Effect Of Aging Temperature Research Articles

The effect of heat treatment on the mechanical and tribological properties of dual size SiC reinforced A357 matrix composites

In the present work, the effect of aging temperature and particle size ratio of SiC particles on the mechanical and tribological properties of A357 composites reinforced with dual particle size SiC were investigated. The composites were prepared by melt-stirring assisted permanent mold casting technique with different weight fractions (3% coarse +3% fine, 4% coarse +2% fine, and 2% coarse +4% fine) of large and small size SiC particles. These three prepared composites are referred as DPS1, DPS2 and DPS3 composites. The solutionizing temperature was maintained constant at 540°C for 9h while the aging was done at 160°C, 180°C and 200°C (T6 treatment) for 6h. Optical and scanning electron microscopy studies showed fairly uniform dispersion of dual size SiC particles in A357 matrix with good interfacial bonding. High-resolution transmission electron microscopy images showed formation of uniformly dispersed needle-like β″ phase and spherical shaped β-Mg2Si precipitates under peak aging conditions. Compared to T6 treated A357 alloy, the T6 treated DPS A357 composites showed improved yield strength, tensile strength, hardness and wear resistance. Among the three composites, hardness and wear resistance of T6 treated DPS2 composite was found to be significantly higher when compared to the other two composites (DPS1 and DPS3). Ratio of large particles to small particles also seems to effect the mechanical and tribological properties. Presence of more small particles was found to be good for strength and ductility whereas more large particles were found to be good for hardness and wear resistance.

Creep behavior and mechanical properties of Al-Li-S4 alloy at different aging temperatures

Creep age forming techniques have been widely used in aerospace industries. In this study, we investigated the effect of aging temperature (143 °C–163 °C) on the creep behavior of Al-Li-S4 aluminum alloy and their mechanical properties at room temperature. The mechanical properties were tested by tensile testing, and the microstructural evolution at different aging temperatures was examined by transmission electron microscopy. Results show that the creep strains and the room-temperature mechanical properties after creep aging increase with the aging temperature. As the aging temperature increases, the creep strain increases from 0.018% at 143 °C to 0.058% at 153 °C, and then to 0.094% at 163 °C. Within 25 h aging, the number of creep steps increases and the duration time of the same steps is shortened with the growth of aging temperatures. Therefore, the increase in aging temperatures accelerates the progress of the entire creep. Two main strengthening precipitates θ′ (Al2Cu) and T1 (Al2CuLi) phases were characterized. This work indicates that the creep strain and mechanical properties of Al-Li-S4 alloys can be improved by controlling aging temperatures.

A Model for Intermetallic Growth in Thin Sn Joints Between Cu Substrates: Application to Solder Microjoints

Thin Sn-based solder microjoints, typically less than 25 μm thick, attached to Cu bond pads on both sides in three-dimensional electronic packages are often converted completely into intermetallic compounds (IMC) during service or accelerated testing. The rate of IMC growth and the proportions of the IMCs relative to the unreacted Sn in the joint have strong implications on solder joint reliability, and hence on the performance of the entire package. Although IMC growth at the interface between two semi-infinite slabs of different components (e.g., Cu and Sn) has been previously modeled, to date, no analytical treatment of intermetallic growth at the interfaces of a thin joint (Sn) sandwiched between two massive substrates (Cu), with concurrent growth of two different intermetallics (Cu6Sn5 and Cu3Sn) at each interface, has been proposed. In this work, a multicomponent diffusion-based model is developed for IMC growth in a thin joint between two semi-infinite substrates, with each interface possessing a multiphase structure. Because the Sn layer is thin, after prolonged aging, Sn may be completely depleted by reaction with Cu from the substrates, with the entire joint becoming IMC. Considering the joint as a finite source of Sn and the substrates as semi-infinite sources of Cu, general solutions of Fick’s second law of diffusion were applied to obtain the concentration of Cu within each phase. Values of interdiffusion coefficients available in literature were used to solve for the interfacial position parameters in the multiphase system, and thence to determine the instantaneous thicknesses of Cu6Sn5 (η), Cu3Sn (e), and Sn. The predictions of the model were validated against experimental data on the growth of IMCs in thin solder joints at 180°C and 210°C. Finally, the model was used to simulate the effects of aging temperature, joint thickness, and initial IMC thicknesses on the growth kinetics of IMCs during isothermal aging.

Effect of Aging Temperature of Support on Catalytic Performance of PtSnK/Al2O3 Propane Dehydrogenation Catalyst

Catalytic dehydrogenation of propane to propylene is one of the vital processes in the petrochemical industry, primarily because of the extensive use of propylene as one of the most crucial building blocks for the production of a wide range of essential chemicals and polymers. In this study, the nano-structural PtSnK was supported on an alumina carrier prepared by an environmentally friendly modified oil-drop method. By adjusting the aging temperature of the alumina carrier, the physical and chemical structural properties of the catalyst can be modulated, and then affect the propane dehydrogenation performance of the catalyst. The effects of aging temperature on the structure and chemical properties of the support and catalyst were studied by N2 sorption, XRD, TEM, TG, NH3-TPD, H2-TPR, CO pulse adsorption, and XPS techniques. As the aging temperature increases, the spherical particles gradually changed from a worm-like structure to a needle or rod-like structure. At the same time, the pore size and volume increase, the pore size distribution becomes wider. Besides, the aging temperature also affects the interaction between the supported metal and the alumina support. The higher aging temperature can inhibit the reduction of SnOx species and enhance the interaction between Sn species and the alumina support. All these features together ensure excellent propane dehydrogenation performance and high stability of the catalyst. When the aging temperature is 140 °C, the PtSnK/Al2O3 catalyst exhibits excellent catalytic propane dehydrogenation performance, with an average propane conversion of 36.5%, average propylene selectivity of 96.5% during 50 h reaction. We reported the modulation of the aging temperature on the physical and chemical properties of the PtSnK/Al2O3 propane dehydrogenation catalyst when the alumina carrier is prepared by the oil-drop method. In order to obtain an optimal propane dehydrogenation catalyst, an optimum aging temperature is preferred to provide a catalyst with high propane conversion, propylene selectivity and catalyst stability.

Aging Effect on Microstructure and Machinability of Corrax Steel

In this paper, the influence of the aging process on the microstructure and machinability of Corrax Steel was investigated for four samples: a solution heat-treated (A0) and three samples aged at 400ºC (A4), 525ºC (A5.25) and 600ºC (A6) for four hours. The effect of aging temperature on hardness was examined. Machining tests were carried out using a CNC lathe with a multi-layer coated PVD (AlTiN) cutting tool, at various cutting speeds (50, 100, 150, 200, 250, 300, 350m/min) with constant feed rate (0.1mm/rev) and 1mm constant cutting depth. The microstructure was investigated using an optical microscope and EDS attached SEM. The effect of aging on reverted austenite formation was also evaluated. In order to understand the changes in surface topology, cutting forces and vibrations were measured. With increasing aging temperature, the lath martensite was transformed to plate martensite because of the formation of precipitates and reverted austenite. Aging at different temperatures increased hardness up to 58%, cutting forces up to 117% and surface roughness up to 450%. The results describe the effect of the aging treatment on cutting forces, surface topology, tool wear and vibrations.

Effect of ageing temperature on microstructure, mechanical property and corrosion behavior of aluminum alloy 7085

The influence of ageing temperatures on mechanical properties, corrosion behavior and precipitation features of aluminum alloy 7085 have been investigated by using tensile testing, intergranular corrosion tests, polarization curve measurements and transmission electron microscopy (TEM) observations. The results show that the precipitate sequence of aluminum alloy 7085 is different at different ageing temperatures. GP II is the main strengthening precipitate in the alloy peak aged at 90 °C, while η′ contributes most to the strength of the alloy peak aged at 150 °C. Similar ultimate yield strength can be obtained under either peak ageing conditions, but the work-hardenability at 90 °C is much better than that at 150 °C due to the predominance of GP II zones. Alloy 7085 peak aged at 150 °C shows better corrosion resistance than at 90 °C.

Effect of Aging Temperature on the Microstructure and Shear Strength of SAC0307-0.1Ni Lead-Free Solders in Copper Joints

This paper presents an investigation of the effects of aging temperature on the microstructure and shear strength of SAC0307-0.1Ni/Cu solder joints. Single-overlap shear solder joints were aged for 1 h at 80, 130, and 180°C. The microstructure of the interface between the solder and the Cu substrate contained phase of the intermetallic compounds (IMCs) (Cu,Ni)6Sn5 formed along the interface. The shape of scallop-like (Cu,Ni)6Sn5 IMCs changed to the long dendrite and grew larger at the interface of solder joints after increased aging temperature. In addition, a phase of particle-like Ag3Sn IMCs was formed in the solder matrix. The growth of the interfacial IMC layer in the solder joints increased with increasing the aging temperature. The thickness of this layer was controlled by diffusion mechanism. The shear strength of the as-reflowed solder joints was greater than that of the aged solder joints, and the shear strength of all the aged solder joints decreased with increasing the aging temperatures. Therefore, the aging temperature mainly affected the thickness of the interfacial layer of IMCs and the shear strength of the solder joints.

Effect of ageing process on carcinogen ethyl carbamate (EC), its main precursors and aroma compound variation in Hakka Huangjiu produced in southern China

SummaryWine ageing is of great importance to the quality and organoleptic properties of Huangjiu. The aim of the present work was to investigate the effect of ageing temperature on the content changes in ethyl carbamate (EC) and its precursors including citrulline, arginine, ornithine and urea in Hakka Huangjiu. Aroma compound changes were also detected using headspace solid‐phase microextraction coupled with gas chromatography spectrometry. Results indicated that with the increase in ageing temperature, citrulline and EC concentrations increased, whereas arginine and ornithine concentrations decreased. Urea was decreased slightly from 4 to 20 °C while increased at 37 °C. Pearson test demonstrated that ageing temperature had significant correlation with EC and arginine. The concentrations of aroma compounds, especially esters, alcohols, acids and heterocyclic compounds were different in different ageing temperatures. Ageing temperature of Hakka Huangjiu was suggested setting in a lower temperature as for strictly controlling contents of urea and citrulline, as well as EC.

Effect of Synthesized Conditions of Cu-K-OMS-2 on Toluene Oxidation Performance

The objective of this study was to optimize synthesis conditions for the Cu-K-OMS-2 hydrothermal process. The effects of ageing temperature, ageing time and amount of copper (Cu) dopant were considered via using the Box-Behnken design (BBD) method to characterize the conditions for gaseous toluene degradation. In the models studied, the independent variables were ageing temperature (55-145ºC), ageing time (6-18 h) and amount of Cu dopant (2-6% mole). The quadratic model fitted very well with the experimental data (15 runs), which showed a higher value of R2 (0.98) and adjusted R2 (0.95), confirming that the model can explain the results successfully. Ageing temperature was found to be the only significant variable for the Cu-K-OMS-2 transformation phase, with CuO and the bixbyite phase appearing as the highest ageing temperature condition. Furthermore, the effects of ageing temperature, ageing time and amount of Cu dopant on the Cu3+/Cu2+ mole ratio were also investigated. Ageing temperature and amount of Cu dopant displayed a significant effect on both toluene removal and the Cu3+/Cu2+ mole ratio. On the other hand, ageing time was not significant for both responses. The high Cu3+/Cu2+ mole ratio led to enhancement of toluene removal. The optimized conditions for Cu-K-OMS-2 synthesis were determined as 120ºC of ageing temperature, 6 h of ageing time and 6% by mole of Cu on K-OMS-2, which removed 80% of toluene at a reaction temperature of 180ºC.

Effects of aging temperature and aging time on the mechanism of martensitic transformation in nickel-rich NiTi shape memory alloys

The effects of aging temperature and time on the shape memory behavior of the high nickel-rich Ni54Ti46 (at.%) alloys were investigated. The changes in transformation temperatures, microstructure, lattice structure and mechanical behavior with aging were revealed. Multiple-stage phase transformation was observed for aged specimens due to the formation of Ti3Ni4, Ti2Ni3, and TiNi3 precipitates. It was revealed that the transformation temperatures can be tailored by aging where Ms was −3 °C after 550 °C–24 h aging and 29 °C after 400 °C–3 h aging. Aged samples showed a shape memory effect with a recoverable strain of <1.6% where 550 °C–3 h aged Ni54Ti46 alloy showed a maximum recoverable strain of 1.55% under 500 MPa. The maximum work output was determined as 7.75 J/cm3 for 550 °C–3 h aged Ni54Ti46 alloys. Partial shape recovery was also observed in aged samples.

Effect of Aging Temperature on Microstructure and Properties of 00Cr12Ni10MoTi Maraging Stainless Steel

Effect of Aging Temperature on Microstructure and Properties of 00Cr12Ni10MoTi Maraging Stainless Steel

A hyper-elastic thermal aging constitutive model for rubber-like materials

Different phenomenological, empirical, and micromechanical constitutive models have been proposed to describe the behavior of incompressible isotropic hyper-elastic materials. Among these models, very few have accounted for the thermal aging effect on the model constants and parameters. This article introduces a new empirical constitutive hyper-elastic model for thermally aged hyper-elastic materials. The model named “the weight function based (WFB) model” considers the effect of aging temperature and time on its parameters. The WFB model formulation can facilitate fatigue analysis and lifetime prediction of rubber-like materials under aging conditions. The WFB model in this article defines all rubber-like material properties, such as fracture stretch, strength, and stiffness, by predicting the full stress–strain curve at any aging time and temperature. The WFB model was tested on natural rubber for uniaxial and biaxial loading conditions. More than 100 specimens were aged and tested uniaxially under various temperatures and aging times to extract the stress–strain behavior. The temperatures used in the test ranged from 76.7°C to 115.5°C, and the aging time ranged from 0 to 600 hours (hrs). A classical bulge test experiment was generated to extract the biaxial natural rubber material behavior. An ABAQUS finite element analysis model was created to simulate and verify the generated biaxial stress–strain curve. The proposed model represents the aging effect on the tested natural rubber under uniaxial and biaxial loading conditions with an acceptable error margin of less than 10% compared to experimental data.

Effects of thermal aging on phase transformation and microstructural characteristics of NiTi shape memory alloy

In this study, the effects of aging temperature and time on microstructure and phase transformation behaviors of the NiTi shape memory alloy were investigated with the effects of precipitates. NiTi SMA was synthesized using powder metallurgy process followed by the solution annealing at 850 °C for 1 h. The thermal aging process has been executed on NiTi alloy in the temperature range of 450 °C–750 °C for 1 h, 3 h and 5 h respectively. It was found that the enhancement of transformation temperatures due to the formation of secondary phases during the transformation of cubic to monoclinic. The lenticular structured Ni4Ti3 precipitate was mainly influenced the phase transformation by changing the Ni composition in the NiTi matrix. The significant changes were observed in the austenite and martensite finish temperatures with increasing the aging temperature and time. This study suggests that the NiTi SMA can be implemented in biomedical applications when heat treated at 650 °C for 5 h.

Effect of Aging Temperature on the Microstructure and Properties of Economical Duplex Stainless Steel.

In this study, NSSC 2120 economical duplex stainless steel was prepared and the effects of aging temperatures on its intermetallic phase morphology, tensile strength, elongation, corrosion resistance, and antimicrobial properties were investigated. The results revealed that after aging the sample at 650 °C, it exhibits better pitting corrosion resistance and higher tensile strength. Upon increasing the aging temperature up to 750 °C, the pitting corrosion resistance and tensile strength of the samples were decreased due to the precipitation of the ε-Cu phase in the matrix. Moreover, with the further increase in the aging temperature to 850 °C, oxides containing Mn and Cr (CrMn1.5O4) and sulfides (MnS) precipitated from the samples, further decreasing their pitting corrosion resistance and tensile strength. Upon aging the samples at 950 °C, no second phase was observed and the corrosion resistance was less than that of the sample after aging at 650 °C, but the tensile strength was greater than that of the sample after aging at 650 °C. Antibacterial test results revealed that the sample after aging at 750 °C exhibited a good antibacterial effect due to the precipitation of the rod-shaped ε-Cu phase.

RILEM TC 252-CMB report: rheological modeling of asphalt binder under different short and long-term aging temperatures

This paper evaluates whether the temperature reduction production during Warm-Mix Asphalt (WMA) leads to a beneficial effect on short- and long-term aging properties of asphalt binder. For this purpose, two 70/100 penetration grade virgin asphalt binders were used. First, the material was short term aged at three different temperature, 123 °C, 143 °C, and 163 °C, and then, long term aged. Shear complex modulus was then measured with the Dynamic Shear Rheometer and the data used to generate master curves and fit the 2 Spring 2 Parabolic 1 Dashpot model. Glover–Rowe parameter and crossover-temperature were next determined to further investigate the effect of aging temperature on the properties of the material. Significant differences were observed between 163 and 123 °C for both short- and long-term aging conditions. However, a remarkable difference between 143 and 123 °C could be detected only for the short-term aged binder. Finally, the statistical analysis confirmed the experimentally observed trend. Based on the results and analysis presented in this paper, it can be hypothesized that a reduction in the temperature of short-term aging, which is commonly experienced during WMA production, may result in an overall substantially milder aging.

The effect of ageing temperature on the sensory qualities of Hibiscus sabdariffa (Roselle) wine

The effect of ageing temperature on the sensory qualities of Hibiscus sabdariffa (Roselle) wine

Micro-mechanisms and precipitation kinetics of delta (δ) phase in Inconel 718 superalloy during aging

The formation of δ phase in Inconel 718 superalloy during aging was quantitatively studied based on improved analyzing techniques to unambiguously determine the mechanism of δ phase precipitation and its kinetics. Based on the general transformation rate expressed in terms of the time corresponding to the transformed fraction of 0.5 or 50% and also the modified Johnson–Mehl–Avrami–Kolmogorov (JMAK) equation, the average activation energy for the formation of δ phase was determined as 212.4 kJ/mol and 197.5 kJ/mol, respectively. These values are comparable to the activation energy for diffusion of Nb in Ni (202.59 ± 4.71 kJ/mol). Therefore, the micro-mechanism for the formation of δ phase was characterized as the diffusion of Nb in the matrix. Based on the kinetic studies, the temperature of 1055.7 K (782.7 °C) was found as the lower bound for the formation of δ phase, which was consistent with the precipitation-temperature-time (PTT) plot developed for this material. Finally, a formula was obtained to quantitatively show the effects of aging temperature and cold rolling reduction on the transformation rate for the precipitation of δ phase.

Correlation of DSR Results and FTIR’s Carbonyl and Sulfoxide Indexes: Effect of Aging Temperature on Asphalt Rheology

AbstractThis paper investigates the effects of different aging temperatures on the performance of asphalt binders through a comprehensive experimental procedure. Two kinds of asphalt binders with t...

Investigation on the combined effect of aging temperatures and cooling medium on rheological properties of asphalt binder based on DSR and BBR

In this paper, the combined effect of aging temperatures and cooling medium on the rheological properties of asphalt binder was experimentally investigated and evaluated. Two 70/100 penetration grade binders, which were part of the core materials used by the active RILEM committee CMB-252, were selected for this purpose. The materials were artificially aged to six different conditions, first with the Rolling Thin Film Oven Test (RTFOT) at three different temperatures (123°C, 143°C, and 163°C), and then, with the standard Pressure Aging Vessel (PAV). Next, temperature and frequency sweep (T-f-sweep) tests were performed on the entire set of materials by using the Dynamic Shear Rheometer (DSR) from −30°C to 80°C while low-temperature creep tests were conducted on the long-term aged asphalt binders with the Bending Beam Rheometer (BBR) devices in air and in ethanol, respectively. Then, the 2 Spring 2 Parabolic element 1 Dashpot model (2S2P1D) and Huet model were used to evaluate the rheological properties of asphalt binders based on the DSR and BBR results, respectively. Moreover, two parameters, crossover temperature, Tδ=45°, and the difference in critical temperature, ΔTc, were used to evaluate the aging properties of the materials. Finally, the relationship between the time domain complex modulus based on DSR and the creep stiffness obtained with the BBR was established to investigate the effect of the cooling medium at low-temperatures. The results indicate that a temperature reduced process may lead to a mitigation of the short-term aging of asphalt binders, while a temperature reduction of only 40°C can result in a consistently milder long-term aging. In the BBR test, higher creep stiffness and smaller m-values can be observed in the air compared to ethanol. Huet and 2S2P1D models show that complex modulus and creep stiffness share the same core parameters only in the case of air. Based on the finding in this research, the temperature reduced mixing process and the use of air for BBR creep tests are recommended.

Effect of ageing temperature on reverse austenite content in AISI 630 stainless steel

AbstractThe alloy AISI 630 (ASTM A564‐89 17‐4 PH) is a precipitation hardening stainless steel with good mechanical and corrosion properties. Mechanical properties strongly depend on the microstructure. Namely, the formation of the reversed austenite and coarsening of copper rich precipitates cause a substantial drop of hardness. Thus, the evolution of the microstructure during ageing was thoroughly investigated in order to explain the processes that have effect on formation of the reversed autenite. The reaustenitization was analyzed with a dilatometer, while the coarsening of copper rich precipitates was observed by transmission electron microscope. The amount of austenite was measured with x‐ray diffraction and the impact of austenite on the fracture appearance transition temperature was observed. It was found that the amount of the so called reverse austenite does not only depend on the amount of transformed austenite but also on its chemistry, as it dictates its ability to transform into martensite during cooling.