High Frequency Induction Research Articles

Growth and Scintillation Properties of Two-Inch-Diameter SrI2(Eu) Single Crystals

The sealed vertical Bridgman (VB) method is the main technique used to grow SrI2(Eu) crystals because SrI2(Eu) is very hygroscopic. In this study, we grew SrI2(Eu) single crystals with two-inch diameters and four-inch lengths using the VB method equipped with a removable chamber. The SrI2(Eu) single crystals were produced by the Liquinert process, which requires careful consideration of the crucible material and growth atmosphere. After a review of available materials, carbon crucibles were selected due to their several advantages over traditional quartz ampules: (1) they are suitable for large size crystal growth due to which they do not require any process for sealing of quartz ampule before the growth; (2) ease in controlling the temperature gradient because carbon crucibles can be heated directly via a high frequency induction heating system; and (3) carbon crucibles can assist in removing oxygen and moisture from the melt. The starting material, seed, and hot zone were prepared inside the glovebox in...

Thermophysical Properties of High-Frequency Induction Heat Sintered Graphene Nanoplatelets/Alumina Ceramic Functional Nanocomposites

This paper concerns the thermophysical properties of high-frequency induction heat (HFIH) sintered alumina ceramic nanocomposites containing various graphene nanoplatelets (GNP) concentrations. The GNP/alumina nanocomposites demonstrated high densities, fine-grained microstructures, highest fracture toughness and hardness values of 5.7 MPa m1/2 and 18.4 GPa, which found 72 and 8%, superior to the benchmarked monolithic alumina, respectively. We determine the role of GNP in tuning the microstructure and inducing toughening mechanisms in the nanocomposites. The sintered monolithic alumina exhibited thermal conductivity value of 24.8 W/mK; however, steady drops of 2, 15 and 19% were recorded after adding respective GNP contents of 0.25, 0.5 and 1.0 wt.% in the nanocomposites. In addition, a dwindling trend in thermal conductions with increasing temperatures was recorded for all sintered samples. Simulation of experimental results with proven theoretical thermal models showed the dominant role of GNP dispersions, microstructural porosity, elastic modulus and grain size in controlling the thermal transport properties of the GNP/alumina nanocomposites. Thermogravimetric analysis showed that the nanocomposite with up to 0.5 mass% of GNP is thermally stable at the temperatures greater than 875 °C. The GNP/alumina nanocomposites owning a distinctive combination of mechanical and thermal properties are promising contenders for the specific components of the aerospace engine and electronic devices having contact with elevated temperatures.

Single Stage Boost Integrated High-Frequency Full Bridge Inverter for Induction Heating System

This paper proposes a new single-stage boost high frequency ac series resonant power inverter for high frequency induction heating (IH) applications. The proposed ac-ac converter consist of a single stage boost (SSB) converter and full-bridge ac series resonant inverter integrated circuit with a ac source voltage control strategy by controlling the inverter switches. The Simulink model is developed using MATLAB simulation software and the simulated results are examined. The output power is maintained to the required level by using phase shift control strategy and the simulated results are validated.

Heat transfer and temperature distribution during high-frequency induction cladding of 45 steel plate

High-frequency induction cladding, a new surface-modification technology with high thermal efficiency and good formability, can be used to improve the surface mechanical properties of metal components. In this study, a three-dimensional electromagnetic–thermal multifield coupling model was developed to investigate heat transfer and temperature distribution in high-frequency induction cladding. Results showed that the heat used to melt the powder coating originates from the substrate–coating interface and that melting proceeds from the interior to the exterior of the coating. The effects of current density, current frequency, and air–gap spacing on temperature distribution were analyzed by using the effective size of the cladding area and the maximum temperature difference in the coating as reflections of temperature distribution. Microstructure analysis indicated that the dissolution of WC particles corresponds with temperature distribution, and a temperature field with low temperature difference in the coating is helpful for obtaining uniform microhardness distribution.

Metallic Glasses as Potential Reinforcements in Al and Mg Matrices: A Review

Development of metal matrix composites (MMCs) with metallic glass/amorphous alloy reinforcements is an emerging research field. As reinforcements, metallic glasses with their high strength (up to ~2 GPa) and high elastic strain limit (~2%) can provide superior mechanical properties. Being metallic in nature, the glassy alloys can ensure better interfacial properties when compared to conventional ceramic reinforcements. Given the metastable nature of metallic glasses, lightweight materials such as aluminum (Al) and magnesium (Mg) with relatively lower melting points are suitable matrix materials. Synthesis of these advanced composites is a challenge as selection of processing method and appropriate reinforcement type (which does not allow devitrification of the metallic glass during processing) is important. Non-conventional techniques such as high frequency induction sintering, bidirectional microwave sintering, friction stir processing, accumulative roll-bonding, and spark plasma sintering are being explored to produce these novel materials. In this paper, an overview on the synthesis and properties of aluminum and magnesium based composites with glassy reinforcement produced by various unconventional methods is presented. Evaluation of properties of the produced composites indicate: (i) retention of amorphous state of the reinforcement after processing; (ii) significant improvement in hardness and strength; (iii) improvement/retention of ductility; and (iv) high wear resistance and low coefficient of friction. Further, a comparative understanding of the properties highlights that the selection of the processing method is important in producing high performance composites.

Experimental study on molten metal spreading and deposition behaviors on wet surface

In this paper, experimental investigation of the molten metal jet's colliding and spreading behaviors on the flat steel surface covered with water layer was carried out. High-frequency induction heating system was utilized to produce the molten metal sample and it was released to the wet surface from a fixed elevation. As the molten metal collides against the surface, it rapidly goes through solidification while spreading on the wet surface. High-speed thermo-camera was utilized to measure the molten metal's surface temperature during the spreading transient. Once the molten metal completely solidifies, molten metal's spread area and thickness were measured. From the obtained database, a dimensional analysis was conducted to investigate the key parameters responsible for the molten metal spreading on the wet surface. Based on the key non-dimensional parameters identified in the current analysis, the new empirical correlation was proposed. Its predictive capability was found to be 18.9% in mean absolute relative deviation.

Microstructures and hardness of model niobium-based chromium-rich cast alloys

Niobium is a candidate base for new alloys devoted to applications at especially elevated temperatures. Elaborating and shaping niobium-based alloys by conventional foundry may lead to mechanically interesting microstructures. In this work a series of charges constituted of pure elements were subjected to high frequency induction melting in cold crucible to try obtaining cast highly refractory Nb-xCr and Nb-xCr-0.4 wt.%C alloys (x=27, 34 and 37 wt.%). Melting and solidification were successfully achieved. The as-cast microstructures of the obtained alloys were characterized by electron microscopy and X-ray diffraction and their hardness were specified by Vickers macro-indentation. The obtained as-cast microstructures are composed of a body centered cubic (bcc) niobium dendritic matrix and of an interdendritic eutectic compound involving the bcc Nb phase and a NbCr2 Laves phase. The obtained alloys are hard to cut and particularly brittle at room temperature. Hardness is of a high level (higher than 600Hv) and is directly driven by the chromium content or the amount of {bcc Nb – NbCr2} eutectic compound. Adding 0.4 wt.% of carbon did not lead to carbides but tends to increase hardness.

Microstructure and Oxidation Resistance of Y Modified Silicide Coatings Prepared on Zr-Ti-Al Alloy

Zr-20Ti-5Al (at. %) alloy used as substrates for Si-Y2O3co-deposition experiments was prepared by firstly vacuum non-consumable arc melting and then high frequency induction skull melting. The results showed that Y modified silicide coating prepared at 1250 °C for 4 h possessed a double-layer structure, mainly consisting of a thick (Zr, Ti)Si2outer layer and a 15 mm thick (Zr, Ti)Si inner layer. Meanwhile, the growth rate of ZrSi2phase changed with temperature, while the growth rate of ZrSi did not vary significantly with temperature. The growth of the coating as well as the two layers followed parabolic laws, and the co-deposition process was controlled by diffusion. ZrSi2was not appropriate as oxidation-resistant coatings to protect Nb based alloy from oxidation due to the lack of the formation of good quality glassy SiO2layer in the scale.

Extremum Co-Energy Principle for Analyzing AC Current Distribution in Parallel-Connected Wires of High-Frequency Power Inductors

Inductor winding is often composed as parallel-connected wires to suppress the copper loss. However, in high frequency inductors, the proximity effect can cause concentrated AC current distribution, hindering suppression of the copper loss. Therefore, optimization of the physical inductor structure requires predicting the AC current distribution. Although simulators are commonly employed for predicting the AC current distribution, simple analytical methods are also required for effective design or invention of the inductor structure with less copper loss. The purpose of this paper is to propose a novel analysis method of the AC current distribution in parallel-connected wires of high frequency inductors. The proposed method is based on a novel insight that the AC current is distributed to give an extremum of the magnetic co-energy contributed by the AC flux and the AC current under the given total AC current. Experiments are presented in this paper to verify the proposed method.

High frequency plant regeneration from cotyledonary node explants of Cucumis sativus L. cultivar ‘Green Long’ via adventitious shoot organogenesis and assessment of genetic fidelity by RAPD-PCR technology

Influence of cytokinins, silver nitrate (AgNO3) and auxins on plant regeneration from cucumber was investigated. The cotyledonary node explants were cultured on MS medium augmented with various concentrations (0.5-2.5mg l-1) of 6-benzyl amino purine (BAP) and kinetin (KIN) for shoot bud induction. BAP at 1.5mg l-1 was found to be the best concentration for induction of high frequency of multiple shoots (98.4%). Interestingly, maximum percent of multiple shoot regeneration (100%) as well as number of shoot buds (54.6 shoots/culture) was recorded on MS medium containing the combination of 4.5mg l-1 AgNO3 and 1.5mg l-1 BAP. Multiple shoot bud regeneration frequency as well as the number of shoots was positively correlated with the concentrations of AgNO3. Addition of silver nitrate in the medium not only enhanced the rate of multiple shoot bud regeneration but also elongation of shoot buds was observed. The highest percent of rooting (96.2%) was noticed on a medium containing the combination of indole 3-butyric acid (IBA), 1.5mg l-1 and KIN 0.5mg l-1. Acclimatized plantlets were successfully established in the field where the survival rate observed was 72%. The RAPD profiles of in vitro regenerated plants were found to be highly monomorphic and identical banding pattern with mother plant. DNA fingerprinting results confirmed that the tissue culture plantlets were found to be true-to-type. The present study describes efficient protocol for high frequency plant regeneration via adventitious shoot organogenesis in cucumber.

Simulation of the Flattening of High Frequency Induction Welded Tubes

Abstract The process of destructive and non-destructive testing of the manufacture of high frequency induction welded steel tubes has always give better results at the Labiod-tèbessa Algeria tube construction plant such as tensile testing, folding, flaring and also the flattening tests whose limits of use were given by the experimental methods which have known deficiencies in measures in particular of the parameter of the height H which is given by the equation and that this difficulty is noted between the calculated and measured height levels. For these reasons it is necessary to find a numerical model of simulation which obviously replaces the experimental process to give reliable results with cheaper conditions in terms of cost and time which has been respected which allowed us to collect data. results and compare the different heights calculated and measure and often confirm the experimental tests.

Investigations On Crack Propagation Under Cyclical Isothermal And Thermo-mechanical Loadings For A Type 304-L Stainless Steel Used For Pressurized Water Reactor

The integrity of structures exhibiting flaws in Pressurized Water Reactor (PWR) has to be assessed to meet safety criteria. This paper deals with crack-propagation under cyclic thermo-mechanical loadings, as encountered in class I austenitic pipes of PWR’s. To have a conservative and reliable assessment of the crack propagation due to the in-service loading, various codes and standards use simplified method. For example, the RSE-M Code introduces a plastic correction depending on the proportion of the mechanical loading. An improvement of the current method requires additional investigations. Moreover, components loaded with transient or thermal fluctuations are not really in loadcontrolled conditions. To this end, a device called PROFATH was designed. The specimen is a pre-cracked thick-walled tube undergoing a set of thermal cycles and loaded with a static mechanical force. During the first part of the thermal cycle, a high frequency induction coil heats the external wall of the tube. Then, the heating system stops and the specimen is cooled down by running water inside the tube. Finite element calculations show that only a region half-way along the tube should be heated to ensure adequate structural effect. In the heated zone, the machining of a sharp circumferential groove ensures the propagation of a unique crack. An electro-mechanical jack controls the level of the mechanical static load. Tests have been carried out, and these tests allow having an evaluation of the pertinence of the correction proposed by the RSE-M Code for a significant plasticity.

High temperature oxidation behavior in dieless drawing of titanium alloy wires

A finite element model considering high frequency induction heating theorem coupled with the software “DEFORM” is developed to analyze the heat transfer and plastic deformation of the titanium alloy wires during dieless drawing processes. Dieless titanium alloy wire drawing experiments are also conducted. The simulated profiles of the drawn products are compared with the experimental results to validate the FE model. On the other hand, an argon gas chamber is designed and dieless drawing experiments of titanium alloy Ti-6Al-4V wires in air and argon gas are conducted. The effects of the oxide layers on the mechanical properties of the drawn titanium alloy wires obtained by tensile tests are examined. The yield stress, elongation and ultimate tensile strength of the drawn products are affected not only by the forming temperature, but also by the oxide layer on the product surface.

Hot mold stamping of optical plastics and glasses with transcription of super-hydrophobic surfaces

The oxide-glass lens as well as metallic-glass, optical elements were a typical targeting product to have their surface hydro-phobic or super-hydrophobic for well-defined water repellency. The micro- or nano-texturing processes were developed with use of the femto-second laser machining to control the surface state from hydrophilic to hydrophobic conditions. The femto-second laser processing had possibility to physically control the contact angle up to θ > 150°. Under this laser induced periodic surface structuring, the ripples with high spatial frequencies were formed on the micro-textured surface by the interference of the incident and reflected laser lights with the scattered or diffracted light near the surface. AISI420 mold was prepared as a die substrate to form the super-hydrophobic surface by the femto-second laser nano-/micro texturing with the tailored design of laser induced periodic surface structuring. This mold was set-up into the cassette die set for hot mold stamping. The mold was directly heated up to the forming temperature above the glass-transition temperature by the high frequency induction heating. The original static contact angle was doubled from 60° to 113° by this hot mold stamping.

非熱処理系アルミニウム合金A5083-Oの高周波誘導加熱を援用した摩擦圧接法の開発

非熱処理系アルミニウム合金A5083-Oの高周波誘導加熱を援用した摩擦圧接法の開発

Evaluation on Joining Strength of Woven CF/PPS Laminates Bonded by Continuous High-frequency Induction Heating

Evaluation on Joining Strength of Woven CF/PPS Laminates Bonded by Continuous High-frequency Induction Heating

In-situ compaction and sintering of Al2O3-B4C composites by using a High-Frequency Induction System

In-situ compaction and sintering of Al2O3-B4C composites by using a High-Frequency Induction System

Characteristics of Mechanical Properties and Micro Structure according to High-Frequency Induction Heating Conditions in Roll Forming Process of a Sill Side Part

Characteristics of Mechanical Properties and Micro Structure according to High-Frequency Induction Heating Conditions in Roll Forming Process of a Sill Side Part

고주파 유도용해로를 위한 범용성 제어 플랫폼 개발

1920년대 말 전동발전기를 사용한 유도용해로가 선을 보인 이후 철강 산업과 기계 산업의 발달에 따른 수요증가로 인하여 본격적으로 산업용으로 보급되기 시작하였다. 그러나 1990년대에 들어서면서 주물공업의 악화, 경기부진으로 보급이 공황기에 접어들고 있는 실정이다. 이러한 이유로 업체가 점차 통합, 대형화되고 있고 또한 에너지 절감, 깨끗한 작업환경에 대한 요구와 화석연료의 사용규제, 화석 연료비 상승 등으로 인하여 대형 유도용해로 설비 수요는 당분간 지속될 전망이다. 본 논문에서는 프로그램 전문 인력이 아닌 누구나 사용 가능한 유도용해로 컨트롤러의 범용화 플랫폼을 개발하였다. 이는 어떠한 용광로의 환경에 대해서 별도의 비용 및 시간지체 없이 즉시 대응할 수 있기 때문에 프로그램 관리 비용의 절감 효과를 기대할 수 있다.

Mixing laws and causality in high frequency induction log applications

High frequency electromagnetic technologies for subsurface formation evaluation provide high spatial resolution and new opportunities for petrophysical interpretation of data. Dispersion of rock properties and up-scaling from pore to reservoir scale (homogenization) represent the two most challenging problems. In electrodynamics of porous media, various mixing and dispersion laws are used to homogenize rock properties and describe their frequency behavior. Mixing laws and dispersion have a close link to the fundamental physical principle of causality and therefore cannot be introduced arbitrarily. For any mixing/dispersion law, we need to prove that causality holds. For testing causality, we use Titchmarsh’s theorem and, particularly, one of its modifications—Kramers-Kronig relations. Causality is discussed for Debye, Cole-Cole, Havriliak-Negami, and CRIM models. Dispersion is closely related to wave propagation. Evaluation of phase and group velocities shed new light on the physics of phase and amplitude measurements in lossy media. We evaluated various definitions of both velocities and their dependence on spatial spectra or, in other words, on the arrangement of transmitting and receiving elements. To illustrate theoretical findings, we use dielectric logging as an exemplary technology. Usually, in modern dielectric tools, amplitude and phase data are acquired, for various frequencies and sensor positions. The measured phase is discontinuous at high frequencies and requires detection of discontinuity as well as unwrapping. Remarkably, one can determine formation attenuation and loss angle based on multifrequency/multisensor amplitude data and transform them into dielectric permittivity, resistivity, and true continuous phase. Transformations of exemplary tool data used in this paper are suitable for a conceptual study and are specific for a uniform formation. We intentionally do not address the accuracy of measurements and propagation of errors in the inversion process, since they are tool- and processing-specific. Different tools require joint analysis of all available data and special noise reduction techniques associated with the structure of the acquisition system.