Temperature Time Research Articles

Thermochromic behavior of pigment red 254 in nylon 6 polymer for high-chromaticity engineering plastics

Advancement in Color-Material-Finishing (CMF) plays a crucial role in enhancing the visual appeal of plastic products, particularly for the high-chroma nylon plastics that are currently in vogue. However, it is inevitable to encounter pigment-dyeing issues in polar engineering plastics during the high-temperature extrusion process, which can lead to intense fluorescence and color fading. This phenomenon, characterized by the dissolution of pigments in a polar environment, can adversely affect the color saturation and weatherability of the pigment, which ultimately cause sharp reduction of aesthetic quality and durability of the plastic. Herein, we develop a modified strategy combined with thermal annealing to realize rapid color recovery in nylon 6, and further reveal the fluorescence and discoloration mechanism of pigment red 254 in nylon 6. Through improving the mobility of nylon chain segments, the rigid heterogeneous nucleation regions centered on the interfacial hydrogen bond between nylon 6 and the pigment molecules loosens with the help of heat treatment, and then the dissolved pigment molecules reaggregate to induce fluorescence quenching. Importantly, as a consequence of the increased lubricity segments, the required thermal annealing temperature and time for color recovery and fluorescence quenching could be significantly shortened from 180 °C for 5 h to 100 °C for 0.5 h. This work provides a feasible approach for the industrial production of high-chroma polar engineering plastics.

Characterization and linear / nonlinear optical aspects of polyaniline (PANI) films incorporated with Ethylenediamine for low-cost limiting optical technologies

Polymer composite combined film with Polyaniline (PANI) and Ethylenediamine (EDA) were successfully synthesized via the spin coating technique on a glass substrate followed by different thermal annealing degrees and times. Successful incorporation of EDA into the PANI polymer matrix and the effect of the annealing temperature have been demonstrated by XRD, FTIR, FESEM and TEM. Using UV–Vis optical spectroscopy, we determine the absorption coefficient, band edge, and Urbach energy. The effects of different annealing temperatures and times on linear/nonlinear optical characteristics were investigated. The band gap of EDA-doped PANI films is reduced with the different thermal annealing from 3.43 eV to 3.19 eV, while the Urbach tail of the 100 °C/4h film which is 0.492 eV was decreased to 0.469 eV for 150 °C/1h sample. However, the absorbance and optical conductivity were both increased. Besides, the optical limiting effect assesses their potential to mitigate intense light. It was found from the study that for green wavelength 100 °C/4h film decreases the input power by 16.5 % whereas the 150 °C/1h sample shows superior limiting behavior of 99.96 %. It has been found that thermal annealing of the EDA-doped PANI films enhances the synthetic composite's optical characteristics, making the 150 °C/1h sample of EDA-doped PANI films appropriate for utilization in both energy applications and optoelectronics.

Effect of tempering process on the structure and properties of M51/X32 bimetal band saw blade

Abstract The mechanical properties of band saw have a great influence on the cutting life. In this paper, through the systematic study of M51/X32 bimetallic band saw blade with different tempering temperatures and times, the metallography of the bimetallic band saw blade under different heat treatment conditions was analyzed. The mechanical properties of the bimetallic band saw blade under different conditions were tested. The results showed that the carbide in the metallography of the tooth tip was uniform and tended to be spherical when tempering at 600°C for five times. The mechanical properties such as hardness, tensile strength, and fatigue properties are well matched, which can extend the service life of bimetallic band saw blades and ensure the cutting quality.

Strength, pliability, and hydrophobicity of mung bean starch straws: Orientation change caused by annealing time.

To achieve starch straws with high strength and large toughness, the effects of annealing time on structural and functional performances of mung bean starch straws were studied. The results revealed that with increasing annealing time from 0to 60min, the ratios of 1047cm-1/1022cm-1 in Fourier transform infrared spectroscopy decreased from 1.37 to 1.20, and the relative crystallinities decreased from 12.09% to 11.01%. The relative crystallinity increased to 13.28% when annealing time increased to 120min. The maximum bending force increased from 10.93 to 104.24 N, and modulus of elasticity enhanced from 0.93 to 62.68 N/mm when annealing time increased from 0 to 120min. Starch straws annealed for 120min had the lowest water absorption (94.61%), while starch straws annealed for 60min had the highest water absorption (127.38%). This outcome not only lay a theoretical foundation for preparing biodegradable starch straws with excellent performance, but also apply for beverages, food container, food packaging films, and so on, strongly promoting starch industrial transformation and development.

EFFECT OF ANNEALING DURATION ON PHOTOCATALYTIC PROPERTIES OF LaFeO3 PEROVSKITE

In this paper, the effect of the annealing duration on the photocatalytic properties of lanthanum ferrite perovskite synthesized by the hydrothermal method is investigated. Lanthanum ferrite was chosen as the object of study due to its high activity under the influence of visible light. During the experiments, the structural changes occurring in the material during annealing during 2, 4 and 6 hours were studied. The main attention was paid to the analysis of the morphology of nanoparticles, phase composition, crystallinity, absorption spectra and photocatalytic activity. The results show that an increase in the annealing time leads to an improvement in the crystal structure, an increase in the size of crystallites and a higher level of oxygenation. The optimal annealing time to achieve maximum photocatalytic activity was determined to be 6 hours. The work confirms the prospects of using long-term annealing to improve the photocatalytic properties of perovskite-based materials.

Amorphous InZnSnO thin-film-transistors performance enhancement with low-energy Xenon Pulsed-light annealing

The electrical characteristics and stability of amorphous indium-zinc-tin oxide (IZTO) thin-film transistors (TFTs) were significantly improved in this study using low-energy Xenon pulsed-light annealing (PLA). In comparison to conventional furnace annealing (FA), PLA treatment significantly reduced the processing temperature and annealing time. Besides, the defect states are obviously reduced from 1.73×1012 cm-2 to 6.53×1011 cm-2 by PLA treatment, resulting in improved device electrical characteristics and enhanced reliability, including improved carrier mobility from 20.08 to 39.61 cm2/V∙s, threshold voltage from 0.82 to 0.24 V, subthreshold swing (S.S.) from 0.54 to 0.24 V/decade, and the ON/OFF current ratio from 2.32×107 to 7.31×108. In addition, the enhanced stability is observed under both positive gate-bias stress (PGBS) of VGS = 30 V and negative gate-bias stress (NGBS) of VGS = –30 V for a stress duration of 3000 s. The threshold voltage shift (ΔVTH) is reduced from 8.31 V to 1.65 V and from –3.93 V to –1.51 V, respectively. This is the first time low-energy PLA was conducted for IZTO TFT performance improvement.

Effect of Annealing Time on Various PtNi/C Binary Alloy Catalysts for ORR in PEFCs

Polymer electrolyte fuel cells (PEFCs) are used in automotive power supplies due to their advantages of low environmental impact and high energy conversion efficiency. However, Pt used for electrocatalysts is expensive and its activity and durability are problematic. In this study, the PtNi/C catalysts were prepared with different annealing times and the oxygen reduction reaction activity was evaluated. The linear sweep voltammograms and current-voltage curves showed that the PtNi/C catalysts annealing time for 60 min performed better than the commercial catalyst. This would be attributed to the internal alloying of Ni and better electronic structure due to the longer annealing time.

Effects of Tempering on Microstructure and Properties of Additive Manufacturing Cu-Bearing AISI 431 Steel.

AISI 431 martensitic stainless steels (MSS) with 2.5 wt% Cu were fabricated via laser-directed energy deposition additive manufacturing followed by single-step tempering treatment. The influences of different tempering times at 600 °C on microstructure and mechanical properties of the as-deposited 431-2.5Cu MSS have been explored and analyzed. The as-deposited MSS specimen primarily consisted of lath martensite, austenite and M23C6 carbide. After the single-step tempering treatment at 600 °C, Cu-enriched (ԑ-Cu) nano-precipitates and reverse austenite can be formed and promoted by extending the tempering treatment. The microhardness, strength and elongation can be improved with increasing the tempering time up to 1.0 h, and subsequently reduced with the tempering time prolonging to 2.0 h. Compared to 431 MSS that requires a multiple-step heat treatment for excellent performance, the 431-2.5Cu MSS specimen presented superior tensile properties after single-step tempering at 600 °C for 1.0 h in the present work. The ultimate tensile strength (UTS), yield strength (YS) and elongation (EL) of one-hour tempered MSS were 1611 MPa, 1334 MPa and 16.3%, respectively. This study provides a quantitative theoretical reference and experimental basis for realizing short-process fabrication of the Cu-bearing MSS with high strength and ductility.

The Fabrication of Gold Nanostructures as SERS Substrates for the Detection of Contaminants in Water.

Gold nanostructures (AuNSs) were used to fabricate surface-enhanced Raman spectroscopy (SERS) substrates. These AuNSs were produced using the solid-state dewetting method from thin films. The fragmentation process was studied at 300 °C, with durations of thermal treatment of 1, 3, 6, and 12 h. These SERS substrates were then employed to detect Rhodamine B (RhB) as the model analyte, simulating a contaminant in the water at a concentration of 5 ppm. The morphology of the AuNSs was examined using SEM, which revealed a spheroidal shape that began to coalesce at 12 h. The size of the AuNSs was estimated to range from 22 ± 7 to 24 ± 6 nm, depending on the annealing time. The localized surface plasmon resonance of the AuNSs was determined using absorption spectroscopy, showing a shift as the annealing time increased. The SERS signals of RhB adsorbed on the AuNS substrates were validated by performing a 10 × 10 point map scan over each sample surface (1, 3, 6, and 12 h), and a comparative analysis showed no significant differences in the positions of the bands; however, variations in intensity enhancement ranged from 5 to 123 times at 6 and 1 h, respectively.

Epitaxial crystallization of polylactic acid on layered zinc phenylphosphonate: Mutual perpendicular rodlike crystals under two lattice matchings

AbstractAs a highly effective nucleating agent, layered zinc phenylphosphonate (PPZn) is incorporated into polylactic acid (PLA) to investigate the epitaxial crystallization of PLA on PPZn in this study. The corresponding lattice spacing change, crystalline morphology, and crystalline structure are emphasized to reveal the epitaxial crystallization mechanism. As a result, with the increase of PPZn content and the annealing time, the increasing lattice spacing of PPZn and the formation of mutually perpendicular rodlike crystals are observed through x‐ray diffraction (XRD) and polarized optical micrograph (POM) measurements, implying that the interlayer spacing of PPZn crystals is expanded as the PLA α‐form crystals epitaxially grow on its surface, that is, epitaxial crystallization. To be specific, “edge on” lamellae epitaxial grow on the PPZn crystals along the [010] and [100] directions under two excellent lattice matchings, which possess acceptable mismatching of 0.347% and 7.5%, respectively. With the support of the epitaxial crystallization mechanism, the occurrence of the filamentous structure observed in the fracture morphology of PLA/PPZn composites suggests strong interfacial adhesion between PLA and PPZn, which makes the impact toughness of the PLA/PPZn composites increase by 53.6% compared with pure PLA.

The growth kinetics of intermetallic compounds by the fast diffusion path at the interface of Co and molten Zn

This study investigates the growth and microstructure formation of intermetallic compounds at the solid/liquid interface of a Co/Zn diffusion couple prepared using an isothermal bonding method and annealed isothermally at 703 K, 723 K, and 743 K for up to 48 h. The experimental observations and analysis revealed the formation of three Zn-rich intermetallic compounds: γ (Co5Zn21), γ1 (CoZn7), and γ2 (CoZn13). The γ2 phase, having the highest Zn content, formed the thickest layer, while the γ and γ1 phases exhibited slower growth. The total thickness of these layers increased proportionally to the annealing time, following a power function. The growth of intermetallic compounds was predominantly controlled by interdiffusion, with the γ2 phase forming island-like structures that merged over time, creating fast diffusion paths of liquid Zn. The annealing temperature had a minimal impact on the growth rate, with slightly faster growth observed at lower temperatures due to finer needle-like interfaces within the molten Zn, which created more efficient diffusion paths. These findings underscore the importance of understanding the kinetics and mechanisms of intermetallic compound formation for optimizing material properties and processing conditions in industrial applications.

Characterization of methylammonium tin iodide thin films prepared by sequential physical vapour deposition

Methylammonium tin triiodide (MASnI3) films were grown through Sequential Physical Vapour Deposition (SPVD) without breaking the vacuum and optimized by varying MAI thickness and annealing time while keeping SnI2 thickness constant. The film's crystallinity increased with MAI thickness and annealing time. Optimal bandgap was attained for the film with 500 nm MAI annealed for 20 & 40 min. FE-SEM revealed densely packed, large grains, increasing in size with MAI thickness and on annealing from 0 to 40 min and decreasing at 80 min. The film with 300 nm MAI thickness annealed for 40 min showed the strongest PL intensity suggesting reduced carrier recombination losses. Trap densities reduced with annealing time and MAI thickness due to improvements in films' crystallinity, grain sizes and reduced grain boundaries which act as carrier trapping sites. Hence, films prepared through SPVD, exhibit excellent structural, optical, and morphological properties, suitable for photovoltaic applications.

Annealing Time Dependence on Creation of SiV, GeV, and SnV in Diamond by Atmospheric Annealing at 1800 °C

The creation of SiV−, GeV−, and SnV− are presented by the atmospheric annealing in the argon flow. Compared to high‐pressure annealing, in which gas cannot flow, atmospheric annealing with an inert gas flow not only causes less degradation of the sample surface but also has the advantage of reducing equipment cost and preparation time. Excessive annealing time has been shown to reduce the amount of centers created. The optimal annealing time that maximizes formations depends on the type of diamond sample and the implanted ions. Furthermore, inspired by the split‐vacancy structure of the group IV–V centers, atmospheric pre‐annealing at 600 °C to increase the amount of di‐vacancy is demonstrated, followed by annealing at 1800 °C for 1 min. A shorter duration of high‐temperature annealing is expected to qualitatively reduce stress and deterioration of the crystallinity of the diamond sample.

Shear mechanical properties of AISI 316L stainless steel processed by unidirectional/cross rolling and annealing treatment

The effects of cold rolling routes followed by annealing on the mechanical properties of AISI 316L stainless steel were characterized. Both unidirectional and cross rolling methods were applied and the evolutions of shear mechanical properties by shear punch testing (SPT) and hardness during reversion/recrystallization annealing were systematically investigated. It was revealed that cross rolling promotes strain-induced martensitic transformation during rolling and also enhances grain refinement during annealing, leading to improved hardness and ultimate shear strength (USS). The variation of USS with annealing time was similar to that of Vickers hardness (HV), so that the simple and useful equation of USS = 0.196HV was derived. Moreover, by relating the USS to the ultimate tensile strength (UTS) via von Mises criterion, the finalized equation of HV = 2.95UTS was obtained, confirming the empirical formula of HV = 3UTS for steels. Accordingly, this work can shed light on the application of SPT for investigating the mechanical properties of austenitic stainless steels.

Fabrication and characterization of NiO nanoparticles deposited via reactive DC magnetron sputtering technique

Nickel oxide (NiO) nanostructure was successfully prepared via reactive DC magnetron sputtering on the soda-lima glass substrate, which can be used for various applications. Xray diffraction (XRD) investigations were used to evaluate NiO with two annealing durations. The results revealed that the deposited films had a cubic structure and polycrystalline nanoparticles. A significant polycrystalline structure could be seen in the sputtered films as a diffraction peak oriented toward NiO (200). Field-emission Scanning Electron Microscopy (FE-SEM) analysis identified the surface morphology of NiO nanoparticles prepared at two different annealing times with the two average sizes (24 and 32 nm) respectively. The samples' roughness was assessed using atomic force microscopy (AFM). Increased annealing time was shown to result in a decrease in grain size. The energy band gap (Eg) expanded with increasing annealing time, according to UV-visible spectroscopy (UV-Vis). FTIR spectroscopy was used to determine the functional groups of NiO nanoparticles and their bonding nature. The results indicate that optical characterizations are more sensitive to the annealing period.

Effect of microstructural inheritance window on the mechanical properties of an intercritically annealed Q&P steel

Different initial microstructures significantly influence the final microstructures and mechanical properties of the intercritically annealed quenching and partitioning steels. Previous studies have primarily focused on the mechanism for the inheritance of different initial microstructures into the final microstructures, which affects the phase fraction and mechanical properties. However, these studies have overlooked the existence of an inheritance window in the intercritical annealing process. In this study, we investigated the inheritance window and explored the impact of varying initial microstructures on the reverse transformation of austenite, final phase fraction, and mechanical properties. Our findings reveal that the varying initial microstructure exhibits minimal influence on the final microstructure and mechanical properties for short or long annealing times. However, for the intercritical annealing treatment for 60 s, the initial microstructure of martensite with more nucleation sites accelerated the austenite reverse transformation fraction, enhanced the reverse-transformed austenite content, increased the primary martensite content, and improved the yield strength. Conversely, the coil-cooled sample, with initial microstructures consisting of ferrite and pearlite without dissoluble Mn-rich cementites, reduced the austenite reverse transformation rate, decreased the reverse-transformed austenite content, enhanced the ferrite and RA content, and improved ductility.

Fabrication and characterization of NiO nanoparticles deposited via reactive DC magnetron sputtering technique

Nickel oxide (NiO) nanostructure was successfully prepared via reactive DC magnetron sputtering on the soda-lima glass substrate, which can be used for various applications. Xray diffraction (XRD) investigations were used to evaluate NiO with two annealing durations. The results revealed that the deposited films had a cubic structure and polycrystalline nanoparticles. A significant polycrystalline structure could be seen in the sputtered films as a diffraction peak oriented toward NiO (200). Field-emission Scanning Electron Microscopy (FE-SEM) analysis identified the surface morphology of NiO nanoparticles prepared at two different annealing times with the two average sizes (24 and 32 nm) respectively. The samples' roughness was assessed using atomic force microscopy (AFM). Increased annealing time was shown to result in a decrease in grain size. The energy band gap (Eg) expanded with increasing annealing time, according to UV-visible spectroscopy (UV-Vis). FTIR spectroscopy was used to determine the functional groups of NiO nanoparticles and their bonding nature. The results indicate that optical characterizations are more sensitive to the annealing period.

The influence of annealing process on the sagging resistance of AA3003 foil and laminated AA4343/AA3003/AA4343 composite foil materials

Upon 98% reduction cold-rolling, a single layer AA3003 foil material of 115 μm thick was intermediately annealed at 300–420 °C/1-8 h, and the preferred temperature and time of the intermediate annealing for the laminated AA4343/AA3003/AA4343 composite foil material were determined. All of these samples were cold rolled by 40% to 70 μm thick and finally annealed at a temperature in the range of 300–550 °C for 1–9 h. Their sagging resistance and microstructure were investigated using simulated brazing treatment, optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). For the single layer AA3003 foil, the sagging distance decreased first and then increased with increasing intermediate annealing temperature, and the lowest sagging distance corresponds to the coarsest grain in the recrystallized sample. After the final annealing for the single layer, the sagging distance decreased monotonously. For the laminated foil subjected to the final annealing, the sagging distance curves decreased first and then increased with increasing annealing temperature and time. The improvement of sagging resistance was attributed to the recovery of two types of materials during annealing process. The deterioration of the sagging resistance in the laminated foils was due to the corrosion in the brazing process, resulted from the Si diffusion from the cladding layer into the core layer. It is the coarse grains, few dislocations and minimal diffusion of Si that are crucial for improving the sagging resistance of the laminated foils.

Effects of diamond/Al interface structure evolution on interfacial thermal conductance during the carbonization of the Cr interlayer

The correlation between the interface structure evolution and the interfacial thermal conductance (ITC) in diamond particles reinforced Al matrix (diamond/Al) composites has been largely unclear. Herein, diamond/Cr/Al nanolayered structures with the interlayers in different carbonization stages were prepared via magnetron sputtering and annealing treatment to simulate the interfaces in diamond/Al composites. As the annealing time increases, the formed Cr3C2 phase progressively grows from discrete particles to a continuous layer at the diamond/Cr interface, during which the thickness of the carbide layer gradually increases. The formation of Cr3C2 phase improves the interface bonding and provides a more convenient channel for the heat exchange of hot carriers between the interfaces. Accordingly, the ITCs of the samples gradually increases with the annealing time and reaches the maximum value of 436.66 MW/(m2·K) at 120 min due to the formation of a thin and continues Cr3C2 layer. However, considering high interfacial thermal resistance was introduced at the interface when the Cr3C2 interlayer is too thick, the ITC of the sample decreased to 321 MW/(m2·K) as the annealing time extended to 240 min. In addition, Al8Cr5 phase is generated at the Al/Cr interface, but its impact on the ITC of the samples is negligible due to the small amount.

Effect of Carbon Content on the Phase Composition, Microstructure and Mechanical Properties of the TiC Layer Formed in Hot-Pressed Titanium-Steel Composites

During the hot pressing of pure titanium and different carbon steels in a temperature range of ϑ = 950–1050 °C, a compound layer up to dL≈10 μm thick is formed at the titanium–steel interface. With a higher carbon content of the used steel, the layer thickness increases. The carbon concentration within the layer is in the range of stoichiometry for TiC. Apart from TiC, no other phases can be detected by X-ray diffraction (XRD) measurements inside the formed layer. The calculation of the activation energy for the TiC layer formation is Q = 126.5–136.7 kJ mol−1 and is independent of the carbon content of the steel. The resulting microstructure has a grain size gradient, wherein the mechanical properties, such as hardness and Young‘s modulus, are almost constant. Statistical analysis using Response Surface Methodology (RSM) indicates that the carbon content of the steel has the most significant influence on layer thickness, followed by annealing temperature and annealing time. By selecting the appropriate carbon steel and the subsequent removal of the steel, it is possible to produce targeted TiC layers on titanium substrates, which holds enormous potential for this material in wear-intensive applications.