In order to overcome the shortcomings of conventional hot pressing, a novel near net-shape technique, called radial hot pressing, for P/M parts with large height-to-diameter (H/D) ratio was introduced. Effects of proc...In order to overcome the shortcomings of conventional hot pressing, a novel near net-shape technique, called radial hot pressing, for P/M parts with large height-to-diameter (H/D) ratio was introduced. Effects of processing parameters on the microstructures and density of P/M TiAl base alloy valves were studied. Results show that the radial hot pressing is an effective technique for manufacturing valves with a H/D ratio of about 10:1, and the perfect joint interface between the Mo sheet and the parts is helpful for subsequent HIPing.展开更多
The continuing miniaturization of electronic devices in microelectronics and semiconductors drives the development of new packaging materials with enhanced thermal conductivity to dissipate the heat generated in elect...The continuing miniaturization of electronic devices in microelectronics and semiconductors drives the development of new packaging materials with enhanced thermal conductivity to dissipate the heat generated in electronic packages. In recent years, several promising composite materials with high thermal conductivity have been developed successfully for high performance electronic equipment to replace the traditional Kovar and Cu/W or Cu/Mo alloys, such as SiCp/Al, SICp/Cu, diamond/Al and diamond/Cu. However, these materials with high content of reinforcements have not been widely used in packaging field because they are hard to be machined into complex-shaped parts due to their greater hardness and brittleness. So, it is necessary to explore a near-net shape forming technology for these composites. In this paper, a novel technology of powder injection molding-infiltration is introduced to realize the near-net shaped preparation of the composite packages with high thermal conductivity.展开更多
Laser consolidation(LC) is a novel computer-aided manufacturing process developed by the Industrial Materials Institute of National Research Council of Canada(NRC-IMI).This rapid manufacturing process produces net-sha...Laser consolidation(LC) is a novel computer-aided manufacturing process developed by the Industrial Materials Institute of National Research Council of Canada(NRC-IMI).This rapid manufacturing process produces net-shape functional metallic parts layer-by-layer directly from a computer aided design(CAD) model by using a laser beam to melt the injected powder and re-solidifying it on the substrate or previous layer.As an alternative to the conventional machining process,this novel manufacturing process builds net-shape functional parts or features on an existing part by adding instead of removing material.In this review paper,LC of CPM-9V tool steel,Ni-based IN-625 and IN-718 superalloys,and Ti-6Al-4V alloy will be discussed.The microstructures and functional properties of these laser consolidated materials will be examined along with several potential industrial applications.展开更多
The fabrication of near-net-shaped objects of RE123 superconductors by 'infiltration processing' is discussed. Near-net-shape processing involves the infiltration of preshaped porous green bodies of either 211...The fabrication of near-net-shaped objects of RE123 superconductors by 'infiltration processing' is discussed. Near-net-shape processing involves the infiltration of preshaped porous green bodies of either 211 or yttria phases by liquids containing barium cuprates and copper oxides followed by a controlled peritectic solidification. The process yields poly- and also single-crystalline superconducting objects with a shrinkage of less than half of one percent of the green bodies. The preservation of the initial structure of the green bodies results in fabrication of RE 123 in a wide variety of dimensions and complex shapes. The demonstrated products include bulk components like cylinders, single domain thick films on a variety of substrates, freestanding fabrics and open porous superconducting foams. This paper presents a comprehensive description of the infiltration processing technique and the resulting microstructures of the superconducting bodies. The advantages of this technique and practical applications of the processed superconducting structures are highlighted.展开更多
粉末近净成形(Powder metallurgy near net shaping,PM-NNS)技术能够制备出具有优异综合力学性能的粉末合金复杂部件。介绍了粉末热等静压(Hot isostatic pressing,HIP)近净成形技术原理及优势,综述了近年来国内外粉末近净成形在航天发...粉末近净成形(Powder metallurgy near net shaping,PM-NNS)技术能够制备出具有优异综合力学性能的粉末合金复杂部件。介绍了粉末热等静压(Hot isostatic pressing,HIP)近净成形技术原理及优势,综述了近年来国内外粉末近净成形在航天发动机领域的研究现状,从工艺路线和构件研制两方面展开,简述了构件制备过程的影响因素及缺陷控制,结合中国科学院金属研究所粉末近净成形技术在航天发动机领域的研究及应用情况,总结了粉末近净成形技术当前存在的主要问题及发展方向,以期进一步拓宽该技术的应用范围。展开更多
文摘In order to overcome the shortcomings of conventional hot pressing, a novel near net-shape technique, called radial hot pressing, for P/M parts with large height-to-diameter (H/D) ratio was introduced. Effects of processing parameters on the microstructures and density of P/M TiAl base alloy valves were studied. Results show that the radial hot pressing is an effective technique for manufacturing valves with a H/D ratio of about 10:1, and the perfect joint interface between the Mo sheet and the parts is helpful for subsequent HIPing.
基金Supported by the National Natural Science Foundation of China (Grant No. 50774005)the Program for New Century Excellent Talents in University (Grant No. NCET-06-0081)
文摘The continuing miniaturization of electronic devices in microelectronics and semiconductors drives the development of new packaging materials with enhanced thermal conductivity to dissipate the heat generated in electronic packages. In recent years, several promising composite materials with high thermal conductivity have been developed successfully for high performance electronic equipment to replace the traditional Kovar and Cu/W or Cu/Mo alloys, such as SiCp/Al, SICp/Cu, diamond/Al and diamond/Cu. However, these materials with high content of reinforcements have not been widely used in packaging field because they are hard to be machined into complex-shaped parts due to their greater hardness and brittleness. So, it is necessary to explore a near-net shape forming technology for these composites. In this paper, a novel technology of powder injection molding-infiltration is introduced to realize the near-net shaped preparation of the composite packages with high thermal conductivity.
文摘Laser consolidation(LC) is a novel computer-aided manufacturing process developed by the Industrial Materials Institute of National Research Council of Canada(NRC-IMI).This rapid manufacturing process produces net-shape functional metallic parts layer-by-layer directly from a computer aided design(CAD) model by using a laser beam to melt the injected powder and re-solidifying it on the substrate or previous layer.As an alternative to the conventional machining process,this novel manufacturing process builds net-shape functional parts or features on an existing part by adding instead of removing material.In this review paper,LC of CPM-9V tool steel,Ni-based IN-625 and IN-718 superalloys,and Ti-6Al-4V alloy will be discussed.The microstructures and functional properties of these laser consolidated materials will be examined along with several potential industrial applications.
基金German Federal Ministry of Higher Education and Research(BMBF)(No.13N1571/l)
文摘The fabrication of near-net-shaped objects of RE123 superconductors by 'infiltration processing' is discussed. Near-net-shape processing involves the infiltration of preshaped porous green bodies of either 211 or yttria phases by liquids containing barium cuprates and copper oxides followed by a controlled peritectic solidification. The process yields poly- and also single-crystalline superconducting objects with a shrinkage of less than half of one percent of the green bodies. The preservation of the initial structure of the green bodies results in fabrication of RE 123 in a wide variety of dimensions and complex shapes. The demonstrated products include bulk components like cylinders, single domain thick films on a variety of substrates, freestanding fabrics and open porous superconducting foams. This paper presents a comprehensive description of the infiltration processing technique and the resulting microstructures of the superconducting bodies. The advantages of this technique and practical applications of the processed superconducting structures are highlighted.
文摘粉末近净成形(Powder metallurgy near net shaping,PM-NNS)技术能够制备出具有优异综合力学性能的粉末合金复杂部件。介绍了粉末热等静压(Hot isostatic pressing,HIP)近净成形技术原理及优势,综述了近年来国内外粉末近净成形在航天发动机领域的研究现状,从工艺路线和构件研制两方面展开,简述了构件制备过程的影响因素及缺陷控制,结合中国科学院金属研究所粉末近净成形技术在航天发动机领域的研究及应用情况,总结了粉末近净成形技术当前存在的主要问题及发展方向,以期进一步拓宽该技术的应用范围。
