Effects Of Two-step Heat Treatment Research Articles

Effects of two-step heat treatment on the structure of cotton-derived activated carbon fibres

Activated carbon fibre (ACF), a novel material, has attracted considerable research attention. The pore structures found on the surfaces of ACFs are strongly related to their functionality. Herein, ACF was prepared via a two-step thermal treatment of cotton. The diameters and width distributions of thus-prepared ACFs were characterised using scanning electron microscopy (SEM). SEM analysis also revealed that the pore structures on the surfaces of the cotton-derived ACFs were activated by carbon dioxide. Successful adsorption functionality of these ACFs was characterised using a methylene blue (MB) solution. The effects of the two-step thermal treatment and potential applications of this methodology are also discussed. The proposed method can be used on other fibre products or industrial waste materials generated during the manufacture of cloth and fibres, and the generated ACFs can be used for energy-storage applications.

Effects of two-step heat treatment on the structure of cotton-derived activated carbon fibres

Effects of two-step heat treatment on the structure of cotton-derived activated carbon fibres

Effects of two-step heat treatment on crystallization behavior, densification and microwave dielectric properties of MgO-Al2O3-SiO2-TiO2-Sb2O3 glass-ceramics

Glass-ceramics with a mass fraction composition (wt%) of 19MgO-23Al2O3-53SiO2-4TiO2-3Sb2O3 (M-A-S-T-S) were prepared by two-step (nucleation and crystallization) heat treatment of the parent glass at selected temperatures for 2h and/or 20h, respectively. A microwave dielectric characterization was performed in order to evaluate the suitability of M-A-S-T-S glass-ceramics as a lower permittivity (εr<4) dielectric substrate. X-ray diffraction analysis revealed that the addition of TiO2 and Sb2O3 into MgO-Al2O3-SiO2 glass could induce the coexistence of μ-cordietire and α-cordietire as the main phases, a small fraction of SiO2, MgSiO3 and Sb6O11 additionally crystallized as the second phases in this glass-ceramic system. Meanwhile, the prolonged heat treatment time~20h at selected nucleation and crystallization temperatures would cause the appearance of a small amount of MgTiO3 phase. The longer annealing time could not promote the densification and final dielectric properties, while a slightly increase in nucleation temperature~880°C of a short-time sintering (~2h) could reduce the dielectric loss. Wherein, after the two-step heat treatment (880°C/2h+930°C/2h), a better microwave dielectric properties of εr~3.65, Q×f~7900GHz (at 13.293GHz) and τf~−7.92ppm/°C can be obtained in this M-A-S-T-S glass-ceramic sample.

The effect of two-step heat treatment on hardness, fracture toughness, and wear of different biased diamond-like carbon coatings

A conventional furnace heat treatment critically reduces hardness and fracture toughness after a certain temperature. This study reports the effects of two-step heat treatment on hardness, fracture toughness, and wear of bias varied diamond-like carbon (DLC) coatings deposited without buffer layer on silicon substrates using unbalanced magnetron sputtering system. Pristine specimens were directly heated (1-step) at 300°C in a tube furnace for 30min and took out after 20h furnace cooling. For 2-step 300°C, pristine specimens were heated at 150°C for 30min and furnace cooled for 20h and then re-heated at 300°C followed by the same procedure. The residual stresses in pristine DLC specimens were calculated with Stoney equation. Raman spectroscopy was performed to understand atomic disorder and clustering under bias and heat treatment effects. The reciprocating wear test was performed to understand the effect of bias voltage and heat treatment on wear volume of DLC coatings. Indentation studies were performed to analyze hardness, cracking behavior, and fracture toughness of bias varied pristine to re-heated specimens. 1-step 300°C heat treatment decreases hardness and fracture toughness up to 20% in general, whereas, the 2-step 300°C heat treatment process generally retained pristine values along with the prominent increase of 43% hardness and 9% fracture toughness for specimens which are deposited at a bias of −60V and −140V respectively.

Effects of two-step heat treatment on properties of In2O3:Zr thin film epitaxially grown on c-face sapphire substrate

A two-step heat treatment was carried out on a zirconium-doped indium oxide thin film epitaxially grown on a c-face sapphire substrate by a radio-frequency magnetron sputtering method. First, the as-grown film was heat-treated to improve its crystallinity. Air was selected as the heat-treatment atmosphere to avoid the precipitation of indium that occurs at high temperatures, and the crystallinity of the as-grown film was successfully improved by adopting this first-step heat treatment. The film with crystallinity improved by the first-step treatment was then heat-treated in N2 to lower its resistivity. The resistivity of the film could be lowered about three orders of magnitude compared with that of the as-grown film after the second-step heat treatment under conditions at which the optical transmittance of the film remained sufficiently high in the wavelength region from 350 to 2000 nm.

Effect of two-step heat treatment on the phase formation of MgAlB 14

Functional ceramics MgAlB 14 disks were prepared by a two-step heat treatment. In the first step, Mg 6AlB 14 disks were fabricated through composition of uniformly mixed Mg, Al, and B powders in the form of pressed disks heated at 850 °C in closed argon atmosphere. And in the second step, target MgAlB 14 disks were obtained by decomposition of the Mg 6AlB 14 disks sintered in vacuum. It has been found that the main peaks of MgAlB 14 were sharp except the common impurity-MgAl 2O 4 according to X-ray diffractions (XRD). The nano-hardness of the sample was about 11 GPa. And the heat treatment effects in the second step on the phase formation of MgAlB 14 were also studied.

A high ductility TiAl alloy made by two-step heat treatment

The effect of two-step heat treatment on the microstructures and room temperature tensile properties of Ti–47Al–2Cr (at.%) was investigated. A high ductility TiAl alloy, whose room temperature tensile elongation, yield strength and ultimate tensile strength are 6.7%, 597 and 677 MPa, respectively, was made. The formation mechanism of high ductility TiAl alloy during two-step heat treatment was discussed.