack length went from 23.60 Å to 29.01 Å. The type of plates affected the mechanical properties in nanosheets, and nanosheets with armchair edges had better mechanical properties. Finally, the effect of impurities on graphene nanosheets was investigated. The simulations showed improved mechanical properties and resistance to crack growth in the presence of boron, nitrogen, or a combination of these atoms.

Design of a super-hydrophilic/super-oleophobic g-C3N4/Ti(OH)4/PFOA nanocomposite coated mesh as a smart nanofilter with robust anti-fouling properties for separation of oil and water emulsions

The design and development of efficient approaches for water–oil separation have had widespread interest. This study aimed to synthesize nanocomposites based on Ti(OH)4 and g-C3N4 nanosheets (CN-NS) to show experimentally that the inclusion of Ti(OH)4 nanoparticles of 9.2 nm size into CN-NS leads to an improved oil-water separation efficiency and anti-fouling performance. So, a novel, reusable, and recyclable super-hydrophilic/underwater super-oleophobic CN-NS/Ti(OH)4 nanocomposite-coated stainless steel mesh was developed to separate oil-in-water emulsions. Super-wettability was obtained in the CN-NS/Ti(OH)4 nanocomposite with WCA = 0° and UOCA = 154°, respectively, showing significant super-hydrophilicity and underwater super-oleophobicity. Surface hydrophilicity increased after anchoring Ti(OH)4 on the CN-NS surface, resulting from oxygen-containing functional groups and consequently making defects on the mesh surface. Enhanced underwater oleophobicity of nanocomposite coated mesh is attributed to its higher surface roughness, which is a result of its micro-nano meter and mesoporous hierarchical structure. Moreover, the self-cleaning property of the as-prepared mesh was demonstrated by visible light irradiation on the contaminated mesh. In addition, perfluorooctanoic acid (PFOA) reduced energy in CN-NS/Ti(OH)4/PFOA mesh, resulting in a super-hydrophilic/super-oleophobic mesh. The CN-NS/Ti(OH)4/PFOA nanocomposite-coated filter was observed to separate water from a 1 wt% water-in-oil emulsion at 0.2 bar pressure with a filtration flux of 317.2 L m−2 h−1 and 95% separation efficiency.

Chronic Plantar Fasciitis Treatment: A Randomized Trial Comparing Corticosteroid Injections Followed by Therapeutic Ultrasound with Extracorporeal Shock Wave Therapy

This study aims to compare the effect of corticosteroid injection (CSI) followed by therapeutic ultrasound (TUS) with that of extracorporeal shock wave therapy (ESWT) in patients with chronic plantar fasciitis (PF) and to explore the impact of a sedentary lifestyle and obesity on treatment outcomes. Female patients with PF were randomly allocated to receive ESWT (group A, n = 25) or CSI + TUS (group B, n = 25). Interventions: Group A received four once-weekly sessions of ESWT (2000 shocks, 2.5 bar pressure, 10.0 Hz frequency). Group B received a local injection of 40 mg triamcinolone acetonide with 2 mL 1% xylocaine, followed by three sessions of TUS per week for two weeks. Pain visual analog scale (VAS pain), plantar fasciitis pain and disability scale (PFPDS), and fascia thickness using musculoskeletal ultrasound were all measured at baseline, 4 weeks, and 12 weeks after the end of treatment. VAS pain and PFPDS improved significantly in both groups after 4 and 12 weeks. In the ESWT group, the pain improved significantly more at 12 weeks (p = 0.004). In obese patients (BMI > 29.9 kg/m2), ESWT gave more long-term pain relief at 12 weeks follow-up. In both the ESWT and CSI + TUS groups, after 12 weeks, the VAS pain improved more in patients with a sedentary daily life than in those with active life (p = 0.021 and p = 0.014, resp.), as well as the PFPDS (p = 0.014 and p = 0.019, resp.). Plantar fascia thickness decreased in both groups at 12 weeks. In both groups, improvements in function (PFPDS) correlated significantly with decreased plantar fascia thickness at 4 and 12 weeks. In the CSI + TUS group only, the decrease in plantar fascia thickness was correlated with pain improvement at both follow-up visits. Echogenicity changed from hypoechoic to iso- or hyperechoic and improved significantly in both groups at 12 weeks follow-up, but changes were not different between the groups (p = 0.208). Both CSI + TUS and ESWT are effective treatments for female patients with chronic plantar fasciitis resulting in pain relief and improved function and fascia thickness. ESWT gave more pain relief at 12 weeks follow-up. CSI + TUS is effective as a rapid and short-term modality for relieving PF pain. According to previous studies, the addition of TUS does not appear to make CSI much more effective.

Study on water and gas permeation characteristics with ZIF-8 mixed matrix membranes

Abstract The membrane separation process lacks intrinsic permeation characteristics to compete with other separation technologies like adsorption, sedimentation, coagulation, skimming, and distillation. A mixed matrix membrane (MMM) is one of the strategies to improve the separation characteristics with embedded nanofillers particles. Zeolite imidazolate framework (ZIF) has a new subclass of inorganic–organic hybrid materials that are being introduced as new fillers for incorporation into the polymer matrix for various applications such as oily wastewater separation, wastewater treatment, natural gas dehydration, landfill gas upgrading, and mixed gas separation. In this experimental work, a metal-organic framework called ZIF-8 was synthesized and used as a filler for modification of MMMs and characterized with FTIR and SEM. ZIF-8 nanoparticles up to 5 wt% loading were added to PSF casting solution then the permeation characteristics of MMMs showed an improved result like the pure water flux of the modified membrane at 2.5 bar was increased up to 456.38 L/m2h. In the case of pure gas separation, at 5 wt% ZIF-8 loading in PSF, the pure gas CO2 permeability at 9 bar pressure had increased to 10.54 barrer.

Characterization of plywood made from heat-treated rubberwood veneers bonded with melamine urea formaldehyde resin

The objective of the study is to evaluate the properties of the plywood made from rubberwood veneers thermally treated at various temperatures. Rotary-peeled rubberwood veneers were thermally treated at 160, 170, 180, and 190 °C under 1 bar pressure. 5-ply plywood panels were produced using melamine urea formaldehyde (MUF) resin as binder. Dimensional stability, i.e., water absorption (WA) and thickness swelling (TS) as well as mechanical properties of the plywood were assessed. The results demonstrated that the dimensional stability of the plywood made from thermally treated rubberwood veneers improved as indicated by lower WA and TS values. The reduction in WA and TS values increased along with treatment temperatures. Darkening in the plywood as a result of heat treatment was observed. Meanwhile, heat treatment at 170 °C and 180 °C resulted in plywood with the highest modulus of rupture (MOR), modulus of elasticity (MOE) and shear strength. However, beyond that temperature, the mechanical strength of the plywood started to decline. Based on the findings in this work it appears that heat treatment of rubberwood veneers at temperatures ranging from 160 to 180 °C could have a potential to improve overall properties of plywood panels.

A neutron tomography study to visualize fluoride salt (FLiNaK) intrusion in nuclear-grade graphite

Manufactured graphite is a preferred material for in-core components of molten salt reactors and fluoride salt-cooled high-temperature reactors, which are in permanent contact with liquid salts. However, owing to the porous nature of nuclear graphite, under certain conditions, molten salts may intrude graphite's pores and affect graphite's properties and functionality. Therefore, a better understanding of molten salt intrusion (distribution across sample cross section and penetration depth) is needed to assess its effects. In this work, we have demonstrated the use of neutron imaging (computed tomography) in the evaluation of salt penetration and distribution of a wide range of graphite grades with diverse microstructures that have been subjected to FLiNaK (LiF–NaF–KF) intrusion at 750 °C and 5 bar pressure for 12 h. Because of the great neutron attenuation contrast from scattering and adsorption between Li (from FLiNaK) and the graphite matrix, we have obtained direct visualization of FLiNaK salt distribution in the salt-impregnated graphites for the first time. Three-dimensional reconstructed images and cross-sectional concentration profiles demonstrate that salt penetration and density distribution are greatly dependent on the microstructural properties of the graphite grade.

Impact of Irrigation on the Yield, Total Cost, and Its Influence on Hydraulic Conductivity in a Soil Under Vinasse Application

This study had the objective to evaluate the effect of irrigation and fertigation (N) in the crop yield and its impact on the total cost, in addition to its influence on the conductivity hydraulic capacity and logarithmic hydraulic conductivity in an Oxisol under vinasse application cultivated with sugarcane (second year), in state of Goiás, Brazil. The experimental design comprised randomized blocks in a 5 × 2 factorial scheme, with four replications. Treatments consisted of five levels of water replacement (100, 75, 50, 25 and 0%), with and without fertirrigation (N). The planting of sugarcane, cultivar RB85-5453, was performed in a double row (W-shaped), 8 m long, with 1.80 m spacing between the double rows, the distance between the crops in the double row was 0.40 m, with a total area of 52.8 m2 in each paddock. For treatments with water, replacement (WR) a drip tube was placed in the ground at a depth of 0.20 m among the furrows of the double row. The drip tube (DRIPNET PC 16150) comprised a thin wall, 1.0 bar pressure, nominal discharge 1.0 L h-1, and 0.50 m spacing between drippers. Nitrogen was applied by fertirrigation at a dose of 100 Kg ha-1, at 30-day intervals, with 10 applications throughout the development of the sugarcane culture. Potassium fertilization was fully realized at planting. The total cost with irrigation did not increase significantly with fertirrigation (< 3%) in an Oxisol under vinasse application.

Thermal aging effect of polyamide 6 matrix composites produced by Tailor Fiber Placement (TFP) under compression molding on sliding wear properties

AbstractToday, the aim is to reduce the harm caused by vehicles to the environment in accordance with decisions made to address environmental pollution and the global climate crisis. To this end, in addition to design improvements, and technological advancements, materials that can reduce the weight of the vehicles and provide the desired mechanical properties, are being studied. Glass fiber‐polyamide composites offer a unique combination of properties that make them suitable for a wide range of applications in the automotive industry. This study focused on the production of GF‐PA6 composites using compression molding and Tailor Fiber Placement (TFP) technology. The production was carried out at a constant temperature of 300°C, and 16 bar pressure, with holding times of 270–300–330 s. Short‐term thermal aging cycles were also applied to evaluate the effects of environmental exposure on the GF‐PA6 composite material. The wear behavior of the composite was then assessed through sliding wear tests, which indicated that an increase in holding time improved the wear resistance, while the aging process had a negative impact. The experimental results were analyzed statistically using response surface methodology (RSM) and showed a statistically consistent response. It was found that aging had no significant effect on the coefficient of friction (COF), but significantly impacted the wear rate. The COF of composite samples decreased approximately 35% with increasing holding time. When the sliding distance increased from 150 to 300 m, the wear rate value decreased by 24% in non‐aged samples and by 35% in aged samples.