Key Laboratory for Solar Energy Photovoltaic of Liaoning Province

Dalian, China

Key Laboratory for Solar Energy Photovoltaic of Liaoning Province

Dalian, China
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Fu Y.,Dalian University of Technology | Dong W.,Dalian University of Technology | Dong W.,Key Laboratory for Solar Energy Photovoltaic of Liaoning Province | Li Y.,Dalian University of Technology | And 4 more authors.
Advanced Materials Research | Year: 2012

A simulation method was used to study the effects of physical parameters, including the contact angle between molten metal and material of orifice, surface tension and viscosity on particle formation of POEM. Stable droplets can be obtained only when the surface tension is adequate and the contact angle is at least 90° or higher. Within a wide range, viscosity has little effect on droplet formation; as the viscosity increases, necking time is postponed and vibration time is shortened. © (2012) Trans Tech Publications.


Li Y.,Dalian University of Technology | Dong W.,Dalian University of Technology | Dong W.,Key Laboratory for Solar Energy Photovoltaic of Liaoning Province | Fu Y.,Dalian University of Technology | And 4 more authors.
Advanced Materials Research | Year: 2012

A new method to evaluate the critical cooling rate, R c of Fe-based metallic glass alloy was proposed and discussed. [(Fe 0.5Co 0.5) 0.75B 0.2Si 0.05] 96Nb 4 alloy particles were prepared with narrow size distribution and high sphericity by Pulsated Orifice Ejection Method in Ar, He and 50%Ar+50%He mixed atmosphere, respectively. Phase transition of a particle from amorphous to amorphous-crystalline and fully crystalline occurred with the increase of particle diameter. R c of the formation of fully amorphous phase was estimated to be in the range of 700-1100 K/s, lower than that measured by time-temperature transformation diagram of bulk metallic alloy. No change of R c occurred in Ar, He or 50%Ar+50%He mixed atmosphere, which proved it an effective method to evaluate the critical cooling rate of Fe-based metallic glass alloy. © (2012) Trans Tech Publications.


Xu F.,Dalian University of Technology | Xu F.,Key Laboratory for Solar Energy Photovoltaic of Liaoning Province | Xu F.,University of New South Wales | Wu S.,Dalian University of Technology | And 9 more authors.
Separation Science and Technology (Philadelphia) | Year: 2014

Numerous studies have searched for methods of Si refining for the production of photovoltaic cells to alleviate the global shortage of solar-grade Si. An alloy refining progress with a Si-Al-Sn melt was developed in this paper. To elucidate the relationship between Sn and B, the interaction parameter between them at 1173 K was determined as 2506 ± 143. This result indicated the strongly repulsive force between Sn and B. Thermodynamic analysis and experiments showed that the purification efficiency of Si-Al-Sn alloy weakened with increased Sn content in the melt. © 2014 Copyright Taylor and Francis Group, LLC.


Zhang L.,Dalian University of Technology | Zhang L.,Key Laboratory for Solar Energy Photovoltaic of Liaoning Province | Tan Y.,Dalian University of Technology | Tan Y.,Key Laboratory for Solar Energy Photovoltaic of Liaoning Province | And 8 more authors.
Separation Science and Technology (Philadelphia) | Year: 2013

The global shortage of solar grade silicon for production of solar cells has motivated a lot of research on the refining of metallurgical grade silicon. However, approaches to upgrade metallurgical grade silicon have been mainly handicapped by difficulties in reducing boron and phosphorus levels. In the present study, the possibility of refining metallurgical grade silicon to remove impurity boron using Na2O-CaO-SiO2 slags was investigated. Before slag melting, a process of mixing pulverized slags and silicon under an action of mechanical force was used to provide a higher probability of contact and reaction of slags and silicon. The melting time was reduced with an increase in contact area AS, resulting in improved efficiency of boron removal. The parameters, including the slag basicity, and the weight ratio of silicon to slag were discussed. The process of slag treatment was performed twice and directional solidification was conducted to promote the separation of slags from silicon. A maximum value of LB (5.81) was obtained when the basicity was 1.21, and the weight ratio of silicon to slag was 5. © 2013 Copyright Taylor and Francis Group, LLC.


Peng X.,Key Laboratory for Solar Energy Photovoltaic of Liaoning Province | Peng X.,Dalian University of Technology | Dong W.,Key Laboratory for Solar Energy Photovoltaic of Liaoning Province | Dong W.,Dalian University of Technology | And 7 more authors.
Gongneng Cailiao/Journal of Functional Materials | Year: 2010

In order to investigate Ca evaporation behavior in the electron beam melting process, metallurgical-grade silicon was melted in an electron beam furnace with electron beam power kept constant while the melting time changed. And the relationship between yield of Si and Ca content was discussed. The results showed that the content of impurity Ca was significantly decreased in the early period of melting, and then changed slowly with the extension of the melting. The free evaporation of Ca at 2133K, the calculated surface temperature of the liguid silicon, followed first order kinetics. The overall mass transfer coefficient of Ca was determined to be 2.64 × 10-5m/s, and the removal rate of Ca was controlled by the transfer of Ca atoms from the bulk liquid silicon to liquid/gas phase interface.


Tan Y.,Dalian University of Technology | Tan Y.,Key Laboratory for Solar Energy Photovoltaic of Liaoning Province | Ren S.,Dalian University of Technology | Ren S.,Key Laboratory for Solar Energy Photovoltaic of Liaoning Province | And 12 more authors.
Vacuum | Year: 2014

A multicrystalline silicon ingot was obtained from metallurgical-grade silicon by vacuum induction melting and directional solidification. Based on the concentration distributions of aluminum and calcium along the growth direction, the removal mechanism of such impurities with both high saturated vapor pressures and low segregation coefficients is investigated. The results show that the removal of this type of impurities only depends on evaporation during vacuum induction melting process, thus their contents decrease significantly due to the strongly evaporation under the high temperature and high vacuum conditions. During subsequent directional solidification process, a model including both segregation and evaporation is used to simulate the concentration distribution. The results show that the impurity distribution is controlled by both two mechanisms in the initial stage of solidification and is mainly determined by segregation in the end stage due to the decrease of the diffusibility and evaporability of the impurity atoms. © 2013 Elsevier Ltd. All rights reserved.


Dong W.,Key Laboratory for Solar Energy Photovoltaic of Liaoning Province | Dong W.,Dalian University of Technology | Wang Q.,Key Laboratory for Solar Energy Photovoltaic of Liaoning Province | Wang Q.,Dalian University of Technology | And 7 more authors.
Cailiao Yanjiu Xuebao/Chinese Journal of Materials Research | Year: 2010

Metallurgical grade silicon was purified by electron beam melting (EBM) method. The distribution of aluminum in the ingot was found that aluminum was dragged from the bottom to the top and from the edge to the center of the ingot. The aluminum content in the edge was the lowest, even lower than the detection limit (1×10-5%) of ICP-AES. The evaporation of aluminum during EBM process was studied both theoretically and experimentally. The relationship between the removal efficiency for aluminum and the surface temperature of the melting silicon and melting time was deduced from Langmuir's equation and Henry law. It showed that the removal efficiency of impurity aluminum increased with the increase of the melting time and the surface temperature of the melting silicon. Good agreement was found between the calculated value and the measured value. © Copyright.


Peng X.,Dalian University of Technology | Peng X.,Key Laboratory for Solar Energy Photovoltaic of Liaoning Province | Dong W.,Dalian University of Technology | Dong W.,Key Laboratory for Solar Energy Photovoltaic of Liaoning Province | And 4 more authors.
Vacuum | Year: 2011

Small amounts of metallurgical grade silicon were melted in an electron beam furnace in different experimental conditions in order to investigate the aluminum (Al) evaporation behavior during the electron beam melting (EBM) process. Impurity was significantly decreased in the early periods of melting at 9, 15, and 21 kW. These changes slowed down with the extension of the melting time. Moreover, the removal reaction of Al by evaporation from molten silicon during the EBM process occurred in accordance with the first order kinetics. The calculated mass transfer coefficients of Al at 1941, 1964, and 2051 K increased with the increase of melting temperature. The removal rate of Al was controlled by the transportation of Al from the bulk of silicon metal to the molten/vacuum interface within the range of the experimental temperature. Crown Copyright © 2011 Published by Elsevier Ltd. All rights reserved.


Zhang L.,Dalian University of Technology | Zhang L.,Key Laboratory for Solar Energy Photovoltaic of Liaoning Province | Tan Y.,Dalian University of Technology | Tan Y.,Key Laboratory for Solar Energy Photovoltaic of Liaoning Province | And 6 more authors.
Materials Science in Semiconductor Processing | Year: 2013

Solar energy is expected to be in great demand within the next few years. In relation to this, a global shortage in the solar-grade silicon (SoG-Si) used in the production of solar cells has motivated numerous studies on metallurgical-grade Si (MG-Si) refining. However, improvements in this material are limited by the difficulties involved in reducing boron (B) and phosphorus content. The present study investigated the removal of B using (CaF 2)-Al2O3-CaO-SiO2 and Na 2SiO3-CaO-SiO2 slag in an ambient air atmosphere in order to refine MG-Si. The mass transfer coefficients of B in molten Si (kd[B]=1.19×10-4 cm s-1) and BO1.5 in molten slag (kd(B3+)=1.01×10-5 cm s-1) were deduced through kinetic analysis. The mass transfer process of boron oxide limited slag refining; however, secondary slag treatment effectively improved the efficiency of B removal. LB was determined by the combined effect of the oxygen partial pressure and the molten slag structure. © 2013 Elsevier Ltd.


Shi S.,Dalian University of Technology | Shi S.,Key Laboratory for Solar Energy Photovoltaic of Liaoning Province | Dong W.,Dalian University of Technology | Dong W.,Key Laboratory for Solar Energy Photovoltaic of Liaoning Province | And 6 more authors.
Applied Surface Science | Year: 2013

An experimental investigation into the removal of phosphorus from molten silicon using electron beam melting has been carried out. The time variation of phosphorus content is obtained at the electron beam power of 9, 15, and 21 kW, respectively. The results show that, at a constant power, the content of phosphorus decreases rapidly within the range of approximately 0-900 s after silicon is melted completely, and then tends to level out with further extension of the melting time. The content of phosphorus is decreased from 33.2 × 10-4 wt.% to 0.07 × 10-4 wt.% after 1920 s at a power of 21 kW, which achieves the target for solar-grade silicon of less than 0.1 × 10-4 wt.%. Moreover, the removal reaction of phosphorus by evaporation from the surface of silicon melt during electron beam melting occurs in accordance with the first order kinetics. The mass transfer coefficients in different removal steps are calculated and discussed, which indicate the removal reaction of phosphorus is controlled by both the transport of phosphorus atom from the bulk to the melt free surface and the vaporization from the free melt surface into the gas phase. © 2012 Elsevier B.V. All rights reserved.

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