Increasing Solution Temperature Research Articles

Influences of solution temperature on microstructures and performance of electron beam welded joints of laser powder bed fusion TC11 thin-walled samples

The effects of subtransus treatment (750 °C, 800 °C, 850 °C, 900 °C, and 950 °C) as well as supertransus treatment (1100 °C) on the microstructures and mechanical performance of electron beam welded (EBW) joints of laser powder bed fusion (LPBF) TC11 alloy were investigated. At a solution temperature of 950 °C, globular α phases and transformed β phases were observed in the joint. When the solution temperature exceeded the β transus temperature (Tβ), α colonies and massive α phases emerged in the joints, resulting in Widmanstatten structures. The base metal (BM) exhibited the highest microhardness, followed by the heat affected zone (HAZ), whereas the fusion zone (FZ) demonstrated the lowest microhardness. As the solution temperature increases, the microhardness of joints decreases at first and then increases. Notably, the joint subjected to a solution temperature of 850 °C exhibited the lowest microhardness. When the solution temperature was ≥900 °C, transformed β phases emerged within the joints, resulting in an elevation of microhardness. Below Tβ, the elongation of welded joints gradually augmented while the tensile strength reduced at first and then increased with the rising solution temperature. Microstructures in joint with solution temperature of 950 °C consisted of lamellar α phases, globular α phases, and transformed β phases. As a result, the joint exhibited an optimal balance between strength (1103.1 ± 34.9 MPa) and plasticity (9.37 ± 0.20%). Ductile fracture characteristics with dimples on the fracture surface were observed in the tensile samples. Therefore, it can be concluded that a solid solution temperature of 950 °C is optimal for LPBF TC11 alloy.

Investigation on work hardening rate of Al-Zn-Mg-Cu alloy under solid solution process and thermomechanical coupled multi-step fast aging process

In this paper, the work hardening rate of Al-Zn-Mg-Cu alloy in the conditions of solid solution and thermo-mechanical coupled fast aging were investigated separately, and the main research content and results are as follows. Under the solid solution processes at different temperatures, the uniaxial tensile test curves of work hardening rate are relatively dispersed at a lower strain rate, and the work hardening rate increases with the increase of solution temperature. Then, as the strain rate increasing, the work hardening rate curves at each solution temperature gradually converge, until all curves intersect at a common intersection point. The above mechanism is attributed to the comprehensive effect of precipitates, solid solutions, and dynamic strain aging in the matrix. For the thermo-mechanical coupled aging, the work hardening rate has a great different with that of solid solution process. Consequently, the influence of pre-deformation on the work hardening rate were investigated, which concludes the curve shape type and the softening coefficient. The introduction of dislocation have some significant influences on the work hardening rate. Firstly, it makes the shape of work hardening rate curves change from shape 1 to shape 2. On the other hand, as the pre-deformation increasing, the variation law of softening coefficient shows an abnormal trend that is different from the ordinary law, which is due to the coordinated effect between dislocation density and dislocation induced precipitation. Furthermore, in order to reveal the internal mechanism in depth, the microstructure are observed by TEM (Transmission electron microscope). Finally, a targeted set of analytical models for work hardening rate were established, especially the mathematical explanation of the multicollinearity phenomenon of work hardening rate curves in the solid solution condition.

Effect of Temperature and NaClO on the Corrosion Behavior of Copper in Synthetic Tap Water

The corrosion behavior of copper was investigated in synthetic tap water with and without sodium hypochlorite (NaClO) at different temperatures during immersion for 70 d by using scanning electron microscopy (SEM), X-ray diffraction (XRD), and electrochemical measurement techniques. The weight loss corrosion rate and pit depth of copper first increase and then decrease with the change in solution temperature from 25 to 80 °C. This is mainly related to the corrosion products formed on the copper surface. The main corrosion products change from Cu2O and Cu2(OH)2CO3 to CuO with the increase in solution temperature. The presence of 3 ppm NaClO slightly increases the weight loss corrosion rate and pit depth of copper under all temperatures except for 50 °C and reduces the temperature of the maximum corrosion rate from 50 to 40 °C. Free chlorine reduction accelerates the cathodic reaction of the corrosion process.

Effect of Two-Step Solution Treatments on the Microstructure and Mechanical Properties of B357 Aluminum Alloy

AbstractThis study investigates the effect of two-step solution treatments and aging times on the microstructure and mechanical properties of B357 Al–Si alloy, part of the most widely used cast aluminum alloy. Three sets of artificial aging heat treatments were conducted on the tensile samples prepared from B357 alloy produced by low-pressure die casting. Firstly, the conventional artificial aging heat treatment (T6) was carried out by solutionizing the tensile samples at 543 °C for 8.5 h, water quenching at 60 °C, and then artificially aging for 8.5 h at 160 °C. In the two-step solution treatment, the samples were solutionized at 400, 440, 480, and 520 °C for 4 h and then solutionized at 543 °C for 8.5 h and water quenched to 60 °C and then artificially aged for 8.5 h at 160 °C. Thirdly, the samples were solutionized at 480 °C for 4 h, solutionized at 543 °C for 8.5 h, water quenched to 60 °C, and artificially aged for 3–192 h. Despite different solutioning and aging processes, no significant differences were observed in the microstructures of the samples. Si particle coarsening was observed with increasing solution temperature (400–520 °C) and aging times (3–192 h). Si-containing dispersoids and dispersoid-free zones (DFZ) were observed in the primary-α matrix. While DFZ width increased with temperature and aging, dispersoid zones in primary-α dendrites significantly decreased. Differential Scanning Calorimetry (DSC) analysis shows that two-step solution treatment in B357 alloy increases β′ precipitates for Mg2Si precipitation strengthening. The two-step solutionized and aged sample showed the best combination of strength and ductility among all aged samples. B357 alloy exhibited the highest yield and tensile strength (309.7, 366.1 MPa) with 6% elongation for two-step solutionizing and 48 h aging. All aged B357 alloys showed ductile fracture as the primary fracture mode. However, brittle fractured Si particles were observed on the fracture surfaces.

Adaptation of a heat-treatment condition to a precipitation-hardened nickel-based superalloy produced by laser powder bed fusion

This study evaluated the microstructural evolution and mechanical properties of a novel printable nickel-based superalloy subjected to a solution aging treatment. The microstructures of the alloys in as-fabricated and solution-treated states were characterized using a combination of electron backscatter diffraction analysis and scanning electron microscopy. The findings indicate that the cellular crystals gradually transitioned into equiaxed grains with increasing solution temperature. The grain orientation shifts from the <001> orientation perpendicular to the building direction to a random orientation. The average grain size increased, the proportion of low-angle grain boundaries (LAGBs) decreased, and the percentage of annealing twin boundaries (TBs) increased from 0.18% in the as-fabricated state to 65.68% at 1230 °C solution treatment (ST). After lower-temperature ST, a large amount of primary γ′ and η phases precipitated in the as-fabricated alloy, with spherical and needle-like shapes, respectively. As the solution temperature increased, the quantity of the primary γ′ phase gradually decreased, and the η phase became relatively more elongated. At 1130 °C ST, both phases dissolved; following aging treatment, γ′ phase precipitated fully. High strength (1493 MPa) was achieved after direct aging treatment, attributed to the combination of cellular structures and numerous LAGBs produced during deposition with the complete precipitation of γ′ phase during aging. This study demonstrated that laser powder bed fusion alloys can achieve excellent mechanical performance through direct aging without needing ST.

Influence of quenching plus aging on microstructures and mechanical properties evolutions for Ti-Al-Sn-Zr-Mo-Si-Nb-Ta-Er-C near-α high temperature titanium alloys

The microstructures and mechanical properties of β-forged and as-heat treated high temperature titanium alloys were carefully investigated. Heat treatments with solution processes varying from 940℃～1010℃ and aging at 650℃ after water quenching were adopted. After forging, prior β grains were squashed and elongated. The content of the primary α phase decreased with increasing solution temperatures, while the content of the transformed β structures increased. After water quenching plus aging processes, super-fine secondary α lamellas with widths of 80～400 nm precipitated in transformed β structure. Secondary nano-scale silicides with a size of ～82 nm re-precipitated. More α2 phase particles with a mean size of 8.00 nm were dispersively and uniformly precipitated. After heat treatment at 1000℃, the room temperature ultimate strength and yielding strength were enhanced by 241 MPa and 228 MPa, reaching 1256 MPa and 1151 MPa, respectively. The high temperature ultimate strength and yielding strength were enhanced by 119 MPa and 128 MPa, reaching 756 MPa and 669 MPa, respectively. The high temperature elongation increased to 13.6%. The excellent mechanical properties compared to the previously studied were ascribed to the precipitation of super-fine secondary α lamellas in βt, dispersed nano-scale silicides and α2 particles, and the superior mixing proportion of Pα and βt acquired after optimization of heat treatments.

Synergistically achieving high strength and impact toughness in Ti–6Al–4V-0.5Mo-0.5Zr alloy pipe with bimodal microstructure

To achieve high strength and high impact toughness, three kinds of bimodal microstructure of Ti–6Al–4V-0.5Mo-0.5Zr alloy pipe were tailored through solution treatment at the α+β phase region (860 °C, 890 °C, and 920 °C) and followed by aging at 500 °C. The bimodal microstructure consists of the primary α (αp) and β-transformed domain (βt), in which the secondary α phase (αs) precipitated in the β matrix, with different volume fraction. With the increase in solution temperature, the grain size of αp remained unchanged while the volume fraction decreased. At the same time, the volume fraction of βt and the width of αs phase increased. Furthermore, the content of low-angle grain boundaries inside the αp phase decreased. Subsequent aging resulted in finer precipitation of αs within the βt domain. Solution treatment at 890 °C and ageing at 500 °C (denoted as the STA890 sample) achieved an excellent combination of yield strength 903 MPa, tensile strength 1023 MPa, elongation 12.9%, and impact energy 31 J. With the increase of αs width, the strength of the alloy decreased, and the ductility increased slightly. Higher impact energy originated from {10 1‾ 2} tension twins activated in the STA890 sample during the impact loading process, αp and βt underwent severe bending and plastic deformation. The present study provides a feasible industrial heat treatment strategy for improving impact energy with high strength of the α+β titanium alloy pipe used for oil drilling.

Chemotherapeutics Loaded Poly(Dopamine) Core-Shell Nanoparticles for Breast Cancer Treatment.

Chemophotothermal therapy is an emerging treatment for metastatic and drug resistant cancer anomalies. Among various photothermal agents tested, polydopamine provides an excellent biocompatible alternative that can be used to develop novel drug delivery carriers for cancer treatment. This study explores the synthesis of starch encapsulated, polydopamine coated core-shell nanoparticles, in a one pot synthesis approach and by surfactant free approach. The nanoparticles produced are embellished with polymeric stealth coatings and are tested for their physiological stability, photothermal properties, and drug delivery in metastatic triple negative breast cancer cell (TNBC) lines. Our results indicate that stealth polymer coated nanoparticles exhibit superior colloidal stability under physiological conditions, and are excellent photothermal agents, as was determined by the increase in temperature of solution in the presence of nanoparticles, upon laser irradiation. The chemotherapeutic drug loaded nanoparticles also showed concentration dependent toxicities in TNBC and in a brain metastatic cell line. Significance Statement This study for the first time develops biocompatible core-shell nanoparticles in template free approach that can serve as drug delivery carrier and as photothermal agents for cancer treatment.

Improving the comprehensive mechanical property of the AlSi10Mg alloy via parameter adaptation of selective laser melting and heat treatment

In this work, the AlSi10Mg alloys with distinct molten pool structures, namely fish-scale and lamellar, were fabricated by using selective laser melting (SLM) technology. The effects of solid solution temperature on the microstructural evolution and mechanical properties of the two types of alloys were systematically investigated. The relationship among initial structure, heat treatment and mechanical properties was revealed. The experimental results showed that for the alloy with fish-scale structure, Si diffused more easily after solid solution treatment due to the finer eutectic network, resulting in a larger Si particle size. At 510 °C, the nano Si particles in the fish-scale sample basically disappeared, but a small amount of nano Si particles still existed in the lamellar sample, leading to a bimodal distribution in the Si particle size. Different sizes and distributions of Si particles present different strengthening mechanisms and affect the nucleation and growth of recrystallized grains in the α-Al matrix, leading to significant differences in mechanical properties. The strength of the lamellar sample decreased with increasing the temperature, and the abnormally growth of grains could be found after being treated at 510 °C, resulting in a poor mechanical property. The strength of fish-scale sample first decreased and then increased with the increase of solid solution temperature. When the alloy with fish-scale structure was solid solution treated at 510 °C, Si particles could promote the nucleation of recrystallized grains but hinder their growth, and the ultimate tensile strength decreased from 478.8 MPa of SLMed state to 393.4 MPa, a reduction of 17.8%, while the elongation increased from 7% to 21%, an increase of 300%, showing an excellent overall mechanical property. Therefore, the present study demonstrates that adjusting the SLMed molten pool structure and heat treatment parameters is necessary to obtain a good combination of microstructure and mechanical property.

The beneficial effect of yttrium microalloying in the solid solution treatment of AISI 321 stainless steel：Grain refinement and inclusions modification

Solid solution treatment is an important means of regulating the microstructure and mechanical properties of austenitic stainless steel, and a suitable solid solution process window is critical for austenitic stainless-steel service. In this paper, the effect of (RE) yttrium and solid solution temperatures on the microstructure and mechanical properties of austenitic stainless steel was investigated by adding trace amounts of RE yttrium to AISI 321 stainless steel with different solid solution temperature treatments. The results show that the austenite grains gradually coarsen with the increase of solid solution temperature, and the addition of RE yttrium effectively inhibits the coarsening of grains and keeps an excellent the comprehensive mechanical properties of AISI 321 stainless steel at 1150 °C for 30 min, this indicates that the addition of RE yttrium broad solid solution process window for AISI 321 stainless steel. In addition, the RE yttrium microalloying has a positive modification effect on the carbonitrides with refinement and spherization, which has a good contribution to the strength and plasticity retention of the material. This research is expected to provide more options for the heat treatment of austenitic stainless steels.

Effect of Fly Ash on the Mass Transfer Performance of CO2 Removal Using MEA and DEA Solutions in a Packed Tower

The accumulation of uncollected fly ash from flue gas in post-combustion CO2 capture processes is a significant concern in current coal-fired power plants due to its potential impact on the performance of CO2 absorbent and absorption towers. In order to determine the effect of fly ash on the mass transfer performance of CO2 absorption into monoethanolamine (MEA) and diethanolamine (DEA) aqueous solutions, experimental studies were carried out using a small-sized packed tower equipped with θ-ring random packing. These studies were conducted under various operating parameters, including solution temperature, liquid/gas ratio (L/G), packing height, and fly ash concentration. The results show that the effect of fly ash on the outlet CO2 concentration was primarily observed during the initial stages of the experimental process. Moreover, the presence of fly ash leads to a reduction in the volumetric overall mass transfer coefficient (KGav) when using MEA and DEA solution, and increasing the fly ash concentration further exacerbates this negative impact. However, the effect of fly ash on the reduction in KGav is not significantly related to its chemical composition but rather depends on the operational parameters. With increasing solution temperature, liquid/gas ratio (L/G), and packing height, the KGav values for different solutions exhibit an upward trend. The negative effect of fly ash on KGav remains relatively stable for MEA as solution temperature and packing height increase. Compared to MEA, fly ash has a greater negative effect on DEA solution under the same experimental conditions. The analysis reveals that the detrimental effect of fly ash on KGav primarily stems from its ability to alter the distribution state of the absorption liquid within the packed tower.

Hydrogen bonding regulation on phase change in stimuli responsive copolymer aqueous solution

Hydrogen bonding (HB) is vital for the phase transition and physical properties of stimuli responsive copolymers. However, the governing mechanism remains unclear. Herein, we investigated the HB dynamics in a representative thermo-responsive copolymer (PNIPAM-AM) aqueous solution. Three types of HB were identified: polymer-polymer chain (CO:H–N), polymer chain-water molecule (CO:H–O) and water-water molecules (H–O:H–O) by vibrational spectroscopy. Increasing polymer concentration, the H–O:H–O softened and CO:H–O stiffened, leading to the destruction of HB network in water-water clusters. Upon increasing solution temperature, CO:H–O softened while CO:H–N stiffened, resolving the dehydration and cross-linking of polymer chains. Confinement of water molecules in the “cages” (∼ tens to hundreds of micrometers) after sol-gel phase transition was visualized, disclosing the mechanism of water holding capacity of PNIPAM-AM. The correlation of molecule vibration and copolymer microscopic structure was established, contributing to the fundamental understanding of phase behavior and physical properties regulations in stimuli responsive copolymer aqueous solution.

Microstructure evolution and coarsening behavior of precipitated O phase in Ti–22Al–24Nb-0.5Mo (at. %) alloy during the heat treatment

Microstructure evolution and coarsening behavior of precipitated O phase were systematically investigated in this study, and the corresponding microstructures were characterized by scanning electron microscopy and transmission electron microscopy. The results showed that the original microstructure was composed of lath O phase, α2 phase and B2 matrix. The precipitated O phase presented different morphologies and sizes during heat treatment. With the increase of solution temperature and holding time, the O phase occurred coarsening, with a thickness ranging from 0.73 increased to 2.64 μm. But the volume fraction decreased from 57.65 to 18.40 %. During aging treatment, large amounts of fine secondary acicular O phase have precipitated from the matrix. As the aging temperature increases, the O phase underwent coarsening and the thickness increases from 0.70 to 1.40 μm. However, the aging temperature has little effect on the precipitation of acicular O phase, and the volume fraction decreases from 37.66 to 33.32 %. Research found that the small-sized O phase gradually dissolved in the matrix, while the large-sized O phase grew. This phenomenon can be explained by Ostwald ripening mechanism. The TEM analysis revealed that the O phase occurred separation, mainly due to the diffusion of solute atoms and the embedding of B2 matrix. Meanwhile, the O phase had been completed and segmented. The coarsening mechanism of the O phase was also explained by the boundary splitting mechanism and terminal migration mechanism.

Obtaining Excellent Mechanical Properties in an Ultrahigh-Strength Stainless Bearing Steel via Solution Treatment

A novel versatile ultrahigh-strength stainless bearing steel was prepared by first solution treating the steel at temperatures between 1000 °C and 1100 °C for 1 h, followed by performing cryogenic treatment at −73 °C for 2 h, and tempering at 500 °C for 2 h, with the cryogenic and tempering treatments being repeated twice. The microstructures were characterized using multiscale techniques, and the mechanical properties were investigated using tensile testing, as well as via Rockwell hardness and impact toughness measurements. Tensile strength was found to be independent of solution temperature, with a value of about 1800 MPa. In contrast, yield strength decreased from 1530 MPa to 1033 MPa with increasing solution temperature, while tensile elongation increased from 15.3% to 20.5%. This resulted in an excellent combined product of tensile strength and elongation for steels initially treated at 1080 °C and 1100 °C, with values of 33.9 GPa·% and 37.0 GPa·%, respectively. Furthermore, the steels showed excellent impact toughness, increasing from 37.0 J to 86.2 J with increasing solution temperature. The microstructural and mechanical investigations reveal that the excellent mechanical properties and impact toughness are related to three factors, namely (i) a transformation-induced plasticity effect, mainly attributed to a high volume fraction of retained austenite, (ii) a high strengthening capacity arising from a high dislocation density, and (iii) a synergistic effect due to cobalt additions and the nanoprecipitation of M2C and M6C carbides.

Quantitation and evaluation of NO2−, NO3−, and H2O2 in the sonolysis of aqueous NaOH solution under air and air-Ar mixture: Effects of solution temperature, ultrasonic power, and ratio of gas mixture

When an aqueous solution containing dissolved air is sonicated, H2O2, HNO2, and HNO3 are formed. This is a result of the formation of active bubbles with extremely high-temperature and high-pressure. The yields of H2O2, NO2−, and NO3− are representative indexes for understanding the chemical effects of ultrasonic cavitation in water. However, these yields often vary under the acidic conditions caused by sonication. In this study, we measured the yields of H2O2, NO2−, and NO3− in the presence of NaOH, which suppresses the reaction between NO2− and H2O2 and prevents the formation of NO3− in a bulk solution. Therefore, the yields obtained should correspond to the actual yields just after bubble collapse, directly reflecting the chemical effects of the active bubbles themselves. It was confirmed that the yields of NO2− and NO3− decreased, while the ratio of [NO3−] to [NO2−] ([NO3−]/[NO2−] ratio) increased with increasing solution temperature, suggesting that the temperature and pressure in collapsing bubbles decreased with an increase in the solution temperature. Ultrasonic power clearly affected the yields of NO2− and NO3−, but it did not affect the [NO3−]/[NO2−] ratio, suggesting that 1) the quality of the active bubbles did not change largely with increasing ultrasonic power, and 2) the quantity related to the number and/or size of active bubbles increased with increasing ultrasonic power up to a certain power. Additionally, the effects of the ratio of air to Ar on the yields of NO2−, NO3−, and H2O2 were investigated. These yields could be affected not only by the bubble temperature but also by the concentration of reactants and intermediates inside the collapsing bubbles. The chemical reactions are quite complex, but these yields could be valuable analytical tools for understanding the quantity and quality of active bubbles.

Microstructure, segregation and mechanical properties of A356 alloy components fabricated by rheo-HPDC combined with the swirled enthalpy equilibration device (SEED) process

The challenges commonly associated with conventional high pressure die casting (HPDC) have led to increased interest in semi-solid metal (SSM) forming processes. In the present study, semi-solid slurries of A356 alloy prepared by the Swirled Enthalpy Equilibration Device (SEED) process were used for manufacturing components with complex shape by using a high pressure die casting machine. The segregation phenomenon and the effect of heat treatment on the microstructure evolution and mechanical properties were investigated. The results showed that the alloy consists of primary spherical α-Al grains, secondary solidified α-Al grains, eutectic Si, iron-rich intermetallic phases and low porosities. The microstructural investigations revealed that the eutectic Si particles underwent fragmentation, spheroidization and coarsening with increasing solution temperature. Furthermore, the solution treatment results in the dissolution of the π-Al8FeMg3Si6 phase and the growth of the β-Al5FeSi phase. The hardening peaks at 170 °C could be obtained with ageing for 5 h. Due to both solution and precipitation strengthenings, the yield strength, ultimate tensile strength and hardness of A356 alloy after heat treatment increase significantly compared to those in the as-rheocast state: they reach 266 MPa, 343 MPa and 110 HV0.2, respectively. The analysis of fracture surfaces of rheo-HPDC samples in both the as-rheocast and the heat-treated states revealed a mixed mechanism of dimples and quasi-cleavage. The microstructure inside the part was found to be quasi-homogeneous while the segregation phenomenon in different zones of the part is affected by die geometry during the filling process. The results imply that the SEED-HPDC process has the potential to be industrialized by implementing appropriate heat treatments for producing complex components with good mechanical properties.

Experimental investigations on a solar assisted packed bed regeneration system for building air conditioning applications

In the current study, an experimental investigation carried out on a binary liquid desiccant-based adiabatic counter flow regenerator is presented. The heat harvested from solar collector was supplied into the desiccant for desiccant regeneration. The corrosion characteristics of the binary desiccant solution on stainless steel material were studied using potentiodynamic test. Subsequently, the effects of various inlet process parameters on the performance parameters of the regenerator were studied employing structured pads as packing material. The effect of the phase change phenomena involved in a desiccant regeneration system was also assessed experimentally, along with the system performance under the inlet solution temperatures of 53, 55, 60, 65 and 70 °C at a constant desiccant solution of 50 wt%. It was observed that the corrosion rate of lithium bromide (LiBr), calcium chloride (CaCl2) and LiBr + CaCl2 (85:15) was found to be 0.0303 mm/year, 0.0144 mm/year and 0.0161 mm/year, respectively. The results showed that with the increased solution temperature and air mass flux rate, the desorption rate was increased, whereas the regeneration effectiveness was decreased. The highest desorption rate was found to be 6.8 g/m2-s at the desiccant solution temperature of 70 °C, whereas the highest regeneration effectiveness of 0.85 was obtained at the air mass flux rate of 1.1 kg/m2-s.

Localized Corrosion Behavior of UNS N07718 in a Solution Simulating a Diluted-sour Environment

The localized corrosion behavior of precipitation-hardened UNS N07718 was investigated by immersion tests in 6 wt% FeCl3 + 1.0 wt% HCl and the use of electrochemical techniques in a simulating solution of a diluted-sour environment of 25 wt% NaCl + 0.5 wt% CH3COOH. The Ti carbides and Nb-Mo carbides with 1-10 µm size were distributed in the alloy. After immersion at a solution temperature higher than 45oC, localized corrosion with a depth of over 25 µm was identified, and the critical pitting temperature was determined to be 45oC. Potentiodynamic polarization showed that the surface of the UNS N07718 was immediately passivated in the experimental solution. The passivity-maintaining current density was gradually increased with increasing solution temperature, and finally, localized corrosion was initiated or propagated at 0.5 VSSE in 80oC. The localized corrosion was initiated or propagated at the interface between the Ti and Nb-Mo carbides and the alloy substrate. Scanning Kelvin probe microscopic images revealed that the contact-potential difference values were in the order of Ti carbide &gt; Nb-Mo carbide &gt; alloy substrate, indicating that the carbides and alloy substrate act as a cathode and an anode, respectively, forming a micro-galvanic couple. Therefore, it is concluded that localized corrosion is initiated at the interface between the carbides and substrates in UNS N07718.

Intraocular Lens Unfurling Time Exponentially Decays with Increased Solution Temperature.

Intraocular lens (IOL) unfurling can be a rate-limiting step in cataract surgery, limiting operative efficiency. Furthermore, inefficient unfurling has important implications for clinical outcomes. We examine the effects of solution temperature on IOL unfurling time using three in vitro models of the ocular environment. IOLs were injected into a 6-well plate filled with balanced salt solution (BSS), dispersive ophthalmic viscoelastic device (OVD), or cohesive OVD. Experiments were also performed in a plastic eye filled with dispersive or cohesive OVD. IOL unfurling time was recorded against the temperature of the respective solution. IOL unfurling time decayed exponentially as solution temperature increased in all experiments, including the BSS-filled 6-well plate, the OVD-filled 6-well plate, and the OVD-filled plastic eye. IOLs failed to unfurl within 10 min at 10°C, below the glass transition temperature of the tested IOLs. Increasing solution temperature from 20°C to 30°C decreases IOL unfurling by greater than 2 min. Further heating to 40°C did not significantly decrease IOL unfurling time. Increased solution temperature rapidly decreases IOL unfurling time in vitro. IOLs do not unfurl within a clinically acceptable timeframe at or below their glass transition temperature. Increased BSS and/or OVD temperature may be a potential method to decrease IOL unfurling time in cataract surgery. However, future research is needed to elucidate potential consequences of warmed BSS and/or OVD on post-operative outcomes. This study demonstrates the potential for temperature regulation to decrease cataract surgery operative time and provides preliminary evidence to justify future clinical validation of this relationship.

Study on the effect of KMnO4−modified humic acid residues on the removal of Hg(Ⅱ)/Pb(Ⅱ) from solution

As a solid waste, a coal−based humic acid residue (HAS) is less researched for its resource utilization. HAS is advantageous to the adsorption of heavy metals in water bodies because of its high adsorption capacity and low cost. In this study, HAS was modified using KMnO4 solution to improve the adsorption of Hg(Ⅱ)/Pb(Ⅱ), while the modification process was optimised by response surface methodology (RSM) and named K−HAS. The Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X − ray photoelectron spectroscopy (XPS) and X − ray diffraction (XRD) were jointly adopted to characterize the HAS and K−HAS. The batch sorption experiments were used to study the adsorption characteristics of external factors such as initial concentration, pH, and reaction time on the adsorption of Hg(Ⅱ)/Pb(Ⅱ) by K−HAS, and the isothermal adsorption model and kinetic model were used to fit the behavior of Hg(Ⅱ)/Pb(Ⅱ) adsorption by K−HAS. The results show that the pseudo−second−order model and the Langmuir adsorption isotherm model can better describe the adsorption behavior of K−HAS on Hg(Ⅱ)/Pb(Ⅱ), with the maximum adsorption amounts of 128.40 and 342.43 mg·g−1, respectively; there is competitive adsorption between Hg(Ⅱ) and Pb(Ⅱ), and Pb(Ⅱ) has a stronger competitive ability, as the concentration of Hg(II) increased, the adsorption of Pb(II) by K-HAS decreased by 20.29% and the adsorption of Hg by K-HAS decreased by 22.77% as the concentration of Pb(II) increased; the thermodynamic parameters indicate that the adsorption of Hg(Ⅱ)/Pb(Ⅱ) by K−HAS is a spontaneous heat absorption reaction. The adsorption mechanism of K−HAS for Hg(Ⅱ)/Pb(Ⅱ) mainly consisted of precipitation and complexation, which contributed 58.7% and 20.6% to Hg(Ⅱ) and 50.7% and 27.5% to Pb(Ⅱ), respectively. In addition, the site energy distribution (SED) shows that Hg(Ⅱ)/Pb(Ⅱ) preferentially occupy the high−energy adsorption sites and then gradually occupies the low−energy sites and that the K−HAS surface becomes more and more inhomogeneous as the solution temperature increases. The experiments demonstrate that K−HAS is effective in the adsorption of Hg(Ⅱ)/Pb(Ⅱ), and the investigation of the adsorption mechanism can be useful for further studies.