Resistance Heating Furnace Research Articles

Effects of different Bismuth concentrations of InSbBi crystals grown by Bridgman technique

InSb1-xBix (x = 0, 0.005, 0.010, 0.015) crystals are grown by vertical Bridgman technique using single-zone resistive heating furnace. The main objective of this paper is to study the improvement of thermoelectric quality factors by different concentrations of Bismuth (Bi) in InSbBi crystals. EDAX (Energy Dispersive Analysis of X-rays) confirms that the grown crystals are pure and show the presence of In, Sb, and Bi in proportion. Powder X-ray diffractogram confirms the cubic zinc blend structure of these crystals with space group F-43m and all the diffraction peaks are matched well to the standard JCPDS-ICDD No. 6-0208. Raman spectra are recorded from 80 K to 300 K and Raman mapping spectra at room temperature for all above crystals have shown the presence of TO mode at 179.91 cm−1 and LO mode at 190.16 cm−1. The sharpness and intensity of Raman spectra have clearly reflected the purity and quality of the grown crystals. The electrical conductivity σ is found to increase slowly upto 450 K and then increases linearly upto 600 K and above that, it gets saturated in all crystals. The Seebeck coefficient remains negative showing that these crystals are n-type semiconductor and its value is found to be increased to −200 μV/K for InSb0.985Bi0.015 in comparison to −150 μV/K for pure InSb near 600 K. From the lattice thermal conductivity, power factor and thermoelectric figure of merit i.e. ZT calculations, it is concluded that InSb0.985Bi0.015 at 670 K gives the highest value of ZT = 0.45 in comparison to other grown crystals.

Development of Resistance Sintering Furnace for Heat Treatment of 22MnB5

This paper presents the development of resistance heating furnace based on the direct electrical conduction method that can perform with lower energy. Based on the concept of resistance welding, resistance heating furnace was developed for heat treatment of 22MnB5 Boron steel with the aim to change the microstructure from pearlite to austenite phases before quenched into martensite phase. The main component for this machine consisted of transformer, copper electrodes, copper cable coil and wood frame structure. The design of the machine resembled resistance welding with upper and lower electrodes were assembled together mounted by the wood frame. The heating energy collected from the electrical current that flow through cooper cable that rolled through toroidal transformer. The result shows that the machine capable to heat the 22MnB5 Boron steelwith maximum temperature of 721.2°C. However, the machine demonstrates overheat after 7 minutes due to the insulation burn of cooper cable. Further improvement of cooling system and copper insulation need to be addressed to prolong the heating operation.

Development of a methodology for optimizing the component composition of the charge for the processing of gts of steelmaking, providing the efficiency of useful components extraction

The article deals with the recycling issues of electric steelmaking dusts by thermodynamic extraction of iron, zinc and lead in order to reduce the impact on the environment and increase the industry resource base. The purpose of the research was to determine the influence of the quantitative content of low-calorie and high-calorie carbon on the processes of zinc oxide reduction in gas purification dust and its further sublimation using a vacuum in a closed system of a resistance heating furnace. Determined the dependence of the zinc extraction degree and the increase of iron oxides in the samples studied.

On online texture quality control and management of continuous processes for the production of non-ferrous sheets

The results of the studies of the connection of texture parameters and the quality characteristics of commercial batches of the finally rolled or finally annealed tape made of fcc- materials, which differ in the value of stacking fault energy, phase composition and processing technology are considered. Strips of brass L68 and L63 containing ~62.5 and ~64% of copper and aluminum alloy AMg2 were hot rolled from ingots that were cast in water-cooled and electromagnetic casting mould respectively. Cold rolling was carried out with intermediate annealing to the state of complete recrystallization in the resistance heating furnace (AMg2) or in the induction annealing line (brass) to the finite thickness: ~0.3 mm (AMg2) and 0.6–1.0 mm (brass), varying the degree of the finite plastic deformation. During the final annealing of the brass strip in the line of induction annealing and etching, the speed was varied. The tape was tested for breaking, Vickers hardness number, cutting-out and draw-forming of “glasses” in the combination die. In particular, we controlled the characteristics of the anisotropy of plastic properties, the magnitude of the relative earing and intensity 200 and 220 lines of the texture on the general purpose diffractometers in Fe Karadiation by the Schulz reflection method. The texture parameters T and Т, expressing the ratio of the components of the recrystallization texture and the rolling texture of fcc-materials, were determined. It was found that the accuracy of texture control during annealing of brass L63 rolled products using the same texture parameters is reduced in comparison with materials with high stacking fault energy due to the small fraction of {100} <hkl> recrystallization texture component and the dependence of the structure and phase ratio on small, 1.5% for copper, fluctuations in the chemical composition. At the same time, it remains high enough to control the process of organizing feedback when managing the process online. That is, texture control can be extended to annealing materials with very low stacking fault energy, which contain the second phase. At the same time, there are serious restrictions on the degree of deformation during rolling and on the annealing regimes, in which it is reasonable to use the texture control, as well as the absolute need to determine regression dependences of the properties on the texture when changing the technological processing scheme. In each individual case, the necessary condition for organizing the texture control is the presence of the “close” correlation between the texture parameter and the controlled characteristic. The proposed structural scheme of the texture control during rolling is discussed.The authors gratefully acknowledge S. G. Khayutin, Doctor of Technical Sciences, a founder of a texture control research area in Russia, globally pione ering in texture control of mechanical properties, taking part in acquiring some experimental data used in the research paper, and giving important recommendations at the initial stage of preparing the presented paper.

Investigating performance of compound heating furnace subject to heating by two elements, high alumina insulation and silicon control rectifier (scr) system at 1600ᴼc

The present study examines the performance of a resistance heating furnace using two different heating elements, Silicon Carbide (SiC) heating rods and Molybdenum Di-Silicide (MoSi2) heating elements, where SiC rods are used first, starting from the beginning (ambience) temperature of 35ᴼC up to 1300ᴼC, followed by MoSi2 heating elements to raise the chamber temperature from 1300ᴼC to the set temperature of 1600ᴼC. To achieve effective insulation results, newage high alumina (Al2O3), very low thermal conductivity (K), and high density materials such as zirconium tiles, mullite tiles, and zirconium modules, all with such necessary insulation properties sandwiched, are used. Air, a bad conductor of heat transfer, is also used in a gap of 20 mm between two different tiles to lessen heat transfer from the working chamber towards the outer ambience by conduction and radiation to achieve desirable results-maximum thermal efficiency with the least heat loss from the outer surface and to achieve skin temperature equal to the ambient temperature. Also, in this experiment, hot-faced red bricks are used under the hearth in a new design. The system under study consists of a programmable Proportional Integral Derivative (PID), a thyristor power pack, recrystallized alumina tubes, and sensing elements: a thermocouple and Pt-Pt/13%. Rh, semiconductor-based circuit that controls power and current. This makes the system to meet the requirement (step down) and thereby controls voltage automatically with a transformer (depending on the size of the working area, 53 A (I), 220 V for single phase, reduced to 60 V by a step down transformer) auto-current-limiting facilities.

Investigating performance of compound heating furnace subject to heating by two elements and (Silicon Controlled Rectifier) SCR control at 1600ᴼC

The present research examines the performance of a resistance heating furnace using two different heating elements, Silicon Carbide (SiC) heating rods and Molybdenum Di-Silicide (MoSi2) to raise working chamber temperature to 1600ᴼC. SiC rods are used first, starting from the beginning (ambience) temperature 35ᴼC up to 1300ᴼC, followed by MoSi2 heating elements to raise chamber temperature from 1300ᴼC to set temperature at 1600ᴼC. Transition from SiC to MoSi2, heating system is uninterrupted, and swift in heating element effected by inter-locking system (an electronic device or an electro-magnetic system) without any drop in effect. The system under analysis consists of Programmable (Proportional-Integral-Derivative) PID, (Silicon Controlled Rectifier) Thyristor power pack, recrystallised alumina tubes, sensing elements: thermo-couple, Pt-Pt/13%.Rh, semiconductor based circuit that controls power and current to the system requirement (step down) and thereby control voltage automatically with transformer (depending on size of working area, and 53 amp (I), 220 V for single phase, reduced to 60V by a step down transformer) and auto current limiting facilities. Present analysis is designed for programmable and also for non-programmable type of cycles of operations set before starting the furnace within maximum working temperature of 1600ᴼC to achieve objectives, like saving of amperage (current consumption 53 amp) and power at reduced voltage (40V), long life of the heating elements (2 years and more) and optimization of thermal efficiency (60%) for high working temperature 1600ᴼC for long hours of operation in a Compound Heating Resistance (CHR) furnace.

To measure thermal resistance to heat flow at 1600ᴼc in a compound heating resistance furnace for optimization of furnace efficiency

The present paper examines the performance of a resistance heating furnace by measuring the resistance of two different heating elements, namely, Silicon Carbide (SiC) heating rods and Molybdenum Di-Silicide (MoSi2) heating elements, to raise the working chamber temperature to 1600ᴼC for heating the charge materials. SiC rods are used to raise the working chamber temperature, starting from the beginning (ambience) temperature of 35ᴼC up to 1300ᴼC. Then MoSi2 heating elements will be used to raise the chamber temperature from 1300ᴼC to the set temperature at 1600ᴼC. Transition from SiC to MoSi2, heating system is uninterrupted, and swift in heating element effected by inter-locking system (an electronic device or an electro-magnetic system) without any drop in effect. Use of two different heating elements has been tested to achieve many objectives, like saving amperage (current consumption), long life of the heating elements, and optimization of thermal efficiency for high working temperature at 1600ᴼC for long hours. This is achieved by creating resistance to the flow of electrons through an element (a good conductor for electricity as well as heat). Thus, due to high friction, a temperature is developed and heats the charged materials, up to a temperature as high as 1600ᴼC. This method is applied in an environment of air, inert gas, vacuum, etc. with no pollution, for programmable and also for non-programmable types of cycles of operations set before starting the furnace within a maximum working temperature of 1600ᴼC to achieve the objectives of a Compound Heating Resistance (CHR) furnace satisfactorily.

Characterization of VC Coatings on Cold Work Tool Steel Produced by TRD

In This study vanadium carbide coatings obtained by thermo-reactive deposition/diffusion (TRD) technique on cold work tool steel AISI D3. The TRD treatment were carried out in a molten mixture consisting of NaCl, CaCl2, ferrovanadium and aluminum, by heating this mixture at 1000 °C for 4h using a resistance-heating furnace under air atmosphere. The coating process was investigated using light microscopy LM, scanning electron microscopy/energy dispersive spectroscopy SEM/EDS, and X-ray diffraction XRD characterization techniques. The results indicated that the vanadizing process produced a homogeneous coating layer about 13 µm depth and its microhardness is 2300 HV. Carbide compounds that are formed are vanadium carbides phases (V8C7, VC, V4C3, V6C5, V2C), while EDS-Line scan results show chromium carbides phases formed in sublayer. The corrosion resistance of the vanadium carbide coatings was evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in a solution of 3.5 % NaCl. Vanadium carbide coatings improved the corrosion resistance of the substrates, vanadium carbide coatings showed the longest service life compared with the uncoated tool steel AISI D3.

2-inch diameter (1 0 0) β-Ga2O3 crystal growth by the vertical Bridgman technique in a resistance heating furnace in ambient air

A resistance heating vertical Bridgeman (VB) furnace able to maintain high temperatures up to 1830 °C in ambient air was developed to suppress weight loss of both the crucible and raw material Ga2O3. Large-size 50 mm diameter β-Ga2O3 crystals with a growth orientation perpendicular to (1 0 0) plane were grown by the VB growth process in platinum-rhodium alloy crucibles using this furnace. The total weight loss during a VB growth run is very small, amounting to less than 1% of the total weight of the platinum-rhodium alloy crucible and the Ga2O3 raw material.

Nitrogen-doped nanodiamond films grown just by heating solid precursor thin layers for field emission application

Nanodiamond films with nanoscale grain sizes are highly desired for versatile applications, such as sensors and field emitters, due to their special physical and chemical properties. In this paper, a simple, safe, green and cost-effective approach for growing intrinsic and nitrogen (N)-doped nanodiamond films just by heating the solid thin layers of glucose and/or urea on nickel-coated stainless steel in a resistance-heating furnace is reported. The N doping concentration of 0 to 2.63 at.% can be adjusted by the urea addition in the precursors. Moreover, this method can be easily extended to other organic carbon and dopant sources. Measurement of the field electron emission properties indicates that stable emission with a low turn-on electric field strength of 3.6 V µm−1 defined at the current density of 0.01 mA cm−2 can be delivered for the N-doped nanodiamond film grown from the precursor thin layer of glucose + urea (1:1 in mass).

Influence of Mg on Micro-Mechanical Behaviour of as Cast Al–Mg System

In the present work, a study was carried out for various possible Mg concentrations in order to optimize Mg amount in Al–Mg system as far as metallurgical and mechanical properties are concerned. In molten Al, variations of amount of Mg were made from 0.05–7 wt % Mg using a resistance heating furnace. Intermetallics like Al–Mg, Mg–Si, Al–Si, etc.,—were formed at processing temperature. During solidification, these intermetallics were pushed towards the grain boundaries and formed clusters, which was studied using SEM–EDS analysis. Heavier phases revealed as dark regions whereas lighter phases as less dark or bright regions. Due to such pushing effects of intermetallics during solidifications of bath in metallic die, development of grain boundaries started in the form of remarkable thickening of it into the Al matrix. This phenomenon was found to be more pronounced, as the Mg concentration was increased. Hence, in case of 7 wt % Mg, it was found that maximum amount of intermetallics gathered at grain boundaries. Segregation tendencies of various intermetallics and excess free Mg were found non uniform for a higher range of Mg. Ultimate tensile strength, specific strength, and hardness properties were studied and they were found to be highest in Al–3 wt % Mg system along with low density and ductility values. Therefore, in the present study, 3 wt % Mg is considered to be an optimum level of Mg concentration based on its micro-mechanical behaviour.

Verification on Possibility of Nitrogen Diffusion into Steel by High Temperature N-Quench

N-Quench, which is a new surface heat treatment to infiltrate nitrogen into steel parts followed by quenching to achieve hardening, is gathering attention in the nitriding field as it affords low distortion while maintaining a higher effective case depth (ECD) compared with conventional nitriding. N-Quench is conducted mainly between 680°C and 800°C, where the two-phase region of ferrite and austenite exists in the Fe-N phase diagram. However, a few studies have reported on nitriding at temperatures higher than 800°C due to decomposition of NH3, which is a key source of nitrogen infiltration. Our results revealed that in a conventional furnace such as resistance heating furnace, no nitrogen infiltrated the specimen at 930°C, which is the general carburizing temperature. On the other hand, in the infrared heating furnace, nitrogen infiltrated the specimen at 930°C successfully with lesser NH3introduction than that required by the conventional furnace. Therefore, in this study, the limit of NH3decomposition is assessed and possibility of extending the applicability of N-Quench, especially increasing the ECD while maintaining a low distortion, is examined.

Direct patterned growth of intrinsic/doped vertical graphene nanosheets on stainless steel via heating solid precursor films for field emission application

Vertical graphene nanosheets (VGNs), normally consisting of one to several graphene layers vertically aligned on substrates, are promising in a variety of applications including field electron emitters, gas sensors and energy storage devices. Herein, we report a simple, green, easily scalable and cost-effective strategy of growing both intrinsic and nitrogen (N)-doped VGNs on stainless steel (SS) just by heating the solid thin layers of glucose and/or urea in a resistance-heating furnace. It is interesting that VGNs mainly grow on the roughened regions, which can be attributed to the more nucleation and catalyzing sites on such regions than smooth SS. Meanwhile, the N doping concentration can be adjusted by varying the urea addition. Field electron emission measurement indicates that the obtained N-doped VGNs exhibit excellent field emission with a relatively low turn-on electric field strength (~2.6 V μm−1 at the current density of 10 μA cm−2), large field enhancement factor (~9428) and high stability.

Enhancement of thermal efficiency and cost effectiveness by development of melting furnace by revamping and troubleshooting fuel-fired furnace

Technological development of furnaces over conventional melting methods of diesel or gas-fired furnaces is necessary. These furnaces have large amount of heat losses and hence their thermal efficiency is very low. Moreover, these furnaces do not produce good quality melt because of the chances of embedment of impurities from after-combustion gases and agitation. The time required for melting in such furnaces is more. Also, insulation is not provided and there are heat losses which increase the time of melting. An electric resistance heating furnace is developed which overcomes all the problems associated with the fuel-fired conventional furnace. The thermal efficiency of this developed furnace is found to increase quite drastically up to 85%, which is by about 33% more than conventional furnace; while reducing the operating cost of furnace. This benefits industry overall by profit of 70% and certainly can replace the existing conventional fuel-fired furnaces.

Preparation of chromium doped phosphate glass adopting microwave irradiation and comparative analysis of properties with conventional glass

Chromium doped phosphate glass was melted adopting microwave (MW) heating and properties were compared with conventional glass. Standard methods of characterization adopting X-ray diffraction (XRD), density, UV–Vis-NIR absorption spectroscopy, Refractive indices (RI), Fourier Transform Infrared (FT-IR) spectroscopy, X-Ray Photoelectron spectroscopy (XPS), Differential Scanning Calorimetry (DSC) were performed to evaluate the properties of the glasses. XRD analysis confirmed the amorphous nature. Enhanced absorption peaks in UV–Vis spectra at wavelengths 298, 456, 660 and 685 nm suggest higher Cr3+ concentration in MW prepared glass. Alteration in peak intensities and shift in binding energy in XPS confirm the presence of Cr(III) in different coordination and orientation in glass. Spectrophotometric method developing colour complex of Cr[VI] with 1,5-diphenyl carbazide indicates absence of Cr[VI] in the glass. Presence of IR bands due to different phosphate bonds depicts similar structure in both the glasses. Difference in density, RI, and glass transition temperature (Tg) are also observed in MW melted glass. Maximum instantaneous electrical power was 1.4 kW in MW cavity, whereas 4 kW was recorded in resistive heating furnace. Reflected power remains within 15% of forward power. Total melting time was ~ 2 h in MW heating unlike 6–7 h in resistive heating.

Measurement of Zone Temperature Profile of a Resistive Heating Furnace Through RVM Model

In this paper, a system for measuring the zone temperature profile of a horizontal tube furnace is proposed. This system consists of an ultrasonic transducer, quartz tube, resistive horizontal tube furnace, Arduino micro-controller and relevance vector machine (RVM)-based regression model. The ultrasonic transducer is placed in such a way that the acoustic wave is transmitted and then reflected back from the resistive horizontal tube furnace. The variations in the temperature values inside the tube furnace may affect the receiving voltage of the ultrasonic transducer. The RVM model is employed to predict the temperature using the inputs as the ultrasonic transducer voltage and the distance of the propagating path of the ultrasonic wave. The experimental results demonstrate that the proposed system is effective to measure the temperature inside a horizontal furnace and it shows a correlation coefficient value of 0.9695 with the K -type thermocouple readings. Such a system can be employed in an industrial furnace to measure the temperature with a higher accuracy.

Investigation on Tensile Behaviour of Laser Welded Al–Mg–Sc–Zr In Situ TiB2 Reinforced Metal Matrix Composite

The objective of the present work is to investigate the tensile behavior on laser welded Al–Mg–Sc–Zr in situ nano TiB2 composite. Al–3.5Mg–0.15Sc–0.075Zr–1TiB2 composite was melted in a resistance heating furnace. TiB2 was formed during in situ reaction of K2TiF6 and KBF4 salt mixture at 750 °C for 60 min. Welding was done using Nd:YAG pulsed laser source JK 600 (GSI make) using a robotic (IRB1410 of ABB) laser set up. The autogenous welding experiments were carried out using some of the significant parameters such as frequency—75 Hz, laser beam energy—8.10 J, pulse width—2.5 ms and welding speed—5 mm/s. It was observed that laser beam power played a major role and lower value of energy with higher repetition rate resulted better and uniform weld bead with full penetration. Five different processing methods were utilized to investigate the mechanical and metallurgical properties namely: (a) as cast (AC), (b) as cast followed by welding (AC + W), (c) as cast followed by aging (AC + A), (d) as cast followed by aging and then welding (AC + A + W) and finally (e) as cast followed by welding and then aging (AC + W + A). The ageing treatment followed was heating the samples at 300 °C for 5 h followed by air cooling. The obtained results infered that apart from the obvious superior properties shown by as cast followed by aging treatment (AC + A: 248 MPa); the AC + W + A specimens showed better properties (235 MPa) along with AC + A + W specimens (226 MPa). The fracture surface analyses revealed the following: (a) the weld region in the laser welded as cast material did not show any TiB2 in the structure probably due to the fact that temperature experienced during laser welding process might have melted the particles and was dissolved in the solid solution, (b) the interface of the weld-base region showed the presence of few TiB2 particles which lost their hexagonal shape due to preferential melting along the edges. (c) The fracture morphology of both AC + A + W and AC + W + A specimen’s showed typical mixed mode fracture with fine precipitates along the interface. The strength increased in AC + W + A at the expense of ductility due to formation of Al3Sc precipitates.

Fabrication and characterisation of non-polar M-plane AlN crystals and LEDs

Aluminium nitride crystals and devices grown along the polar c-axis direction are affected by the strong spontaneous and piezoelectric polarisation fields. It is necessary to grow non-polar plane aluminium nitride crystals in order to solve the problem. The M-plane surface-oriented aluminium nitride single crystals were grown by physical vapour transport on a resistance heating furnace, which was designed by ourselves and included two heaters on sublimation region and crystalline region, respectively. The M-plane aluminium nitride light-emitting diode was further fabricated and characterised. The current–voltage characteristic showed a Schottky diode behaviour. A white light emission from the biased diode can be clearly seen by naked eyes in a dark place at room temperature. The ultra-wide electroluminescent spectrum covered from deep UV (200 nm) to infrared (1100 nm) and centred at 496 nm (2·5 eV). At last, the emission mechanism was discussed.

Higher Fe2+/total Fe ratio in iron doped phosphate glass melted by microwave heating

Iron doped phosphate glasses containing P2O5–MgO–ZnO–B2O3–Al2O3 were melted using conventional resistance heating and microwave heating in air and under reducing atmosphere. All the glasses were characterised by UV–Vis–NIR spectroscopy, Mössbauer spectroscopy, thermogravimetric analysis and wet colorimetry analysis. Mössbauer spectroscopy revealed presence of iron predominantly in the ferrous oxidation state on two different sites in all the glasses. The intensity of the ferrous absorption peaks in UV–Vis–NIR spectrum was found to be more in glasses prepared using microwave radiation compared to the glasses prepared in a resistance heating furnace. Thermogravimetric analysis showed increasing weight gain on heating under oxygen atmosphere for glass corroborating higher ratio of FeO/(FeO+Fe2O3) in glass melted by direct microwave heating. Wet chemical analysis also substantiated the finding of higher ratio Fe+2/ΣFe in microwave melted glasses. It was found that iron redox ratio was highest in the glasses prepared in a microwave furnace under reducing atmosphere.

Effect of Fuel Concentration on the Properties of Combustion Synthesized MgAl2O4 Spinel Powders

Stoichiometric solution of aluminium nitrate and magnesium nitrate along with 4.66 to 7.66 moles of urea (fuel) concentrations were prepared and heated slowly to evaporate the water till a homogeneous gel was formed. Critical temperatures for the formation of MgAl2O4 spinel were identified using TG/DSC analysis of the gel and the reaction mixture was introduced into the resistive heating furnace preheated at 350oC. Powder mass thus obtained was characterized and was calcined at 1000oC for removal of retained carbon and crystallization. The powder was further characterized for phase purity, powder morphology, particle size and BET surface area. A fuel concentration beyond 6.66 moles generated excess gases resulting from the decomposition of unreacted urea which got occluded in the foamy combustible mixture. On reaching the self-ignition temperature, combustion occured and the sudden escape of these gases led to highly porous, fragile fluffy mass. Surface area and sinterability of the powder showed a clear correlation with the fuel concentration in the reaction mixture. Spark plasma sintered samples in comparison to the conventional sintered samples exhibited enhanced density values with finer grain sizes.