针对石墨烯增强相在焊缝中难以分散均匀、结构完整性差、易团聚等问题.采用等离子增强化学气相沉积(PECVD)方法在泡沫铜表面原位制备高质量石墨烯,得到石墨烯增强泡沫铜复合中间层.使用该复合中间层钎焊碳/碳(C/C)复合材料与铌(Nb).采用...针对石墨烯增强相在焊缝中难以分散均匀、结构完整性差、易团聚等问题.采用等离子增强化学气相沉积(PECVD)方法在泡沫铜表面原位制备高质量石墨烯,得到石墨烯增强泡沫铜复合中间层.使用该复合中间层钎焊碳/碳(C/C)复合材料与铌(Nb).采用Raman, SEM, HRTEM方法表征石墨烯以及钎焊接头的微观组织结构.结果表明,泡沫铜独特的多孔网络结构使其表面原位生长的高质量石墨烯在焊缝中均匀分布.同时,石墨烯优异的化学惰性保证了泡沫铜骨架的完整性,并协同石墨烯自身的低线膨胀系数充分发挥了缓解残余应力的作用,有效提高了接头的抗剪强度.展开更多
针对发动机连杆复杂曲面设计难度大及设计效率低等问题,提出了实体逆向设计的方法。采用Geomagic Design X重构实体模型,并采用Geomagic Control X比对重构模型,验证了重构模型的正确性;采用ANSYS对重构模型进行了有限元静力学分析,并...针对发动机连杆复杂曲面设计难度大及设计效率低等问题,提出了实体逆向设计的方法。采用Geomagic Design X重构实体模型,并采用Geomagic Control X比对重构模型,验证了重构模型的正确性;采用ANSYS对重构模型进行了有限元静力学分析,并校核连杆强度。结果表明:对汽车连杆逆向设计与优化方法正确,提高了工作效率。展开更多
Problems such as poor structural integrity,inhomogeneous dispersion,and agglomeration of graphene in the brazing seam are typically encountered for graphene additives in a brazed joint interface.To resolve these probl...Problems such as poor structural integrity,inhomogeneous dispersion,and agglomeration of graphene in the brazing seam are typically encountered for graphene additives in a brazed joint interface.To resolve these problems,a plasma-enhanced chemical vapor deposition process was employed for in-situ preparation of a high-quality graphene-coated copper(Cu)foam composite interlayer prior to be applied for brazing carbon/carbon composite and niobium.The prepared graphene and the brazed joints were characterized via Raman spectroscopy,scanning electron microscopy,and high-resolution transmission electron microscopy.The results revealed that graphene was evenly distributed in the brazing seam with the help of the Cu foam,which was characterized by interconnected porosity.Simultaneously,the excellent chemical inertia of graphene inhibited the collapse of the Cu foam,based on which the thermal residual stress in the joint was effectively mitigated due to the synergistic reinforcement effect of the Cu foam(with good plastic deformation capacity)and graphene(with extremely low coefficient of linear expansion).This effect led to significant improvement in the average shear strength of the joint.展开更多
文摘针对石墨烯增强相在焊缝中难以分散均匀、结构完整性差、易团聚等问题.采用等离子增强化学气相沉积(PECVD)方法在泡沫铜表面原位制备高质量石墨烯,得到石墨烯增强泡沫铜复合中间层.使用该复合中间层钎焊碳/碳(C/C)复合材料与铌(Nb).采用Raman, SEM, HRTEM方法表征石墨烯以及钎焊接头的微观组织结构.结果表明,泡沫铜独特的多孔网络结构使其表面原位生长的高质量石墨烯在焊缝中均匀分布.同时,石墨烯优异的化学惰性保证了泡沫铜骨架的完整性,并协同石墨烯自身的低线膨胀系数充分发挥了缓解残余应力的作用,有效提高了接头的抗剪强度.
文摘针对发动机连杆复杂曲面设计难度大及设计效率低等问题,提出了实体逆向设计的方法。采用Geomagic Design X重构实体模型,并采用Geomagic Control X比对重构模型,验证了重构模型的正确性;采用ANSYS对重构模型进行了有限元静力学分析,并校核连杆强度。结果表明:对汽车连杆逆向设计与优化方法正确,提高了工作效率。
基金Project was supported by the National Nature Science Foundation of China(51575135,51622503,U1537206).
文摘Problems such as poor structural integrity,inhomogeneous dispersion,and agglomeration of graphene in the brazing seam are typically encountered for graphene additives in a brazed joint interface.To resolve these problems,a plasma-enhanced chemical vapor deposition process was employed for in-situ preparation of a high-quality graphene-coated copper(Cu)foam composite interlayer prior to be applied for brazing carbon/carbon composite and niobium.The prepared graphene and the brazed joints were characterized via Raman spectroscopy,scanning electron microscopy,and high-resolution transmission electron microscopy.The results revealed that graphene was evenly distributed in the brazing seam with the help of the Cu foam,which was characterized by interconnected porosity.Simultaneously,the excellent chemical inertia of graphene inhibited the collapse of the Cu foam,based on which the thermal residual stress in the joint was effectively mitigated due to the synergistic reinforcement effect of the Cu foam(with good plastic deformation capacity)and graphene(with extremely low coefficient of linear expansion).This effect led to significant improvement in the average shear strength of the joint.
