Effect Of Oxidation Time Research Articles

The influence of anodization on laser transmission welding between high borosilicate glass and TC4 titanium alloy

This study investigates the influence of the thickness of the oxide film formed on the surface of TC4 titanium alloy after anodization on the laser transmission welding between the titanium alloy and high borosilicate glass. The effects of oxidation time on the morphology and thickness of the oxide film were examined, and the elemental and phase composition of the oxide film were characterized. The differences in welding strength, weld morphology, and fracture surface between the titanium alloy before and after oxidation treatment and high borosilicate glass welding were compared, and analyzed the welding seam formation mechanism. Within our research scope, the results indicate that with an increase in oxide film thickness, the surface roughness gradually increases and the internal voids gradually increase, resulting in a decrease trend in the bonding strength of the welded joints with the increase in oxide film thickness. The interpenetrating structure formed by the mutual infiltration of glass and metal in the molten pool is identified as the main reason for their connection.

Effects of OCF content and oxidation treatment on thermal conductivity and corrosion resistance of CF/BN/EPN coating

The effects of oxidation time and content of oxidized carbon fiber (OCF) on the thermal conductivity (TC) and corrosion resistance of the OCF/BN/EPN coating are investigated. The results show that the oxidation treatment does not change the chemical organization of OCF, while the amount of carboxyl group grafting and the roughness of OCF surface increase with the increase in the oxidation time. Moreover, SEM results show that the higher content OCF fillers causes the more severe contact in the coatings. As the oxidation time increases, the TC gradually enhances, whereas the EIS results increase firstly and then decrease. This can be attributed to the dual effect of the oxidation treatment and content of OCF. The positive effect of oxidation treatment is that it enhances the interfacial compatibility between the coating and the OCF, improving the thermal conductivity and corrosion resistance of the coating. The downside is that the increase in the amount of carboxyl groups on the surface of the OCF with the oxidation time increases the hydrophilicity of the coating, which reduces the corrosion resistance. In terms of content, it significantly shortens the transmission distance of phonons between fillers and improves phonon transmission efficiency but leads to the increase in the number of defects between the filler and resin interfaces, thus enhancing the thermal conductivity of the coating and reducing the corrosion resistance. As a result, when the oxidation time of the OCF is 1.5 h and 15 wt% OCF is added, the best comprehensive performance can be obtained, i.e., and the TC of the coating reaches 1.4 W/m·K while the impedance modulus at 0.1 Hz is 4.6 × 109 Ω·cm2. This work provides an important guidance for the design of heat exchanger coatings with excellent TC and corrosion resistance.

Varying the degree of oxidation of graphite: effect of oxidation time and oxidant mass.

In this work, we employ a fast and less toxic modified Hummers' method to develop graphene oxide (GO) with varying degrees of oxidation and investigate the effect of the latter on the structure and the thermal properties of the synthesized materials. Two different key parameters, the time of the oxidation reaction and the mass of the oxidation agent, were systematically altered in order to fine tune the oxidation degree. All graphene oxides were characterized by a plethora of experimental techniques, like X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) as well as infrared spectroscopy (IR) and X-ray photoelectron spectroscopy (XPS) for their structural, thermal and chemical identification. The results revealed that for a certain amount of oxidant, the time does not affect the final degree of oxidation of the materials, at least for the examined reaction times, because very similar structural patterns and thermal properties were obtained. At the same time, the oxygen-containing functional groups were found very similar. On the other hand, the degree of oxidation was found highly dependent on the mass of the oxidizing agent. XRD analysis showed a systematic increase of the interlayer distance of the synthesized GOs with the increase of the oxidant mass, whereas both the enthalpy of reduction and the % weight loss were increased. Moreover, XPS measurements provided a quantitative evaluation of the amount of carbon and oxygen in the materials; the increase of the oxidant mass led to a decrease of the total carbon content with the concurrent increase of the total oxygen amount.

Effect of oxidation time on fracture behavior of C/SiC composites at 800 °C in air

The fracture behavior of C/SiC composites after oxidation treatment for different time at 800 °C in air was studied by in-situ test technology combining DIC, AE and X-CT. From results of fracture toughness tests, it can be found that with the increase of oxidation time, the stress intensity factor and the work of fracture show different trends, and the fracture mode after oxidation changes from quasi-brittle to ductile. Combined with AE clustering analysis and X-CT images obtained through in-situ load tests, the mechanism of the coupling effect of oxidation time, toughening behavior and C-phase consumption on energy dissipation is explained. In addition, long-term oxidation causes the crack initiation point to deviate from the prefabricated notch tip and the delamination damage, which may lead to the change of failure position and unexpected damage mode in the engineering structures.

Formation of TiO2 nanoporous layer on the surface of Ti13Nb13Zr titanium alloy treated by ECAP-Conform and Rotary Swaging

This paper focuses on the formation of nanoporous layer on the surface of the third-generationbiomedical Ti13Nb13Zr titanium alloy widely used in the biomedical field. First of all, the alloy was asubject to equal channel angular pressing (ECAP) + conform treatment (ECAP-Conform) and RotarySwaging forging. Then the anodic oxidation method with 0.5 wt% HF electrolyte was used to preparea uniformly arranged porous layer on the surface of the samples with the different microstructurefrom EACP-Conform. The features of the formed porous layer were investigated. The effects ofoxidation time and oxidation voltage on the porous morphology of the surface porous layer wereinvestigated in detail. The optimal anodic oxidation parameters for the formation of surface porouslayer were established. The hydrophobic properties of the samples were tested and the contact angleswere calculated. Finally, the weightlessness of body fluid corrosion in Hanks´ solution was simulated.

Effect of oxidation time on the structure and properties of Ti–25Nb–3Zr–2Sn–3Mo titanium alloy microarc oxide film layer

In order to improve various properties of medical titanium alloys, Ti–3Zr–2Sn–3Mo–25Nb titanium alloy specimens were subjected to microarc oxidation (BMAO) in 0.1 mol/l sodium tetraborate electrolyte to cover the substrate with a micro-nano double-graded structured coating. The effect of oxidation time on the microstructure, physical phase, hardness, corrosion resistance, and wettability of the micro-nano film layer was investigated. The results show that the microporous size of the film increases with the increase in oxidation time, and the hardness of the BMAO film increases with the increase in oxidation time; the corrosion resistance of the BMAO film is better than that of the substrate, and the self-corrosion potential is the largest at 14 min of oxidation time, reaching −0.1349 V, which is 65% higher than that of the substrate, and the self-corrosion current is the lowest, at 1.1376 × 10−9 A cm−2, which is one order of magnitude lower than that of the substrate; the micro-nano film layer exhibits superhydrophilicity, which increases and then decreases with time, and the contact angle is the smallest at 6 min of oxidation time, 4.4°, which is one order of magnitude lower than that of the substrate, 73.75°.

Thermal-oxidation coupled analysis method for unidirectional fiber-reinforced C/SiC composites in air oxidizing environments below 1000 °C

The thermal analysis method for unidirectional fiber-reinforced C/SiC composites (C/SiC-UFRC) in air oxidizing environment below 1000 °C is developed, including a mathematical theoretical model and a finite element model. The mathematical model (MM) is established by combining the thermal resistance network method and the oxidation kinetics theory. The influence of oxidation characteristics on C/SiC-UFRC axial thermal conductivity is firstly introduced into MM, which provides a reference for the theoretical calculation method of C/SiC-UFRC axial thermal conductivity under oxidation conditions. The finite element model (FEM) is constructed on the representative volume element (RVE) of C/SiC-UFRC and the numerical heat transfer method. The FEM numerically simulated the microstructure in the oxidation process and firstly be applied to study the effects of oxidation on the micro temperature field and heat transfer of C/SiC-UFRC. Through the mutual confirmation of MM and FEM, the prediction of thermal conductivity of CMC in air oxidation environment is verified. The effects of oxidation time, oxidation temperature and random distribution of initial cracks are investigated to reveal their influences on the heat transfer behavior of C/SiC-UFRC.

Analytical model for strength of MAX phases considering high‐temperature oxidation and plastic deformation

AbstractAs a promising high‐temperature material, MAX phases have attracted much attention owing to their combined merits of metals and ceramics. In this study, a temperature‐dependent analytical model for prediction of the strength of MAX phases considering high‐temperature oxidation and plastic deformation was proposed. A relationship among the strength, Young's modulus, strain‐hardening exponent, crack size, and temperature was established. The accuracy of the model was verified by a comparison between the model predictions and available experimental data. The proposed analytical model can provide a straightforward and effective way to predict the strength of MAX phases over a wide range of temperatures. Moreover, the quantitative effects of oxidation time, strain‐hardening exponent, and Young's modulus on the strength, as well as their evolution with temperature, were analyzed. The findings of this study would be useful for the high‐temperature strength prediction and design of MAX phase materials.

Effect of oxidation time on microstructure and mechanical properties of Cf/SiC–Al composites after high-temperature oxidation

Effect of oxidation time on microstructure and mechanical properties of Cf/SiC–Al composites after high-temperature oxidation

Evaluating the Effect of Oxidation Time on Nanozyme-mediated Oxidation of 3, 3’-diaminobenzidine

Evaluating the Effect of Oxidation Time on Nanozyme-mediated Oxidation of 3, 3’-diaminobenzidine

Hydroxyapatite Growth on Activated Carbon Surface for Methylene Blue Adsorption: Effect of Oxidation Time and CaSiO3 Addition on Hydrothermal Incubation

Many adsorbent materials are now commercially available; however, studies have focused on modifying them to enhance their properties. In this study, an activated carbon (AC) and hydroxyapatite (HAp) composite was synthesized by the immersion of ACs in a simulated body fluid solution, varying the AC oxidation degree along with the addition of CaSiO3. The resulting composites were characterized by ash %, X-ray fluorescence (XRF), Fourier-transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and point of zero charge (PZC). The characterization results indicated that the addition of CaSiO3 and the oxygenated functional groups in the AC surface are key factors for HAp growth. The composites were tested on methylene blue (MB) adsorption as a potential application for the synthesized materials. Adsorption isotherms were modeled with Langmuir and Freundlich isotherms, and the composites were fitted to a Langmuir model with the highest qmax value of 9.82. The kinetic results indicated that for the pseudo-second-order model, the composites fitted, with a contact time of 180 min to remove a 95.61% average of the MB. The results indicate that composite materials can be an efficient adsorbent for the removal of MB from aqueous solutions at low concentrations since the material with the highest amount of HAp growth removed 99.8% of the MB in 180 min.

Effect of Oxidation Time on the Structure and Corrosion Resistance of Micro-Arc Oxidation Coating of AZ91D Magnesium Alloy in (NH4)2ZrF6 Electrolyte System

Micro-arc oxidation (MAO) coatings were obtained from an AZ91D magnesium alloy at different oxidation times (5, 10, 15, and 20 min), using a zirconium salt electrolyte system, with (NH4)2ZrF6 as the main salt. The morphology of the coatings was studied using a scanning electron microscope (SEM) and confocal laser scanning microscopy (CLSM). Energy dispersive spectrometry (EDS), X-ray diffractometry (XRD), and X-ray photoelectron spectroscopy (XPS) were employed to determine the type of element and the composition of its phase. The potentiodynamic polarization curve (PDP) was applied to illustrate the corrosion resistance of the coatings. We found the coatings had minor porosity and the best compactness when the MAO treatment time was 10 min. The coatings mainly comprised MgO, ZrO2, MgF2, and Zr3O2F8 phases and amorphous magnesium phosphate. Among the MAO coatings prepared in this experiment, the 10 min coating had the lowest corrosion current density (Icorr), and the Icorr was 4.864 × 10−8 A/cm2, which was three orders of magnitude lower than the uncoated AZ91D magnesium alloy.

Treatment of hospital wastewater by potassium ferrate

It has been investigated how well potassium ferrate (K2FeO4) treats hospital wastewater effluents. In the treatment of water and wastewater, potassium ferrate serves as an oxidant, disinfectant, and coagulant with several functions. The effects of combining the oxidation and coagulation processes on features have not been extensively studied. The objective of this study is to evaluate the oxidation and coagulation effects of potassium ferrate treatment methods. An optimization technique based on response surface mythology (RSM) and Box-Behnken design was utilized to identify the ideal conditions for increased removal efficiency of chemical oxygen demand COD.. Potassium ferrate has a significant impact, according to experiments. With a COD of 790 ppm as the starting point, the effects of oxidation time (30-90 minutes), potassium ferrate concentration (20-100 ppm), pH (3-9), and process stirring speed (100-400 rpm) on COD removal efficiency were examined. To find the best COD removal efficiency, it also used an optimization strategy based on Box-Behnken design via the Surface Response Method (RSM). According to the findings, time, mixing speed, and pH are the factors that have the highest impact on the effectiveness of COD removal.. Based on the study of the Minitab-19 program, Regression analysis results revealed that a Fisher value of 13.68. pH value 3, oxidation time of 62 minutes, mixing speed of 300 rpm, and potassium ferrate content of 92 ppm were discovered to be the optimal operating parameters. Based on this ideal scenario, the final concentration reached had a COD elimination effectiveness of 98 percent.

The effect of oxidated glucose on the performance and structures of polyamide resins synthesized by citric acid and hexanediamine

A thermoset polyamide resins were synthesized by citric acid and hexanediamine (CH), and was modified by oxidized glucose (OG). The effect of oxidation time and addition amount of oxidized glucose on shearing strength of plywood were characterized. Fourier transform-infrared (FT-IR) and liquid chromatography-mass spectrometry (LCMS) were used to determine the structures of the resins, the result shows that CH and OG reacted to form macromolecules. Differential Scanning Calorimeter (DSC), dynamic mechanical properties (DMA) were used to analyze its thermal properties, the results indicate that OG improved the storage module and the heat resistance. The CHOG resin exhibited a good bonding strength and water resistance, when the oxidation time is 0 min and the molar ratio of oxidized glucose to hexamethylene diamine is 1:1.6. Dry strength, 24 h wet strength and 63 °C hot water soaking wet strength of the plywood bonded with it are 1.36 MPa, 1.60 MPa, 1.49 MPa, respectively. Therefore, OG enhanced the shearing properties, and improve water resistance, which sheds new light on the preparation of bio-based wood adhesive for the manufacture of plywood.

Effects of oxidation time on the formation of nanosized cerium oxide film from direct current sputtered cerium

Effects of oxidation time on the formation of nanosized cerium oxide film from direct current sputtered cerium

Research on the effects of surface modification of ceramic powder on cure performance during digital light processing (DLP)

Digital light processing (DLP) is one of the most important additive manufacture technologies to fabricate ceramic parts with complex geometries. Compared with pure photosensitive resin, the cure performance of ceramic suspensions is obviously different due to the optical property change after the addition of ceramic powders. In this paper, a unique oxidation process was used to modify the optical properties of nitride powders including AlN and Si 3 N 4 . The properties of oxidized ceramics were investigated and the cure performance of ceramic suspensions was then characterized. The effect of oxidation time on cure performance was evaluated. The results showed that for AlN, oxidation process leads to the smaller cure depth and smaller excess cure width as compared with non-oxidized AlN and for Si 3 N 4 , oxidation process leads to the larger cure depth and larger excess cure width as compared with non-oxidized Si 3 N 4 , indicating that both refractive index and light absorbance of ceramic powders have obvious effects on cure behaviors. Additionally, the cure behavior of oxidized ceramic suspension in this study shows that the relationship of cure depth vs. incident energy agrees well with Beer- Lambert model, but the excess cure width vs. incident energy is not consistent with quasi Beer-Lambert model due to the nature of digital micromirror device (DMD).

Effect of Oxidation Time and CaSiO3 Addition on Hydrothermal Incubation for Hydroxyapatite Growth on Activated Carbon Surface: Methylene Blue Adsorption

Effect of Oxidation Time and CaSiO3 Addition on Hydrothermal Incubation for Hydroxyapatite Growth on Activated Carbon Surface: Methylene Blue Adsorption

Effect of Oxidation Time on the Properties of Cellulose Nanocrystals Prepared from Balsa and Kapok Fibers Using Ammonium Persulfate.

This study aimed to evaluate the effect of ammonium persulfate’s (APS) oxidation time on the characteristics of the cellulose nanocrystals (CNCs) of balsa and kapok fibers after delignification pretreatment with sodium chlorite/acetic acid. This two-step method is important for increasing the zeta potential value and achieving higher thermal stability. The fibers were partially delignified using acidified sodium chlorite for four cycles, followed by APS oxidation at 60 °C for 8, 12, and 16 h. The isolated CNCs with a rod-like structure showed an average diameter in the range of 5.5–12.6 nm and an aspect ratio of 14.7–28.2. Increasing the reaction time resulted in a gradual reduction in the CNC dimensions. The higher surface charge of the balsa and kapok CNCs was observed at a longer oxidation time. The CNCs prepared from kapok had the highest colloid stability after oxidation for 16 h (−62.27 mV). The CNCs with higher crystallinity had longer oxidation times. Thermogravimetric analysis revealed that the CNCs with a higher thermal stability had longer oxidation times. All of the parameters were influenced by the oxidation time. This study indicates that APS oxidation for 8–16 h can produce CNCs from delignified balsa and kapok with satisfactory zeta potential values and thermal stabilities.

Characterization of TEMPO-oxidized chitin nanofibers with various oxidation times and its application as an enzyme immobilization support.

Chitin nanofibers have recently received increased attention and are considered to be a promising material for a wide range of applications because of their excellent characteristics. In this study, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized chitin nanofibers (CNFs) with various oxidation times were prepared and characterized. CNFs with different oxidation times were then utilized for enzyme immobilization, using chymotrypsin as a model enzyme. The effects of oxidation time on enzyme immobilization were explored. Results showed characteristics of chitin nanofibers can be controlled by adjusting oxidation time. CNFs treated with TEMPO for 360min showed the lowest crystallinity (79.13 ± 1.43%), the shortest length (241.70 ± 74.61nm), the largest width (12.67 ± 3.43nm), and the highest transmittance (73.01% at 800nm). The activity of immobilized enzymes and enzyme loading showed good correlation to the carboxylate content of CNFs. The enzyme efficiency based on CNFs and the content of carboxylate groups peaked at the oxidization time of 60min. When the additional amount of chymotrypsins (CTs) was 500 or 2000mg/g carrier, the highest loading amount of CTs was 307.17 ± 4.08 or 726.82 ± 12.05mg/g carrier, respectively.

Modeling the Failure Time and Residual Strength of C/SiC Composites under Stress-Oxidation Environment

Based on the oxidation kinetics of C/SiC composites at 900o-1200oC in stress-oxidation environment, a non-uniform model of oxidation has been suggested in this paper. Combined with fiber notch model, Curtin’s strength model and BHE model, the non-uniform model is able to predict the failure time and residual strength of C/SiC composites accurately. Besides, the initial defects of the model (matrix coating crack and open porosity), the effects of coating were taken into account, and the fiber strength and broken ratio were analyzed. Furthermore, the effects of oxidation time, stress, temperature, Si C coating thickness and volume fraction of fiber on the failure time and residual strength were discussed, and the predicted results showed a good consistency with the experimental data.