Vacuum Resistance Furnace Research Articles

Lead and zinc selective extraction from EAF dust while heating in resistance furnace with flowing argon

The elemental and phase compositions of electric arc furnace (EAF) dust from PJSC Severstal were studied. We carried out the thermodynamic modeling of zinc and lead selective extraction process and determined its possible mechanisms. EAF dust was heated in the temperature range of 20 – 1300 °C in vacuum resistance furnace and the Tamman furnace with flowing argon. Experiments in the vacuum resistance furnace with linear heating showed that lead and zinc removal from the sample occurs in the temperature range of 800 – 1200 °C, with higher lead removal rate. Intensive lead removal was observed at temperature above 1000 °C, while intensive zinc removal occurs at temperature above 1200 °C. Clarifying isothermal experiments performed in the Tamman furnace showed that lead complete transition to the gas phase was achieved at a temperature of 1100 °C (holding time – 12 min) and at a temperature of 1200 °C (holding time – 6 min or more). At the same time, zinc removal was observed in the amount of 14.4 % ratio and 32.2 % ratio, respectively, which allows us to conclude that it is possible to consistently obtain two products: lead and zinc mixture and zinc not contaminated with lead. When comparing experimental and thermodynamic modeling data, the reactions that are most likely to occur during the carbon reduction of lead- and zinc-containing phases were determined.

Study of Controlled Aluminum-Vanadium Alloy Prepared by Vacuum Resistance Furnace

In this paper, V2O3 is used as the raw material, and an Al-V alloy is synthesized by vacuum resistance furnace heating. The results show that with the extension of the heating time, the separation effect of the alloy and the slag and the uniformity of the alloy are significantly improved. The slag is fully separated from the alloy, and the composition of the alloy is more uniformly distributed when the heating time is controlled at 1 hour. In addition, the composition of the alloy is affected by increasing content of Al. In particular, the obtained alloy composition meets commercial standards when the mass ratio of Al is 31-36 wt%. The effect of different mass ratios of CaO on the quality of slag series and alloys was also investigated. The results show that the composition distribution of the slag system can be effectively changed with increasing the mass ratio of CaO, and the uniformity of the alloy composition is also optimized. When the mass ratio of CaO is 27 wt%, the alloy and slag are well separated, and the composition distribution in the obtained alloy is more uniform. In addition, the content of impurities in the alloy can be effectively improved under vacuum. Therefore, it is suggested that a vacuum resistance furnace should be applied in the industrial production of high-quality Al-V alloy.

Numerical and Experimental Investigation of Germanium Refining via Fractional Crystallization Based Innovative Rotary Cooling Device

This paper focuses on the principle study and application of a fractional crystallization methodology using a rotating and internally gas cooled crystallizer (so called cooled finger, developed at IME/RWTH Aachen) first applied to the refining of germanium. For this purpose, a series of experimental trials were performed using a model metal—Aluminum—to gather the temperature profile needed for the numerical simulation that provides an initial process window used for the purification of germanium in a vacuum resistance furnace. The results of the simulation showed good agreement with the experimental results and the conducted trials based on that process window enabled the single step purification of germanium from an initial purity of 98.8% up to 99.9%.

Thermal Analysis of Vacuum Resistance Furnace

The current paper describes the effect of insulation thickness in a vacuum resistance furnace. An existing furnace was optimized for insulation thickness using analytical and numerical studies. Furnace heating efficiency was improved up to 64% by controlling the heat flow at the insulation face. The numerical results were validated experimentally and vice versa. The numerical results predicted a decrease in heat flow of 70%, while the experimentally achieved value was 64%. The percentage difference in numerical and experimental results was calculated to be 1.5–5% maximum in temperature value. The effect of mesh finesse was evaluated for thermal analysis and it was concluded that a very little difference of 5 °C occurs when element size is reduced 5 times. The study using numerical methods will help in designing better and upgraded furnaces with greater energy savings. Also, the application of numerical methods is proposed as an effective design and performance prediction tool during manufacturing and operational activities of vacuum furnaces, respectively.

Разработка бесконтактной системы управления регулятором температуры вакуумной печи сопротивления

Разработка бесконтактной системы управления регулятором температуры вакуумной печи сопротивления

Разработка бесконтактной системы управления регулятором температуры вакуумной печи сопротивления

Разработка бесконтактной системы управления регулятором температуры вакуумной печи сопротивления

Study on the fatigue properties of as-extruded α + β dual phase Mg-Li-Al alloy

The as-cast dual phase Mg-9Li-3Al (LA93) alloy was designed and prepared by vacuum resistance furnace under the protection of argon atmosphere, then processed by hot extrusion. Tension and compression fatigue properties of as-extruded dual phase LA93 alloy was studied. The as-extruded LA93 alloy had a certain hardening phenomenon during axial tension and compression fatigue. The fatigue limit of the as-extruded LA93 alloy is estimated to be σ−1 = 78.15 MPa, which is 0.37 times the tensile strength. The measured fatigue life values of the samples are in line with lognormal distribution and strong linear correlation. The S-N curve can be obtained by straight-line fitting and it is lgN = −13.72lgσ + 32.63. The P-S-N equation of confidence 90% is σ = −14.35lgN + 171.65. The crack source of the alloy sprouted on the surface of the sample and radiated diffused in the shape of the fan. There was obvious fatigue stripe on the fracture surface of the fracture surface in the crack propagation area.

Modelling of degradation processes for refractory metallic heating elements of vacuum resistance furnace

The mechanism of degradation of the vacuum resistance furnaces heating elements manufactured of pure refractory metals (primarily, tungsten or molybdenum) is analysed. The algorithm of expected life calculation for such heating elements at various values of temperature and vacuum (residual pressure) in the furnace is developed and is programmatically realized. Dependences of expected life on diameter (thickness) of the heater, temperature and pressure are received. The temperature control system for the high- temperature vacuum furnace in the indirect parameter of heaters resistance taking into account their degradation is offered.

Contribution to the aluminum–tin–zinc ternary system

The Sn–Zn–Al alloys are one of significant candidates in the proposal of alternative lead-free solders for higher temperature soldering. This paper deals with the study of the aluminum–tin–zinc system. Twenty Sn–Zn–Al alloys together with six binary Sn–Zn alloys were prepared and studied experimentally. Alloys were prepared from pure Sn, Zn and Al (melting and cooling in a vacuum resistance furnace). The specimens were studied metallographically including the micro-hardness measurements, complete chemical analysis (ICP-AES, OES), X-ray micro-analysis of alloys by SEM and EDX in order to determine the composition and identification of individual phases. Significant temperatures and enthalpies of phase transformations were determined by DTA. After long-term annealing of selected alloys in vacuum followed by quenching the structural and chemical microanalyses of the present phases and their limit concentrations were carried out. The achieved results were compared with the thermodynamic modelling of the ternary Sn–Zn–Al system (computer programs THERMOCALC, MTDATA, PANDAT and databases CALPHAD, COST). Electrical resistivity, density, magnetic susceptibility and wettability of Sn–Zn–Al solders were measured as well.

Features of a mathematical model of heat transfer in a vacuum resistance furnace

The paper presents a mathematical model of heat transfer developed for the purposes of modeling the operation process in large-scale vacuum furnaces. It has been implemented on the basis of the author’s software complex “SigmaFlow”.

Interface characteristics and performance of pre-brazed diamond grains with Ni–Cr composite alloy

This study aims to improve the bonding strength of diamond abrasive grains to the matrix in sintering diamond segments. To achieve this goal, a new method of surface metallization of diamonds was developed by brazing using Ni–Cr composite alloy. The diamonds metallized by brazing are called pre-brazed diamonds. Brazing equipment was a vacuum resistance furnace. Diamond segments consisting of the pre-brazed diamonds and the metal matrix were fabricated. The static compressive strength and impact toughness of the pre-brazed diamonds were measured. The bending strength of the segments was also measured. The interfacial microstructure of the pre-brazed diamonds and the segment fracture surface were characterized. The compressive strength and impact toughness of the pre-brazed diamonds peaked when 30wt.% Ni–Cr alloy was used in the Ni–Cr composite alloy. Elemental distribution showed that Cr mainly concentrated at the joining interface of the pre-brazed diamonds. An interfacial resultant composed of Cr3C2 and Cr7C3 was formed at the joining interface of the pre-brazed diamonds. A strong bond was formed at the joining interface between the pre-brazed diamonds and the metal matrix when sintering diamond segments.

Kinetic study on the corrosion behavior of AM60 magnesium alloy with different Nd contents

AM60 alloys with different Nd contents were melted, refined and prepared in vacuum resistance furnace. The alloys were investigated by weight loss test in 3.5% NaCl solution at 25°C. The obvious changes of microstructures before and after the corrosion were characterized by scanning electron microscopy and X-ray diffraction. With the use of experimental data, a combination model was established to describe the galvanic corrosion rate of AM60 alloys. The constant of apparent corrosion rate (k) was calculated. The effect of Nd content on the grain size (d), organizational structure and corrosion rate of specimens were discussed. The results showed that the constant of apparent corrosion rate was affected by Nd content. Their relationship is described as k=0.6exp(-2.7Nd%)+0.58. The maximum and minimum value of k is 1.21 and 0.53μm/h, respectively. The reason for k decreasing is that trace Nd refined the grain size and generated different forms of Al11Nd3 phases. Corrosion protection film was formed in the area near rare earth-enriched phase. The film played an important role in corrosion together with the corrosion products on the surface of the alloy, indicating an improvement of corrosion resistance of AM60 alloys.

Microstructure and mechanical properties of pre-brazed diamond abrasive grains using Cu–Sn–Ti alloy

A new method of surface metallization of diamond abrasive grains was developed using Cu–Sn–Ti brazing alloy. The diamond grains metalized by brazing are called pre-brazed diamond grains. Brazing equipment was vacuum resistance furnace and high-frequency induction furnace separately. Diamond segments consisting of the pre-brazed diamonds and metal matrix were sintered. The static compressive strength of the diamonds and the bending strength of the segments were measured. The interfacial microstructures of the diamonds and the segment fracture surface were characterized. The surface micrograph of the diamonds brazing in vacuum resistance furnace was better. When the mean weight gain rate of the diamonds was 6.4%, the mean strength value of the diamonds was 2533.4MPa. Elemental distribution showed that Ti mainly concentrated at the joining interface of diamond/Cu–Sn–Ti alloy. The interfacial resultant containing TiC was formed at diamond/Cu–Sn–Ti alloy interface. Good interfacial bonding strength was formed at the joining interface of pre-brazed diamonds/metal matrix.

Thermodynamics of Ferro-based Friction Material by in-situ Carbothermic Reduction Form Vanadium and Titanium Iron Concentrate

Ferro- based friction material was fabricated by reaction sintering technology, using Fe and Ti elements containing in vanadium and titanium iron concentrate as main raw materials, adding other ingredient on the basic of composition of ferro-based friction material, synthesis and sintering were accomplished unanimously in vacuum resistance furnace. Thermodynamic of the reduction of vanadium and titanium iron concentrate was calculated and studied, and the mass change of the reduction was studied by TG–DSC. The results show that the reduction temperature of Fe and Ti oxides is above 979 K, in the reduction process of vanadium and titanium iron concentrate, Fe3 O4 is reduced by carbon firstly, and then titanomagnetite and ilmenite are reduced into Fe and Ti oxides, and finally different valent titanium oxides are reduced into TiC.Good interface bonding and compact structure have been got in experimental research by making reasonable process route.

Kinetics of Nitrogen Diffusion in Granular Manganese

The kinetics and the influence of time on granular manganese nitriding were studied by means of a vacuum resistance furnace, X-ray diffraction technique, and LECO TC-436 oxygednitrogen determinator. The longer the nitriding time, the more the nitrogen pickup. Except for a trace of oxide MnO that developed, the metal manganese could thoroughly be nitrided to form Mn4N and a little ζ-phase (the stoichiometric components as Mn2N) with the nitriding time lasting. A kinetic model is developed to reveal the nitriding situation and agrees well with the experimental results.

A high-temperrature vacuum furnace for melting quartz glass

An economical high-temperature unit for quartz glass test melts was created based on a vacuum resistance furnace. To update the melting chamber of the standard furnace, a heating unit with a working temperature of up to 2200°C was developed and manufactured; it consists of a tungsten heater and molybdenum heat shields which allow melting small blocks of quartz glass. The updated furnace is used to evaluate the technological properties of natural quartz from different deposits.

1678. Elevator vacuum resistance furnace: Anon,Electrotermiya N-T Sh,43,1965, 6–7 (in Russian)

1678. Elevator vacuum resistance furnace: Anon,Electrotermiya N-T Sh,43,1965, 6–7 (in Russian)

New vacuum resistance furnace

Recent legislation opening commercial operations to small drones, also known as Micro Aerial Vehicles (MAVs) under 55 lbs, is leading to increased use across many facets of society including first responders, news agencies, commercial entities, and hobbyists. However, the widespread use of such systems will be limited unless a few key hurdles are overcome, namely improved usability and support for safe operation in dynamic environments. To this end, we present the Collision and Obstacle Detection and Alerting (CODA) display, a novel interface that enables safe piloting of MAVs with a mobile device in obstacle-dense real-world settings. We describe the system design, architecture, and development. In addition, we present observations from a proof-of-concept technical demonstration and an empirical study with minimally-trained users. Results showed that CODA reduced collisions and improved operator awareness of obstacle proximity, confidence going around corners and perceived performance in avoiding walls and obstacles.

High Temperature High Vacuum Resistance Furnace

An experimental high temperature high vacuum furnace with self-supported tungsten resistance heating elements is described. The furnace is assembled from readily obtainable parts, and knife-edge vacuum seals are used through-out. The volume of the hot chamber is approximately 2 in. diameter by 8 in. high; the uniform zone is 2 in. long. A temperature of 2000°C can be attained at a pressure of ∼10−5 mm Hg and at a power expenditure of 12 kw.

Ein neues Verfahren zur Messung der Unterschiede im 18O‐Gehalt von Silikatgesteinen

AbstractA new method for measuring the relative abundances of oxygen isotopes in silicate rocks is described. The silicate is reacted with carbon at about 2000° in a high vacuum resistance furnace and the CO thus produced is collected and fed into a double collector mass spectrometer. By taking the necessary precautionary measures it is possible to determin the 18O/16O ratios with a relative accuracy of about 0,6°/00.