Resistance Furnace Research Articles

The effect of hold-melt time of micro-regime precipitation size and hardness in Al-Cu alloy

This study aims to control the characterization and mechanical properties of smelting Al-Cu Alloy through Hold-Melt Time. This research uses aluminum scrap and copper wire scrap to produce quality as-cast ingots, clean the environment, and increase waste utilization. Copper melting point of 1083 °C is immersed in molten aluminum at a temperature of 900 °C for 10–30 minutes causing copper to dissolve in aluminum due to smelting events based on diffusion phenomena. Parameters of temperature and immersion time of copper in molten aluminum in this study are expressed by hold-melt time. In the copper aluminum alloy trade, commonly called Duralumin, it is commonly used for impact loads and is heat-treatable. Resistance to cryogenic temperatures, in the future Duralumin has the potential to replace stainless steel. This study used an electric resistance furnace with the specifications for smelting aluminum 3 kg, electric power 2.5–3.0 kW, electric voltage 220 Volts, maximum temperature 1000 °C. It had been conducted an experiment where copper had been melted under its melting point in duralumin ingot casting. In this study, copper pieces were soaked in liquid aluminum with temperature of 900 °C. After 10–30 minutes of holding melt, the soaked copper became Al-Cu alloys and was called molten Duralumin. After the molten duralumin had been cleaned from dross, it was poured into ingot casting. From specific weight test, more soaking time of the copper in liquid aluminum caused specific weight of ingot duralumin increase from 47.08 % to 57.56 % and its hardness increase from 93 to 113 BHN. This study contributes on melting energy saving and improves the characteristic and hardness of ingot aluminum type 2xxx

Procedure to Obtain Cu2O Isolate Films, Structural, Electrical, and Morphological Characterization, and Its Use as an Electrical Isolator to Build a New Tube Furnace

Copper oxide is a widely studied compound in wastewater decontamination, hydrogen production, solar cell production, and sensor fabrication. In recent years, many architectures and structures with the potential for developing clean technologies have been synthesized. A procedure by thermal oxidation to grow electrical insolate Cu2O films on copper surfaces in an air atmosphere was developed. The results of the morphological and structural characterization of the copper oxide layers evidence the presence of Cu2O polycrystalline films. The films have polyhedral architectures of approximately 1.4 μm thickness and are electrically insulating. A novel copper resistive furnace was built using this copper oxide film which was used as an electrical insulator between the electrical resistance of the heater and the surface of the copper thermal block. The application improves the efficiency of the resistive furnace in terms of the temperature reached and the thermal coupling response time relative to the performance of conventional furnaces using ceramic insulation. Over the entire operating temperature range explored for the same power supply, the copper oxide-coated furnace achieved higher temperatures and faster response times than the traditionally coated furnace.

Effect of electromagnetic melt mixing on the technological process of aluminium powder production

Effect of electromagnetic melt mixing on the technological process of aluminium powder production

Change in wear resistance of alloy when alloying aluminium alloy with germanium oxide

Various studies are being conducted on alloying materials for mechanical engineering with various unique elements. In particular, studies have been conducted to improve its properties by including elements such as lithium, zirconium, ytterbium, and erbium in the composition of the aluminum alloy. The article examines the change in the wear resistance ability of alloys in aluminum-silicon and aluminum-copper systems with germanium oxide based on their mechanical properties. The samples were poured into a resistance furnace. In this case, a germanium oxide compound was added to the charge of one to three percent. Wear resistance was determined using a diamond stone meter. At the same time, the samples were measured on the device with the strength of wear resistance at certain intervals. Based on the results obtained, a graph of the dependence of the wear resistance of the samples on the GeO mass was developed. The conclusions of the authors based on the results obtained are given in the final part of the article. The study was tested in the laboratory of the Department of Foundry Technologies of Tashkent State Technical University.

Vplyv Sr, Zr a Mo na vybrané vlastnosti AlSi5Cu2Mg zliatiny

Hypoeutectic AlSi5Cu2Mg alloy is a relatively new alloy that finds application in the production of high stress cylinder head castings. This work focuses on the investigation of the solubility of the additive elements Sr, Zr, and Mo in AlSi5Cu2Mg alloy. The main objective of the work was to characterize the influence of the additive elements on selected properties of the experimental alloy AlSi5Cu2Mg with respect to the melting method of the additive elements. The additive elements Sr, Zr, and Mo were introduced into the melt in the form of AlSr10, AlZr20, and AlMo10 master alloys were melted in 2 ways in an electric resistance furnace and an electric induction furnace. Depending on the melting method, the experimental alloys were designated Sr-Z, Zr-Z, Mo-Z (electric resistance furnace), and Sr-I, Zr-I, and Mo-I (electric induction furnace). The results showed that the presence of Sr, Zr, and Mo in the AlSi5Cu2Mg alloy led to a negative increase in the area fraction of porosity and a decrease in the physical properties, regardless of the melting method of the master alloys. Based on the summarized results, it was shown that the experimental alloys Sr-I, and Sr-Z did not show a significant increase in mechanical properties. A negative effect on the selected mechanical properties was noted by the experimental alloy Zr-Z. The most favourable combination of mechanical properties was obtained by the experimental alloys Mo-I and Zr-I.

Effect of heat treatment on the precipitation of Mg17Al12 in Mg-7Al alloy

Mg–7Al alloy is synthesized using a protective atmosphere electrical resistance furnace in which both the melting and casting compartments have provision for operation under a protective atmosphere. The maximum solid solubility of Al in Mg is around 12 wt% at 437 °C and is decreased to 0.1 wt% at room temperature as dictated by the phase diagram. Microstructural observation of the cast structure confirmed that most of the aluminium present in the alloy forms a eutectic β phase segregated around the grain boundaries of α-magnesium and hampered the mechanical properties significantly. To understand the precipitation behaviour, the Mg alloy is heat treated employing three sets of heat treatment cycles. The cast Mg alloy is solutionized at 420 °C for 24 hrs and then quenched in ice water at 7 °C to achieve a supersaturated solid solution (SSSS). The quenched samples are aged at 350 °C, 227 °C, and 150 °C for 8, 10, and 12 hrs respectively. The microstructure confirms that the alloy aged at 350 °C, forms continuous precipitation of β-phase whereas the alloy aged at low temperature i.e., at 150 °C forms discontinuous precipitation, while the sample aged at intermediate temperature i.e., 227 °C both the continuous and discontinuous precipitation are observed. Vickers hardness values of the solutionized sample are 48 ± 3 HV and aged at 350 °C, it is 55 ± 5 HV. At low-temperature ageing i.e., at 150 °C the hardness value is decreased to 44 ± 5 HV, whereas ageing at 227 °C, the hardness value is found 53 ± 5 HV.

High-performance temperature control system for resistance furnace annealing and crystal growth of semiconductor compounds

This paper describes the control system for the annealing and growth of semiconductor crystals. In this process, precise temperature control is crucial to obtain high-quality samples. For this reason, a high-performance temperature control based on the PID controller augmented in the gain-scheduling (G-S) path has been applied. To overcome the drawback related to the synthesis procedure of the controller directly on the plant, the modeling stage has been introduced. At this stage, in the MATLAB/Simulink environment, a simulation model was built, the task of which is to approximate the operation of the test stand. Simulation and experimental tests indicate an advantage of the proposed control system compared to the reference solution. Simulations and experiments were performed for the PID controller in standard configuration and with G-S. A shortening of the temperature output signal rise time for a system with G-S was observed compared to a standard close system.

Combined effect of calcium and zinc on the hot cracking of Al – Mg аlloys

This paper examines the effect of calcium and zinc on the hot cracking of cast magnaliums and how their hot cracking behaviour is related to their structure. The authors rely on the Thermo-Calc methods (TTAl5 database) to substantiate the composition of the Al – Mg – Ca – (Zn) alloys in view. Pure burden components were smelted in a resistance furnace and then cast in graphite and steel moulds. Structural and compositional analyses relied on optical and scanning electron microscopy. Specimens for structural and characterization studies were made out of flat castings with a 10×20 mm section, which were then remelted and cast into pencil-shaped specimens for hot cracking tests. It was found that as the concentration of calcium in the alloys rises, their eutectic becomes coarser, i.e. certain dendrite branches tend to get shorter and thicker. Combined inoculation with calcium and zinc does not modify the structure. A hot cracking study showed that a shorter crystallization interval applied when selecting an alloy did not impact that parameter in the studied system. For example, alloy Al – 10 Mg – 4 Ca has a shorter crystallization interval compared with alloy [АМг10ч]; at the same time the former is much more prone to hot cracking. Inoculating the experimental alloy Al – 6 Mg – 2 Ca – 2 Zn with zinc ensures a better resistance to hot cracking compared with the commercial alloy [АМг10ч]. A study that looked at the effect of superheating on castings showed that the best effect is achieved when heating 50 oC above the liquidus temperature. As the superheat temperature increases, so does the grain size of the Al – 6 Mg – 2 Ca – 2 Zn alloy. The hardness and density of this alloy are similar to those of the base one.This research was funded by the Russian Science Foundation under Grant No. 21-79-00134.

Aluminum 4.5 wt. % Copper Alloy Powder Sintering Temperature Effect on Microstructure and Mechanical Properties of Spark Plasma Sintered Compact

The aluminum 4.5 wt. % copper alloy was melted in an electrical resistance furnace and atomized to produce the powder of 350 µm to 500 µm size of different shapes and sizes. The atomized powder was graded using standard set of sieves. The powder is compacted with the help of spark plasma sintering by applying the required pressure and temperature simultaneously. The sintering pressure of 25 MPa and temperatures of 480 °C and 540 °C was employed to produce sintered compacts at two different temperatures. The density of the sintered compact was measured using Archimedes principle. The surface topography of both the compacts revealed the cellular, elongated grains and dendritic microstructure. The average micro Vickers hardness of compact sintered at 480 °C and 540 °C were found to be 55.9 HV1 and 65.4 HV1 respectively. The compression strength of compact sintered at 480 °C is 185 MPa and the compact sintered at 540 °C is reported as compacts was reported as 250 MPa.

Experimental study on the preparation of ferrophosphorus alloy using dephosphorization furnace slag by carbothermic reduction

Abstract With the development of the duplex converter process, the amount of dephosphorization furnace slag is increasing, and it has relatively low basicity. It has been indicated that the recovery of valuable elements from dephosphorization slag by carbothermic reduction has great environmental and economic benefits due to its high content of P, Fe, and Mn. In this work, the experimental slag was reduced by carbon powder in a resistance furnace at 1,550°C. The results show that 76.82% of P, 99.60% of Fe, and 11.82% of Mn in the slag are recycled at basicity 1.0, and the recovery ratios of P, Fe, and Mn are 34.58, 78.89, and 13.85% at basicity 2.0, respectively. The ferrophosphorus obtained from the reduction of the dephosphorization furnace slag can be used as a raw material for steel-making alloy, and the residual steel slag can be used as cement and other building materials. This work provides a reference for recycling and resource utilization of dephosphorization furnace slag.

Kinetic Study on Reduction of FeO in a Molten HIsarna Slag by Various Solid Carbon Sources

To investigate the reduction behaviour of different reductants such as charcoal (CC), thermal coal (TC), and carbon black (CB) with HIsarna slag, a series of isothermal reduction experiments were performed in a vertical tube resistance furnace (VTF), coupled with a Quadrupole mass spectrometer (QMS) at 1450 °C, 1475 °C and 1500 °C. The results confirm that the highest overall reduction rate was achieved by CC, followed by TC and CB. The reduction mechanism between FeO containing molten slag and the selected carbonaceous materials is determined by studying the morphology of the water quenched samples at the intervals of 1.5, 3 and 5 minutes, using optical and scanning electron microscopes. The results reveal that the overall reaction is controlled by two main mechanisms: (1) nucleation and growth of CO bubbles, proceeded by the gaseous intermediates CO and CO2; and (2) diffusion of FeO in the molten slag. The initial reduction period in which chemical reaction control is dominant, can be described by the Avrami–Erofeev model, whereas the final period is described by the three-dimensional diffusion model.

Down-conversion based Tm3+:LiY1-XYbXF4 temperature sensors

Single crystals of Tm3+ (0.2 at.%):LiY1-XYbXF4 (X = 0.2, 0.4, 0.6, 0.8, 1.0) phosphors were grown in the resistive furnace by the Bridgman-Stockbarger method. The obtained samples have a tetragonal structure. The samples were excited by λex = 688 nm pulse laser irradiation (3H6 – 3F2,3 absorption band of Tm3+). The presence of Yb3+ emission under excitation of Tm3+ ions indicates energy transfer from Tm3+ to Yb3+. It was suggested, that in the studied system, there is only the phonon-assisted energy transfer from 3H4 (Tm3+) to 2F5/2 (Yb3+). The luminescence intensity ratio (LIR) of Tm3+ (3H4 – 3H6) and Yb3+ (2F5/2 – 2F7/2) lead to absolute temperature sensitivity values of 0.0025–0.0035 K-1.The short-lived decay time increases with the temperature increase. The maximum Sr value obtained from short-lived decay time dependence on temperature is equal to 0.36%·K−1.In the frames of the present work, we developed a model allowing determining the probability values of energy transfer between Tm3+ and Yb3+ ions in the heavily-doped samples. The model takes into consideration multiphonon nature of interaction between the doping ions.

Possibilities of Repairing Functional Surfaces of Molds for Injecting Al Alloys Using Manual GTAW Cladding

The paper presents the results of research that is focused on the renovation of molds for high-pressure aluminum casting. An analysis of the worn molds was carried out after they were removed from the operator. The extent and mechanism of the wear were determined. GTAW (Gas tungsten arc welding) technology was chosen for the renovation of the shaped parts of the molds. The renovation layers were realized with four types of additional materials Cronitex RC 44, UTP A 73 G 3, UTP A 673 and Dievar® TIG. The quality of the coatings was assessed by destructive as well as non-destructive tests. The mixing of the build-up layers with the base material was determined on the basis of structural analyses. The hardness of the cladding was determined by a metallographic analysis of the cross crowns with the Vickers method. The resistance of the cladding was tested by a complete immersion in a melt of AlSi8Cu3 aluminum alloy which was maintained at a temperature of 680 ± 20 °C in a laboratory resistance furnace for 120 and 300 min. The tribological properties of the produced deposits were determined using the ball-on-disc dry method. Based on the experiments that were carried out, it is possible to recommend the additive material UTP A 73 G 3 for the restoration of the functional surfaces of molds for the injection of Al alloys as the patterns that were created by it have shown the best results in terms of their resistance to Al melt, which is the dominant degradation factor limiting the life of the molds.

Effects of Thermal Shock on the Microstructures and Mechanical Properties Evolution of 310S Welded Joints at 1100 °C

In order to reveal the effects of the glass solidification bottling process of high-level liquid radioactive wastes on the welded joints of containers, the microstructure evolution and mechanical properties of 310S stainless steel welded joints were investigated. For this purpose, samples were heat-treated in a resistance furnace at 1100 °C, with two groups of samples being thermally shocked and heat-treated in the furnace. The results indicated that the grain-size distribution changed from unimodal to bimodal for the thermally shocked samples, which was caused by abnormal growth due to the grain growth driving force during recrystallization. Spinel oxide ((Fe, Cr, Ni)3O4) and Cr2O3 were the main oxides at 1100 °C. The dislocations almost disappeared and needle-like structures that were rich in N and Cr formed in the welded joints after being thermally shocked. The tensile properties of the thermally shocked welded joints showed decreases in yield strength and plasticity. The fracture morphologies of the samples heated in the furnace and the as-welded samples presented with dimples. However, the morphologies of the fracture surfaces of the thermally shocked samples presented large numbers of secondary cracks and smooth characteristics.

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.

Effect of Deoxidizing and Alloying Routes on the Evolution of Non-Metallic Inclusions in 55SiCr Spring Steel

Compared to the conventional deoxidation process with Al or Si-Mn for 55SiCr spring steel production, the possibility of using a Si-Ca-Ba compounded deoxidizer to control the behavior of non-metallic inclusions in spring steel was explored in this study. The effect of the addition sequence of deoxidizer and alloys into molten steel on the morphology, size, and composition of the inclusions was emphatically studied at 1873 K (1600 °C) using a high-temperature electric resistance furnace. The results indicate that adding alloy first can form less harmful inclusions in steel, which are roughly spherical and smaller than 3 μm in diameter, and its inclusion evolution path is MnO-SiO2-Al2O3→CaO-SiO2-Al2O3 and CaO-Al2O3-MgO. While adding deoxidizer first, the inclusions in steel are harmful due to its mostly irregular geometry and relatively large size over 5 μm. The inclusion evolution path is Fe-O→CaO-Al2O3(-SiO2) and CaO-Al2O3-MgO. The formation and evolution mechanism of inclusions under different addition sequences were discussed. In addition, the solubility limits of MgO from refractory into steel were studied to inhibit its corrosion by molten steel.

Mid-infrared ZBLAN glass optical components made by hot embossing technique

We demonstrate the successful development of refractive lenses made of ZBLAN fluoride glass using the hot embossing technique. Synthesized in-house ZrF4-BaF2-LaF3-AlF3-NaF glass is thermally stable and has high transmission in the range of 0.4–8.0 µm. A lens was formed with a brass stamp inside a resistant furnace under standard atmosphere conditions. No mechanical or chemical postprocessing is used to obtain the optical quality of the lens surface. As a proof-of-concept, we have developed plano-convex lenses with a diameter of 10 mm and f#=3. The tested lenses have good imaging properties with a resolution of 23 pl/mm and 8 pl/mm for 1.5 µm laser and broadband thermal source emitting in the mid-infrared range, respectively.

Mechanical behaviour of Al7075 alloy Al2O3/E-Glass hybrid composites for automobile applications

Due to their light weight, high strength, and improved tribological qualities, aluminium alloy composite material are in high demand for sophisticated technological applications. The aluminium alloy (Al7075) hybrid composite was created using a sand mold technique in an electric resistance furnace, and it was reinforced with aluminium oxide (Al2O3) particles and E-glass shot fibres. The goal of this study was to look at the mechanical behaviour of Al7075-Al2O3-E-glass hybrid composites with various Al2O3 (3–12%) and E-glass weight percentages (2–8 %). In this study, Al7075 alloy hybrid composites were developed using a sand molding process to investigate their density and mechanical properties. The presence of reinforced particulate matter in the Al alloy was revealed by EDS and XRD analyses. Mechanical properties such as tensile strength, yield strength, and hardness increased to 9 percent by weight Al2O3 and 6 percent E-glass and then decreased slightly, according to the results. The density of the hybrid composites increased as the volume portion of the reinforcement increased.

Modified algorithm of automatic temperature control in an electric resistance furnace for metal heat treatment

Modified algorithm of automatic temperature control in an electric resistance furnace for metal heat treatment

Designing lightweight multicomponent magnesium alloys with exceptional strength and high stiffness

Magnesium (Mg) alloys have a great potential for applications in the automobile, aerospace, and 3C industries due to their light weight, high specific strength, good conductivity, high damping capacity, and superior recyclability. However, the low strength and relatively low stiffness of Mg alloys seriously hinder their large-scale applications. In this work, a series of lightweight multicomponent Mg90.5-xAl5ZnxCu4Ce0.5 (x = 4, 8, 14, 18, and 23 at.%) alloys with high strength and high Young's modulus were designed based on the multicomponent alloys concept to obtain a high alloying degree by precipitating a large number of high Young's modulus phases, and prepared successfully by electric resistance furnace. The present results show that these alloys exhibit an excellent combination of exceptional compressive strength (up to 627 MPa) and high Young's modulus (up to 65 GPa), which is attributed to a large number of stable intermetallic phases with high cohesive energy and high Young's modulus, as verified by first-principles calculations. Our results may have implications for the design of Mg alloys and Mg-based composites with high strength and high stiffness.