Papers by Keyword: Holding Time

Abstract: Lithium-ion batteries are the preferred choice for electric vehicles (EVs) due to their high energy density, low self-discharge, thermal stability, and long cycle life. Morphology of materials is essential in assessing the effectiveness of lithium-ion battery cathodes. One effective way to evaluate cathode quality is by examining its precursor (NMC-811) morphology using SEM. Samples were taken every 20 minutes over 2 hours, revealing that longer reaction times improve the homogeneity and semi-spherical shape of the NMC-811 precursor, with increased particle density and a reduced average diameter. NMC-811 was synthesized by a calcination process at temperatures of 450°C, 600°C, and 700°C, and sintering temperatures of 800°C and 900°C. SEM analysis revealed that higher calcination temperatures resulted in a more homogeneous particle structure, with variations in holding time having minimal impact on particle shape.

Abstract: This study investigates the mechanical properties and microstructure of sintered tungsten under varying sintering conditions. Bending strength tests revealed that sintering at 1400 °C resulted in low flexural strength due to inadequate temperature, whereas sintered tungsten at 1500 °C exhibited improved strength attributed to grain growth. However, temperatures exceeding 1600 °C led to excessive grain growth and a subsequent decline in strength, indicative of grain coarsening and potential localized bonding. Additionally, analysis of holding times at 1500 °C demonstrated that extended durations promoted neck bonding between grains, contributing to the formation of interconnected grains and enhanced mechanical properties. This study underscores the importance of optimizing sintering parameters to control grain growth and achieve desired mechanical properties in sintered tungsten materials.

Abstract: The problem of jatropha waste that has not been managed optimally has an impact on environmental pollution. Therefore, it is necessary to conduct research to utilize and utilize jatropha waste in products that are beneficial to the community. The purpose of this study was to find the best variation of particle size, time pressure, removal, and drying temperature to produce the best briquettes. The independent variables in this study were particle size (60 mesh, 80 mesh and 100 mesh); pressure (100 kg/cm2, 200 kg/cm2 and 300 kg/cm2); removal time (3 minutes, 6 minutes, 9 minutes) and drying temperature (100 C, 105 C and 110 C). The variables considered in this study were the water content and the compressive strength of the briquettes. The criteria to get the best product using R2 and R Adj. The results showed that the water content of the briquettes was 7.12%, and the best compressive strength was 23,768 kg/cm2. The water content model was declared feasible and valid to predict the water content of quality briquettes as indicated by all independent variables having VIF<10 and TOL> 0.1 and Durbin Watson value: 2.165 in the range of 1.767<D<2.233. Particle size, pressure, removal time, and drying temperature have a percentage contribution to the briquette pressure is 30.769%, respectively; pressure 29.338%; time eliminated 22.315%; drying temperature 7.952% and the remaining factors that are not used in this study and errors. The compressive strength model is declared feasible and valid to predict the compressive strength of quality briquettes as indicated by all independent variables having VIF < 10 and TOL > 0.1 and Durbin Watson value: 2.286 in the range of 2.233 < D < 2.687.

Abstract: There is a lack of complete understanding of the mechanism and kinetics of reduction of metals from oxides. This paper presents results and methods of a series of experiments on direct reduction of metals by solid carbon in the form of graphite from a complex oxide with a low iron content in a laboratory muffle furnace at temperatures of 1300, 1400, 1500, 1600 °C and holding time of 1, 3, 5, 7 hours. The statistical analysis of amount and average size of reduced iron particles inside the oxide was studied. Dependence of amount and average size of the reduced iron particles on temperature and time of reduction is presented. The phenomena of iron crystals’ growth, occurring as a result of changes in the crystal lattice of oxide, was studied under experimental conditions. The influence of temperature and holding time on iron particles’ nucleation and their growth in the crystal lattice of a complex oxide were compared. Investigation of mechanism of metals’ reduction from complex oxides and influence of experimental conditions on the nucleation and growth enables to identify new patterns in the process of reduction of metals from their oxides, in general.

Abstract: Cyclic deformations of two ferritic, ductile cast irons, SiMo51 and SiMo1000, were studied in air and Ar using a new method, SRTC (stress relaxation with thermal cycling). Locked specimens were thermally cycled up to 800°C with isothermal holds, varying temperature interval, heating/cooling rates and hold times. A description of the mechanical response to thermal cycling of a locked specimen is given.

Abstract: Generally, metal injection molding (MIM) method utilizes SS 17-4 PH as material for application of orthodontic bracket. One of the process of MIM is thermal debinding, which binder is eliminated by thermal energy. In this study, thermal debinding process is conducted with variation of temperature, i.e. 480, 510, and 540°C, holding time, i.e. 0.5, 1 and 2 hours, heating rate, i.e. 0.5, 1, 1.5, and 2°C/min.The effect of temperature shows that the increased temperature will result in the mass reduction percentage due to formation of oxide on the sample, which will be proven through TGA testing. The highest mass reduction was 6.4137 wt% which was obtained at 480°C. For the variation of holding time, the longer the holding time will result in increased mass reduction and the highest mas reduction was 6.255 wt% which was obtained during 2 hours of holding time. For the heating rate, the slower the heating rate will result in increased mass reduction and decreased the presence of crack formation. The best variable was obtained at heating rate of 0.5°C/min, which resulted mass reduction of 6.2488 wt% and less crack formation.

Abstract: The purpose of this research was to evaluate the hardenability of ASSAB 760 (equivalent to AISI 1045 and JIS S45C) steel subjected to the gas cementation, the quenching and the tempering processes. Gas cementation is a heat treatment surface process by means of carbon diffusing into steel. This process is carried out in a furnace in a fluidized bed by using media of liquid petroleum gas (LPG) and nitrogen gas at a temperature of 1203 K and various holding times of 7.2, 10.8 and 14.4 ks, respectively. The rapid quenching process is carried out in an oil media for 420 sec. In order to remove the tension in the specimen, the tempering process is carried out in a furnace at a low temperature of 473 K with holding time of 3.6 ks. The result shows that, the Vickers hardness values can be achieved from 568 to 584 HV. Therefore, it is confirmed that by using these processes, the hardening of ASSAB 760 steel can be carried out and the punch holder can be manufactured.

Abstract: The purpose of this research was to study the microstructure change of ASSAB 760 (equivalent to AISI 1045 and JIS S45C) steel subjected to the gas cementation and the quenching process. Gas cementation is a heat treatment surface process by means of carbon diffusing into steel. This process is carried out in a furnace in a fluidized bed by using media of liquid petroleum gas (LPG) and nitrogen gas at a temperature of 1203 K and various holding times of 7.2, 10.8 and 14.4 ks, respectively. The rapid quenching process is carried out in oil media for 420 sec. The results shows, that remnant austenite is formed on the specimen with a holding time of 7.2 ks and the networks of existing bainite structure are clearly spread on the specimen with holding time of 10.8 and 14.4 ks. Additionally, this gas cementation process when followed by the quenching process is effective in forming the martensite and austenite microstructures.

Abstract: In this study, the effect of holding time on the microwave sintered 84Fe-11Cr-5Al₂O₃ metal matrix composite (MMC) was investigated. Sintering was carried out in a tubular microwave furnace HAMiLab-V3 under N₂ atmosphere. The holding time was selected between 0 to 75 minutes with increment of 15 minutes respectively. A study of microstructure and physical properties was carried out on sintered samples. It was discovered that, when the samples sintered at 1400oC with 20oC/min heating rate, the hardness was significantly increased from 110Hv to 160 Hv for holding time ranging from 30 to 45oC/min. Further increment until 75 minutes of holding time, no significant changes were obtained and hardness values were at steady state. The enhancement of bulk density and reduction of porosity were observed commences at 30 minutes until 45 minutes holding time. However, the results showed that the optimum holding time was at 45 minutes where the micro hardness is at the highest point which is about 160Hv.

Abstract: The application of steel products have been widely used and various research have been developed to find a good and appropriate quality of steel and can be produced in the country without have to be imported, for example alloy steels. One of the alloy steels that have been constantly developed is Ni-Cr-Mo alloy steel with additional nickel, chromium and molybdenum which can increase hardness, tensile strength, ductility and toughness. The effect during the production process is at the heating process that causes the formation of iron oxide layer (scale) and the loss of steel weight. Therefore, the selection of heat treatment methods and techniques are required to increase the mechanical properties of steel, such as hardness, tensile strength, and toughness, with the scale is about <5% of steel weight. In this research, the heat treatment was carried out at austenisation temperature of 800°, 850°, 900°C and at holding time of 20, 40, 60 minutes, then followed by a rapid cooling (quenching) to improve the mechanical properties of hardness. This research also tested the mechanical properties of steel that consist of hardness test and impact test, and metallographic observation that consist of micro structure observation and scale thickness observation. The micro structure from heat treatment process is martensite, it is due to a rapid cooling (quenching) that rapidly change the austenite phase into martensite. The data showed the highest hardness is 588.35 HVN at 850°C of temperature and 60 minutes of holding time, 8.5 Joules of impact energy, and 91.5 μm of scale thickness. While the lowest hardness is 539.34 HVN at 800°C of temperature, 5 Joules of impact energy, and 47.81 μm of scale thickness.