The distribution of the magnetic flux density in a soft-contact electromagnetic continuous casting （EMCC） rectangular mold was investigated. The experimental results show that with an increase in electric power, the...The distribution of the magnetic flux density in a soft-contact electromagnetic continuous casting （EMCC） rectangular mold was investigated. The experimental results show that with an increase in electric power, the magnetic flux density increases. The position where the maximum magnetic flux density appears will shift up when the coil moves to the top of the mold. At the same time, the maximum magnetic flux density will increase and the effective acting range of electromagnetic pressure will widen. As a result, in practice, the coil should be placed near the top part of the mold. The meniscus should be controlled near the top part of the coil, as this not only remarkably improves the billet surface quality but also saves energy. With the same electric power input, the higher the frequency, the lower the magnetic flux density.展开更多
The steady development of high-temperature gas-cooled reactors(HTRs) has increased the requirements for the production cost and quality of fuel elements. Green fuel element pressing is one of the key steps to increase...The steady development of high-temperature gas-cooled reactors(HTRs) has increased the requirements for the production cost and quality of fuel elements. Green fuel element pressing is one of the key steps to increase the production capacity. This paper proposes a proprietary vacuum dry-bag isostatic pressing(DIP) apparatus. The structural change of the matrix graphite powder during the DIP process was examined by analyzing the density change of the matrix graphite spheres with pressure. The soft molding process was simulated using the finite element method. The dimensional changes in the spheres during the pressing, carbonization, and purification stages were explored. The performance of the fuel matrix produced by the DIP method was comprehensively examined. The fuel matrix met the technical requirements and its anisotropy was significantly reduced. The DIP method can significantly improve both the production efficiency and quality of fuel elements. This will play a key role in meeting the huge demand for fuel elements of HTRs and molten salt reactors.展开更多
Nanoimprint lithography（NIL） is widely used in the fabrication of nano-scale semiconductor devices for its advantages of high resolution,low cost,and high throughput.However,traditional hard stamp imprinting has som...Nanoimprint lithography（NIL） is widely used in the fabrication of nano-scale semiconductor devices for its advantages of high resolution,low cost,and high throughput.However,traditional hard stamp imprinting has some drawbacks such as short stamp lifetime,bad uniformity in big areas,and large particle influence.In this paper, a flexible intermediate polymer stamp（IPS） is proposed to solve the drawbacks mentioned above.Meanwhile, we use a method of temperature-pressure variation imprinting to improve the resist liquidity in the process of imprinting,and eventually we achieve high quality patterns.This method combined with IPS has been used to fabricate a high quality grating whose half pitch is 50 nm.展开更多
基金ItemSponsored by National Natural Science Foundation of China (50274203) , National High Technology Research andDevelopment Programof China (2001AA337040) and National Fundamental Research and Development Plan of China(G1998061510)
文摘The distribution of the magnetic flux density in a soft-contact electromagnetic continuous casting （EMCC） rectangular mold was investigated. The experimental results show that with an increase in electric power, the magnetic flux density increases. The position where the maximum magnetic flux density appears will shift up when the coil moves to the top of the mold. At the same time, the maximum magnetic flux density will increase and the effective acting range of electromagnetic pressure will widen. As a result, in practice, the coil should be placed near the top part of the mold. The meniscus should be controlled near the top part of the coil, as this not only remarkably improves the billet surface quality but also saves energy. With the same electric power input, the higher the frequency, the lower the magnetic flux density.
基金supported by the National S&T Major Project (No.ZX06901)。
文摘The steady development of high-temperature gas-cooled reactors(HTRs) has increased the requirements for the production cost and quality of fuel elements. Green fuel element pressing is one of the key steps to increase the production capacity. This paper proposes a proprietary vacuum dry-bag isostatic pressing(DIP) apparatus. The structural change of the matrix graphite powder during the DIP process was examined by analyzing the density change of the matrix graphite spheres with pressure. The soft molding process was simulated using the finite element method. The dimensional changes in the spheres during the pressing, carbonization, and purification stages were explored. The performance of the fuel matrix produced by the DIP method was comprehensively examined. The fuel matrix met the technical requirements and its anisotropy was significantly reduced. The DIP method can significantly improve both the production efficiency and quality of fuel elements. This will play a key role in meeting the huge demand for fuel elements of HTRs and molten salt reactors.
文摘Nanoimprint lithography（NIL） is widely used in the fabrication of nano-scale semiconductor devices for its advantages of high resolution,low cost,and high throughput.However,traditional hard stamp imprinting has some drawbacks such as short stamp lifetime,bad uniformity in big areas,and large particle influence.In this paper, a flexible intermediate polymer stamp（IPS） is proposed to solve the drawbacks mentioned above.Meanwhile, we use a method of temperature-pressure variation imprinting to improve the resist liquidity in the process of imprinting,and eventually we achieve high quality patterns.This method combined with IPS has been used to fabricate a high quality grating whose half pitch is 50 nm.
