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Tm∶YAP/YAP composite laser crystal boule with diameter more than 40 mm is directly grown by induction heating Czochralski method through improving the thermal field, changing raw materials, and secondary welding growth. The boule shows no visible cracks, good optical homogeneity and uniform residual stress. For the cylinder part of the boule, the length of the YAP segment is 21 mm, and the length of the Tm∶YAP segment is 44 mm. Under the irradiation of green laser and He-Ne laser, there is no any scatters and bubbles observed at the composite interface. The interference fringes on both sides of the composite interface are basically continuous, and the wavefront difference of transmission is very small. Two composite Tm∶YAP/YAP crystal rods with size of ϕ5 mm ×30 mm each and YAP segment without doping at the end of 4 mm long were prepared from the boule. Both rods show excellent optical quality. The laser performances of the rods were tested on 1 940 nm solid-state laser. By single end pump of laser diode, the laser output of 42. 8 W is achieved when the input pump power is 117. 7 W. Compared with the non-composite laser crystal, the composite Tm∶YAP/YAP crystal shows higher output power, higher conversion efficiency and better beam quality. [ABSTRACT FROM AUTHOR]

Due to the huge volume， complex structure and end effect of wind power gear， it is difficult to realize the uniform heating of tooth profile and tooth width， which affects the final strengthening quality. In this paper， the average temperature， the maximum temperature difference and the relative temperature fluctuation rate are taken as the evaluation indexes of the heating effect. The temperature fields along the tooth profile and the tooth width direction of wind power gear in the scanning induction heating process are studied， and the phase transformation and hardening of the gear are analyzed. It is found that the temperature uniformity increases gradually in the direction of tooth width from top to bottom within a certain range， which is due to the drastic change of tooth structure thickness. To gears strengthened by induction hardening in steady-state positions， the depth of hardened layer in the direction of tooth profile is almost the same as the depth of macroscopic phase change layer， and the transition region is relatively narrow. The heating effect and strengthening result of gear scanning induction heating are expounded， which provides the research foundation for the wide application of high-performance steel materials in the field of wind power. [ABSTRACT FROM AUTHOR]

The thermal field of growing Yb:YAG laser crystal with a diameter of 10 inch has been designed and fabricated, and the structure of single crystal growth furnace has been improved. The Yb : YAG crystal with a diameter of 252 mm and a cylinder length of nearly 260 mm has been successfully grown by induction heating Czochralski method combined with automatic diameter control system. There is no visible crack and scattering particle under the irradiation of 5 mW green laser and 20 mW He-Ne laser in the boule. The optical uniformity and stress of the boule was inspected after polishing. The results show that the available sectors of this boule have good optical uniformity and uniform stress distribution. A crystal slab with size of 152 mm x 11. 5 mm x 260 mm can be selected in one available sector of this boule, and its transmitted wavefront distortion is 0. 29λ/ inch@633 nm. [ABSTRACT FROM AUTHOR]

In order to solve the problem of poor molding quality of CFRP (carbon fiber reinforced polymer) caused by the system' s weak anti-interference, slow response speed during the induction heating of CFRP, a Fuzzy-Pill algorithm based on improved particle swarm optimization ( IPF-PID) was proposed. IPF was used to optimize and self-adjust the three parameters of Pill. The algorithm combines the advantages of PSO and Fuzzy-Pill algorithm, while avoiding falling into the local optimum, it ensures the control accuracy and the best optimization performance. The results show that the algorithm used to enhance the adaptive ability of the controller and reduce the adjustment time has a significant effect. Compared with the traditional Pill algorithm, it has smaller overshoot and steady-state error, and it is more suitable for induction heating CFRP temperature control system. [ABSTRACT FROM AUTHOR]

In order to solve the problem that induction heating device can not be installed in the tundish of traditional continuous casting equipment, a new butterfly induction heating tundish was designed. A three-dimensional unsteady magnetic-thermal-flow coupling mathematical model was then established to study the effect of electromagnetic field on the flow and temperature fields in the butterfly tundish, revealing the relationship between induction heating power and temperature rising characteristics. The results showed that the induced current formed a closed loop in the tundish and was mainly concentrated in the channel. The eccentric electromagnetic force rendered the steel to spin in the channel with large tangential velocity, and the steel flowing out of the channel moved up to the casting chamber. When the flow rate of tundish was 2 t / min and without induction heating, the outlet temperature drop was 7 K. However, under induction heating, when the heating power increased from 600 kW to 1 000 kW, the outlet temperature rise was elevated from 8 K to 27 K. [ABSTRACT FROM AUTHOR]

The Al/SnPb composite layer was prepared by brushing a layer of SnPb alloy on the surface of Al by mechanical rupture and induction heating. The binding interface was characterized by polarized light microscopy (PM), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and X-ray energy spectroscopy (EDS). The results show that the bonding interface of Al/SnPb composites was good, and the microscopic interface exhibited a distinct transitional state. The bonding interface was jagged and had a small amount of Al-Sn supersaturated solution. The Al matrix was effectively bonded to the Sn-Pb alloy through the transition layer. [ABSTRACT FROM AUTHOR]

Aiming at the problem of energy loss in the electromagnetic induction heating device of magnesium reduction tank, the influence factors and the relationship between the energy transfer, the heat loss and the resistance loss of the excitation coil were studied. A new design method of electromagnetic induction heating device for high temperature excitation coil magnesium reduction tank was put forward. The coupling model of electromagnetic system and heat transfer system was established by using electromagnetic working module in CST software.And the heat loss of the reduction system and the resistance loss of the excitation coil were simulated by this model. The results indicate that the total loss of the magnesium reduction system is minimal when the excitation coil allows a maximum working temperature of 900 ℃. The method reduces the total loss of the magnesium reduction system and improves the energy efficiency. It can provide a new idea for the design of the electromagnetic induction heating device for the magnesium reduction tank. [ABSTRACT FROM AUTHOR]

A new induction heating method was proposed for tundish and three kinds of side-type electromagnetic induction heaters were designed. The distribution of electromagnetic force of heaters， and its effects on flow field and temperature distribution in tundish were studied by numerical simulation. The optimal heater and heating power was obtained by analyzing the RTD (residence time distribution) curve. The results show that the flow field and temperature distribution of the molten steel in the tundish are improved by moving electromagnetic induction heater towards the end of the tundish. With the same heating power， the heating effect of the U-type heater is superior to E-type heater， and compared with bilateral and symmetrical distribution of U-type heater， the unilateral U-type heater has a better thermal efficiency. Increasing the induction heating power is beneficial to improve the flow of molten steel and improve the quality of the casting. For a four-strand tundish， the heating power of 800~1000kW is enough to compensate the heat loss. [ABSTRACT FROM AUTHOR]

The calculation model for deformation between wires was derived based on the Hertz contact theory and the structural characteristics of steel strands, and the contact area width between steel strand wires in the induction heating process was calculated with this model, which helped establish a precise finite element model for the induction heating of steel strands. Then the temperature fields in the steel strand under induction heating were simulated with the finite element method, where temperature data at different current densities and frequencies were given. Through the regression analysis of the temperature data, the average relative errors were used to evaluate the quality of several mathematical fitting models, so the optimal mathematical model for induction heating effects was found. The present work provides a theoretical basis for the control of the induction heating temperature in steel strands based on the classical control theory. [ABSTRACT FROM AUTHOR]

The global numerical simulation was performed for the YAG crystal growth with the micro-pulling-down method. The induction heating,the convection of both gas and melt and the heat transfer of solid/melt/gas were solved simultaneously. In the melt zone,buoyancy convection and thermocapillary flowwere considered. In order to uniformly discretize the controlling equations with the finite volume method,the electromagnetic field was modelled with the complex function method,and the computation of the electromagnetic field was verified with the results from the stream function method. Both the temperature and flowfields in the global furnace( including gas and melt) were investigated. As for the lowtemperature gradient at the solid-liquid interface,the effects of the afterheater was parametrically investigated. This work is useful for the optimal design of crystal growth furnaces. [ABSTRACT FROM AUTHOR]

Aiming at the impact of induction coil parameters on the heating temperature field, finite element calculation of induction heating processes under different process parameters' levels was carried out, using ANSYS and magnetic-thermo coupling analysis. The impact of the induction coils shape, the distance between the induction coils and the heating surface, the width of the copper tube, and the distance between these copper tubes on the heating temperature field were studied by comparing the simulating results. And an induction heating temperature test experiment using a plate as the heated object was designed to testify the simulation results. The results indicate that the shape of induction heating temperature field is similar to the shape of the coil. The closer the coil and heating surface, the higher the heating temperature amplitude, while the distance between the coil and heating surface has little impact on the temperature field. The slenderer the copper tube and the closer the copper tubes, the higher the maximum heating temperature, and the high temperature area moves towards the edge of the plate. [ABSTRACT FROM AUTHOR]