Effect Of Heating Temperature Research Articles

Material corrosion characteristics of heat-treated SLM-ed Hastelloy X in electrochemical machining process

Selective laser melting (SLM) technology and electrochemical machining (ECM) offer new methods for producing nickel-based superalloys with complex structures and high surface quality, including Hastelloy X parts. However, SLM-fabricated parts exhibit significant anisotropy, and there are no effective criteria for evaluating material corrosion characteristics in actual ECM due to the detachment of research and application, making the parameter selection challenging in actual ECM. To address this issue, this article proposes a comprehensive evaluation system based on the corrosion characteristics in the actual machining process and investigates the effect of heat treatment temperature on the corrosion characteristics of Hastelloy X in ECM. The results show that at a heat treatment temperature of 1000°C, machining efficiency, accuracy, and localization can all be achieved at a good level with good consistency in different directions at the expense of a certain machining accuracy. The 800℃ heat-treated specimen exhibits strong corrosion resistance, providing a significant advantage in machining localization and accuracy. When the heat treatment temperature exceeds the solid solution temperature (more than 1175℃), the mechanical properties and corrosion characteristics of the specimen are significantly degraded. The results of various material testing methods, including electrochemical testing, EBSD, XRD, and EDS indicate that changes in grain size due to recrystallization and the galvanic effect of precipitates are the primary causes of these changes.

Electrodeposited Ni–Co–B coatings: Preparation and evaluation of its wear resistance

Ni–Co–B coating was electrodeposited in sulfate bath with dimethylamine borane (DMAB) as reducing agent. The experiment explored the effect of DMAB concentration (CDMAB, 1–10 g/L), current density (Jk, 2–8 A/dm2), bath temperature (Tbath, 30–60 °C) on the coating morphology and hardness, and determined the best parameters: CDMAB = 8 g/L, Tbath = 60 °C, Jk = 4 A/dm2. The average hardness of the crack-free coating is 818 HV, and the B content is about 2 wt%. In order to develop a stress-relieving heat treatment scheme, the effects of heat treatment temperatures (100–500 °C) and holding times (1.5 h and 3 h) on the hardness of Ni–Co–B coating were studied. The highest hardness (1130 HV) is obtained at 350 °C for 1.5 h. The heat-treated Ni–Co–B coating was characterized by XRD, SEM and EPMA, and the second phase Ni3B was detected. In addition, the wear resistance and wear mechanism of the coating at room temperature and high temperature (300 °C) were studied. The results show that the wear volume of Ni–Co–B coating is reduced by more than 55% compared with Ni–Co coating. In general, Ni–Co–B coating can be used as an alternative to Ni–Co wear-resistant coating.

Study on the heat treatment of multispectral ZnS for residual stress reduction

Multispectral ZnS (M − ZnS) will inevitably introduce stresses during the chemical vapor deposition (CVD) polycrystalline growth and hot isostatic pressing (HIPping) stages. In this paper, the generation mechanism and elimination method of residual stresses in M − ZnS are analyzed by means of SEM, transmittance, XRD analysis and mechanical property characterization, and the effects of heat treatment temperature, time and material annealing structure on the apparent morphology, optical and mechanical properties of M − ZnS materials are investigated. The results show that the internal stresses of M − ZnS mainly originate from the CVD ZnS growth and HIPping stages, and the most effective method to reduce the stresses is heat treatment. The key factors affecting the effect of heat treatment include temperature, time, and annealing structure. Selecting a GZ(G) annealing structure combined with a suitable cooling rate for heat treatment of M − ZnS materials will significantly improve the heat treatment effect. More annealing time has a significant effect on the transmittance in the 0.38–3 μm band, and insignificant effect on the transmittance in the 3–5 μm and 8–10 μm bands. Heat treatment will bring some degree of structural changes to the material, often manifested including a trace of hexagonal phase structure, which will affect the optical imaging quality of the window material. Heat treatment contributes to secondary grain growth, with an increase in grain size and a decrease in grain boundaries. Excessive heat treatment accelerates the loss of hardness and bending strength, and also leads to the generation of micro-cracks and macro-cracks in the material, reducing the mechanical properties of the material. Heat treatment holding 200 h and 100 h compared to the unannealed, Vickers hardness decreased by 13.518 and 7.96, respectively, bending strength decreased by 4.77 MPa and 1.73 MPa, respectively. Therefore, in actual production, should not be selected excessive heat treatment time.

Eu2+ doping and Mg2+-coupled Zn2+, Ca2+ and Sr2+ cations induce tunable orange-blue luminescence in cordierite

A series of Mg2Al4Si5O18:xEu2+ (x = 0.2, 0.6, 1.4, 2.8, 6.0mol‰) and Mg2Al4Si5O18:0.05B, 1.4Eu2+ (BZn2+, Ca2+ and Sr2+) phosphors were prepared by high-temperature melt ice-water quenching and heat treatment. In this study, using Eu2+ ions as a structural probe, we investigated the effects of heat treatment temperature, Eu2+ ion concentration, and cation position on the crystal phase and local structure, triggering changes in the luminescent properties of the phosphor and achieving coordinated blue and red luminescence. Through heat treatment analysis, we proposed the formation process of the two phases of cordierite. The doping of different concentrations of Eu ions in cordierite triggers the phase transition of the host lattice. The molar distribution ratio of Eu2+ ions was calculated by Gaussian peak-splitting fitting to identify the detailed occupancy distribution of the Eu2+ ions in μ-cordierite and α-cordierite. In the α-cordierite phase, with the doping of Zn2+, Ca2+, and Sr2+ cationic sites, the PL is modulated from orange to blue emission based on the selective occupancy of Eu2+ ions, which is caused by the difference in cationic radii and structural distortion. The comprehensive luminescence intensity of MASE1.4, MASZ0.05E1.4, MASC0.05E1.4, and MASS0.05E1.4 phosphors were 81.18%, 83.49%, 62.67%, and 76.41% at 150 °C compared to that at 30 °C, indicating the better thermal stability of the prepared phosphors. The luminescence tunable strategy by cation and Eu2+ doping simultaneously modifies the emission and achieves different thermal stability, providing a new design concept for the development of Eu2+-doped silicate phosphors.

Effect of heat treatment temperature on microstructure and electrochemical behavior of additive-manufactured AlCoCrFeNi high entropy alloy

In this paper, a high-entropy AlCoCrFeNi alloy were prepared using laser melting deposition (LMD) and the effect of heat treatment on their microstructure and corrosion resistance was studied. XRD, OM, SEM, EDS, EBSD and electrochemical tests were used to investigate the structure, microstructure, and corrosion resistance. The LMD and LMD-500 °C samples showed a single BCC phase structure. After the temperature was increased to 800 °C, a small amount of a Cr-rich and Fe-rich FCC phase and σ phase precipitated at the grain boundaries, Al and Ni were enriched within the crystals. At 1100 °C, the σ phase disappeared, and the FCC phase content increased from 1.4% to 5.2%. The average grain size was the largest at 500 °C, reaching 31.29 μm. In 3.5% NaCl solution, the LMD-500 °C sample showed a high self-corrosion potential and the lowest corrosion current density; the polarization resistance (Rp) and charge transfer resistance (Rct) were 5.266 × 105 Ω∙cm2 and 1.248 × 108 Ω∙cm2, respectively, with the shallowest surface corrosion and the best corrosion resistance. In 0.5 mol/L NaOH solution, there were only a few corrosion holes in the samples before and after the heat treatment, and all the samples showed a good corrosion resistance. In 0.5 mol/L H2SO4 solution, with the increase of temperature, the Cr, Al and other elements underwent intensified segregation. The corrosion resistance gradually improved, the Rp and the Rct was 2.785 × 102 Ω∙cm2 and 7.569 × 103 Ω∙cm2, respectively, at 1100 °C, providing the best corrosion resistance.

Enhanced wear resistance of a multi-phase reinforced Al0.5CrFeNi2.5Si0.25 high-entropy alloy via annealing

In this work, a multiphase reinforced non-equiatomic Al0.5CrFeNi2.5Si0.25 high-entropy alloy (HEA) was prepared by vacuum induction melting. The effect of heat-treatment temperature (1023, 1123, 1323, and 1473 K) on the microstructure, mechanical properties, and wear behavior are systematically investigated. The results indicate that the as-cast and annealed alloys are composed of face-centered cubic (FCC) and body-centered cubic (BCC) structures accompanied by microscale and nanoscale precipitated phases. To be specific, the FCC matrix is enriched in the L12 phase, and BCC particles and σ phases are observed in the B2 matrix. The microstructure of Al0.5CrFeNi2.5Si0.25 HEAs consists of dendritic region (DR) and inter-dendritic (ID) region before and after annealing. The phases and microstructure did not change. After annealing, the size of the Cr-rich BCC particles is reduced. The L12 phase has a density per unit area that first increases and then decreases, reaching its highest density at 1123 K. With the annealing temperature rising, the nanohardness increases slightly and then decreases, reaching a peak value of about 6.29 GPa at 1123 K. The Al0.5CrFeNi2.5Si0.25 HEA annealed at 1123 K also exhibits the lowest specific wear rate of 2.43 × 10−4 mm3/Nm, which is decreased by 23.5% compared to the as-cast one.

Effect of heat-treatment temperature and residence time on microstructure and crystallinity of mesophase in coal tar pitch

Effect of heat-treatment temperature and residence time on microstructure and crystallinity of mesophase in coal tar pitch

Effect of Heat Treatment Temperature on Hardness of Jaw Implant Produced from EDM Die-Sinking Process

Hardness is the main problem in making jaw implants using the die-sinking EDM process. Heat treatment can increase the hardness of jaw implants resulting from the EDM process. This research investigates the influence of temperature during the heat treatment process on the hardness of jaw implants produced from the EDM process. Heat treatment uses a quenching process. The quenching temperatures used were 940, 950, and 960 ºC, while the holding time was 30 minutes. The aging temperature is 550 ºC. The research results show that the greater the quenching temperature, the greater the increase in hardness. The hardness of the white layer reaches 713 VHN when using a temperature of 960 ºC. Meanwhile, the hardness of the inner jaw implant reaches 354 VHN.

Effect of heat treatment on microstructural evolution and mechanical properties of the TiAlV0.5CrMo refractory complex concentrated alloy

Ultra-fine grain TiAlV0.5CrMo refractory complex concentrated alloy (RCCA) was prepared by using mechanical alloying (MA) and spark plasma sintering (SPS), and the effects of heat treatment temperature on phase composition, microstructural evolution and mechanical properties were investigated. The results indicate that the phase composition of as-SPSed alloy comprises disordered BCC1 and BCC2 solid solution phases, along with a minor amount of Al2O3 phase. The system demonstrates exceptional microstructural and phase stability after the heat treatment at 1200 °C for 6 h, with only a slight decrease in hardness to a value of 9.86 GPa. With the increase in heat treatment temperature, the volume fraction of recrystallized grains gradually increases, leading to an initial growth and subsequent refinement in grain size. Under heat treatment at 800 °C and 1000 °C, the increase in volume fraction of Al2O3 was found to enhance the room temperature compressive yield strength of the alloy while deteriorating the plasticity. Specifically, the strength-plasticity trade-off was achieved after heat-treated at 1200 °C for 2 h, with a compressive yield strength of 2667 MPa and a plastic strain of 10.7% at room temperature. The excellent mechanical properties were attributed to the synergistic effects of lattice distortions, reduced dislocation density, weakened texture and refined grain structure. Furthermore, this alloy demonstrated a compressive yield strength of 153 MPa at a temperature of 1100 °C without fracturing at a strain of 50%. The flow stresses exhibited typical dynamic recrystallization (DRX) characteristics at elevated temperatures.

Understanding the Effects of Heat Treatment Temperature and Atmosphere on Platinum Nanoparticle Sintering Processes on Different Engineered Catalyst Supports (ECS) for Fuel Cell Applications

Understanding the Effects of Heat Treatment Temperature and Atmosphere on Platinum Nanoparticle Sintering Processes on Different Engineered Catalyst Supports (ECS) for Fuel Cell Applications

Effect of Heat Treatment Temperature on Microstructure, Tensile Properties and δ-Precipitate Phase in Ni-based Superalloy

Here, we investigated the influence of δ-precipitate (orthorhombic D0a Ni<sub>3</sub>Nb-ordered phase) on the room- and high-temperature tensile properties in wrought nickel-based Inconel 625 superalloys subjected to solution and aging heat treatment. Typically, solution heat-treatment temperatures in these alloys affect the solid-state precipitation of δ-phase, which governs high-temperature tensile properties. While precipitation of fine D0<sub>a</sub> δ-phase is known to have beneficial effects on the mechanical properties owing to the retardation of grain coarsening, Widmanstätten δ precipitation plays a deleterious influence on the fracture toughness, tensile ductility, and fatigue resistance. Therefore, to enhance the mechanical properties of this alloy series, it is key to generate a high number density of fine D0<sub>a</sub> δ precipitate by adjusting solid solution treatment temperatures. In this study, solution heat treatments were conducted above and below δ-phase solvus temperatures. By applying solution heat treatment at 900°C and 970°C, this alloy was confirmed to have a Widmanstätten δ phase and is composed similarly to the annealed microstructure. This Widmanstätten δ precipitate was densely distributed at both intergranular and intragranular grains. On the other hand, when solution treatment was applied at 1040 and 1100°C, more coarse particles (approximately 30 μm) with a significant reduction of Widmanstätten type δ phase were obtained. We found that grain size and Widmanstätten δ-phases have an important role in the high-temperature tensile properties of Inconel 625 superalloy series.

The effect of heat treatment temperature on the mechanical properties of TIMETAL® 575

TIMETAL® 575 is an α + β alloy reported to possess superior dwell fatigue capabilities over the conventionally used Ti–6Al–4V. The increased performance of this alloy has in part been linked to the presence of fine-scale tertiary α precipitates, which are present in the microstructure following suitable post-forging heat treatments. However, there is currently little understanding as to the extent that these precipitates influence the mechanical properties. When this is coupled with limited information regarding the temperatures over which tertiary α is expected to form, and other microstructural changes which may be occurring concurrent to the evolution of tertiary α in the microstructure, an incomplete picture arises to the true nature of tertiary α on mechanical behaviour. Therefore, this study aims to characterise the mechanical properties of TIMETAL® 575 across a number of different heat treatment temperatures to assess the sensitivity of the mechanical properties on the microstructure.

Using Mn/Fe enriched-roots of P. Stratiotes to synthesize multi-metallic catalysts for activating peroxymonosulfate to degrade bisphenol A

Aquatic plants used for phyto-extracting toxic metals from water are often enriched in certain metals and recycling these metal-enriched plants will achieve the sustainable application of phytoremediation/phytoextraction technology. The present study systematically explores the potential recycling of Mn-enriched-roots of P. Stratiotes used in the treatment of electrolytic manganese residue leachates as catalysts for activating peroxymonosulfate [1] to degrade organics in water. The effects of heat treatment temperature and atmosphere on the catalyst activity were first investigated and the results indicate that catalyst prepared in air at 400 °C contains active Mn(IV) while Mn(IV) was not detected in the catalyst prepared in N2 at the same temperature, and thereby catalyst obtained in air under 400 °C (MF400) performs better catalytic activity in degrading bisphenol A (BPA). The removal of BPA was found to reach 99.9 % in the MF400/PMS system at 120 min. The BPA degradation pathways were inferred by density flooding calculations (DFT) and then confirmed by liquid chromatography-mass spectrometry coupled detection, indicating that the radical pathway depending on·OH, SO4− and·O2– is the mechanism for BPA degradation in the MF400/PMS system. The ECOSAR assessment reveals that most BPA degradation intermediates are less toxic than their parent molecule. This work provides a simple and effective way for recycling Mn/Fe enriched aquatic plants used in phytoextraction process.

Effects of Heat Treatment Temperature on the Physicochemical Properties and Catalytic Performance of Bulk Ni–Mo–W Catalysts

Effects of Heat Treatment Temperature on the Physicochemical Properties and Catalytic Performance of Bulk Ni–Mo–W Catalysts

Effect of Heat Treatment Temperature on the Crystallization Behavior and Microstructural Evolution of Amorphous NbCo1.1Sn.

Heat treatment-induced nanocrystallization of amorphous precursors is a promising method for nanostructuring half-Heusler compounds as it holds significant potential in the fabrication of intricate and customizable nanostructured materials. To fully exploit these advantages, a comprehensive understanding of the crystallization behavior of amorphous precursors under different crystallization conditions is crucial. In this study, we investigated the crystallization behavior of the amorphous NbCo1.1Sn alloy at elevated temperatures (783 and 893 K) using transmission electron microscopy and atom probe tomography. As a result, heat treatment at 893 K resulted in a significantly finer grain structure than heat treatment at 783 K owing to the higher nucleation rate at 893 K. At both temperatures, the predominant phase was a half-Heusler phase, whereas the Heusler phase, associated with Co diffusion, was exclusively observed at the specimen annealed at 893 K. The Debye-Callaway model supports that the lower lattice thermal conductivity of NbCo1.1Sn annealed at 893 K is primarily attributed to the formation of Heusler nanoprecipitates rather than a finer grain size. The experimental findings of this study provide valuable insights into the nanocrystallization of amorphous alloys for enhancing thermoelectric properties.

Evolution of phase stability and structural properties in CrFeNiTiV high-entropy alloy under high-temperature heat treatment conditions

A novel equiatomic CrFeNiTiV high entropy alloy (HEA) was prepared by mechanical alloying (MA) and following spark plasma sintering (SPS). Further, the effects of heat treatment temperature on the phase, microstructure, and mechanical properties of HEAs were investigated. The results indicated the formation of a single body-centered cubic (BCC) phase after 30 h of MA. After SPS, it is found that the separation of a single phase into BCC, Ni3Ti, and TiC-rich phases, owing to the large atomic radius and mixing enthalpy of Ti with other elements. Compared with sintered HEA, the initial phases did not change after heat treatment at elevated temperatures, but the coarsening of phases was observed. The microscopic results confirmed that all phases are homogeneously distributed with good interfacial bonding after heat treatment at 1000 °C. The hardness and elastic modulus of HEA increased with increasing heat treatment temperature up to 1000 °C, due to increased precipitation of Ni3Ti and TiC-rich phases and then slightly reduced for the sample heat treated at 1100 °C HEA owing to the coarsening of existing phases. The creep displacement was reduced for the heat-treated HEAs compared to the SPS sample, suggesting improved creep resistance after heat treatment. In addition, an artificial neural network was used to predict the hardness behavior of heat-treated HEAs, and it exhibited an excellent accuracy of about 93.4%. Therefore, the present study provides valuable insights into the phase stability and mechanical properties of HEAs suitable for high-temperature applications.

Effect of Heat Treatment on the Crystallization Behavior of Amorphous Manganese Dioxide and its Electrochemical Properties in Zinc‐Ion Battery Cathodes

Herein, amorphous manganese dioxide (AMO) is prepared by the liquid‐phase coprecipitation method, the effect of heat treatment temperature on the microstructure, and phase composition of AMO and the electrochemical properties as cathode materials for aqueous Zn–MnO2 batteries are investigated. The results show that the AMO didn't crystallize at 250 °C, but its structure stability increases. When the temperature is 350 and 400 °C, part of the AMO crystallizes into rod‐shaped nano‐α‐MnO2 crystals. At 540 °C, the products crystallize into nano‐α‐MnO2 crystals. Continuing to increase the temperature to 650 °C, the structural stability of the products is further improved. Heat treatment leads to reduced specific surface area and porosity of the material, which in turn leads to reduced specific capacity and cycling stability. In addition, the heat‐treated products show a sharp drop in capacity during the discharge process; this was because the volume change caused by the irreversible phase change of the electrode material is difficult to release in the anisotropic crystal, resulting in the collapse of the structure. This study shows that unheated AMO is better than heat‐treated AMO as a cathode material for aqueous Zn–MnO2 battery cathode material in terms of overall performance and cost.

Effect of heat treatment temperature on the morphology and upconversion properties of LaF3:Yb,Er nanoparticles

LaF3:5%Yb3+,0.5%Er3+ upconverting nanoparticles were synthesized with co-precipitation method and heat treated at temperatures 300–600 °C. The morphology of the particles was characterized by high-resolution transmission electron microscopy coupled with energy-dispersive spectrometry and dynamic light scattering. Crystal structure was studied by X-ray diffraction (XRD), and thermal behaviour was investigated by simultaneous thermogravimetry and differential thermal analysis (TG/DTA). Upconversion behaviour was studied in detail by fluorescence spectroscopy, with 980 nm excitation. Particle sizes increased with increasing heat treatment temperature, and samples showed significant aggregation above 500 °C. Hexagonal LaF3 crystal structure was identified for all samples, with increased crystallinity after heat treatment at 400 °C, which was corroborated with TG/DTA results. XRD and energy-dispersive spectrometry results revealed that at higher temperatures new crystal phases formed, as some Yb3+ and Er3+ dopant ions segregated into new nanocrystals, made of, for example, YbOF and YbOOH, which caused a significant decrease in the upconversion emission of the samples. The highest upconversion emission was achieved after heat treatment at 400 °C.

The effect of heat-treatment temperature (HTT) on the carbon matrix development of both polyarylacetylene-and phenolic-derived carbon–Carbon (C/C) composites

Phenolic resins have been successfully used in the manufacture of C/C Composite hardware. However, they require costly, multiple impregnation–carbonization cycles due to their low char yield. Polyarylacetylene (PAA) resin is a promising alternative carbon precursor that possesses numerous advantages due to its higher char yield and low mass loss. In addition, both thermoset-derived carbons are non-graphitizable and rely on stress graphitization for matrix development, which ultimately dictates composite mechanical performance. The stress graphitization behavior of both composite systems was investigated and related to their mechanical behavior. PAA and phenolic-derived/T50 C/C composites were processed to a series of heat-treatment temperatures (HTTs), (1100°, 1800°, 2800°C) and compared. Increases in localized graphitization as verified by image analysis, AFM, and Raman were observed with increasing HT for both systems, though notably to a much higher degree for the phenolic system. We believe this to be a result of the larger degree of matrix pyrolysis shrinkage experienced at the fiber-matrix interface promoting molecular alignment. The mechanical properties of both composites were strongly affected by the HTT, primarily due to a weakening of the fiber-matrix interface. However, the phenolic-derived composite exhibited a 40% greater increase in fiber strength utilization over the PAA-derived composites after 2800°C, which is attributed to this highly oriented microstructure which contributes favorably to intra-matrix failure and crack deflection. Although there are benefits in utilizing high char yield carbon precursors that reduce manufacturing timelines, one must also account for possible differences in microstructure development when designing these composites for next generation systems.

Reversible Photobleaching of Silver Clusters in Silica‐Based Glass under Ultraviolet Irradiation

AbstractInorganic glasses doped with luminescent silver clusters are promising materials for photonic applications as white light generation, optical data storage, and spectral conversion. This work reports the photostability study of luminescent silver clusters dispersed in silica‐based glass under continuous ultraviolet irradiation. The photobleaching process model is proposed and the quantum yield of photobleaching is derived from the experimental data. The proposed mechanism of photobleaching is photoionization of silver clusters. Degradation of cluster luminescence is reversible and restores after the heat treatment, indicating the possibility to release trapped electrons and return the initial charge state of clusters. The effect of heat treatment temperature on the luminescence restoration is studied, the amount of restored luminescent clusters depends linearly on the heat treatment temperature.