Effect Of Aging Time Research Articles

Effect of thermal aging on corrosion behavior of duplex stainless steels

Despite their exceptional mechanical and corrosion properties, duplex stainless steels (DSS) have not found widespread use in high-temperature applications due to concerns over thermal aging and embrittlement at elevated operational temperatures (> 300 °C). The present study investigated the effect of thermal aging time on the electrochemical properties of lean and standard grade DSS that are exposed to a range of pressurized water reactors containing LiOH and H3BO3. The results indicated that the electrolyte chemistry plays a significant role in the corrosion behavior of the DSS alloys. Corrosion resistance decreased with thermal aging time for all DSS alloys; however, standard grade DSS (2205 and 2209-w) alloys showed better corrosion resistance than lean grades (2003, 2101, 2101-w). The presence of dissolved oxygen in the electrolytes resulted in a significant increase in corrosion rate for the DSS alloys, but it did not affect the general trend of corrosion rates with aging time. All DSS alloys became vulnerable to pitting corrosion due to chloride addition, but the pitting resistance decreased with increasing thermal aging time. Increased boron B content resulted in degradation of corrosion resistance of the DSS alloys, while minor changes in pH did not show a significant change in corrosion resistance. Mechanical and metallurgical characterization coupled with electrochemical characterization of the DSS alloys gave a comprehensive insight into the effects of thermal aging on the electrochemical response of the DSS.Graphical abstract

Effect of aging time on the microstructure and hardness of maraging steel 03Ni18Co9Mo5TiAl

Maraging steel is used to make parts that need high hardness and durability while it is also needing great ductility for processing and shaping. In order to achieve the above mechanical properties, the steel needs to be quenched and aged with an appropriate amount of time to control the precipitation of intermediate phase on martensite. In this study, the maraging steel (03Ni18Co9Mo5TiAl) was quenched at 920 oC and then aged at 490 oC with a time interval from 2 h to 10 h to evaluate the effect of aging time on the microstructures and hardness of steel. The results have shown that, at the first 6 h aging interval, the hardness value is proportional to aging time and reaches its maximum value at 53.5 HRC. If the aging time continues to increase, the tendency expands the particle size of intermediate phase will decrease the hardness value on the obtained samples.

Effects of aging time on the crystallization/transformation of hydrothermal synthesis alkali-activated fly ash-based zeolite

Zeolites with unique framework structure have wide applications, such as ions’ exchangers, molecular sieves and catalysts. This work focused on the synthesis and characterization of zeolite by recycling coal fly ash as the starting material via hydrothermal method. The intermediate phases and final products were characterized by XRF, XRD, FT-IR, SEM and BET techniques. The effects of aging time on the crystallization/transformation of zeolite were discussed. The results showed that the alkali-activated coal fly ash after hydrothermal process could lead to the formation of zeolite Na-P1. Furthermore, the aging treatment benefited the formation of homogenous zeolite Na-P1 with smaller particle size, larger specific surface area, total pore volume and pore size.

Alloy Partitioning Effect on Strength and Toughness of κ-Carbide Strengthened Steels.

Alloy partitioning during heat treatment in a lightweight precipitation hardened steel was investigated using transmission electron microscopy and atom probe tomography. The mechanical properties are discussed as a function of the effect of solution treatment temperature and aging time, giving rise to variations in chemical modulation. A wrought lightweight steel alloy with a nominal composition of Fe-30Mn-9Al-1Si-1C-0.5Mo (wt. %) was solution-treated between 1173–1273 K and aged at 773 K. Lower solution treatment temperatures retained a finer grain size and accelerated age hardening response that also produced an improved work hardening behavior with a tensile strength of −1460 MPa at 0.4 true strain. Atom probe tomography indicated these conditions also had reduced modulation in the Si and Al content due to the reduced aging time preventing silicon from diffusing out of the κ-carbide into the austenite. This work provides the framework for heat-treating lightweight, age hardenable steels with high strength and improved energy absorption.

Effect of Aging Time on the Composition of the Volatile Components of An–tea

To investigate the effects of different aging times, three An–tea samples were selected for comparison with a non-aged sample as the control (CK, one-year-old) and labeled as high-aged (HAS, 12 years old), medium-aged (MAS, 7 years old), and low-aged samples (LAS, 2 years old). Changes in the volatile components of the different An–tea samples were investigated using headspace–solid-phase microextraction (HS-SPME) combined with gas chromatography–mass spectrometry (GC-MS). The volatile components of An–tea consisted of eight types of compounds. Aldehydes and hydrocarbons were dominant in LAS, while esters, ketones, alcohols, nitrogen-containing compounds, and ethers were the most abundant compound in MAS. Esters were dominant in HAS, while phenols were only present in LAS and CK. As aging time increased, the number of identical compounds gradually decreased, while the relative contents of the alcohols also decreased. Except for CK, the contents of ketones and aldehydes gradually decreased as the aging time increased. The content of aldehydes greatly increased during the initial aging period. Ketones and esters had markedly increased in HAS, while their abundance in LAS was close to that in CK. The comprehensive quality score of the volatile components obtained by principal component analysis was highest for MAS, followed by HAS and LAS, with CK having the lowest score.

Effect of aging time on microstructural and mechanical properties of 6061 aluminum alloy

Aluminum alloy 6061 have moderate strength, good formability, and excellent corrosion resistance, it has a wide use in several engineering sectors. Age hardening is the main feature of this alloy. In this study, some mechanical characteristics of Aluminum 6061 samples aged to different times has been studied. The specimen’s mechanical properties were improved in general; best mechanical properties were achieved after 2 hours of heat treatment at 200oC. Ultimate tensile stress, yield stress, ductility and microhardness variation with aging time are discussed regarding to the microstructural alteration caused by heat treatment. We found that the Mg2Si initiation and growth was a function for aging time, which was the main cause for improvement of the alloy mechanical features.

Interfacial Microstructure and Mechanical Reliability of Sn-58Bi/ENEPIG Solder Joints

The 42 wt.% Sn–58 wt.% Bi (Sn-58Bi) Ball Grid Array (BGA) solder balls were mounted to electroless nickel-electroless palladium-immersion gold (ENEPIG) pads by employing the reflow process profile. The effects of reflow cycles and aging time on the interfacial microstructure and growth behavior of intermetallic compounds, as well as the mechanical properties, were investigated. Pd-Au-Sn intermetallic compound (IMC) was formed at the Sn-58Bi/ENEPIG interface. With the increase in reflow cycles and aging time, the IMC grew gradually. After five reflow cycles, the shear strength of the Sn-58Bi/ENEPIG solder joints first decreased and then increased. After 500 h of aging duration under −40 °C, the shear strength of the Sn-58Bi/ENEPIG solder joints decreased by about 12.3%. The fracture mode transferred from ductile fracture to ductile and brittle mixed fracture owing to the fact that the fracture location transferred from the solder matrix to the IMC interface with the increase in reflow cycles and aging time.

Yield stress and microstructure of composite halloysite-LAPONITE® gels: Effects of mixing ratio, surface chemistry, and ageing time

The dependences of yield stress and microstructure of composite halloysite (Hal)-LAPONITE® (Lap) gels on the Lap/Hal mixing ratio, surface chemistry (pH and ionic strength), and ageing time were investigated in this study. The yield stress was measured using the vane technique and the microstructure was revealed by the cryogenic scanning electron microscopy (cryoSEM) images. At a fixed solid loading, the yield stress of composite Hal-Lap gels first quickly decreased to a lowest point and then kept increasing as Lap/Hal mixing ratio increased. The corresponding microstructure changed from Hal dominated network to Lap dominated network showing strong interactions between Hal and Lap particles through heterogeneous charge attractions. Six stages, each with distinct features, were identified during the transition. The maximum of yield stress displayed at around pH 11 for composite Hal-Lap gels and pure Hal gel. The attractive interactions between pure Hal-Hal and Lap-Lap particles and composite Lap-Hal particles were still present in a significant manner at pH 12 as reflected by the high yield stress. The microstructure of composite Hal-Lap gels and pure Hal gel displayed a high content of fibre end-face interactions even at high pH. However, “phase separation” occurred at low pH 4. Increasing ionic strength resulted in higher bond strength due to the van der Waals attraction and heterogeneous charge attraction, so it produced higher yield stress gels of pure Hal gel and composite Hal-Lap gels with low Lap content. At high ionic strength, small Hal particles formed aggregates with large Hal nanotubes while Lap particles formed large agglomerates. The H18L2 showed microstructure with circular agglomerates dispersed in a suspension of Hal rods. The agglomerates consisted of a mixture of tightly packed Hal rods and Lap particles. The microstructure of composite Hal-Lap gels was also strengthened during ageing due to the particle rearrangement. A water-gel phase separation due to the Hal particles sedimentation was observed for composite gels with low Lap/Hal mixing ratio as increasing ageing time.

Effects of seawater temperature and NaCl concentration on interlaminar shear behavior of CFRP laminates

The aim of this paper is to study the interlaminar shear behavior of CFRP in critical service conditions. The specimens were immersed in the prepared artificial seawater for 7 months to investigate the ageing time, ambient temperature and salt concentration effects. Analytical balance was used to weight the samples for analyzing the dynamic moisture absorption behavior. Short beam shear tests were carried out to evaluate the interlaminar shear properties. Scanning electron microscopy (SEM) was used to observe the ageing damage and failure morphology. The results show that moisture absorption behavior of composites follows Fickian diffusion law. Moisture absorption rate and the maximum absorption content are mainly affected by ambient temperature but not by NaCl concentration. Compared with ageing time and NaCl concentration, the shear stiffness and shear strength are more sensitive to aging environmental temperature. After exposed in 3.5%–70 °C seawater environment for 7 months, the retention rate of shear strength is only 68.8% and the failure displacement decreases by 20.5%. The shear strength increases first and then decreases with the increase of the maximum moisture absorption, which is mainly related to the release of curing shrinking stress and the damage of interface properties. The shear properties degradation after aging is mainly related to the damage of materials induced by environment (delamination, fiber/matrix interface debonding and matrix cracking).

Dissolution kinetics and solubility of copper oxide nanoparticles as affected by soil properties and aging time.

Nano copper oxide (CuO NP) was added to eight soils to study the effect of aging time of copper on the concentration of diethylenetriaminepentaacetic acid (DTPA)-extracted copper (DTPA-Cu), with bulk copper oxide (CuO BP) and copper nitrate [Cu(NO3)2] used for comparison. Moreover, the effect of soil properties on the dissolution of CuO NP was studied. A dissolution model was used to quantitatively describe the dissolution kinetics of CuO NPs in different soils. The results showed that the concentration of DTPA-Cu decreased with increasing aging time in soils spiked with Cu(NO3)2, while the concentration increased to varying degrees in soils spiked with CuO NPs or CuO BPs. In acidic soils, the equilibrium concentrations of DTPA-Cu were 93.3-98.7mg·kg-1 for CuO NP treatments, 65.5-94.3mg·kg-1 for CuO BP treatments, and 81.4-90.0mg·kg-1 for Cu(NO3)2 treatments, which were greater than those in alkaline soils (43.4-56.9mg·kg-1, 6.26-8.61mg·kg-1, and 73.9-80.0mg·kg-1, respectively). In acidic soils, DTPA-Cu equilibrium concentration ranked the different forms of copper treatments as CuO NPs > Cu(NO3)2 > CuO BPs, while in alkaline soils, the order was Cu(NO3)2 > CuO NPs > CuO BPs. The dissolution rate constants and solubility of CuO NPs were 0.33-6.42 and 37.1-100.1mg·kg-1, respectively. Pearson correlation analysis indicated that the dissolution parameters of CuO NPs were negatively correlated with soil pH and positively correlated with the contents of organic matter, clay, iron oxides, and aluminum oxides. Further, the dissolution rate constant and solubility of CuO NPs could be well predicted by soil pH and the content of free or amorphous aluminum. Our study identified the main factors controlling the dissolution of CuO NPs in farmland soils and highlighted the higher availability of CuO NPs in acidic soils.

Assessment and Prediction Model of GFRP Bars’ Durability Performance in Seawater Environment

In this study, the performance degradation law and mechanism of glass fiber reinforced polymer (GFRP) bars were investigated by being immersed in natural seawater (denoted as SW), saline-alkali solution (SA), or wrapped with concrete, and then submerged in natural seawater (SWC). A series of short-beam shear tests were conducted to investigate the effects of aging temperature and time on the interlaminar shear strength (ILSS) of GFRP bars. Microstructure changes, glass transition temperature (Tg) difference, and hydrolysis degree of GFRP bars after aging in three environments for 183 days were analyzed using scanning electron microscopy (SEM), differential scanning calorimeter (DSC), and Fourier transform infrared spectroscopy (FTIR). Test results demonstrated that the temperature could accelerate the strength degradation of GFRP bars significantly. After 183-day aging treatment at 60 °C, the ILSS retention rates of GFRP bars in the three environments of SW, SWC, and SA were 66.41%, 53.10%, and 45.36%, respectively; and Tg was 1.7%, 7.0%, 7.8% lower than that of unconditioned sample, respectively. Meanwhile different degrees of damage, such as separation between fiber and resin and few holes in the resin, were observed on the GFRP bars in the SWC and SA environments. It was also found that irreversible hydrolysis took place in some resins. The durability prediction model of GFRP bars serving in the Yellow Sea of China was established by using Arrhenius equation, and the correlation coefficient with the test data was not less than 0.94.

Effect of aging treatment on corrosion behavior of Mg-4Nd-2Gd-0.5Zr alloy

The effects of aging time on corrosion behavior of Mg-4Nd-2Gd-0.5Zr alloy in 3.5% NaCl solution were investigated by microanalysis, weight loss test and electrochemical test. The results show that the corrosion rate of Mg-4Nd-2Gd-0.5Zr alloy decreases first and then increases with the extension of aging time. Aging treatment alters the grain size and the distribution of the second phases. The second phases and grain size are the key factors affecting the corrosion rate of magnesium alloy. Among the tested alloys, the T6-8 h alloy shows the lowest corrosion rate, which is mainly attributed to the continuous distribution of second phases restricting the expansion of corrosion, hence the T6-8 h alloy showed the highest corrosion resistance. The corrosion rate of T6-16 h alloy increases obviously because of the growth of the grain size and the segregation of second phases, which accelerates the corrosion progress.

Effects of Aging Time on Microstructure and Oxidation Behavior of Inconel 690 Alloy

Effects of Aging Time on Microstructure and Oxidation Behavior of Inconel 690 Alloy

Effect of NaOH concentration and aging time on the properties of synthesized Ca(OH)2 by sol–gel method

The sol–gel method is one of the most versatile techniques to produce calcium hydroxide (Ca(OH)2) since it provides a flexible chemical route to synthesize materials with the desired properties. The work aims to investigate the influence of sodium hydroxide (NaOH) concentration and aging time on the properties of the synthesized Ca(OH)2. In the study, Malaysian limestone (CaCO3) from Baling, Kedah was applied as a precursor to synthesized Ca(OH)2 using the sol–gel technique. The synthesis was carried out with varying the NaOH concentration (0.5 M, 1.0 M and 2.0 M) and aging time (12 h, 24 h and 48 h). The synthesized Ca(OH)2 powder was subjected to X-ray Diffraction (XRD), Field Emission Scanning Electron Microscope equipped with Energy Dispersive X-ray Spectroscopy (FESEM-EDX), Fourier Transform Infrared (FTIR) spectroscopy, X-ray Fluorescence (XRF) and Particle Size (PSA) analysis. The results exhibit the existence of calcite and aragonite phases at higher concentrations of NaOH, indicating an incomplete reaction of the hydrolysis process. The particle size of Ca(OH)2 increases as NaOH concentration and aging period increase. At higher concentrations of NaOH, agglomeration of Ca(OH)2 was more likely to occur. These findings suggested the potential use of Malaysian limestone as the precursor for Ca(OH)2 synthesis with desired properties by controlling the sol–gel reactions.

Investigating the Effects of Aging Time on Corrosion Resistance and Antibacterial Property of Newly Designed Medium-Entropy Super Austenitic Stainless Steels

Investigating the Effects of Aging Time on Corrosion Resistance and Antibacterial Property of Newly Designed Medium-Entropy Super Austenitic Stainless Steels

Effects of Aging on the Dry Shrinkage Cracking of Lime Soils with Different Proportions

In this study, the reasonable aging time of lime soils with different ratios was determined to investigate the effect of aging on the internal mechanism of the dry shrinkage cracking of lime soil. To this end, the effects of aging time, lime content, and particle size on the volume crack rate, expansion and shrinkage rate, particle size distribution, and pH were analyzed using a dry–wet cycle, screening, and pH tests. In addition, the changes in the particle structure of the samples and the formation of new substances were analyzed. The results revealed that the volume crack and expansion shrinkage rates of the sample initially decreased, and then stabilized with increasing aging time. In addition, the aging time of the sample increased with increasing lime content and particle size. Further, at the initial aging stage, the volume crack and expansion/shrinkage rates of the sample increased with increasing lime content and particle size. With an increase in the aging time, the pH increased and then decreased significantly to 0.57–1.1% at the reasonable aging time. These indicate that the pH exhibited a significant effect on the reasonable aging time, and this will provide useful insights for the restoration of lime soil sites.

Effects of Neck-Arm Restraint Suspension of Beef Carcasses on Meat Quality and Proteome of Different Muscles During Post-mortem Aging.

Beef quality is the first deciding factor for consumers to consider before purchasing. The aim of this study was to evaluate the effects of suspension and aging time on beef quality. We compared the differences in pH, drip loss, cooking loss, color, shear force, myofibril fragmentation index (MFI), and electron microscope of three muscle tissues between Achilles tendon (AT) and neck-arm restraint (NR) suspensions during seven aging periods (days 0, 1, 2, 3, 7, 14, and 21) after slaughter using the carcasses of six Xinjiang brown cattle. We found that NR suspension could significantly increase the water loss rate and MFI, as well as reduce the shear force compared to AT suspension. The muscle fiber structure with NR suspension was more severely damaged. The proteomics of longissimus dorsi was checked for the post-mortem days 1, 7, and 14. We detected 50, 26, and 29 differentially expressed proteins between NR and AT suspension at post-mortem days 1, 7, and 14, respectively. These proteins were involved in metabolic and muscle structure associated pathways and contributed to a comprehensive understanding of suspension-dependent meat quality regulation by proteins in beef cattle. To conclude, NR suspension can accelerate the aging time of beef carcasses, which will reduce the cost of carcass suspension and bring more benefits in the beef industry.

The Effect of Aging Time and Breed on Some Meat Quality Traits in Morkaraman and Awassi Ram Lambs

Bu çalışmanın amacı, Morkaraman ve İvesi erkek toklularında bazı et kalite özellikleri üzerine olgunlaştırma süresi ve ırkın etkisini incelemektir. Çalışma Erzurum ili Atatürk Üniversitesi Gıda ve Hayvancılık Uygulama ve Araştırma Merkezi Koyunculuk Şubesinde yetiştirilen ve ortalama 7.5 aylıkken kesime gönderilen on baş Morkaraman ve İvesi kuzularından alınan m. longissimus dorsi (MLD) kasında gerçekleştirilmiştir. Et kalite özelliklerinin belirlenmesi için 12 gün boyunca +4 °C'de tutulan MLD kasında kesimden sonraki 24. saat, 2., 4., 7. ve 12. günlerde renk (L*, a*, b*, C, ve H), pH, sızıntı su kaybı ve TBA değerleri belirlenmiştir. Et kalitesi parametreleri üzerine L*, pH ve sızıntı su kaybı dışında ırkın etkisi olmazken, olgunlaştırma süresine bağlı olarak incelenen tüm et kalite parametrelerinde değişimler olduğu gözlenmiştir. Olgunlaşma esnasında proteolitik enzimler tarafından kasın yapısal bozulmasına bağlı olarak etin renk, pH, sululuk ve TBA gibi özelliklerinde önemli gelişmeler ortaya çıkmıştır. Fakat olgunlaştırma süresinin ilerleyişine bağlı olarak a* değerinin düştüğü, sızıntı su kaybı ve TBA değerlerinin ise yükseldiği gözlenmiştir.

Volatile Profile of Dry and Wet Aged Beef Loin and Its Relationship with Consumer Flavour Liking.

This study investigated the effect of ageing method and ageing time on the volatile profiles of grilled beef striploins (Longissimus thoracis et lumborum) and their relationship with consumer flavour liking. Volatiles were measured in grilled steaks subjected to 35 days of dry ageing, 35 days of wet ageing, 56 days of dry ageing or 56 days of wet ageing, using headspace-solid-phase microextraction followed by gas chromatography-mass spectrometry. Gas chromatography-olfactometry-mass spectrometry was also conducted on 35-day wet and dry aged samples to identify volatiles with high odour impact. The concentration of many odour impact volatiles, e.g., 3-hydroxy-2-butanone, 2-acetyl-2-thiazoline, and various alkyl-pyrazines, was significantly higher in dry aged beef compared to wet aged beef (p < 0.05). Several odour impact volatiles, e.g., 2-acetyl-1-pyrroline, and alkyl-pyrazines, decreased significantly with ageing time (p < 0.05), while volatile products of lipid oxidation and microbial metabolism increased with ageing time. Partial least-squares regression analysis showed that the higher consumer flavour liking for 35-day dry aged beef was associated with higher concentrations of desirable odour-active volatiles.

Primary and secondary compression behavior of dredged clay at low effective stresses

This study presents an experimental investigation on the time-dependent compression behavior of dredged clay samples at high initial water contents under lower effective stress. A series of laboratory one-dimensional consolidation tests with or without aging were conducted on dredged clay samples with various initial water contents. Test results showed that initial water content has a significant effect on the primary compression of dredged clay specimen. All dredged clay specimens follow the same decreasing trend in void ratio with time. Compared with the significant decrease in void ratio in the primary consolidation stage, void ratio decreases less significantly with time in the secondary consolidation stage and tends to level off. The aging strain will not continue increasing as the increase in initial water content more than two times the liquid limit. Aging strain of specimens at different initial water contents consistently increase linearly with the increasing time. The value of secondary compression index is influenced by both aging time and initial water content. It consistently reduces with increasing aging time yet increases with increasing initial water content. We should fully consider the effect of initial water content and aging time on the secondary compression index to predict the secondary compression settlement.