Phase Content Research Articles

Experimental study on flow boiling heat transfer characteristics of zeotropic mixture R1233zd(E)/R1234yf in horizontal tube

This paper experimentally investigated the flow boiling heat transfer characteristics of zeotropic mixture R1233zd(E)/R1234yf with different mass fractions (80/20, 70/30, 60/40) within an 8 mm inner diameter horizontal tube. An analysis of the impact of different experimental conditions on the flow boiling heat transfer coefficient (HTC) was conducted under different vapor quality 0–1, mass fractions 80/20, 70/30, 60/40, mass velocity 196.97–328.28 kg m−2 s−1, heat flux 35.95–48.93 kW/m−2(−|−), and saturation temperature 40–60 °C. Results indicated that the variety in the density of vapor phase components and concentration gradients within the mixture under diverse conditions exhibited a notable influence on the HTC. Using the experimental data, the accuracy of several widely used correlations for estimating the flow boiling HTC of mixture is evaluated. Considering the impact of property variations on convective boiling during flow boiling, a new correlation is proposed. The new correlation yields a higher prediction accuracy compared to other correlations, demonstrating its effectiveness in predicting the HTC of this mixture working fluid.

Study of the phase formation of transparent magnesium aluminosilicate glass-ceramic materials

Current trends in the development of materials for optics and laser technology were analyzed. The prospects of creating passively Q-switched Yb-Er glass lasers with eye-safe emission wavelengths based on glass-ceramic magnesium aluminosilicate materials for compact pulsed lasers were established. The main types of transparent glass-ceramic materials were analyzed and the main criteria for the synthesis of transparent nanostructured glass-ceramic materials with a crystalline phase content of approximately 70–80 vol.% were substantiated. Compositions of magnesium aluminosilicate glasses were synthesized and the differences of compositions with different types of optical transparency were determined, taking into account their thermal prehistory. The mechanism of phase formation and the differences of MgO, Al2O3, MgO/Al2O3 and RO2 in their composition, which determine the character of crystallization, optical transparency and density under the conditions of heat treatment with a duration of 0.5 and 6 hours, were studied. The developed magnesium aluminosilicate glasses can be used as a basis for the creation of protective and functional high-strength nanostructured glass-ceramic materials based on spinel or cordierite with adjustable optical transparency for optics and laser technology.

Achieving superior compressive strength-ductility synergy in a novel ODS-CrFeNi/AlCrFeNi heterostructured high-entropy composite

A novel high-entropy heterostructured composite (ODS-CrFeNi/AlCrFeNi) was fabricated by powder metallurgy method. The microstructure and mechanical properties of the composites with various sintering temperatures (950 °C to 1100 °C) and various addition amounts (0% to 20%) of FCC-structured reinforcing phase (ODS-CrFeNi) were investigated. The results revealed a reduction in porosity and an increase in relative density, reaching up to 99% with increasing sintering temperature. The optimal sintering temperature is 1100 °C. In the composites with the addition of 5% and 10% ODS-CrFeNi reinforced phases, spinodal decomposition (SD), forming BCC and B2 phases, takes place both in the matrix and in the reinforcing phase. As the reinforcing phase content is increased to 15% and 20%, SD occurs exclusively in the matrix while is suppressed in the reinforcing phase. The reinforcing phase consists of hard BCC structured Cr rich phases and soft FCC-structured FeNi phases, forming a gradient network structure. The composite with 15% reinforcing phase exhibits high hardness of 841 HV and compressive yield strength, ultimate strength and strain of 6960 MPa, 7690 MPa and 15.5%, respectively, which are 2.5, 2.7 and 1.9 times higher than those of the reference alloys (without reinforcing phase). The excellent strength-ductility synergy originates from the unique gradient network structure formed in the reinforcing phase, i.e. complex heterogeneous structure, which results in hetero-deformation induced (HDI) strengthening for higher strength and HDI strain hardening for higher ductility.

Correlation analysis of various characteristics of fly ash based on particle separation

Due to the diversity of fly ash particles, it is a scientific way to promote the comprehensive utilization of fly ash with high efficiency to sort and classify the particles. The correlation between sorting indices and various characteristics of fly ash is the theoretical basis for its separation and classified application. In this paper, fly ash from three different coal-fired power stations is separated according to particle size and apparent density. The composition, morphology, and pozzolanic activity of the separated fly ash particles were characterized by several test techniques including X-ray fluorescence, X-ray diffraction, polarized light microscopy, scanning electron microscopy and lime absorption test. The correlation laws between different characteristics common to three types of fly ash were analyzed. The results show that the alkaline oxide (CaO+MgO+K2O+Na2O) content of fly ash varies accordantly with particle size, apparent density, glass phase content and pozzolanic activity. 40 μm and 80 μm are the critical particle size for the obvious change of glass phase content and microstructure of fly ash particles, and 2.5g·cm-3 is the critical apparent density for the change of phase composition. Pozzolanic activity is determined together by alkaline oxide content and acid oxide (SiO2+Al2O3) content, and there is no obvious single factor relationship between pozzolanic activity and particle size or apparent density.

Microstructure and mechanical properties of tungsten matrix composites synergistically reinforced with TiC-ZrC particles prepared by spark plasma sintering

In this paper, W-TiC-ZrC composites with extremely high strength were prepared by high-energy ball milling followed by spark plasma sintering. The microstructure morphology and structural evolution of the composites were thoroughly analyzed by SEM, EDS, EBSD, XRD, XPS and TEM, and the mechanical properties of the composites were accurately evaluated by microhardness tests and compression tests at room temperature and high temperatures. The results show that the micromorphology of W-TiC-ZrC composites changes from a spherical shape to an elongated shape with the increase of TiC-ZrC addition. Meanwhile, the grain size decreased from 1.32 μm to 0.32 μm with the increase of the reinforcing phase content, however, the strength has a significant enhancement, and the microhardness and compressive strength of the W-3%TiC-3%ZrC composites are 952.0 HV and 2754.6 MPa, respectively. In addition, the W-3%TiC-3%ZrC composites were also shown to exhibit sufficient thermal stability, with compressive strengths of 2716.2 MPa, 2560.8 MPa, and 2323.8 MPa at 200 °C, 400 °C, and 600 °C, respectively. The extremely high strength of W-matrix composites is due to the formation of various second phases in the composites. The appearance of the second phases plays a role in fine grain strengthening, dispersion strengthening, solid solution strengthening, and thermal mismatch strengthening.

Effect of different Zn/Mg ratios on the uniformity of 7185+TiB2/TiC aluminum alloy thick plates

Three types of 7185+TiB2/TiC aluminum matrix composites with different Zn/Mg ratios were prepared in this work through a water-cooled copper casting process. The effects of Zn/Mg ratio on the microstructure and mechanical properties of 20-mm-thick composites were studied by optical microscopy, electron back scattering diffraction, transmission electron microscopy, and tensile mechanical testing. The results showed that the addition of appropriate TiB2/TiC particles refined the as-cast microstructure of the alloy, and with a decrease in Zn/Mg ratio, the grain size distribution became more uniform, the crystalline phase content gradually increased, and the uniformity of the alloy increased. After aging, as the Zn/Mg ratio decreased, the size of the precipitated phase decreased, and the strengthening effect of the alloy improved. The tensile strengths of the surface layer, 1/4 layer, and center position of the A3 alloy were 558, 568, and 572 MPa, respectively. The strength difference among the different thickness layers was the smallest, and the elongation rate was greater than 12%, resulting in the best uniformity.

Behavior of free-standing atmospheric plasma sprayed Al2O3–Cr2O3 solid solution-based coatings under cyclic heating at 1000 °C

This paper investigates the cyclic heating behavior of free-standing atmospheric plasma sprayed Al2O3 - Cr2O3 coatings containing a solid-solution phase. The coatings are deposited on steels by spraying mechanically blended Al2O3 - Cr2O3 powder mixture with variable Cr2O3 content (2–6 wt%) in the feedstock. The tests are performed up to 50 cycles at 1000 °C temperature in a muffle furnace in a normal atmosphere. After each cycle, the weight gain of the coatings is measured, and the oxidation rate constant (Kp) for each material is estimated. The microstructure and phases of the coatings are studied by using scanning electron microscopy (SEM) and X-ray diffractometry (XRD) techniques respectively. The porosity and crack length are estimated by image analysis (Image J) technique. The hardness of the coatings is measured by Vickers microhardness tester. After 50 cycles, all the free-standing coatings are found to be intact without fragmentation. At higher cycles, the Al2O3 - Cr2O3 coatings form α-Al2O3 and (Al0.9Cr0.1)2O3 solid-solution phase only. The Al2O3 - Cr2O3 coatings gain much less weight than the pure Al2O3 coating due to the major presence of oxidation resistant α-Al2O3 phase in the former. However, among the Al2O3 - Cr2O3 coatings with an increase in Cr2O3 content, the Kp value tends to increase due to the high presence of metastable (Al1.8Cr0.05)2O3 solid-solution phase. On the other hand, the (AlxCr1-x)2O3 phase helps to reduce crack formation due to its high fracture toughness properties. With the highest amount of solid-solution phase content, the Al2O3-4 wt% Cr2O3 coating shows the highest fracture toughness among all. The micro-porosity of the coatings is increased with an increase in the heating cycle, and the coating hardness is reduced accordingly.

Evolution of cracks in laser powder bed fused AA2024 and its processing parameter dependence

Hot cracking is one of the most hideous issues in the fabrication of high-strength aluminum alloys via laser powder bed fusion (LPBF). This study investigated the evolution of hot cracking in LPBFed AA2024 and explored its processing parameter dependence. Results showed that most cracks distribute along continuous eutectic phases residing at grain boundaries. At the last stage of solidification, the eutectic composition with low melting point exists as a liquid film, which can be easily ruptured under stress caused by thermal contraction. This leads to the formation of cracks along grain boundaries. This cracking process is also related to the misorientation angle of grains, where higher angle results in more stable liquid films. Furthermore, increasing the laser power transforms the grain structure from fine columnar grains to coarse columnar grains, which eventually transform to a mixture of columnar and equiaxed grains. This grain structure transition results in the decrease followed by increase of critical stress for the rupture of liquid film. On the other hand, decreasing the scanning speed increases the eutectic phase content, which could enhance the permeability of mushy zone and thus reduce the cracking susceptibility. These findings could provide guidance for the fabrication of crack-free high-strength aluminum alloys via LPBF.

Preparation and mechanical performance analysis of porous Ti6Al4V scaffold fabricated by direct ink writing

In order to mitigate the stress-shielding effect resulting from the stiffness disparity between titanium alloy and bone, the use of additive manufacturing to create porous Ti6Al4V components shows promise for orthopedic implant applications. In this study, a novel hot-melt–quick-frozen polyvinyl alcohol hydrogel was developed for direct ink writing to create porous titanium structures using Ti6Al4V powders with an irregular morphology. The rheological and sintering properties of inks with varying solid phase contents were examined to assess their molding quality. Furthermore, the effect of porosity on the morphology, shrinkage, and mechanical properties of the scaffolds was thoroughly investigated. The results of the experiments show that inks loaded with 65 vol. % Ti6Al4V particles exhibit the highest printing performance. Furthermore, the analysis revealed a positive correlation between the total porosity of the scaffold and its mechanical performance. In particular, the strength of the scaffold with a porosity of 54.8% exceeded that of human bone, and it also exhibited matched stiffness. Upon analyzing the final microstructure and mechanical properties, it is evident that these scaffolds meet the necessary criteria for use as orthopedic implants.

Investigation on gas–liquid–solid three-phase flow model and flow characteristics in mining riser for deep-sea gas hydrate exploitation

In response to the problem of gas–liquid–solid three-phase flow in deep-sea hydrate extraction pipelines, a gas–liquid–solid three-phase flow model considering the dynamic decomposition of hydrates is established using continuity equations, momentum equations, and energy equations. The numerical solution of the theoretical model is achieved using the finite difference method. Comparing the theoretical model with the experimental results, the results showed that the average error of gas holdup, liquid holdup, solid phase content, gas phase velocity, liquid phase velocity, and solid phase velocity obtained from the theory and experiment are 8.24%, 0.41%, 1.88%, 5.80%, 2.81%, and 2.22%, respectively, which verified the correctness of the theoretical model. On this basis, the influences of hydrate abundance, liquid phase displacement, and wellhead backpressure on the gas–liquid–solid three-phase flow characteristics in the pipeline were investigated, and it was found that the gas holdup rate will increase with the increase in hydrate abundance, liquid phase displacement, and wellhead backpressure, with the influence of hydrate abundance being more sensitive. The liquid holdup rate increases with the increase in hydrate abundance and liquid phase displacement, but decreases first and then increases toward the wellhead position with the increase in wellhead backpressure. The solid phase content decreases with the increase in hydrate abundance, and first increases and then decreases toward the wellhead position as the liquid phase displacement and wellhead backpressure increase. The influence of gas phase velocity on the abundance of hydrates is relatively small, but it increases with the increase in liquid phase displacement. When the wellhead backpressure increases, the instantaneous increase then tends to flatten out. The influence of hydrate abundance on the liquid phase velocity is also relatively small, but it increases with the increase in liquid phase displacement and decreases with the increase in wellhead backpressure. The solid phase velocity will increase with the increase in hydrate abundance and liquid phase displacement, but it will not show significant changes with the change of wellhead backpressure. The research results can provide a theoretical basis for the safety of hydrate mining.

Efficient lithium separation from alkali metal brine with ultrasonic assisted composite ionic liquid membrane processing

Membrane is a raising technology for selective metal mining from brine that could be used for lithium extraction. Selective and efficient ultrasonic assisted separation of lithium from brine containing alkali metals salts is conducted using composite membrane formed by sealing supported ionic liquid membrane (1-alkyl-3-methylimidazolium hexafluorophosphate ([RMIM][PF6]) + tributyl phosphate (TBP) in polyvinylidene fluoride (PVDF)) with polyvinyl chloride (PVC) thin film membrane. This process is examined by adjusting of parameters of membrane, feed, and ultrasonic to reveal the best condition for selective separation of lithium from alkali metals. Results show that membrane containing 0.5:0.5 mass fraction of [MOIM][PF6]:TBP is more selective between the studied membranes. The flux of lithium is higher during short sonication times, while it decreases with increment of the duration of ultrasonic irradiation. At 100 kHz, 50 % amplitude and sonication sequence with a feed phase concentration containing 500 ppm of chlorine slats of Li, Na, and K in the presence of different concentration of ILM, flux of Li was 10.45 mg cm−2 min−1 Pa−1 with selectivity indexes of 2.21 Li:Na and 2.49 Li:K.

Щодо взаємодії і захоплення металевих крапель доменним шлаком

The mechanism of capture of metal drops by the slag melt was investigated using blast furnace slag as an example. The role of the viscosity of the blast furnace slag in reducing iron loss at the output from the blast furnace is shown. Reducing the viscosity of slags contributes to the rapid settling of small drops of cast iron in the slag volume. It is noted that the CaO/SiO2 ratio is an important parameter that changes the viscosity of blast furnace slag. To ensure the minimum viscosity of blast furnace slag, it is necessary to establish the optimal chemical composition of the slag, in particular the CaO/SiO2 ratio. A study of the temperature dependence of the viscosity of blast furnace slag melts was carried out using the method of estimating the content of the solid phase in the melt during its cooling. Calculations of the volume fraction of the solid phase for blast furnace slags were performed. An increase in the CaO/SiO2 ratio in slags leads to an increase in their crystallization ability. The microstructure and chemical composition of individual phases of a blast furnace slag sample were studied using scanning electron microscopy (SEM). It was established that the experimental slag contained at least three phases. The main (matrix) phase was an amorphous phase, which contained mainly SiO2 and Al2O3. The volume of the matrix phase contained interspersions of the crystalline phase of different sizes, which mainly included CaO and SiO2. In the volume of the crystalline phase, a metallic phase was found, which consisted mainly of Fe and Mn and had a regular rounded shape. The mechanism of capture of a metal droplet by slag is described. The metal drop serves as a frame (center) for the nucleation of the crystalline phase in the slag volume, as its surface energy decreases at the "metal drop - slag" interface. An increase in the mass of the crystalline phase around the metal drop leads to an increase in its lifting force and capture of the metal drop. Keywords: blast furnace slag, viscosity, metal loss, crystallization, scanning electron microscopy.

Effect of Si and Holding Time on Ti2Al20La Phase in Al-Ti-La Intermediate Alloy.

The effects of holding time and Si on the content, shape size and structure of Ti2Al20La phase in Al-Ti-La intermediate alloy were investigated by an X-ray diffractometer, scanning electron microscope and transmission electron microscope. The results show that the volume fraction and aspect ratio of Ti2Al20La phase in Al-Ti-La intermediate alloy decrease significantly, from 21% and 2.3 without Si addition to 4% and 2.0 with the addition of 2.3 wt.% Si at a holding time of 15 min at 750 °C, respectively. The Si element will attach to the Ti2Al20La phase and form La-Si binary phase at the grain boundary of α-Al. With the increase of holding time from 15 min to 60 min, the content of Ti2Al20La phase in the alloy gradually decreases and the size decreases significantly. Meanwhile, Al11La3 will dissolve and disappear, while the content of La-Si binary phase increases, and part of Ti2Al20La phase transforms into Ti2(Al20-x,Six)La phase.

Effective Transport Recovery of Palladium(II) from Hydrochloric Acid Solutions Using Polymer Inclusion Membrane with Tetrabutylammonium Bromide.

This article reports on the extraction of palladium(II) from hydrochloric acid (HCl) solutions using polymer inclusion membranes (PIMs) containing tetrabutylammonium bromide (TBAB) as the ion carrier. The membranes were based on cellulose triacetate (CTA) as the polymer support. The main aim of this study is to determine the possibility of TBAB's application as the effective ion carrier/extractant of Pd(II) from hydrochloric acid solutions. At first, the effect of the hydrochloric acid concentration in the aqueous phase on palladium(II) extraction was investigated. Next, cellulose triacetate membranes with TBAB as the carrier were prepared and applied for the recovery of Pd(II) from HCl solutions. As a result of the investigations, the optimal composition of the receiving phase was determined to be 0.5 M thiourea in 0.1 M hydrochloric acid. The effect of the acid concentration in the source phase was investigated. The results show a linear decrease in the permeability coefficient and initial flux of palladium(II) with an increase in the hydrochloric acid concentration in the source phase. The separation of Pd(II) from Pt(IV) from the hydrochloric acid solution was also studied. The transport rate of Pd(II) was higher than Pt(IV). The separation coefficient SPd/Pt was 1.3. The results show that transport through PIMs with TBAB can be used as an effective method to recover Pd(II) from hydrochloric acid, especially at a low concentration of this acid.

Widespread occurrence of pesticides in low-income housing

BackgroundLow socioeconomic status (SES) residents living in social housing, which is subsidized by government or government-funded agencies, may have higher exposures to pesticides used in indoor residences since pesticides are applied due to structural deficiencies, poor maintenance, etc.ObjectiveTo estimate exposure of residents in low-SES social housing built in the 1970s to legacy and current-use pesticides and to investigate factors related to exposures.MethodsTwenty-eight particle-phase pesticides were measured in the indoor air of 46 units in seven low-income social housing, multi-unit residential buildings (MURBs) in Toronto, Canada using portable air cleaners deployed for 1 week in 2017. Pesticides analyzed were legacy and current use in the classes: organochlorines, organophosphates, pyrethroids, and strobilurins.ResultsAt least one pesticide was detected in 89% of the units with detection frequencies (DF) for individual pesticides of up to 50%, including legacy organochlorines and current-use pesticides. Current-use pyrethroids had the highest DF and concentrations, with the highest particle-phase concentration for pyrethrin I at 32,000 pg/m3. Heptachlor, restricted for use in Canada in 1985, had the highest estimated maximum total air (particle plus gas phase) concentration of 443,000 pg/m3. Heptachlor, lindane, endosulfan I, chlorothalonil, allethrin, and permethrin (except in one study) had higher concentrations than those measured in low-income residences reported elsewhere. In addition to the intentional use of pesticides to control pests and their use in building materials and paints, tobacco smoking was significantly correlated with the concentrations of five pesticides used on tobacco crops. The distribution of pesticides with high DF in individual buildings suggested that pest eradication programs by the building management and/or pesticide use by residents were the major sources of measured pesticides.ImpactLow-income social housing fills a much-needed demand, but the residences are prone to pest infestation and hence pesticide use. We found exposure to at least 1 of 28 particle-phase pesticides in 89% of all 46 units tested, with the highest DF and concentrations for current-use pyrethroids and long-banned organochlorines (e.g., DDT, heptachlor) due to very high persistence indoors. Also measured were several pesticides not registered for use indoors, e.g., strobilurins used to treat building materials and pesticides used on tobacco crops. These results, which are the first Canadian data for most pesticides indoors, show widespread exposure to numerous pesticides.

Fabrication and Stability Improvement of Monoglyceride Oleogel/Polyglycerol Polyricinoleate-Stabilized W/O High Internal Phase Pickering Emulsions.

To decrease the lipid content in water-in-oil (W/O) emulsions, high internal phase Pickering W/O emulsions (HIPPE) were fabricated using magnetic stirring using a combination of monoglyceride (MAG) oleogel and polyglycerol polyacrylate oleate (PGPR) as stabilizers. Effects of MAGs (glyceryl monostearate-GMS, glycerol monolaurate-GML and glycerol monocaprylate-GMC) and internal phase components on the formation and properties of HIPPEs were investigated. The results showed that milky-white stabilized W/O HIPPE with up to 85 wt% aqueous phase content was successfully prepared, and the droplet interfaces presented a network of MAG crystals, independent of the MAG type. All HIPPEs exhibited great stability under freeze-thaw cycles but were less plastic. Meanwhile, GML-oleogel-based HIPPEs had larger particle size and were less thermal stable than GMS and GMC-based HIPPEs. Compared to guar gum, the internal phase components of sodium chloride and sucrose were more effective in reducing the particle size of HIPPEs, improving their stability and plasticity, and stabilizing them during 100-day storage. HIPPEs presented great spreadability, ductility and plasticity after whipping treatment. This knowledge provides a new perspective on the use of oleogels as co-stabilizers for the formation of W/O HIPPEs, which can be used as a potential substitute for creams.

Limonene-enriched ultra-structural cubosomes to augment ocular delivery of a poorly water soluble anti-fungal drug: Fabrication, characterization, statistical optimization, in vivo corneal uptake and histopathological evaluation in rabbits

The target of this investigation was to obtain the composition of the optimized Fenticonazole nitrate (FCN)-loaded cubosomal formula that can prolong precorneal retention, increase corneal absorption, enhance corneal permeation, and anti-fungal efficacy of FCN. Cubosomes are bi-continuous structural vesicles fabricated using the hot emulsification technique in accordance with a 23-full factorial design. The selected fabrication factors were the concentration of the Lipid phase (X1), glyceryl monooleate: lipid phase stabilizer ratio (X2), and aqueous phase stabilizer types (X3). Whereas, the encapsulation efficiency percent (EE%), Mean particle size (PS), Polydispersity index (PDI), and Zeta potential (ZP) were chosen as measured responses. The numerical optimization criterion of the design expert software was utilized to select the optimized formula (Op) for extra investigations. The Op formula had EE% of 87.94 ± 0.7 %, PS of 249.75 ± 1.48 nm, and ZP of −34.25 ± 0.64 mV. The in vitro release study of the Op formula in comparison with FCN suspension showed a zero-order and controlled kinetic release behavior. Moreover, the results of the pH, refractive index, surface tension, and mucoadhesion study confirmed the superiority and the safety of the Op formula. Further, the ex vivo permeation study demonstrated a significant enhancement in the transcorneal permeation of the Op formula than FCN suspension by 2.69-fold. Besides, the in vivo corneal uptake confirmed the higher permeation of the Op formula in comparison with FCN suspension. Draize test and histopathological examination ensured the in vivo safety and tolerability of the Op formula. Overall, the previous findings ensured the efficacy of cubosomes in enhancing ocular retention, absorption, permeation, and bioavailability of FCN.

Fabrication and luminous properties of BaAl2O4-LuAG:Ce composite phosphor ceramics for solid-state laser lighting

Based on the “effective ionic radius match effect” and the “charge balance substitution rule of ions”, mixed Ba2+, Al3+, Lu3+, and Ce3+ ions can be effectively regulated to a BaAl2O4-LuAG:Ce biphasic structure. The contribution of BaAl2O4 like as scattering centers can reduce overall reflection losses and enhance the light extraction efficiency of these composite phosphor ceramics (CPCs). In this work, a series of x wt.% BaAl2O4-LuAG:Ce (x = 0, 3, 5, 10, 15) CPCs were fabricated by vacuum sintering using co-precipitated composite powders. Homogenization at the atomic level of mixed Ba3+, Al3+, Lu3+, and Ce3+ ions in multiphase powders provides uniform distribution of BaAl2O4 and LuAG:Ce constituent phases in composite ceramics. The introduction of BaAl2O4 has an additive effect, which also consists in uniform aggregation of pores near their grains during sintering. It allows to adjust the size and amount of microstructural defects by varying the secondary phase content. Under the excitation of 10.8 W 450 nm LDs in a reflection mode, 3 wt% BaAl2O4-based CPCs show the optimum luminous flux of 2244 lm and a luminous efficiency of 208 lm·W−1. The obtained CPCs show a high application potential in solid-state laser lighting.

Effect of laser energy density on cracking susceptibility and wear resistance of laser-clad tribaloy T-800 coatings on DD5 single-crystal alloys

In order to enhance the wear resistance of DD5 single-crystal alloys, Tribaloy T-800 wear-resistant coatings were prepared on their surfaces using laser-cladding technology. This study examines the effect of laser energy density on the cracking susceptibility and wear resistance of laser-clad Tribaloy T-800 coatings on DD5 single-crystal alloys. Three distinct laser energy densities (η1=33 J/mm², η2=50 J/mm², η3=60 J/mm²) were applied to create the coatings. The results show that the microstructures of the T-800 laser-clad coatings mainly consist of primary, coarsened, and spheroidized Laves phases, as well as Co-based solid solution and eutectic structures. The phases include Co3Mo2Si phase (Laves phase) and face-centered cubic Co-based solid solution. However, increasing laser energy density enhanced elemental diffusion at the heterogeneous joining interface of the DD5 substrate/T-800 coating, leading to higher Ni content in the coating. This resulted in a reduction in the tendency and content of Mo-rich Laves phase formation respective contents of 53.2 %, 49.2 %, and 47.5 %. Moreover, the decrease in the difference between laser cladding temperature and initial temperature, ∆T, led to reduced thermal stress at the interface, σ, contributing to a decrease in cracking susceptibility (a), with corresponding values of 0.16184, 0.00034, and 0.00022. Thermal expansion coefficients of materials in the cracked region near the interface, measured according to the CALPHAD method, Jmatpro software, and average EDS elemental content data at the crack edge, surpassed those of the corresponding DD5 substrate. Consequently, cracks in the coatings originated from stretching at the interface, with paths tending to cross Laves phase particles in a cleavage mode. The average microhardness of the coatings decreased due to reduced Laves phase content, with values of 783.4 HV0.5, 741.7 HV0.5, and 708.2 HV0.5, respectively, while the fatigue wear of T-800 coatings increased due to exacerbated wear damage from cracking defects. Specifically, average COFs were 0.659, 0.583, and 0.506, with corresponding mass losses of 7.1 mg, 3.4 mg, and 2.9 mg, respectively. The wear mechanisms observed encompassed fatigue wear, abrasive wear, and oxidative wear.

Effects of membrane content, feed phase, and stripping phase for palladium solution extraction by using a polymer inclusion membrane.

Palladium is now frequently utilized in fuel cells, electroplating, electronics, and catalysis. Due to their rarity and high cost, precious metal recovery has taken on a significant role. The extraction method frequently utilized in polymer inclusion membranes (PIMs) is both efficient and simple since it has been demonstrated that precious metal adsorption on the membrane significantly controls the mechanism of chemical adsorption. In this study, polyvinyl chloride (PVC) as a polymer, A336 as a plasticizer, and trioctylamine (TOA) as a carrier were used to produce a PIM by evaporation. After the production of PIMs, palladium extract was studied. The stripping phase, palladium concentration in the feed phase, and components of the membrane were changed to determine the optimum condition with better extraction ability. When 0.5 M of HCl was used, higher kinetic parameter results and higher than 85% extraction efficiency were achieved compared to other concen- trations. When the EDX results were examined, 3.3% palladium was retained on the membrane surface. When the palladium concentration was selected at 2.5 ppm, higher kinetic parameters were observed, and the extraction efficiency was over 90%. The best membrane was the PIM containing 40% PVC-40% A336-20% TOA.