Papers by Keyword: Annealing

Abstract: Steel produced by PT. Krakatau steel is the most used product in construction applications to compete with the other structural steel and have the minimum standard. PT. Krakatau Steel produced the steel with 0.08% carbon as JIS 3302 grade SGC 400 standards, resulting in low yield and tensile strength. This study aims to investigate the effect of temperature and the number of cycle spheroidizing on mechanical properties and microstructure. Steel with 0.08% carbon heated at 580, 650, and 720 °C for 6 minutes each cycle (3 cycles) and subsequently cooled by forced air with a 3 °C/s cooling rate. At a temperature of 580 °C on cycles 1, 2, 3, and 650 °C in the third cycle 3, resulting in mechanical properties that meet the JIS G 3302 grade SGC 400 standards.

Abstract: Multiple PIN diodes with junction termination extension (JTE) were fabricated on 4H-SiC wafers with 10 μm thick epilayers by ion implantation with various dosages of Al ions at room temperature (RT) and high temperature (600 °C). The subsequent annealing process was conducted at 1650 °C for 10 minutes to activate the dopant atoms and recover the lattice damages introduced by the implantation. Synchrotron X-ray topography was used to characterize the defects in the devices, and it is observed that basal plane dislocations (BPDs) were generated during the annealing process from the boundaries between the high (P+) and low (P-) doping concentration in devices implanted with relatively high doses at RT. Further, topographs also manifest motion of BPDs due to implantation-induced stresses, where BPDs with opposite sign Burgers vectors move in directions accommodative of nature of stress (tensile/compressive). On the other hand, generation of BPDs due to implantation was not observed in devices implanted either at relatively low dosages at both temperatures or relatively high dosages at high temperature. Measurements of blocking behaviors of devices illustrate that devices with higher densities of process-induced BPDs yield higher leakage currents.

Abstract: The layers of Al and Co are deposited successively on SiO₂ substrates using magnetron sputtering technique. Thereafter, annealing is provided at 1100°C in 2-195 minutes in the muffle furnace. The color of the layers is changed gradually from brown at 2 minutes to blue at 195 minutes. The change of the structure during annealing is seen from the Raman spectra. The line at 188 cm^-1 shifts to 203 cm^-1, which shows the substitution of the Co³⁺ with less massive Al³⁺ ions during the formation of CoAl₂O₄. The most intensive peak at 505 cm^-1 disappears after the process is finished in 60 minutes. the annealing is provided in the Ar+O₂ atmosphere with 5% and 0.07% of oxygen in the temperature range from 850 to 1100 °C. The film with the layered structure is obtained at the low oxygen conditions.

Abstract: The two-phase titanium alloy Ti6Al4V (often referred to as GRADE 5 or Ti64) is currently probably the most widely used type of Ti alloy. It is characterized by an excellent combination of strength - toughness - chemical stability. However, at temperatures above 500 - 800 °C it is prone to the diffusion of oxygen into surface layers, where the increased oxygen content creates the so-called “alpha-case” layer. The formation of this layer is associated with a reduction mainly in the deformation characteristics of the alloy. The paper focuses on the metallographic analysis of the "alpha-case" layer after annealing at 1050 °C with a holding time of 3 hours and cooling at different cooling rates (500 °C/s, 1 °C/s and 0.08 °C/s). Microstructure changes were observed by light microscopy using polarized light – PL, dark field – DF and phases were identified by SEM methods. The influence of changes in the microstructure on the mechanical properties was determined by measuring the microhardness HV0.2 /10 (STN EN ISO 6507) with Zwick / Roell ZHµ and measuring the resistance to impact stress KU (Charpy system STN EN 10045-1). Based on the microhardness measurement, an increase in the microhardness of the surface layers was observed at all cooling rates and at the same time, a decrease in the impact resistance was observed compared to the initial state.

Abstract: The synthesis of zinc-substituted cobalt ferrite (Co_0.9Zn_0.1Fe₂O₄) using the sol gel method has been successfully carried out. The thermogravimetric analysis and differential thermal analyzer curve shows that at 400°C the Co_0.9Zn_0,1Fe₂O₄ sample has formed the final phase of nanoparticles. Therefore, the modification of physical properties was carried out by annealing treatment at temperature of 450°C, 550°C, 650°C, and 750°C. The X-rays diffraction show that all samples are in a single phase with a face center cubic space group Fd-3m structure according to the ICDD 221086. The crystal size increased with the annealing temperature 33.69 nm to 45.88 nm. The Co_0.9Zn_0.1Fe₂O₄ showed as excellent antibacterial properties on Staphylococcus aureus and Escherichia coli. The most superior antibacterial activity to Staphylococcus aureus was Co_0.9Zn_0,1Fe₂O₄ sample which was annealed at 650°C with a clear zone diameter of 39.81 mm. Meanwhile, the Escherichia coli bacteria which had the most superior antibacterial activity were Co_0.9Zn_0,1Fe₂O₄ samples which were annealed at 450°C with a clear zone measuring 21.04 mm.

Abstract: The annealing temperature dependent on the structural and magnetic properties of hematite (α-Fe₂O₃) powders synthesized via the sol-gel method was studied. The sol-gel method is used to prepare nanoparticles for this experiment. The annealing treatment of 200°C, 400°C, 600°C, and 800°C has been carried out to modify the physical properties. The obtained nanoparticles are characterized by their structural properties using X-ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy. Then, magnetic properties were evaluated using Vibrating Sample Magnetometer (VSM). XRD results have shown an increase in crystallite size with an increase in annealing temperature from 35.10 nm to 60.17 nm. The increase in crystallite size can be attributed to the increase in the crystal structure’s internal energy, which promotes atomic diffusion. The FTIR results show an absorption that appears at the peak around ~530 cm^-1. It indicates that the Fe³⁺ cation has successfully formed. The VSM results show an increase in the value of H_c with an increase in the annealing temperature from 117 Oe to 461.5 Oe. It is supported by the increase of anisotropy constant and increasing temperature annealing.

Abstract: The effect of annealing temperature on the structural and magnetic properties of a rare earth (La³⁺) doped cobalt ferrite with fine sediment from the Bengawan Solo River as the source of Fe³⁺ has been studied. Co-presipitation method is use for preparation nanoparticles whole this experiment. In order to modified the physical properties, the annealing treatment of 2000C, 3000C, and 4000C are performed. The obtained nanoparticles are characterized their structural properties by using X-ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy. Then, magnetic properties evaluated by using Vibrating Sample Magnetometer (VSM). XRD results have shown that there is an increase in crystallite size with an increase in the given annealing temperature from 24.56 nm to 27.83 nm. The increase in crystallite size can be attributed to the increase in the internal energy of the crystal structure which promotes atomic diffusion. Meanwhile, there is a decrease in the value of the lattice parameter with an increase in the given annealing temperature. The decrease in lattice parameters with increasing crystallite size is generally due to the lattice parameters reaching a minimum energy with increasing crystallite size. The formation of La³⁺-O^2- for the incorporation of rare earth ions into the lattice requires high energy. The FTIR results show an absorption that appears at the peak around ~580 cm^-1. This indicates that the La³⁺ cation has successfully replaced the original structure of cobalt ferrite. The VSM results show that there is an increase in the value of Hc with an increase in the annealing temperature given from 100 Oe to 160 Oe. This is supported by the increase of anisotropy constant and increasing temperature annealing.

Abstract: Deep drawing has become the most general method in cartridge manufacturing process which use brass alloy as the main component. To perform deep drawing on this type of alloy, there are several physical and mechanical properties re-quired, especially the ductility and hardness. In this paper, the CuZn35 brass alloy, which still does not fulfill the requirements, had been annealed in the several annealing parameters (holding time and annealing temperature) to achieve the re-quired properties. It also discussed the microstructure evolution in every annealing parameter and the affiliation to its mechanical properties. The temperature annealing process of CuZn35 brass alloy was conducted in 300, 400, 500, and 600°C for 60 minutes. Then, the heat-treated product will be observed to get the composition, microstructure, hardness, strength, and also deep drawing formability. The-ꞵ precipitation was successfully eliminated by annealing process which significantly decrease its hardness and tensile strength whereas the increased grain size affect the ductility.

Abstract: We study the crystal structure of carbon-doped Al-rich MnAl thin films deposited on Si substrates. The effects of carbon content and vacuum heat treatment parameters are studied. It is shown that the carbon content, in combination to heat treatment, allows to tailor structural phase transitions in the films. The main phases detected are Al₂Mn₃, pure Mn, and pure C. As carbon content increases, the amount of Al₂Mn₃ phase decreases and the content of pure crystallized Mn phase increases. In addition, it is shown that as the heat treatment temperature increases – up to 500 °C – the Al₂Mn₃ phase content increases, whereas a pure C phase appears at lower temperatures.

Abstract: Nowadays life style practices demand more packed foods in the market around the world. In this trend increases the demand for researches on developing new packaging materials. In this research focuses novel AA8079/ SS304/ Wood ash hybrid nanocomposites development for meeting packaging related applications. The materials like aluminum alloy AA8079 (matrix material) obtained from waste food cans, Nanoparticles of stainless steel SS304 and Nanoparticles of Wood ash which obtained from waste bamboo woods were utilized to compose through stir casting process. Two set of Six different novel AA8079/ SS304/ Wood ash hybrid nanocomposites by varying the reinforcement from 0 wt.% to 10 wt.% with the step of 2 wt.% in the AA8079 matrix. The prepared composites included for examinations to test their Ultimate Tensile strength, yield strength, percentage of elongation, shear strength and hardness properties. Apart from this, the effect of heat treatment and annealing on strength of developed novel AA8079/ SS304/ Wood ash hybrid nanocomposites were investigated.