Papers by Keyword: Heating Rate

Abstract: In this study the effects of heating rate on the sharpness and size of Goss oriented ({110}<001>) grains during secondary recrystallization annealing at 900 °C was observed. The results show that, at the same annealing temperature, rapid heating of the samples to this temperature generates a higher drag force compared to a slower heating rate (5°C/min). The two groups of samples show different growth kinetics for Goss grains, in which at the longest annealing time, the rapid heating sample exhibits larger maximum Goss grain size compared to the slower heated samples.

Abstract: Alloy 5182 has been extensively used in the O temper for automotive sheet parts requiring high formability and moderate strength. The grain size of the sheet has been shown to impact strength, formability, and Lüdering behavior during forming. The present study examined the effect of heating rate on the recrystallization behavior of the alloy. Various heating rates, recovery treatments and annealing temperatures were used to manipulate the final grain size. Metallographic observations, EBSD and hardness tests were used during the research. The results are discussed in terms of operative recrystallization mechanisms for this alloy.

Abstract: Two 6xxx alloys with different Mn-content have been homogenised in a furnace at 575 ^oC for 2 hours and 15 minutes. Three different heating rates to the homogenisation holding temperature were chosen, as this was expected to affect the precipitation behaviour of the dispersoids. The study focused on developing a reliable procedure for the characterization of the density and spatial distribution of dispersoids in aluminium alloys; both in terms of sample preparation, microscopic techniques and quantitative analyses of results. Scanning electron microscopy (SEM) has been used to evaluate the dispersoid characteristics for the different alloys and heating rates. The results indicate an increase in dispersoid number density and a more uniform distribution of dispersoids for the lowest heating rate, as compared to the more rapid heating rates, for the alloy with 0.05 wt% Mn. For the alloy with 0.15 wt% Mn the number density increased with the heating rate. This is suggested to be due to particle coarsening as an effect of the low heating rate where the samples spend longer time in the furnace.

Abstract: The surface effects on the critical dimensions of ferromagnetic nanoparticles have been studied. Iron nanoparticles with different mean diameter from 5.9 nm to 21.4 nm were prepared by thermal decomposition of iron pentacarbonyl in the presence of oleic acid/octyl ether. The heating response of these ferromagnetic nanoparticles suspended in water were measured experimentally during which the same amount of iron nanoparticles and di-ionized water were irradiated by an alternating magnetic field and the increase in temperature of the system was measured. The heating performance of the nanoparticles was described in terms of Specific Absorption Rate (SAR) which depends on the heating rate. The heating rate was calculated from the initial slope of the heating curve at an inflection point whereby there is minimum heat loss to the surrounding. Results were analyzed to find the critical diameters for the transition from single-domain to superparamagnetic regime and from single-domain to multi-domain regime. Also, the frequency and current dependence of SAR were studied. The maximum value of SAR was obtained when the applied frequency and current were at 175 kHz and 15 A, respectively. An equation for the critical radius for the transition from single-domain to multi-domain regime with low anisotropy was derived and numerically solved by using a program written in C++ and results were analyzed to find the effect of surface parameters on the critical diameter of nanoparticles. The SAR as a function of nanoparticle’s diameter shows two maxima which can be connected with the two critical dimensions. One is D_C1 at 18 nm for the transition from single-domain to multi-domain configuration and the second is D_C2 at 10 nm for the transition from single-domain to superparamagnetic regime. Comparison of these experimental results with the bond order-length-strength correlation theory was discussed.

Abstract: This paper introduces the research and design of a light moisture tester. In the coal quality analysis field, moisture test most of the use of infrared heating pipe heating or drying box to measure, low heating rates, nitrogen through a single mode, before heating furnace uniform nitrogen filled with test conditions and have the test conditions, the same way caused by nitrogen, nitrogen waste. Based on this study, the heating pipe comprises an infrared tube into a light tube, the heating rate is improved; the general nitrogen control size flow switching mode using 2.5min before the experiment, large flow quick heating furnace filled with nitrogen, achieved through experimental conditions drying nitrogen, open a small flow, keep the atmosphere. The improved design of a light moisture meter analysis of water air drying method precision test, analysis of water air drying method accuracy experiments, 6 water - air drying method of precision experiment, 6 water - air drying method accuracy experiments, analysis of water through nitrogen drying method precision experiment, analysis of water. Nitrogen drying method accuracy experiments, Ȼ 6 full water through nitrogen drying method precision experiment, Ȼ 6 full water through nitrogen drying method accuracy experiments, results in line with national standard test, repeatability. Instrument for field application test in Tiefa Coal Industry Group, good test effect.

Abstract: In this paper, the thermogravimetic (TG) and differential thermogravimetric (DTG) curves of deinking sludge from Huatai Group Co., Ltd were derived from tests of thermal gravimetric analyzer (TGA). Pyrolysis character and kinetics of deinking sludge were investigated using thermalanalysis. The result showed that the pyrolysis process was composed of three stages: water lose stage, organic decomposition and decomposition of residues. The dynamical model of this pyrolysis process could be expressed by three first-order parallel reaction. The kinetic parameters of pyrolysis reaction were calculated respectively by Coats-Redfern integration method, the effect of heating rate on the deinking sludge pyrolysis characteristics was discussed.

Abstract: Conversion and yield of liquid product using semi-batch reactor are investigated. Selected reaction parameters were optimized, using Taguchi L9 Orthogonal Array method for the design of experiments, to yield the highest liquid product. The investigated parameters include nitrogen flow rate, sample particle size, temperature and heating rate. The effects and significance of each parameter was studied and verified through repetitive experiments. Optimum conditions for the reaction were established. Optimum conditions for pyrolysis process were at 100 ml/min of nitrogen flow rate, temperature at 500 ^oC, 20 ^oC/min of heating rate and 250μm - 500μm of particle size with liquid yield of 35.48wt%.

Abstract: In order to clarify the austenite reverse transformation of a 0.2C-3Mn-1.7Si steel during intercritical region with an ultra-slow heating rate of 0.05°C/s, DIL (dilatometer), SEM, XRD and EPMA were carried out. The experimental results indicated that the dilatometric cures exhibited the shape of two “valleys” and the growth of austenite from quenched martensite was composed of three consecutive sub-stages. This phenomenon is associated with Mn-rich and Mn-poor regions in martensite matrix. During the heat treatment,the austenite forms firstly in region enriched in Mn. However, with increasing temperature, the growth of γ is restrained owing to the concentration of Si. Upon the further process of heating, the free energy for the reverse transformation increases, and the residual Mn-depleted regions start to transform at a higher temperature.

Abstract: This paper introduces the research and design of a light moisture tester. In the coal quality analysis field, moisture test most of the use of infrared heating pipe heating or drying box to measure, low heating rates, nitrogen through a single mode, before heating furnace uniform nitrogen filled with test conditions and have the test conditions, the same way caused by nitrogen, nitrogen waste. Based on this study, the heating pipe comprises an infrared tube into a light tube, the heating rate is improved; the general nitrogen control size flow switching mode using 2.5min before the experiment, large flow quick heating furnace filled with nitrogen, achieved through experimental conditions drying nitrogen, open a small flow, keep the atmosphere. The improved design of a light moisture meter analysis of water air drying method precision test, analysis of water air drying method accuracy experiments, 6 water - air drying method of precision experiment, 6 water - air drying method accuracy experiments, analysis of water through nitrogen drying method precision experiment, analysis of water. Nitrogen drying method accuracy experiments, ¢ 6 full water through nitrogen drying method precision experiment, ¢ 6 full water through nitrogen drying method accuracy experiments, results in line with national standard test, repeatability.

Abstract: For passive RDX, fluent software was applied to simulate the cook-off for explosive of different charge density at heating rates of 1, 5, 10k/min to improve thermal safety in the ammunition storage, transport and battle. The results show that the heating rate has great effect on ignition time and position for passive RDX. Charge density also has great influence on ignition time but no influence on ignition position. The ignition time decreases and ignition position moves from the center to the two ends of the cylinder edge with the increase of the heating rate. The ignition time increases with the increase of charge density under the same condition. Therefore, increasing the charge density can effectively improve the thermal safety of ammunition.